U.S. patent application number 13/339162 was filed with the patent office on 2012-07-12 for robust binder bonded grinding wheel.
This patent application is currently assigned to Saint-Gobain Abrasifs. Invention is credited to Lingyu Li.
Application Number | 20120174493 13/339162 |
Document ID | / |
Family ID | 46383852 |
Filed Date | 2012-07-12 |
United States Patent
Application |
20120174493 |
Kind Code |
A1 |
Li; Lingyu |
July 12, 2012 |
ROBUST BINDER BONDED GRINDING WHEEL
Abstract
An abrasive tool includes a matrix material and an abrasive
grain contained within the matrix material. The matrix material
includes a binder and an block copolymer. The block copolymer
including a binder miscible block and a binder immiscible block.
The binder immiscible block of the block copolymer can form
toughening domains within the matrix material. A method of forming
an abrasive tool includes blending a binder powder, an block
copolymer powder, and an abrasive grain to form a blended powder,
shaping the blended powder, and curing the blended powder.
Inventors: |
Li; Lingyu; (Shrewsbury,
MA) |
Assignee: |
Saint-Gobain Abrasifs
Conflans-Sainte-Honorine
MA
Saint Gobain Abrasives, Inc.
Worcester
|
Family ID: |
46383852 |
Appl. No.: |
13/339162 |
Filed: |
December 28, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61427577 |
Dec 28, 2010 |
|
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Current U.S.
Class: |
51/298 |
Current CPC
Class: |
B24D 3/28 20130101; B24D
3/34 20130101; C09K 3/1409 20130101 |
Class at
Publication: |
51/298 |
International
Class: |
B24D 3/28 20060101
B24D003/28 |
Claims
1.-82. (canceled)
83. An abrasive tool comprising: a matrix material comprising a
binder and a block copolymer, the block copolymer including a
binder miscible block and a binder immiscible block, wherein the
binder immiscible block forms a plurality of toughening domains
dispersed within the matrix material; and an abrasive grain
contained within the matrix material.
84. The abrasive tool of claim 83, wherein the binder is a phenolic
resin, an epoxy resin, or any combination thereof
85. The abrasive tool of claim 83, wherein the block copolymer
includes poly(methyl methacrylate), polystyrene, polybutadiene, or
any combination thereof
86. The abrasive tool of claim 83, wherein the abrasive tool has a
percent increase G1C of at least about 20% over a similar abrasive
tool without the block copolymer, wherein the percent increase is
based on the equation ((GN-GC)/GC.times.100%) wherein GN represents
the G1C of an abrasive tool having the block copolymer and GC
represents the G1C of the abrasive tool without the block
copolymer.
87. The abrasive tool of claim 83, wherein the abrasive tool has a
percent increase SpWOF of at least about 10% over a similar
abrasive tool without the block copolymer, wherein the percent
increase is based on the equation ((SN-SC)/SC.times.100%) wherein
SN represents the SpWOF of an abrasive tool having the block
copolymer and SC represents the SpWOF of the abrasive tool without
the block copolymer.
88. The abrasive tool of claim 83, wherein the matrix material
includes from about 70 wt % to about 95 wt % binder.
89. The abrasive tool of claim 83, wherein the matrix material
includes from about 5 wt % to about 30 wt % block copolymer.
90. The abrasive tool of claim 83, wherein the abrasive grain is
present in an amount from about 50 wt % to about 80 wt % of the
abrasive tool.
91. The abrasive tool of claim 83, wherein the body comprises an
outer diameter within a range of about 15 cm to about 100 cm.
92. The abrasive tool of claim 83, wherein the body comprises an
average thickness of not greater than about 3 cm.
93. The abrasive tool of claim 83, wherein the matrix material
comprises a plurality of toughening domains having a first phase
formed from the binder immiscible block and wherein each of the
toughening domains is at least partially surrounded by a second
phase formed from the binder miscible block and the binder
94. A method comprising: blending a binder powder, a block
copolymer powder, and an abrasive grain to form a blended powder,
the block copolymer including a binder miscible block and a binder
immiscible block; shaping the blended powder; and curing the
blended powder to form an abrasive tool.
