U.S. patent application number 15/847231 was filed with the patent office on 2018-06-28 for abrasive articles and methods for forming same.
The applicant listed for this patent is SAINT-GOBAIN ABRASIFS, SAINT-GOBAIN ABRASIVES, INC.. Invention is credited to Gurulingamurthy M. Haralur, Shyam Prasad Komath, Nivarthi Ramesh, Jagadis Sankaranarayanan.
Application Number | 20180178349 15/847231 |
Document ID | / |
Family ID | 62625896 |
Filed Date | 2018-06-28 |
United States Patent
Application |
20180178349 |
Kind Code |
A1 |
Haralur; Gurulingamurthy M. ;
et al. |
June 28, 2018 |
ABRASIVE ARTICLES AND METHODS FOR FORMING SAME
Abstract
An abrasive article can include a body including a bond material
and abrasive particles contained within the bond material. The bond
material can include a siloxane functional group covalently bonded
to a plurality of benzene rings. In an embodiment, the bond
material can include at least one siloxane functional group
covalently bonded to a phenoxy. In a particular embodiment, the
bond material can include polydimethylsiloxane covalently bonded to
a phenoxy. The body can include an improved wet strength, which may
be represented by wet flexure stress retention. In an embodiment,
the body includes a wet flexure stress retention of at least
52%.
Inventors: |
Haralur; Gurulingamurthy M.;
(Chennai, IN) ; Komath; Shyam Prasad; (Chennai,
IN) ; Sankaranarayanan; Jagadis; (Chennai, IN)
; Ramesh; Nivarthi; (Chennai, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAINT-GOBAIN ABRASIVES, INC.
SAINT-GOBAIN ABRASIFS |
Worcester
Conflans-Sainte-Honorine |
MA |
US
FR |
|
|
Family ID: |
62625896 |
Appl. No.: |
15/847231 |
Filed: |
December 19, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24D 3/28 20130101; B24D
7/02 20130101; B24D 18/0009 20130101 |
International
Class: |
B24D 3/28 20060101
B24D003/28; B24D 7/02 20060101 B24D007/02; B24D 18/00 20060101
B24D018/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2016 |
IN |
201641043918 |
Claims
1. A bonded abrasive article, comprising: a body including abrasive
particles contained within a bond material, wherein the bond
material comprises a polymer including a plurality of benzene rings
that are covalently bonded to one another and at least one siloxane
functional group covalently bonded to the plurality of benzene
rings.
2. The bonded abrasive article of claim 1, wherein the bond
material has a FTIR signature peak at a wavelength from 1258
cm.sup.-1 to 1275 cm.sup.-1.
3. The bonded abrasive article of claim 1, wherein the body
comprises a wet flexural stress retention of at least 52%.
4. The bonded abrasive article of claim 1, wherein the bond
material comprises siloxane covalently bonded to the plurality of
benzene rings, wherein the siloxane is represented by a formula I:
##STR00003## wherein R includes a methyl or phenyl group, X and Y
independently represents hydrogen atoms, a hydrocarbyl group, or an
alkoxy group, and n is at least one.
5. The bonded abrasive article of claim 4, wherein the siloxane is
covalently bonded to an oxygen atom, wherein the oxygen atom is
directly and covalently bonded to one of the plurality of benzene
rings.
6. The abrasive article of claim 4, wherein the bond material
comprises a content of the siloxane in a range from at least 1 wt.
% to at most 30 wt. % for a total weight of the bond material.
7. The abrasive article of claim 4, wherein the siloxane consist
essentially of polymethylsiloxane.
8. The bonded abrasive article of claim 1, wherein the plurality of
benzene rings are covalently bonded to one another by a methylene
bridge.
9. The bonded abrasive article of claim 1, wherein each of the
plurality of benzene rings is covalently bonded to an oxygen atom
that is covalently bonded to at least one siloxane functional
group.
10. The abrasive article of claim 1, wherein the bond material
comprises a polymethylsiloxane including the at least one siloxane
functional group.
11. The abrasive article of claim 10, wherein the
polymethylsiloxane is present in the bond material in a content
from at least 1 wt. % to at most 30 wt. % for the total weight of
the bond material.
12. The abrasive article of claim 1, wherein the body comprises a
filler including barium sulfate, cryolite, or any combination
thereof.
13. The bonded abrasive article of claim 1, wherein the body
comprises: the bond material in a content from at least 5 vol % to
at most 55 vol % for a total volume of the body; the abrasive
particles in a content from at least 8 vol % to at most 65 vol %
for the total volume of the body; and a porosity in a content from
at least 3 vol % to at most 60 vol % for the total volume of the
body.
14. A bonded abrasive article, comprising: a body including
abrasive particles contained within a bond material, wherein the
bond material comprises a polymer including a plurality of benzene
rings that are covalently bonded to one another and siloxane
covalently bonded to the plurality of benzene rings, wherein the
siloxane is represented by a formula I: ##STR00004## wherein R
includes a methyl or phenyl group, X and Y independently represents
hydrogen atoms, a hydrocarbyl group, or an alkoxy group, and n is
at least one.
15. The bonded abrasive article of claim 14, wherein the siloxane
comprises polydimethylsiloxane covalently bonded to an oxygen atom
that is covalently bonded to the plurality of the benzene rings,
and wherein the siloxane is presented in the bond material in a
content from at least 3 wt. % to at most 25 wt. %.
16. A process of forming an abrasive article, comprising: forming a
green body with a mixture comprising abrasive particles and a bond
precursor material, wherein the bond precursor material comprises a
phenolic resin covalently bonded to at least one siloxane
functional group.
17. The process of claim 16, wherein the resin has a FTIR signature
peak at a wavelength from 1257 cm.sup.-1 to 1261 cm.sup.-1.
18. The process of claim 16, wherein the phenolic resin is
covalently bonded to siloxane represented by a formula I:
##STR00005## wherein R includes a methyl or phenyl group, X and Y
independently represents hydrogen atoms, a hydrocarbyl group, or an
alkoxy group, and n is at least one.
19. The process of claim 18, wherein the siloxane comprises
polydimethylsiloxane, wherein the polydimethylsiloxane is directly
and covalently bonded to an oxygen atom of the phenolic resin.
20. The process of claim 18, wherein the bond precursor material
comprises the siloxane in a content from at least 1 wt. % to at
most 30 wt. % for a total weight of the bond precursor material.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Indian Patent
Application No. 201641043918, entitled "ABRASIVE ARTICLES AND
METHODS FOR FORMING SAME", by Gurulingamurthy M. HARALUR, et al.,
filed Dec. 22, 2016, which is assigned to the current assignee
hereof and incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
Field of the Disclosure
[0002] The present invention relates to abrasive articles and
methods of forming the abrasive articles.
Description of the Related Art
[0003] Abrasive articles, such as abrasive wheels, can be used to
remove materials from workpieces and may leave undesirable scratch
marks on workpieces. In wet grinding processes, fluids are used to
cool and lubricate grinding wheels and workpieces to remove debris
and improve grinding efficiency. Wet retention abilities of
grinding wheels affects consistency of wheel performance. The
industry continues to demand improved abrasive articles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The present disclosure may be better understood, and its
numerous features and advantages made apparent to those skilled in
the art by referencing the accompanying drawings. The drawings are
not necessarily to scale.
[0005] FIG. 1 includes a flow chart for forming an abrasive
article.
[0006] FIG. 2 includes a graph of FTIR readouts of conventional
bond precursor material and a bond precursor material in accordance
with an embodiment.
[0007] FIG. 3 includes a graph of FTIR readouts of conventional
abrasive article, an abrasive article in accordance with an
embodiment, and a bond precursor material in accordance with
embodiment.
[0008] FIG. 4 includes a graph of FTIR readouts of representative
abrasive articles.
[0009] FIG. 5 includes a plot of FTIR absorption intensity versus
contents of siloxane in bond materials of representative abrasive
articles.
[0010] FIG. 6 includes a plot of scratch mark count versus scratch
mark size of a set of wheel samples.
[0011] FIG. 7 includes a plot of scratch mark count versus scratch
mark size of another set of wheel samples.
[0012] Skilled artisans appreciate that elements in the figures are
illustrated for simplicity and clarity and have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements in the figures may be exaggerated relative to other
elements to help to improve understanding of embodiments of the
invention.
DETAILED DESCRIPTION
[0013] The following description in combination with the figures is
provided to assist in understanding the teachings disclosed herein.
The following discussion will focus on specific implementations and
embodiments of the teachings. This focus is provided to assist in
describing the teachings and should not be interpreted as a
limitation on the scope or applicability of the teachings. However,
other teachings can certainly be used in this application.