95. The method of claim 94, wherein the blended powder includes
from about 15 wt % to about 50 wt % binder, about 1 wt % to about
15 wt % block copolymer; and about 50 wt % to about 80 wt %
abrasive grain.
96. An abrasive tool comprising: a matrix material comprising: a
binder; a block copolymer within the binder, the block copolymer
having at least a first portion and a second portion; a plurality
of toughening domains dispersed within a binder, wherein each of
the plurality of toughening domains comprise the first portion of
the block copolymer; and an abrasive grain within the matrix
material.
97. The abrasive tool of claim 96, wherein the toughening domains
include an average diameter between and including 0.1 .mu.m and
25.0 .mu.m.
98. The abrasive tool of claim 96, wherein the toughening domain
hardness is between and includes about 60% of the binder hardness
and about 90% of the binder hardness.
99. The abrasive tool of claim 96, wherein the matrix material
includes a toughening domain concentration between and including 1
toughening domain per 1.mu.m.sup.2 and 10 toughening domains per
1.mu.m.sup.2.
100. The abrasive tool of claim 96, wherein the block copolymer
comprises a polydispersity index between and including about 1.1
and about 1.4.
101. The abrasive tool of claim 96, further comprising a burst
speed of at least about 6800 RPM.
102. The abrasive tool of claim 96, wherein the block copolymer
comprises a molar mass of at least about 3000 g/mol.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] The present application claims priority from U.S.
Provisional Patent Application No. 61/427,577, filed Dec. 28, 2010,
entitled "ROBUST BINDER BONDED GRINDING WHEEL," naming inventor
Lingyu Li, which application is incorporated by reference herein in
its entirety.
BACKGROUND
[0002] 1. Field of the Disclosure
[0003] The following is directed to an abrasive tool, and
particularly directed to a robust binder bonded grinding wheel.
[0004] 2. Description of the Related Art
[0005] Abrasive wheels are typically used for cutting, abrading,
and shaping of various materials, such as stone, metal, glass,
plastics, among other materials. Generally, the abrasive wheels can
have various phases of materials including abrasive grains, a
bonding agent, and some porosity. Depending upon the intended
application, the abrasive wheel can have various designs and
configurations. For example, for applications directed to the
finishing and cutting of metals, some abrasive wheels are fashioned
such that they have a particularly thin profile for efficient
cutting.
[0006] However, given the application of such wheels, the abrasive
articles are subject to fatigue and failure. In fact, the wheels
may have a limited time of use of less than a day depending upon
the frequency of use. Accordingly, the industry continues to demand
abrasive wheels capable of improved performance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] 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.
[0008] FIG. 1 includes an illustration of an abrasive tool in
accordance with an embodiment.
[0009] FIG. 2 includes an illustration of diblock copolymer in
accordance with an embodiment.
[0010] FIG. 3 includes an illustration of triblock copolymer in
accordance with an embodiment.
[0011] FIG. 4 includes a micrograph illustrating the microstructure
formed by a block copolymer and a resin in accordance with an
embodiment.
[0012] FIG. 5 includes a bar graph illustrating the burst speed of
a standard abrasive article and a block copolymer abrasive article
in accordance with an embodiment.
[0013] The use of the same reference symbols in different drawings
indicates similar or identical items.
DETAILED DESCRIPTION
[0014] The following is directed to bonded abrasive tools utilizing
abrasive grains contained within a matrix material for cutting,
abrading, and finishing of work pieces. The matrix material can
include a binder and an amphiphilic block copolymer including a
binder miscible block and a binder immiscible block. Certain
embodiments herein are directed to abrasive wheels that are
particularly suited for cutting and/or shaping metal.
[0015] FIG. 1 includes an illustration of an abrasive tool in
accordance with an embodiment. Notably, the abrasive tool 100
includes a body 101 having a generally circular shape as viewed in
two dimensions. It will be appreciated, that in three-dimensions
the tool has a certain thickness such that the body 101 has a
disk-like or a cylindrical shape. In an embodiment, the body can
have an average thickness of at least about 0.1 cm and not greater
than about 3 cm. For example, the average thickness can be within a
range between about 0.5 cm and about 2 cm. As illustrated, the body
can have an outer diameter 103 extending through the center of the
tool. The outer diameter 103 can be within a range of 15 cm to
about 100 cm. In a particular embodiment, the outer diameter can be
at least about 45 cm.
[0016] As further illustrated, the abrasive tool 100 can include a
central opening 105 defined by an inner circular surface 102 about
the center of the body 101. The central opening 105 can extend
through the entire thickness of the body 101 such that the abrasive
tool 100 can be mounted on a spindle or other machine for rotation
of the abrasive tool 100 during operation.
[0017] In an embodiment, the body can include a tapered region
extending circumferentially around a portion of a periphery of the
body. The tapered region can extend through the entire
circumference of the body. Additionally, the tapered region extends
radially from a flat region of the body. In a particular
embodiment, the tapered region of the body comprises an average
thickness that is greater than an average thickness of the flat
region of the body.
[0018] In an embodiment, the body of the abrasive tool can include
an abrasive grain contained within a matrix material. In an
example, the abrasive grain can include superabrasive material,
such as diamond, cubic boron nitride, and a combination thereof. In
another example, the abrasive grains comprise a material selected
from the group of materials consisting of oxides, carbides,
borides, nitrides, and a combination thereof. In a particular
embodiment, the abrasive grains can consist essentially of oxides.
The oxide material can include alumina, zirconia, silica, or any
combination thereof. Additionally, the abrasive grains comprise a
Vickers hardness of at least about 5 GPa. In an embodiment, the
abrasive grain can be present in an amount from about 50 wt % to
about 80 wt % of the abrasive tool.
[0019] The matrix material can include a binder, such as a phenolic
resin or an epoxy resin, and an amphiphilic block copolymer. In an
example, the matrix material can include from about 70 wt % to
about 95 wt % binder and from about 5 wt % to about 30 wt %
amphiphilic block copolymer.
[0020] The amphiphilic block copolymer can include at least two
blocks and can include blocks comprising poly(methyl methacrylate),
polystyrene, polybutadiene, or any combination thereof. In an
example, the amphiphilic block copolymer can be a diblock copolymer
or a triblock copolymer.
[0021] FIG. 2 includes an illustration of an exemplary diblock
copolymer 200. The diblock copolymer 200 can include blocks 202 and
204. Additionally, the diblock copolymer can include repeating
units consisting of blocks 202 and 204, such that block 204 is
followed by block 202 and block 202 is followed by block 204. The
block 202 can comprise a different polymer from the block 204, and
as such, the properties of block 202 can be different from the
properties of block 204.
[0022] FIG. 3 includes an illustration of an exemplary triblock
copolymer 300. The triblock copolymer 300 can include blocks 302,
304, and 306. Additionally, the diblock copolymer can include
repeating units consisting of blocks 302, 304, and 306, such that
block 306 is followed by another block 302. Block 304 can comprise
a different polymer from block 302 and from block 306.
Additionally, block 302 can comprise a different polymer from block
306, such that each of block 302, 304, and 306 comprises a
different polymer form the other blocks. In an alternate
embodiment, block 302 and 306 can comprise a substantially similar
polymer.
[0023] Further, the amphiphilic block copolymer can include a
binder miscible block and a binder immiscible block. A binder
miscible block can be a polymer block that is soluble in the resin
such that the miscible block and the resin form a single phase of
the matrix. In contrast, a binder immiscible block can
substantially insoluble in the resin and can form a separate phase
within the matrix. In an example, a polystyrene block is miscible
in phenolic resin but immiscible in epoxy. In contrast, a
poly(methyl methacrylate) block is immiscible in phenolic resin but
miscible in epoxy. As such, a copolymer consisting of a polystyrene
block and a poly(methyl methacrylate) block can be an amphiphilic
block copolymer for both phenolic resins and epoxy resins.