[0014] As used herein, the terms "comprises," "comprising,"
"includes," "including," "has," "having" or any other variation
thereof, are intended to cover a non-exclusive inclusion. For
example, a method, article, or apparatus that comprises a list of
features is not necessarily limited only to those features but may
include other features not expressly listed or inherent to such
method, article, or apparatus. Further, unless expressly stated to
the contrary, "or" refers to an inclusive-or and not to an
exclusive-or. For example, a condition A or B is satisfied by any
one of the following: A is true (or present) and B is false (or not
present), A is false (or not present) and B is true (or present),
and both A and B are true (or present).
[0015] Also, the use of "a" or "an" is employed to describe
elements and components described herein. This is done merely for
convenience and to give a general sense of the scope of the
invention. This description should be read to include one or at
least one and the singular also includes the plural, or vice versa,
unless it is clear that it is meant otherwise. For example, when a
single item is described herein, more than one item may be used in
place of a single item. Similarly, where more than one item is
described herein, a single item may be substituted for that more
than one item.
[0016] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. The
materials, methods, and examples are illustrative only and not
intended to be limiting. To the extent that certain details
regarding specific materials and processing acts are not described,
such details may include conventional approaches, which may be
found in reference books and other sources within the manufacturing
arts.
[0017] Embodiments disclosed herein are related to abrasive
articles including a body including abrasive particles contained
within a bond material. The abrasive articles can have improved
performance and increased service life. Representative abrasive
articles can include grinding wheels having improved wet strength
retention and capable of forming reduced number of scratch marks on
a workpiece, as compared to conventional grinding wheels.
[0018] Further embodiments relate to abrasive articles having a
body including a particular bond material. In an embodiment, the
bond material can include a siloxane functional group
(--Si--O--Si--) covalently bonded to a polymer backbone including
aromatic rings connected by methylene bridges. In another
embodiment, the bond material can have a FTIR signature peak at a
wavelength in a range from 1258 cm-.sup.1 to 1265 cm-.sup.1, such
as at 1259 cm-.sup.1 or at 1261 cm-.sup.1. In a particular
embodiment, the bond material can include a polymer including a
polydimethylsiloxane covalently bonded to a phenoxy. More
particularly, the bond material can include a plurality of phenoxy,
each of which is covalently bonded to a polydimethylsiloxane. The
plurality of phenoxy can be covalently bonded to one another by
methylene bridges.
[0019] Additional embodiments are related to a method of forming an
abrasive article utilizing a bond precursor material. According to
an embodiment, the bond precursor material can have a FTIR
signature peak at a wavelength in a range from 1257 cm.sup.-1 to
1261 cm.sup.-1. For example, the bond precursor material can have a
FTIR signature peak at 1257 cm.sup.-1. The bond precursor material
can include a chemically modified resin. In an embodiment, the
resin can include a phenolic resin, and the chemical modification
can include a covalent bond between the phenolic resin and a
siloxane functional group. In a particular embodiment, the
chemically modified resin can include novolac resin chemically
modified by polydimethylsiloxane. Use of the chemically modified
phenolic resin can allow formation of abrasive articles with
improved property and performance, such as improved ability of wet
retention and reduced amount of scratch marks left on a
workpiece.
[0020] FIG. 1 includes a flow chart of a method of forming an
abrasive article in accordance with an embodiment. At step 101, a
mixture can be made including a bond precursor material and
abrasive particles. The mixture may also include one or more
optional additives, including for example, secondary abrasive
particles, fillers, reinforcing materials, and the like.
[0021] According to at least one embodiment, the bond precursor
material can be present in the mixture in a certain content that
can facilitate formation of an abrasive article with improved
property and performance. For instance, the mixture can include at
least 2.5 wt. % of the bond precursor material for a total weight
of mixture, such as at least 3 wt. %, at least 5 wt. %, at least 8
wt. %, or at least 12 wt. %. In another instance, the mixture can
include at most 25 wt. % of the bond material for a total weight of
the mixture, such as at most 22 wt. %, at most 20 wt. %, or at most
18 wt. %. In a further embodiment, the mixture can include the bond
material in a content including any of the minimum and maximum
percentages disclosed herein. For instance, the bond precursor
material can be present in the mixture from 2.5 wt. % to 25 wt. %
for a total weight of the mixture.
[0022] According to an embodiment, the bond precursor material can
include an organic material, such as a natural organic material or
synthetic organic material. An exemplary organic material can
include a resin, such as phenolic resins, epoxy resins, polyester
resins, polyurethanes, polyester, polyimide, polybenzimidazole,
aromatic polyamide, modified phenolic resins (such as epoxy
modified or phenolic resin blended with plasticizers, etc.), and
the like, as well as any combination thereof. According to at least
one embodiment, the bond precursor material can include a phenolic
resin including novolac resin, resole resin, or any combination
thereof.
[0023] According to another embodiment, the bond precursor material
can include a chemically modified resin. The chemical modification
can include a covalent bond between the resin and a particular
functional group that is different from a functional group of the
resin. The particular functional group can be a unit of a molecule,
and the resin can be chemically bonded to the molecule having the
functional group. For instance, the modifying functional group can
be directly or indirectly covalently bonded to the resin.
[0024] According to an embodiment, chemically modified resin can
include a chemically modified phenolic resin. According to another
embodiment, an exemplary modifying functional group can include a
siloxane functional group (--Si--O--Si--). In a particular
embodiment, chemically modified resin can consist essentially of
chemically modified phenolic resin including at least one siloxane
functional group. In another particular embodiment, the bond
precursor material can include phenolic resin chemically modified
by a molecule including a siloxane functional group. Particularly,
chemically modified phenolic resin can include phenolic resin
covalently bonded to a molecule including a siloxane functional
group. The molecule can include a monomer, oligomer, polymer or a
combination thereof. In another embodiment, the molecule can
include a plurality of siloxane functional groups, such as
repeating siloxane functional groups. According to a further
embodiment, chemically modified phenolic resin can include
chemically modified novolac resin, chemically modified resole
resin, or a combination thereof. According to a particular
embodiment, chemically modified phenolic resin can include
chemically modified novolac resin. More particularly, chemically
modified phenolic resin can consist essentially of chemically
modified novolac resin.
[0025] According to a particular embodiment, chemically modified
novolac resin can include novolac resin covalently bonded to an
oligomer including at least one siloxane functional group, novolac
resin covalently bonded to a polymer including at least one
siloxane functional group, or a combination thereof.
According to an embodiment, an exemplary molecule suitable for
chemically modifying a resin can include an oligomer or polymer
represented by the below formula. As used herein, the term,
siloxane, is intended to refer to a molecule represented by the
below formula.
##STR00001##
[0026] R can include a methyl or phenyl group, X and Y can be the
same or different and independently represent hydrogen atoms,
hydrocarbyl groups, or alkoxy groups, and n can be at least one and
up to 500 or higher. X, Y, or both can react with the resin to form
a covalent bond between the resin and the molecule forming a
chemically modified resin. For instance, X, Y, or both can react
with a novolac resin such that the molecule can be covalently
bonded to novolac resin. In at least one embodiment, the molecular
can have a molecular weight of at least 500 Dalton. In another
embodiment, at least one of R, X, and Y can be --CH3. In a
particular embodiment, the molecular can have a molecular weight of
at least 500 Dalton, and each of R, X, and Y can be --CH3.
[0027] According to an embodiment, X, Y, or both can react with a
functional group of the resin forming a covalent bond. For example,
X, Y or both can react to a hydroxyl group of a phenolic resin. In
another embodiment, repeating siloxane functional groups may be
bonded to phenolic resin through a methylene bridge. Particularly,
the methylene group at the X or Y position can be directly bonded
to an oxygen atom of the resin. In another embodiment, chemically
modified resin can include polydimethylsiloxane covalently bonded
to a novolac resin. For instance, the modified novolac resin can
include covalent bond between a methylene bridge and a phenoxy,
wherein the methyl bridge can be covalently bonded to a siloxane
group. In a particular embodiment, the modified resin can include a
direct covalent bond between an oxygen atom directly bonded to a
benzene ring and a methylene group bonded to a siloxane group.
[0028] In yet another embodiment, the bond precursor material can
include a resin, and a chemically modified resin. For instance, the
bond precursor material can include phenolic resin and phenolic
resin chemically modified by a siloxane functional group.