[0024] The alternating properties of the amphiphilic block
copolymer can result in the self-assembly of a particular
morphology when combined with the resin. An example of the
morphology is depicted in the micrograph of FIG. 4. The micrograph
of FIG. 4 is a micrograph of a portion of a matrix material that
can be used to form an abrasive tool, e.g., a grinding wheel.
[0025] In a particular aspect, the matrix material can include a
binder 402 and a block copolymer within the binder. The block
copolymer can include at least a first portion and second portion,
i.e., the block copolymer can include a diblock copolymer, a
triblock copolymer, a tetrablock copolymer, or some other
multi-block copolymer.
[0026] As indicated in FIG. 4, the matrix material can include a
plurality of toughening domains 404 dispersed within the matrix
material. Each of the toughening domains can include the first
portion of the block copolymer and can exist as a first phase
within the matrix material. Further, an abrasive grain can be
dispersed within the matrix material.
[0027] In a particular aspect, the second portion of the block
copolymer and the binder form a single phase different from the
phase of the toughening domains. Moreover, the second phase formed
from the second portion of the block copolymer and the binder can
at least partially surround the first phase formed included in the
toughening domains. In another aspect, the first portion of the
block copolymer includes a binder immiscible portion and the second
portion of the block copolymer comprises a binder miscible portion.
The immiscible/miscible quality of the block copolymer can lead to
the formation of the first phase and the second phase within the
matrix material. Further, the immiscible/miscible quality of the
block copolymer can lead to different morphology of the toughening
domain structures, e.g., spherical domain structures, vesicular
domain structures, cylindrical domain structures, etc.
[0028] As depicted in FIG. 4, each toughening domain can be
generally ellipsoidal in cross-section. Further, each toughing
domain can be generally circular in cross-section. In one aspect,
the toughening domains include an average diameter of at least
about 0.1 .mu.m. In another aspect, the toughening domains can
include an average diameter of at least about 0.2 .mu.m, at least
about 0.3 .mu.m, at least about 0.4 .mu.m, at least about 0.5
.mu.m, at least about 1.0 .mu.m, at least about 2.5 .mu.m, or at
least about 5.0 .mu.m. Further, the toughening domains can include
an average diameter that is not greater than about 25.0 .mu.m, not
greater than about 20.0 .mu.m, not greater than about 15.0 .mu.m,
or not greater than about 10.0 .mu.m. The average diameter can be
within a range between and including any of the minimum and maximum
average diameters described above.
[0029] For example, the toughening domains can include an average
diameter between and including 0.1 .mu.m and 25.0 .mu.m. Also, the
toughening domains can include an average diameter between and
including 0.1 .mu.m and 20.0 .mu.m, between and including 0.1 .mu.m
and 15.0 .mu.m, between and including 0.1 .mu.m and 10.0 .mu.m,
between and including 0.1 .mu.m and 5.0 .mu.m, between and
including 0.1 .mu.m and 2.5 .mu.m, or between and including 0.1
.mu.m and 0.5 .mu.m.
[0030] In still another aspect, the toughening domains can include
a toughening domain hardness that is less than a binder hardness.
Specifically, the toughening domain hardness can be less than about
90% of the binder hardness as given by the equation
[H.sub.TD/H.sub.B].times.100%, wherein H.sub.TD is the toughening
domain hardness and H.sub.B is the binder hardness. Moreover, the
toughening domain hardness can be less than about 85% of the binder
hardness, less than about 80% of the binder hardness, less than
about 75% of the binder hardness, or less than about 70%. In
another aspect, the toughening domain hardness can be greater than
about 60% of the binder hardness. The toughening domain hardness
can be within a range between and including any of the minimum and
maximum percentage values described above.
[0031] In another aspect, the toughening domains can be
substantially uniformly dispersed throughout an entire volume of
the matrix material. In other words, the majority of the toughening
domains can be spaced apart from each other. Specifically, at least
about 70% of the toughening domains can be spaced apart from each
other. Moreover, at least about 75%, at least about 80%, at least
about 85%, at least about 90%, at least about 95%, or at least
about 99% of the toughening domains can be spaced apart from each
other. In another aspect, essentially all of the toughening domains
can be spaced apart from each other.
[0032] In still another aspect, the matrix material can include a
toughening domain concentration of at least about 1 toughening
domains per 1 .mu.m.sup.2 as viewed in cross-section at a
magnification of about 25000.times.. Further, the toughening domain
concentration can be at least about 2 toughening domains per 1
.mu.m.sup.2, at least about 3 toughening domains per 1 .mu.m.sup.2,
at least about 4 toughening domains per 1 .mu.m.sup.2, or at least
about 5 toughening domains per 1 .mu.m.sup.2. The toughening domain
concentration may not be greater than about 10 toughening domains
per 1 .mu.m.sup.2. The toughening domain concentration can be
within a range between and including any of the minimum and maximum
concentration values described above.
[0033] For example, the matrix material can include a toughening
domain concentration between and include 1 toughening domains per 1
.mu.m.sup.2 and 10 toughening domains per 1 .mu.m.sup.2. Further,
the toughening domain concentration can be between and include 1
toughening domains per 1 .mu.m.sup.2 and 5 toughening domains per 1
.mu.m.sup.2.
[0034] The matrix material can include at least about 0.5 wt % of
block copolymer for a total weight of the matrix material.
Moreover, the matrix material can include at least about 1% of the
block copolymer, about 2 wt % of block copolymer, at least about 3
wt % of block copolymer, at least about 4 wt % of block copolymer,
or at least about 5 wt % of block copolymer for the total weight of
the matrix material. Further, the matrix material can include not
more than about 10 wt % of block copolymer for the total weight of
the matrix material. The amount of block copolymer can be within a
range between and including any of the minimum and maximum wt %
amounts described above.
[0035] For example, the matrix material can include between and
including about 0.5 wt % block copolymer and about 10 wt % block
copolymer. The matrix material can include between and including
about 0.5 wt % block copolymer and about 8 wt % block copolymer or
between and including about 0.5 wt % block copolymer and about 5 wt
% block copolymer.
[0036] The block copolymer can include a polydispersity index less
than about 1.4. Further, the polydispersity index can be less than
about 1.3 or 1.2. However, the polydispersity index may be greater
than about 1.1. In another aspect, the polydispersity index can be
between and including about 1.1 and about 1.4. Also, polydispersity
index can be between and including about 1.1 and about 1.3. As the
polydispersity index approaches 1, a length of each chain within
the block copolymer will be substantially the same.
[0037] In another aspect, an abrasive tool constructed using the
matrix material illustrated in FIG. 4 can include a burst speed of
at least about 6800 RPM. Moreover, such an abrasive tool can
include a burst speed of at least about 6850 RPM, at least about
6900 RPM, at least about 6950 RPM, at least about 7000 RPM, or at
least about 7050 RPM. In a particular aspect, the burst speed may
not be greater than about 7100 RPM.
[0038] In yet another aspect, the block copolymer can include a
molar mass of at least about 3000 g/mol. Specifically, the molar
mass can be at least about 3100 g/mol, at least about 3200 g/mol,
at least about 3300 g/mol, at least about 3400 g/mol, or at least
about 3500 g/mol. In another aspect, the molar mass can be at least
about 10000 g/mol, at least about 15000 g/mol, at least about 20000
g/mol, at least about 25000 g/mol, at least about 30000 g/mol, at
least about 35000 g/mol, at least about 40000 g/mol, at least about
45000 g/mol, or at least about 50000 g/mol.
[0039] The toughening domains can act as dampeners during use a
grinding wheel in which the toughening domains are incorporated. In
other words, the toughening domains can absorb energy during use of
a grinding wheel in which the toughening domains are incorporated.
The dampening or energy absorption can be attributed to the
differences in hardness between the toughening domains and the
binder.