Particularly, the bond precursor material can include phenolic
resin and chemically modified novolac resin. More particularly, the
bond precursor material can include phenolic resin, such as novolac
resin, resole resin, or a combination thereof, and novolac resin
chemically modified by a siloxane functional group. In a particular
embodiment, the bond precursor material can include a novolac
resin, a siloxane chemically modified novolac resin, a resole
resin, or any combination thereof. In another particular
embodiment, the phenolic resin can include resole resin and
chemically modified novolac resin.
[0029] According to an embodiment, the mixture can include a
certain content of chemically modified resin that can facilitate
formation of an abrasive article with improved property and
performance. For instance, the chemically modified resin can be
present in the mixture in a content of at least 1 wt. %, such as at
least 2 wt. % or at least 3.5 wt. % or at least 5 wt. % or at least
6.5 wt. % or at least 7.5 wt. % for a total weight of the mixture.
In another instance, the chemically modified resin can be present
in the mixture in a content of at most 20 wt. %, such as at most 18
wt. % or at most 14 wt. % or at most 12 wt. % or at most 10 wt. %
for a total weight of the mixture. In a further embodiment, the
content of the chemically modified resin can be in a range
including any of the minimum and maximum percentages noted herein,
such as in a range from at least 1 wt. % to at most 20 wt. %. In a
particular embodiment, the chemically modified resin can include
siloxane chemically modified novolac resin, and accordingly,
siloxane chemically modified novolac resin can have any of the
contents noted herein.
[0030] According to an embodiment, the bond precursor material can
include novolac resin covalently bonded to polydimethylsiloxane. In
a particular embodiment, the chemically modified resin can consist
essentially of novolac resin chemically modified by
polydimethylsiloxane. For instance, chemically modified novolac
resin can include polydimethylsiloxane covalently bonded to
phenoxy. In this disclosure, polydimethylsiloxane is detected using
Perkin Elmer Frontier Model FTIR with a Diamond/ZnSe Tip ATR probe.
The resin samples in powder form can be analyzed directly under the
probe using Diamond/ZnSe Tip ATR probe. The spectra data of the
samples are compared to data from know-it-all informatics ATR/IR
library to determine what each peak of the spectra represents.
[0031] FIG. 2 includes FTIR spectra of conventional novolac resin,
siloxane resin, and polydimethylsiloxane chemically modified
novolac resin (SMR resin). As indicated in FIG. 2, siloxane resin
demonstrated a signature peak at 1259 cm.sup.-1, while SMR resin
demonstrated a signature peak at 1257 cm.sup.-1. The conventional
resin did not demonstrate a peak at 1259 or 1257 cm.sup.-1.
[0032] According to an embodiment, the bond precursor material can
include chemically modified resin in a content that can facilitate
formation of an abrasive article with improved performance. In a
non-limiting embodiment, chemically modified resin may have a
content of at least 60 wt. % relative to a total weight of the bond
precursor material, such as at least 70 wt. % or at least 75 wt. %
or at least 80 wt. % or even at least 85 wt. % for the total weight
of the bond precursor material. In another non-limiting embodiment,
the chemically modified resin may not be greater than 95 wt. % of
the total weight of the bond precursor material, such as not
greater than 90 wt. % or not greater than 88 wt. %. It is to be
understood that the content of the chemically modified resin can
include any of the minimum and maximum percentages disclosed
herein. In a further embodiment, the chemically modified resin can
include novolac resin covalently bonded to siloxane functional
groups. Particularly, the chemically modified resin can include
novolac resins covalently bonded to siloxane, or more particularly,
can consist essentially of siloxane chemically modified novolac
resin. Accordingly, the content of siloxane chemically modified
resin can include any of the contents noted for the chemically
modified resin. In a particular embodiment, the siloxane chemically
modified resin can include polydimethylsiloxane chemically modified
novolac resin, or more particularly, can consist essentially of
polydimethylsiloxane chemically modified novolac resin. In a more
particular embodiment, the bond precursor material can include the
polydimethylsiloxane chemically modified novolac resin in any of
the contents noted for the chemically modified resin.
[0033] In a non-limiting embodiment, the bond precursor material
can include a particular content of siloxane that is covalently
bonded to the resin. In one embodiment, the bond precursor material
can include at least 1 wt. % of the covalently bonded siloxane for
the total weight of the bond precursor material, such as at least
1.5 wt. % or at least 2 wt. % or at least 2.5 wt. % or at least 3
wt. % or at least 3.5 wt. % or at least 4 wt. % or at least 4.5% or
at least 5 wt. % or at least 5.5 wt. % or at least 6 wt. % or at
least 6.5 wt. % or at least 7 wt. % or at least 7.5 wt. % or at
least 8 wt. % or at least 8.5 wt. % or at least 9 wt. % or at least
9.5 wt. % or at least 10 wt. % or at least 11 wt. % or at least 12
wt. % or at least 12.5 wt. % or at least 13 wt. % or at least 13.5
wt. % of the covalently bonded siloxane for the total weight of the
bond precursor material. Alternatively or additionally, the bond
precursor material can include at most 30 wt. % of the covalently
bonded siloxane for the total weight the bond precursor material,
such as at most 29 wt. % or at most 28 wt. % or at most 27 wt. % or
at most 26 wt. % or at most 25 wt. % or at most 24 wt. % or at most
23 wt. % or at most 22 wt. % or at most 21 wt. % or at most 20 wt.
% or at most 19.5 wt. % or at most 19 wt. % or at most 18.5 wt. %
or at most 18 wt. % of the covalently bonded siloxane for the total
weight of the bond precursor material. Moreover, the content of the
covalently bonded siloxane can be in a range including any of the
minimum and maximum values noted herein. For example, the bond
precursor material can include the covalently bonded siloxane in a
content in a range including at least 1 wt. % and at most 30 wt. %.
In a particular embodiment, the covalently bonded siloxane can
include polydimethylsiloxane, or more particularly, can consist
essentially of polydimethylsiloxane. Accordingly, the bond
precursor material can include polydimethylsiloxane in any content
noted for covalently bonded siloxane.
[0034] According to an embodiment, the bond precursor material can
further include a conventional resin, such as a phenolic resin, in
a content that can facilitate formation of an abrasive article with
improved performance. For example, the resin may be present in the
bond precursor material in a content of at most 40 wt. %, or at
most 30 wt. %, or at most 20 wt. %, or even at most 15 wt. % of the
total weight of the bond precursor material. In yet another
embodiment, the resin may be present for at least 5 wt. % or at
least 10 wt. % or at least 12 wt. % of the total weight of the bond
precursor material. It is to be understood the content of a
conventional resin can include any of the minimum and maximum
percentages disclosed herein. In another embodiment, the phenolic
resin can be in the liquid form.
[0035] In an embodiment, the bond precursor material can be in a
powder or a liquid form, or include a combination thereof. For
instance, the bond precursor material can include a powder phenolic
resin and a liquid phenolic resin. In a further embodiment, the
powder bond material can include chemically modified novolac resin,
such as siloxane chemically modified novolac resin, and the liquid
bond material can include resole resin. The bond precursor material
may be formed into a finally-formed bond material of an abrasive
article by curing.
[0036] In another embodiment, the bond precursor material can
include a curing agent or a cross-link agent. The curing or
cross-link agent can include an amine. Exemplary amines can include
ethylene diamine, ethylene triamine, methyl amines, or the like. In
a particular embodiment, the curing or cross-linking agent can
include hexamethylene tetramine. At temperatures in excess of about
90.degree. C., some examples of the hexamethylene tetramine may
form crosslinks to form methylene and dimethylene amino bridges
that help cure the resin. The hexamethylene tetramine may be
uniformly dispersed within the resin. More particularly,
hexamethylene tetramine may be uniformly dispersed within resin
regions as a cross-linking agent. In a more particular embodiment,
the bond material can include a phenolic resin modified with a
curing or cross-linking agent. In a particular embodiment, the bond
material can include novalce resin modified with a curing agent,
such as hexamethylene tetramine. In a more particular embodiment,
hexamethylene tetramine can be in a content of 5 wt. % to 15 wt. %
of the total weight of the novalac resin. Even more particularly,
the phenolic resin may contain resin regions with cross-linked
domains having a sub-micron average size.
[0037] As disclosed herein, in addition to the bond material, the
mixture can include abrasive particles. The abrasive particles can
be in a content from 55 wt. % to 99 wt. % for a total weight of the
mixture. In an embodiment, the abrasive particles can include
materials such as oxides, carbides, nitrides, borides, carbon-based
materials (e.g., diamond), oxycarbides, oxynitrides, oxyborides,
and a combination thereof. According to one embodiment, the
abrasive particles can include a superabrasive material. The
abrasive particles can include a material selected from the group
of silicon dioxide, silicon carbide, alumina, zirconia, flint,
garnet, emery, rare earth oxides, rare earth-containing materials,
cerium oxide, sol-gel derived particles, gypsum, iron oxide,
glass-containing particles, and a combination thereof. In another
instance, abrasive particles may also include silicon carbide,
brown fused alumina, white alumina, seeded gel abrasive, sintered
alumina with additives, shaped and sintered aluminum oxide, pink
alumina, ruby alumina, electrofused monocrystalline alumina,
alumina zirconia abrasives, extruded bauxite, sintered bauxite,
cubic boron nitride, diamond, aluminum oxy-nitride, sintered
alumina, extruded alumina, or any combination thereof. According to
one particular embodiment, the abrasive particles can consist
essentially of silicon carbide. According to another particular
embodiment, the abrasive particles can consist essentially of
alumina, such as alpha alumina. According to another particular
embodiment, the abrasive particles can consist essentially of
nanocrystalline alumina particles. The abrasive particles can have
a Mohs hardness of at least 7, such as at least 8, or even at least
9.
[0038] The abrasive particles may have other particular features.
For example, the abrasive particles can be shaped abrasive
particles. According to at least one embodiment, the abrasive
particles can include a two dimensional shape, a three-dimensional
shape, or a combination thereof. Exemplary two dimensional shapes
include regular polygons, irregular polygons, irregular shapes,
triangles, partially-concave triangles, quadrilaterals, rectangles,
trapezoids, pentagons, hexagons, heptagons, octagons, ellipses,
Greek alphabet characters, Latin alphabet characters, Russian
alphabet characters, and a combination thereof. In accordance with
an embodiment, the abrasive particles can consist of any of the
above noted two dimensional shapes. Exemplary three-dimensional
shapes can include a polyhedron, a pyramid, an ellipsoid, a sphere,
a prism, a cylinder, a cone, a tetrahedron, a cube, a cuboid, a
rhombohedrun, a truncated pyramid, a truncated ellipsoid, a
truncated sphere, a truncated cone, a pentahedron, a hexahedron, a
heptahedron, an octahedron, a nonahedron, a decahedron, a Greek
alphabet letter, a Latin alphabet character, a Russian alphabet
character, a Kanji character, complex polygonal shapes, irregular
shaped contours, a volcano shape, a monostatic shape, and a
combination thereof. A monostatic shape can be a shape with a
single stable resting position. In accordance with another
embodiment, the abrasive particles can consist of any of the above
noted three dimensional shapes. In a particular embodiment, the
shaped abrasive particles can include a triangular two-dimensional
shape. In another particular embodiment, the shaped abrasive
particles can include a partially-concave triangular
two-dimensional shape. The shaped abrasive particles and methods of
forming can be found in US2013/0236725 A1 by Doruk O. Yener, et al.
and US 2012/0167481 by Doruk O. Yener, et al., both of which are
incorporated herein by reference in their entireties.
[0039] In a particular embodiment, the abrasive particles may have
an elongated shape. In a further embodiment, the abrasive particles
may have an aspect ratio, defined as a ratio of the length:width of
at least about 1:1, wherein the length is the longest dimension of
the particle and the width is the second longest dimension of the
particle (or diameter) perpendicular to the dimension of the
length. In other embodiments, the aspect ratio of the abrasive
particles can be at least about 2:1, such as at least about 2.5:1,
at least about 3:1, at least about 4:1, at least about 5:1, or even
at least about 10:1. In one non-limiting embodiment, the abrasive
particles may have an aspect ratio of not greater than about
5000:1.
[0040] According to another particular embodiment, at least a
portion of the abrasive particles may include shaped abrasive
particles as disclosed for example, in US 2015/0291865 by Kristin
Brender, et al., US 2015/0291866 by Christoher Arcona et al., and
US 2015/0291867 by Kristin Brender, et al., all of which are
incorporated herein by reference in their entireties. Shaped
abrasive particles are formed such that each particle has
substantially the same arrangement of surfaces and edges relative
to each other for shaped abrasive particles having the same
two-dimensional and three-dimensional shapes. As such, shaped
abrasive particles can have a high shape fidelity and consistency
in the arrangement of the surfaces and edges relative to other
shaped abrasive particles of the group having the same
two-dimensional and three-dimensional shape. By contrast,
non-shaped abrasive particles can be formed through different
process and have different shape attributes. For example,
non-shaped abrasive particles are typically formed by a comminution
process, wherein a mass of material is formed and then crushed and
sieved to obtain abrasive particles of a certain size. However, a
non-shaped abrasive particle will have a generally random
arrangement of the surfaces and edges, and generally will lack any
recognizable two-dimensional or three dimensional shape in the
arrangement of the surfaces and edges around the body. Moreover,
non-shaped abrasive particles of the same group or batch generally
lack a consistent shape with respect to each other, such that the
surfaces and edges are randomly arranged when compared to each
other. Therefore, non-shaped grains or crushed grains have a
significantly lower shape fidelity compared to shaped abrasive
particles.
[0041] In at least one embodiment, the abrasive particles can
include crystalline grains (i.e., crystallites), and may consist
entirely of a polycrystalline material made of crystalline grains.
In particular instances, the abrasive particles can include
crystalline grains having a median grain size of not greater than
1.2 microns. In other instances, the median grain size can be not
greater than 1 micron, such as not greater than 0.9 microns or not
greater than 0.8 microns or even not greater than 0.7 microns.
However, the nanocrystalline alumina particles may have an average
crystallite size of not greater than 0.15 microns, such as not
greater than 0.14 microns, not greater than 0.13 microns or even
not greater than 0.12 microns. According to one non-limiting
embodiment, the median grain size of the abrasive particles can be
at least 0.01 microns, such as at least 0.05 microns or at least
0.1 microns or at least 0.2 microns or even at least 0.4 microns.
It will be appreciated that the median grain size of the abrasive
particles can be within a range between any of the minimum and
maximum values noted above. The median grain size is measured by an
uncorrected intercept method by SEM micrographs.
[0042] In accordance with an embodiment, the abrasive particles can
have an average particle size, as measured by the largest dimension
(i.e., length) of at least about 100 microns. In fact, the abrasive
particles can have an average particle size of at least about 150
microns, such as at least about 200 microns, at least about 300
microns, at least about 400 microns, at least about 500 microns, at
least about 600 microns, at least about 700 microns, at least about
800 microns, or even at least about 900 microns. Still, the
abrasive particles of the embodiments herein can have an average
particle size that is not greater than about 5 mm, such as not
greater than about 3 mm, not greater than about 2 mm, or even not
greater than about 1.5 mm. It will be appreciated that the abrasive
particles can have an average particle size within a range between
any of the minimum and maximum values noted above.
[0043] According to an embodiment, the mixture and the resulting
abrasive article can include a blend of abrasive particles. The
blend of abrasive particles can include a first type of abrasive
particle and a second type of abrasive particle that is distinct
from the first type of abrasive particle in at least one aspect,
such as particle size, grain size, composition, shape, hardness,
friability, toughness, and the like. For example, in one
embodiment, the first type of abrasive particle can include a
premium abrasive particle (e.g., fused alumina, alumina-zirconia,
seeded sol gel alumina, shaped abrasive particle, etc.) and the
second type of abrasive particle can include a diluent abrasive
particle. According to a non-limiting embodiment, the secondary
abrasive particles can include alumina oxide, silicon carbide,
cubic boron nitride, diamond, flint and garnet grains, and any
combination thereof. In other non-limiting embodiments, the blend
may include a third type of abrasive particles that may include a
conventional abrasive particle or a shaped abrasive particle. The
third type of abrasive particles may include a diluent type of
abrasive particles having an irregular shape, which may be achieved
through conventional crushing and comminution techniques. The third
type of abrasive particles may be distinct from the first type of
abrasive particles and the second type of abrasive particles in
composition or any other aspect disclosed in embodiments
herein.
[0044] The blend of abrasive particles can include a first type of
abrasive particles present in a first content (C1), which may be
expressed as a percentage (e.g., a weight percent) of the first
type of abrasive particles as compared to the total content of
particles of the blend. For example, in certain instances, the
blend can be formed such that the first content (C1) may be not
greater than 90% of the total content of the blend. In another
embodiment, the first content may be less, such as not greater than
85% or not greater than 80% or not greater than 75%. Still, in one
non-limiting embodiment, the first content of the first type of
abrasive particles may be present in at least 10% of the total
content of the blend, such as at least 15%, at least 20%, at least
25%, at least 30%, at least 35%, at least 40%, at least 45%, or at
least 50%. It will be appreciated that the first content (C1) may
be present within a range between any of the minimum and maximum
percentages noted above.