[0040] Turning to a method of making the bonded abrasive tool, a
binder powder, an amphiphilic block copolymer powder, and an
abrasive grain to form a blended powder.
[0041] The binder powder can include a solid phenolic resin or a
solid epoxy resin. The amphiphilic block copolymer powder, can
include a solid amphiphilic block copolymer. The solid amphiphilic
block copolymer can include a binder miscible block and a binder
immiscible block. In an embodiment, the blended powder can include
from about 15 wt % to about 50 wt % binder, from about 1 wt % to
about 15 wt % amphiphilic block copolymer, and from about 50 wt %
to about 80 wt % abrasive grain.
[0042] The blended powder can be shaped into the form of a bonded
abrasive. In an embodiment, a mold cavity can be filled with the
blended powder, and the blended powder can be compressed within the
mold. For example, the blended powder can be compressed by cold
pressing, or heat can be added to the powder during pressing, such
as by hot pressing.
[0043] After shaping, the matrix material shaped powder can be
cured to form an abrasive tool. For example, the matrix material
can be cured by heating the blended powder to a curing temperature,
such as at least about 200.degree. C. In an embodiment, the matrix
material can be substantially cured while remaining within the mold
cavity. In another embodiment, the matrix material can be partially
cured to a point sufficient to maintain the shape of the abrasive
tool when removed from the cavity. The abrasive tool can be
subjected to additional curing to substantially cure the matrix
material after being removed from the mold cavity.
[0044] The abrasive tools described herein can have certain
features that make the abrasive tool suitable for improved grinding
and/or cutting applications. Notably, the fracture toughness of the
bonded abrasive tool is improved. For example, the fracture
toughness can be determined by measuring the force required to
cause a crack to form in the abrasive tool, designated as the
G.sub.1C, or by measuring the specific work off force (SpWOF) which
corresponds to the force required to break a piece off the bonded
abrasive tool. The abrasive articles of embodiments herein
demonstrate an improved percent increase G.sub.1C and percent
increase SpWOF as compared to conventional abrasive articles.
Notably, for comparative purposes, the conventional abrasive
articles included abrasives of the same design having the matrix
material comprising resin without the addition of the amphiphilic
block copolymer. According to empirical evidence, the abrasive tool
can have a percent increase G.sub.1C of at least about 20% over a
similar abrasive tool without the amphiphilic block copolymer. The
percent increase is based on the equation
((G.sub.N-G.sub.C)/G.sub.C.times.100%) wherein G.sub.N represents
the G.sub.1C of an abrasive tool including the amphiphilic block
copolymer and G.sub.C represents the G.sub.1C of the abrasive tool
without the amphiphilic block copolymer. In other embodiments, the
percent increase G.sub.1C can be at least about 30%, such as at
least about 40%, such as at least about 50%, even at least about
60%. In an embodiment, the percent increase G.sub.1C can be not
greater than about 500%.
[0045] Additionally, empirical evidence also demonstrates that the
abrasive tool can have a percent increase SpWOF of at least about
10% over a similar abrasive tool without the amphiphilic block
copolymer. Further, the percent increase SpWOF can be at least
about 15%, such as at least about 20%. The percent increase is
based on the equation ((S.sub.N-S.sub.C)/S.sub.C.times.100%)
wherein S.sub.N represents the SpWOF of an abrasive tool having the
amphiphilic block copolymer and S.sub.C represents the SpWOF of the
abrasive tool without the amphiphilic block copolymer. In other
embodiments, the percent increase SpWOF can be not greater than
about 500%.
[0046] Liquid amphiphilic block copolymers, such as described in US
Publication 2009/0082486 A1, have been used to toughen epoxy resins
used in applications such as laminating. These applications have
relied upon a amphiphilic block copolymer comprising poly(ethylene
oxide) (PEO) and poly(butylene oxide) (PBO). However, the use of a
liquid resin system can cause problems with the production of
bonded abrasives articles, such as the partial settling of the
abrasive grains within the liquid. This may lead to a non-uniform
distribution of abrasive grains and uneven grinding performance.