[0045] Furthermore, the blend of abrasive particles may include a
second content (C2) of the second type of abrasive particles,
expressed as a percentage (e.g., a weight percent) of the second
type of abrasive particles relative to the total weight of the
blend. The second content can be the same as or different from the
first content. For example, the second content (C2) may be not
greater than 55% of the total content of the blend, such as not
greater than 50%, such as not greater than 40%, not greater than
35%, not greater than 30%, or not greater than 25%. Still, in one
non-limiting embodiment, the second content (C2) may be present in
an amount of at least about 1% of the total content of the blend.
For example, the second content may be at least 5%, such as at
least 8%, at least 10%, or at least 12%. It will be appreciated
that the second content (C2) can be within a range between any of
the minimum and maximum percentages noted above.
[0046] In some embodiments, the blend of abrasive particles may
include a third content (C3) of the third type of abrasive
particles, expressed as a percentage (e.g., a weight percent) of
the third type of abrasive particles relative to the total weight
of the blend. The third content can be the same as or different
from the first content, the second content, or both. For example,
the third content (C3) may be not greater than 50% of the total
content of the blend, such as not greater than 45%, such as not
greater than 40%, not greater than 35%, not greater than 30%, not
greater than 25%, or not greater than 20%. Still, in one
non-limiting embodiment, the third content (C3) may be present in
an amount of at least about 1% of the total content of the blend.
For example, the third content may be at least 3%, such as at least
5%, at least 8%, or at least 10%. It will be appreciated that the
third content (C3) can be within a range between any of the minimum
and maximum percentages noted above.
[0047] As described herein, other materials, such as a filler, can
be included in the mixture. The filler may or may not be present in
the finally-formed abrasive article. An exemplary filler can
include powders, granules, spheres, fibers, pore formers, hollow
particles, and a combination thereof. Filler can include a material
selected from the group consisting of sand, bubble alumina,
chromites, magnetite, dolomites, bubble mullite, borides, titanium
dioxide, carbon products, silicon carbide, wood flour, clay, talc,
hexagonal boron nitride, molybdenum disulfide, feldspar, nepheline
syenite, glass spheres, glass fibers, CaF.sub.2, KBF.sub.4,
Cryolite (Na.sub.3AlF.sub.6), potassium Cryolite
(K.sub.3AlF.sub.6), pyrite, ZnS, copper sulfide, mineral oil,
fluorides, wollastonite, mullite, steel, iron, copper, brass,
bronze, tin, aluminum, kyanite, alusite, garnet, quartz, fluoride,
mica, nepheline syenite, sulfates (e.g., barium sulfate),
carbonates (e.g., calcium carbonate), titanates (e.g., potassium
titanate fibers), rock wool, clay, sepiolite, iron sulfide (e.g.,
Fe.sub.2S.sub.3, FeS.sub.2, or a combination thereof), potassium
fluoroborate (KBF.sub.4), zinc borate, borax, boric acid, fine
alundum powders, P15A, cork, glass spheres, silica microspheres
(Z-light), silver, Saran.TM. resin, paradichlorobenzene, oxalic
acid, alkali halides, organic halides, attapulgite, carbonates,
calcium carbonate, saran, phenoxy resin, CaO, K.sub.2SO.sub.4,
mineral wool, MnCl.sub.2, KCl, and a combination thereof. In
accordance with another embodiment, the filler can include a
material selected from the group consisting of an antistatic agent,
a lubricant, a porosity inducer, coloring agent, and a combination
thereof. In particular instances wherein the filler is particulate
material, it may be distinct from the abrasive particles, being
significantly smaller in average particle size than the abrasive
particles.
[0048] According to a particular embodiment, the mixture can
include a filler including barium sulfate. According to another
particular embodiment, the mixture can include a filler including
cryolite. According to still another particular embodiment, the
mixture can include a filler including at least one of barium
sulfate and cryolite, and one or more of any other fillers
disclosed herein.
[0049] After forming the mixture with the desired components and
shaping the mixture in desired processing apparatus, the process
can continue to step 102 by treating the mixture to form a
finally-formed abrasive article. Some suitable examples of treating
can include heating, curing, polymerization, pressing, and a
combination thereof. Curing can take place in the presence of heat.
For example, the mixture can be held at a final cure temperature
for a period of time, such as between 6 hours and 48 hours, between
10 and 36 hours, or until the mixture reaches the cross-linking
temperature or desired density is obtained. Selection of the curing
temperature depends, for instance, on factors such as the type of
bonding material employed, strength, hardness, and grinding
performance desired. According to certain embodiments, the curing
temperature can be in the range including at least 150.degree. C.
to not greater than 250.degree. C. In more specific embodiments
employing organic bonds, the curing temperature can be in the range
including at least 150.degree. C. to not greater than 230.degree.
C. Polymerization of phenol based resins may occur at a temperature
in the range of including at least 110.degree. C. and not greater
than 225.degree. C. Resole resins can polymerize at a temperature
in a range of including at least 140.degree. C. and not greater
than 225.degree. C. Certain novolac resins suitable for the
embodiments herein can polymerize at a temperature in a range
including at least 130.degree. C. and not greater than 195.degree.
C.
[0050] After finishing the treating process, the abrasive article
is formed including abrasive particles contained within the bond
material. In a particular embodiment, the abrasive article can be a
bonded abrasive article. The bonded abrasive article can include a
body including abrasive grains contained in a three-dimensional
matrix of the bond material. The body may be formed into any
suitable shape as known by those of skill in the art, including but
not limited to, abrasive wheels, cones, hones, cups,
flanged-wheels, tapered cups, segments, mounted-point tools, discs,
thin wheels, large diameter cut-off wheels, and the like.
[0051] According to an embodiment, the bonded abrasive can include
a body having a certain content of the bond material relative to a
total volume of the body, which may facilitate improved formation
and/or performance of an abrasive article. For example, the content
of the bond material can be at least 5 vol %, such as at least 10
vol %, at least 20 vol %, at least 30 vol %, at least 35 vol %, or
at least 40 vol % for the total volume of the body. For another
instance, the content of the bond material may be not greater than
55 vol %, such as not greater than 50 vol %, or not greater than 45
vol %, not greater than 40 vol %, or not greater than 35 vol %, not
greater than 30 vol %, or not greater than 25 vol %. It is to be
appreciated that the content of the bond material can be within a
range including any of the minimum to maximum percentages noted
above. For example, the content of the bond material in the body
can be within a range of within a range of 5 vol % to 55 vol %, or
within a range of 10 vol % to 35 vol %.
[0052] According to an embodiment, the bond material can include a
polymer including a covalently bonded siloxane functional group.
According to a further embodiment, the polymer can include
repeating siloxane functional groups covalently bonded to an oxygen
atom. In another embodiment, the bond material can include a
plurality of oxygen atoms, each of which is bonded to a siloxane
functional group. In a further embodiment, the bond material can
include a polymer including repeating siloxane functional groups
covalently bonded to phenoxy. In still another embodiment, the bond
material can include a polymer including a plurality of phenoxy
covalently bonded to one another by a methylene bridge, wherein at
least one of the phenoxy is covalently bonded to a siloxane group
through the oxygen atom of the phenoxyl. In yet another embodiment,
the bond material can include a polymer including
polydimethylsiloxane covalently and directly bonded to the oxygen
atom of phenoxyl. In a particularly embodiment, the polymer can
include a direct covalent bond between a methylene group and an
oxygen atom, wherein the methylene group is directly and covalently
bonded to one of the repeating siloxane groups and the oxygen atom
is directly and covalently bonded to a benzene ring, and more
particularly, the polymer can include a plurality of the direct
covalent bonds. In another particular embodiment, the bond material
can include a polymer including repeating benzene rings covalently
bonded to one another through a methylene bridge and each of a
plurality of the repeating benzene rings are covalently bonded to
an oxygen atom that is covalently bonded to siloxane group though a
methylene bridge, and more particularly, the methylene bridge is
directly and covalently bonded to one of the repeating siloxane
functional groups. In a particular embodiment, the polymer can
include a plurality of phenoxyl, each of which is covalently bonded
to a polydimethylsiloxane.
[0053] According to an embodiment, the bond material can include a
polymer including polydimethylsiloxane covalently bonded to a
benzene ring. According to a further embodiment,
polydimethylsiloxane can be covalently bonded to phenoxy. In a
particular embodiment, the polymer can include benzene rings
covalently bonded to one another through a methylene bridge, and at
least some of the benzene rings can be covalently bonded to
polydimethylsiloxane through oxygen atoms bonded to benzene
rings.
[0054] In this disclosure, polydimethylsiloxane is detected in
abrasive articles using Perkin Elmer Frontier Model FTIR with a
Diamond/ZnSe Tip ATR probe. A segment of an abrasive article can be
removed for analysis by FTIR. The sample can be crushed, and 10
grams of crushed powder can be sieved to remove abrasive particles.
50 mg of sieved powder can be analyzed directly under the probe.
The spectra data can be compared to data from know-it-all
informatics ATR/IR library to determine what each peak of the
spectra represents.
[0055] The bond material can have a FTIR signature peak. In one
embodiment, the signature peak can appear at a wavelength in a
range from 1258 cm.sup.-1 to 1275 cm.sup.-1. In another embodiment,
the signature peak can appear at a wavelength in a range from 1258
cm.sup.-1 to 1265 cm.sup.-1. FIG. 3 includes FTIR spectra of a
conventional wheel C1 formed with rubber modified resin (RMR
wheel), representative wheel (SMR wheel), and the siloxane
chemically modified resin (SMR resin) used in formation of the
representative wheel. As indicated in the figure, the SMR wheel
sample demonstrated a signature peak of polydimethylsiloxane at
1259 cm.sup.-1, while the RMR sample demonstrated no peak at 1259
cm.sup.-1. FIG. 4 includes FTIR spectra of wheels formed with bond
materials including different contents of covalently bonded
polydimethylsiloxane. The signature peaks are at 1261
cm.sup.-1.
[0056] According to an embodiment, the bond material can include a
certain content of the covalently bonded siloxane, which can
facilitate improved formation and performance of the abrasive
article. In one embodiment, the bond material can include at least
1 wt. % of the covalently bonded siloxane for the total weight of
the bond material, such as at least 1.5 wt. % or at least 2 wt. %
or at least 2.5 wt. % or at least 3 wt. % or at least 3.5 wt. % or
at least 4 wt. % or at least 4.5% or at least 5 wt. % or at least
5.5 wt. % or at least 6 wt. % or at least 6.5 wt. % or at least 7
wt. % or at least 7.5 wt. % or at least 8 wt. % or at least 8.5 wt.
% or at least 9 wt. % or at least 9.5 wt. % or at least 10 wt. % or
at least 11 wt. % or at least 12 wt. % or at least 12.5 wt. % or at
least 13 wt. % or at least 13.5 wt. % of the covalently bonded
siloxane for the total weight of the bond material. Alternatively
or additionally, the bond material can include at most 30 wt. % of
the covalently bonded siloxane for the total weight the bond
material, such as at most 29 wt. % or at most 28 wt. % or at most
27 wt. % or at most 26 wt. % or at most 25 wt. % or at most 24 wt.
% or at most 23 wt. % or at most 22 wt. % or at most 21 wt. % or at
most 20 wt. % or at most 19.5 wt. % or at most 19 wt. % or at most
18.5 wt. % or at most 18 wt. % of the covalently bonded siloxane
for the total weight of the bond material. Moreover, the content of
the covalently bonded siloxane can be in a range including any of
the minimum and maximum values noted herein. For example, the bond
material can include a content of the covalently bonded siloxane in
a range including at least 1 wt. % and at most 30 wt. %. In a
particular embodiment, the covalently bonded siloxane can include
polydimethylsiloxane, or more particularly, can consist essentially
of polydimethylsiloxane. Accordingly, the bond material can include
polydimethylsiloxane in any content noted herein for covalently
bonded siloxane. Referring to FIG. 5, a linear correlation between
absorption intensity at 1261 cm.sup.-1 and contents of
polydimethylsiloxane relative to the total weight of the bond
material is illustrated.
[0057] According to an embodiment, the bonded body of the abrasive
article can include a certain content of the abrasive particles,
which may facilitate improved formation and/or performance of an
abrasive article. For instance, a content of the abrasive particles
can be at least 8 vol %, such as at least 10 vol %, at least 12 vol
%, at least 14 vol %, at least 16 vol %, at least 18 vol %, at
least 20 vol %, at least 25 vol %, at least 30 vol %, or even at
least 35 vol %. In another instance, a content of the abrasive
particles within the bonded abrasive body may be not greater than
65 vol %, such as not greater than 64 vol %, not greater than 62
vol %, not greater than 60 vol %, not greater than 58 vol %, not
greater than 56 vol %, not greater than about 54 vol %, not greater
than 52 vol %, not greater than 50 vol %, not greater than 48 vol
%, not greater than 46 vol %, not greater than 44 vol %, not
greater than 42 vol %, not greater than 40 vol %, not greater than
38 vol %, not greater than 36 vol %, not greater than 34 vol %, not
greater than 32 vol %, not greater than 30 vol %, or greater than
28 vol %, or not greater than 26 vol. It will be appreciated that a
content of the abrasive particles can be within a range including
any of the minimum and maximum percentages noted above. For
example, a content of the abrasive particles in the body can be
within a range of 8 vol % to 65 vol %, within a range of 12 vol %
to 62 vol %, within a range of 20 vol % to 58 vol %, or within a
range of 26 vol % to 52 vol %.
[0058] The body of the abrasive article can be formed to have
certain porosity. In an embodiment, porosity can be at least 1 vol
% for a total volume of the body. For example, porosity can be at
least 3 vol % or at least 5 vol % or at least 8 vol %, at least 10
vol %, at least 12 vol %, at least 14 vol %, at least 16 vol %, at
least 18 vol %, at least 20 vol %, at least 25 vol %, at least 30
vol %, or at least 40 vol. In another embodiment, porosity of the
body may be not greater than 60 vol %. For instance, porosity may
be not greater than 55 vol %, not greater than 50 vol %, not
greater than 45 vol %, or not greater than 40 vol %. It will be
appreciated that porosity of the body can be within a range
including any of the minimum to maximum percentages noted above.
For example, porosity of the body can be within a range of 5 vol %
to 60 vol %, within a range of 8 vol % to 55 vol %, or within a
range of 10 vol % to 40 vol %.
[0059] The porosity of the body can be in various forms. For
instance, the porosity can be closed, open, or include closed
porosity and open porosity. In an embodiment, the porosity can
include a type of porosity selected from the group consisting of
closed porosity, open porosity, and a combination thereof. In
another embodiment, the majority of the porosity can include open
porosity. In a particular embodiment, all of the porosity can
essentially be open porosity. Still, in another embodiment, the
majority of the porosity can include closed porosity. For example,
all of the porosity can be essentially closed porosity.
[0060] The body can include pores having certain average pore
sizes. In an embodiment, the average pore size may be not greater
than 500 microns, such as not greater than 450 microns, not greater
than 400 microns, not greater than 350 microns, not greater than
300 microns, not greater than 250 microns, not greater than 200
microns, not greater than 150 microns, or not greater than 100
microns. In another embodiment, the average pore size can be at
least 0.01 microns, at least 0.1 microns, or at least 1 micron. It
will be appreciated that the body can have an average pore size
within a range including any of the minimum to maximum values noted
above. For example, the average pore size of the body can be within
a range of 0.01 microns to 500 microns, within a range of 0.1
microns to 350 microns, or within a range of 1 micron to 250
microns.
[0061] According to an embodiment, the bonded abrasive can include
a body having improved wet strength retention. In at least one
embodiment, wet strength retention can be represented by wet
flexural stress retention. The body of the bonded abrasive article
can include a wet flexural stress retention of at least 52%, such
as at least 53%, at least 54%, at least 55%, at least 56%, at least
57%, at least 58%, or at least 59%. In at least one other
embodiment, the body may include a wet flexural stress retention of
not greater than 65%, such as not greater than 64%, not greater
than 63%, such as not greater than 62%, not greater than 61%, such
as not greater than 60%, or not greater than 59.5%. It is to be
appreciated that the body can have a wet flexural stress retention
in a range including any of the minimum and maximum percentages
noted herein. For instance, the body can have a wet flexural stress
retention in a range including at least 52% and not greater than
65%.
[0062] Wet flexural stress retention can be measured using the
formula of WR=(MOR.sub.wet/MOR.sub.dry).times.100%, where WR
represents wet flexural stress retention, MOR.sub.wet is the
modulus of rupture (MOR) of a sample after wet treatment, and
MOR.sub.dry is the MOR of the sample prior to wet treatment.
MOR.sub.dry and MOR.sub.wet can be determined using the test method
disclosed in the following paragraph.
[0063] MOR of an abrasive article is tested in accordance with the
three point bending method. The test is performed on a 100 kN Cell
Instron testing machine with a displacement rate of 1 mm/min at
room temperature (e.g., 15 to 25.degree. C.). A test sample can be
a portion of the abrasive article and has a size of 25 mm.times.25
mm.times.100 mm, such as a segment cut from a grinding wheel.
MOR.sub.dry is tested on dry samples without wet treatment. Other
samples cut from the same abrasive article as the dry samples are
immersed in boiling water for 2 hours and then cooled to room
temperature prior to the MOR test to obtain MOR.sub.wet.
[0064] According to an embodiment, the bonded abrasive article of
embodiments herein can be capable of generating a decreased number
of scratch marks on a workpiece in a grinding test, comparing to a
corresponding conventional abrasive article made with a different
bond precursor material but otherwise being the same and tested in
the same condition. The grinding test is performed on forged steel
with 3 wt. % to 5 wt. % of Cr. Wheels having the width of 0350
mm.times.25 mm are mounted on CNC cylindrical grinders powered with
5.5 kW grinding motor, and the wheel speed is 33 m/s. The mode of
grinding is traverse, and volumetric removal rate is targeted in a
range from 1.8 to 9 mm.sup.3/s/mm. Power drawn during grinding is
measured in real-time along with surface finish of the workpiece
and change of diameter of the workpiece.
[0065] In this disclosure, the lengths and count of scratch marks
on a workpiece is determined as follows. A blue paste
(Permatex.RTM. Prussian blue #80038) is applied to the ground
surface of a workpiece. Under white lights, the scratch marks
become visible, as the blue paste fills into the depths of the
scratches. An area of 10 mm.times.10 mm of the surface is marked
and a picture of the area is taken under an Olympus stereo
microscope. The image is processed by the Essentials software
provided by the Olympus stereo microscope. The scratches within the
marked area are counted and the lengths of these scratches are
measured by the software.
[0066] In an embodiment, the bonded abrasive article can generate
at least 30% less scratch marks compared to the corresponding
conventional abrasive article under the same test condition, such
as at least 40% less or 50% less. The decrease of scratch marks is
determined by dividing the difference between the total counts of
scratch marks against the total count of the corresponding
conventional wheel. In another embodiment, the decrease can be at
most 50%.
[0067] Many different aspects and embodiments are possible. Some of
those aspects and embodiments are described herein. After reading
this specification, skilled artisans will appreciate that those
aspects and embodiments are only illustrative and do not limit the
scope of the present invention. Embodiments may be in accordance
with any one or more of the embodiments as listed below.
[0068] Embodiment 1. A bonded abrasive article, comprising:
a body including abrasive particles contained within a bond
material, wherein the bond material comprises a polymer including a
plurality of aromatic rings that are covalently bonded to one
another and a siloxane functional group covalently bonded to the
plurality of aromatic rings.
[0069] Embodiment 2. A bonded abrasive article, comprising:
a body including abrasive particles contained within a bond
material, wherein the body comprises a wet flexural stress
retention of at least 52%.
[0070] Embodiment 3. A bonded abrasive article, comprising:
a body including abrasive particles contained within a bond
material, wherein the bond material has a FTIR signature peak at a
wavelength from 1258 cm.sup.-1 to 1275 cm.sup.-1.
[0071] Embodiment 4. The bonded abrasive article of any one of
embodiments 1 to 3, wherein the bond material comprises a polymer
including a siloxane that is covalently bonded to a plurality of
benzene rings, wherein the siloxane is represented by a
formula:
##STR00002##
wherein R includes a methyl or phenyl group, X and Y independently
represents hydrogen atoms, a hydrocarbyl group, or an alkoxy group,
and n is at least one.
[0072] Embodiment 5. The bonded abrasive article of any one of
embodiments 1 to 4, wherein the bond material comprises a polymer
including polydimethylsiloxane covalently bonded to a phenoxy.
[0073] Embodiment 6. The bonded abrasive article of any one of
embodiments 1 to 5, wherein the bond material comprises
polydimethylsiloxane covalently bonded to an oxygen atom, wherein
the oxygen atom is directly and covalently bonded to a benzene
ring.
[0074] Embodiment 7. The bonded abrasive article of any one of
embodiments 1 to 6, wherein the bond material comprises a polymer
including polydimethylsiloxane covalently bonded to a backbone
including benzene rings covalently bonded to one another by a
methylene bridge.
[0075] Embodiment 8. The bonded abrasive article of any one of
embodiments 1 to 7, wherein the body comprises a wet flexural
stress retention of at least 52%, at least 53%, at least 54%, at
least 55%, at least 56%, or at least 57%, and not greater than
80%.
[0076] Embodiment 9. The bonded abrasive article of any one of
embodiments 1 to 8, wherein the body comprises the bond material in
a content in a range of 5 vol % to 55 vol % for a total volume of
the body.
[0077] Embodiment 10. The bonded abrasive article of any one of
embodiments 1 to 9, wherein the body comprises the abrasive
particles in a content in a range of 8 vol % to 65 vol % for a
total volume of the body.
[0078] Embodiment 11. The abrasive article of any one of
embodiments 1 to 10, wherein the body comprises a porosity in a
range of 3 vol % to 60 vol % for a total volume of the body.
[0079] Embodiment 12. The abrasive article of any one of
embodiments 1 to 11, wherein the body comprises a filler including
barium sulfate, cryolite, or any combination thereof.
[0080] Embodiment 13. A process of forming an abrasive article,
comprising:
forming a green body with a mixture comprising abrasive particles
and a bond precursor material, wherein the bond precursor material
comprises a resin having a FTIR signature peak at 1257 cm.sup.-1 to
1261 cm.sup.-1.
[0081] Embodiment 14. The process of embodiment 13, wherein the
bond precursor material comprises a phenolic resin covalently
bonded to a siloxane functional group.
[0082] Embodiment 15. The process of any one of embodiments 12 to
14, wherein the bond precursor material comprises
polydimethylsiloxane covalently bonded to phenoxy.
[0083] Embodiment 16. The process of any one of embodiments 13 to
15, wherein the mixture comprises the abrasive particles in a
content from 55 wt. % to 99 wt. % for a total weight of the
mixture.
[0084] Embodiment 17. The process of any one of embodiments 13 to
16, wherein the mixture comprises the bond precursor material in a
content from 2.5 wt. % to 25 wt. % for a total weight of the
mixture.
[0085] Embodiment 18. The process of any one of embodiments 13 to
17, wherein the mixture comprises the resin in a content from 1 wt.
% to 20 wt. % for a total weight of the mixture.
[0086] Embodiment 19. The process of any one of embodiments 13 to
18, wherein the mixture comprises a filler including barium
sulfate, cryolite, or a combination thereof.
[0087] Embodiment 20. The process of any one of embodiments 13 to
19, wherein the mixture comprises a filler in a content from 0.1
wt. % to 20 wt. % for a total weight of the bond material.
[0088] Embodiment 21. The process of any one of embodiments 13 to
20, wherein the bond precursor material comprises siloxane that is
covalently bonded to an aromatic ring in a content of at least 1
wt. % and at most 30 wt. % for a total weight of the bond precursor
material.
[0089] Embodiment 22. The process of any one of embodiments 13 to
21, wherein the bond precursor material comprises
polydimethylsiloxane that is covalently bonded to a phenoxy radical
in a content of at least 1 wt. % and at most 30 wt. % for a total
weight of the bond precursor material.
[0090] Embodiment 23. The bonded abrasive article of any one of
embodiments 1 to 12, wherein the bond material comprises siloxane
that is covalently bonded to aromatic rings in a content of at
least 1 wt. % and at most 30 wt. % for a total weight of the bond
material
[0091] Embodiment 24. The bonded abrasive article of any one of
embodiments 1 to 12 and 23, wherein the bond material comprises
polydimethylsiloxane that is covalently bonded to a phenoxy radical
in a content of at least 1 wt. % and at most 30 wt. % for a total
weight of the bond material.
[0092] Embodiment 25. The bonded abrasive article of any one of
embodiments 1 to 12 and 22 to 24, wherein the bond material
comprises a FTIR signature peak at a wavelength of 1259
cm.sup.-1.
[0093] Embodiment 26. The bonded abrasive article of any one of
embodiments 1 to 12 and 22 to 24, wherein the bond material
comprises a FTIR signature peak at a wavelength of 1261
cm.sup.-1.
EXAMPLES
Example 1
[0094] Representative bonded abrasive wheels S1 and conventional
wheels C1 were formed. The abrasive grains were first mixed with
liquid resole in a mixing bowl for 2 to 7 minutes or until all of
the grains were wet and coated by the liquid resole resin. The wet
abrasive grains were then combined with the rest of the bond
material. The mixture of each sample was poured into a mold, and
cold pressed. The samples were then removed from the molds and heat
treated in a furnace at 160.degree. C. for the bond material to
cure. The mixture compositions for wheels S1 and C1 are disclosed
in Table 1 and 2 below, respectively. Each of wheels S1 and C1
included 85 wt. % of abrasive particles, 10 wt. % of bond material,
and 5 vol % of pores.
[0095] As noted below, the wheels S1 and C1 were made using the
same compositions except that a conventional, nitrile rubber
modified novolac resin (RMR) used to form C1, while siloxane
chemically modified novolac resin (SMR) was used to make S1. Wheel
S1 included 13.5 wt. % of siloxane for the total weight of the bond
material. All of the wheels had the dimension of 350 mm
(dia).times.127 mm (bore dia).times.24 mm (thickness), and sections
of the dimension of 25 mm.times.25 mm.times.100 mm were cut and
tested for the wet retention ability as disclosed herein.
TABLE-US-00001 TABLE 1 Mixture Composition of Sample S1 Composition
Components wt. % Abrasive particles Norton Qantum 80 40.614 39C 80
(SiC having a 3.287 grit size of 80) 39C 90 (SiC having a 44.901
grit size of 90) Bond material SMR 8.3 Resole 2.465 Tri Decyl
Alcohol 0.183 Castor oil 0.210
TABLE-US-00002 TABLE 2 Mixture Composition of Sample C1 Composition
Components wt. % Abrasive particles Norton Qantum 80 40.614 39C 80
(SiC having a 3.287 grit size of 80) 39C 90 (SiC having a 44.901
grit size of 90) Bond material RMR 8.3 Resole 2.465 Tri Decyl
Alcohol 0.183 Castor oil 0.210
[0096] MOR.sub.dry and MOR.sub.wet of the S1 and C1 samples were
tested prior to and after wet treatment in accordance with
embodiments disclosed herein. The average values of the MOR of a
group of 3 S1 samples and a group of 3 C1 samples are included in
Table 3. Samples S1 had higher MOR prior to and after wet
treatment, as compared to C1 samples. S1 samples also demonstrated
higher wet strength retention represented by wet flexural stress
retention.
TABLE-US-00003 TABLE 3 Wet Flexural Stress Retention Wet Flexural
Stress Retention Sample MOR.sub.dry (MPa) MOR.sub.wet (MPa) (%) S1
43.91 26 59.2 C1 13.85 7 50.5
[0097] Water uptake of samples S1 and C1 were measured. Weight of
each sample was measured prior to and after wet treatment to
determine the weight change. Water uptake is measured using the
formula: W.sub.U=[(W.sub.wet-W.sub.dry)/W.sub.dry].times.100%.
W.sub.U represents water uptake, W.sub.dry represents the weight of
a sample prior to wet treatment, and W.sub.wet represents the
weight of the same sample after wet treatment. Three samples per
group were tested, and the average of water uptake of each group is
included in Table 4. Si samples had lower average uptake compared
to C1 samples, 7.03% vs. 14.231%.
TABLE-US-00004 TABLE 4 Water Uptake Weight Change Water Uptake
Sample W.sub.dry (g) W.sub.wet (g) (g) (%) S1 113.7 122.3 8.6 7.03
C1 100.65 117.35 16.7 14.231
Example 2
[0098] Additional wheel samples were formed in a similar manner as
disclosed in Example 1. The grinding test was performed on the
samples, and counts and lengths of scratch marks were determined as
disclosed herein. The mixture composition of representative wheel
sample S2 is included in Table 5, and conventional wheel sample C2
was formed with the mixture having the same composition as S2
except siloxane modified resin was replaced with conventional
rubber modified resin.
TABLE-US-00005 TABLE 5 Composition of S2 Composition Components Wt.
% Bond LIQUID RESIN 1.616 Tri Decyl Alcohol 0.257 Siloxane modified
resin 9.157 Castor Oil 0.21 Abrasive particles 38A-White
Al.sub.2O.sub.3 (180 88.76 Grit)
[0099] The mixture composition of representative wheel sample S3 is
included in Table 6, and conventional wheel sample C3 was formed
with the mixture having the same composition as A48 except siloxane
modified resin was replaced with conventional rubber modified
resin. Each of the bond materials of S2 and S3 included 13.5 wt. %
of siloxane for the total weight of the respective bond
material.
TABLE-US-00006 TABLE 6 Composition of S3 Composition Components WT.
% Bond LIQUID RESIN 1.185 Tri Decyl Alcohol 0.299 Siloxane modified
resin 8.691 Castor Oil 0.199 BaSO4 7.535 Abrasive particles
ABRASIVE (60 grit 81.99 Al.sub.2O.sub.3)
[0100] FIG. 6 includes a plot of scratch numbers versus sizes of
samples C2 and S2. Wheel C2 generated 93 scratch marks having
length from 300 microns to 1200 microns, while wheels S2 generated
44 scratch marks in the same length range. FIG. 5 includes a plot
of scratch numbers versus sizes of samples S3 and C3. Wheels C3
generated 94 scratch marks compared to 63 by S3 in a length range
of 300 microns to 1500 microns.
Example 3
[0101] Additional wheel samples were formed in a similar manner as
disclosed in Example 1. The wheel samples included different
contents of covalently bonded polydimethylsiloxane as noted in
Table 7 below. Segments of the samples were cut, prepared and
analyzed for FTIR spectra as described in this disclosure. FIG. 4
includes an illustration of the FTIR spectra of samples S4 to S7,
demonstrating signature peaks at 1261 cm.sup.-1.
TABLE-US-00007 TABLE 7 Samples Content of polydimethylsiloxane S4
1.5 wt. % S5 7.5 wt. % S6 11.25 wt. % S7 13.75 wt. %
[0102] The present embodiments represent a departure from the state
of the art. Notably, abrasive articles of embodiments herein may
include a bond material including polydimethylsiloxane covalently
bonded to a phenoxy. Unexpectedly, abrasive articles of the
embodiments herein may have improved performance, such as improved
wet strength, which can be expected to improve consistency in wheel
grinding performance over a longer time period, and reduced scratch
marks on a workpiece. Improved wet retention can make the abrasive
article of embodiments herein more suitable for organic wet
grinding.
[0103] Note that not all of the activities described above in the
general description or the examples are required, that a portion of
a specific activity may not be required, and that one or more
further activities may be performed in addition to those described.
Still further, the order in which activities are listed is not
necessarily the order in which they are performed.
[0104] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any feature(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature of any or all the claims. Many
different aspects and embodiments are possible. Some of those
aspects and embodiments are described herein. After reading this
specification, skilled artisans will appreciate that those aspects
and embodiments are only illustrative and do not limit the scope of
the present invention. Additionally, those skilled in the art will
understand that some embodiments that include analog circuits can
be similarly implement using digital circuits, and vice versa.
[0105] The specification and illustrations of the embodiments
described herein are intended to provide a general understanding of
the structure of the various embodiments. The specification and
illustrations are not intended to serve as an exhaustive and
comprehensive description of all of the elements and features of
apparatus and systems that use the structures or methods described
herein. Separate embodiments may also be provided in combination in
a single embodiment, and conversely, various features that are, for
brevity, described in the context of a single embodiment, may also
be provided separately or in any subcombination. Further, reference
to values stated in ranges includes each and every value within
that range. Many other embodiments may be apparent to skilled
artisans only after reading this specification. Other embodiments
may be used and derived from the disclosure, such that a structural
substitution, logical substitution, or another change may be made
without departing from the scope of the disclosure. Accordingly,
the disclosure is to be regarded as illustrative rather than
restrictive. Benefits, other advantages, and solutions to problems
have been described above with regard to specific embodiments.
However, the benefits, advantages, solutions to problems, and any
feature(s) that may cause any benefit, advantage, or solution to
occur or become more pronounced are not to be construed as a
critical, required, or essential feature of any or all the
claims.
[0106] The Abstract of the Disclosure is provided to comply with
Patent Law and is submitted with the understanding that it will not
be used to interpret or limit the scope or meaning of the claims.
In addition, in the foregoing Detailed Description of the Drawings,
various features may be grouped together or described in a single
embodiment for the purpose of streamlining the disclosure. This
disclosure is not to be interpreted as reflecting an intention that
the claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter may be directed to less than all features
of any of the disclosed embodiments. Thus, the following claims are
incorporated into the Detailed Description of the Drawings, with
each claim standing on its own as defining separately claimed
subject matter.
* * * * *