The use of a solid amphiphilic block copolymer powder provides a
particular advantage for the formation of bonded abrasive
articles.
[0047] Further, in certain embodiments, the amount of block
copolymer that can be used to increase the strength, or toughness,
of a binder used in a grinding wheel application can be such a
small amount when compared to the binder material that it would be
extremely difficult to get substantially uniform dispersal when
mixing a liquid form of such a copolymer with a binder powder.
However, mixing a powdered form of such a block copolymer can allow
for the uniform dispersal of the block copolymer within the binder
powder prior to formation of an abrasive article from the block
copolymer/binder powder mixture.
EXAMPLES
[0048] Several types of abrasive articles are formed and tested to
compare certain performance parameters including the critical
energy release rate (G1C) and specific work-off force (SpWOF). The
G1C is a measure of the force necessary to cause the test abrasive
article to crack, and the SpWOF is a measure of the force necessary
to cause a portion of the test abrasive article to break off.
[0049] Comparative Sample 1 is a phenolic resin based formulation
prepared by pressing a phenolic resin powder into a mold and
heating it to a temperature of 200.degree. C. for 1 hour.
[0050] Sample 1 is prepared as Comparative Sample 1 with the
addition of an amphiphilic block copolymer powder. The phenolic
resin and the amphiphilic block copolymer are blended at a ratio of
90 wt % resin to 10 wt % copolymer to form a substantially
homogeneous powder blend. The powder blend is pressed into a mold
and heated to a temperature of 200.degree. C. for 1 hour. Table 1
shows the results of the G1C and SpWOF tests.
TABLE-US-00001 TABLE 1 G1C % increase G.sub.1C SpWOF % increase
SpWOF CS1 1304 1635 Sample 1 1890 45% 2446 50%
[0051] Comparative Sample 2 is a phenolic resin based formulation
prepared by pressing a phenolic resin powder into a mold and
heating it to a temperature of 200.degree. C. for 1 hour.
[0052] Sample 2 is prepared as Comparative Sample 2 with the
addition of an amphiphilic block copolymer powder. The phenolic
resin and the amphiphilic block copolymer are blended at a ratio of
90 wt % resin to 10 wt % copolymer to form a substantially
homogeneous powder blend. The powder blend is pressed into a mold
and heated to a temperature of 200.degree. C. for 1 hour. Table 2
shows the results of the G.sub.1C and SpWOF tests.
TABLE-US-00002 TABLE 2 G1C % increase G.sub.1C SpWOF % increase
SpWOF CS2 500 765 Sample 2 620 40% 900 15%
[0053] Comparative Sample 3 is a phenolic resin based formulation
prepared by pressing a phenolic resin powder into a mold and
heating it to a temperature of 200.degree. C. for 1 hour.
[0054] Sample 3 is prepared as Comparative Sample 2 with the
addition of an amphiphilic block copolymer powder. The phenolic
resin and the amphiphilic block copolymer are blended at a ratio of
90 wt % resin to 10 wt % copolymer to form a substantially
homogeneous powder blend. The powder blend is pressed into a mold
and heated to a temperature of 200.degree. C. for 1 hour. Table 3
shows the results of the G.sub.1C and SpWOF tests.
TABLE-US-00003 TABLE 3 G1C % increase G.sub.1C SpWOF % increase
SpWOF CS3 160 720 Sample 3 260 63% 790 10%
[0055] As can be seen by the data provided in Tables 1 through 2,
the addition of particular amphiphilic block copolymer to the resin
of bonded abrasive articles can improve the toughness of the bonded
abrasive articles. Specifically, both the force need to crack the
matrix material and the force needed to break the matrix material
are increased of the comparable formulations without the
amphiphilic block copolymer.
[0056] In another example, a standard abrasive article is prepared
using the formulation detailed in Table 4, below. Table 5 lists the
ingredients for the standard bond referred to in Table 4. A block
copolymer (BCP) abrasive article is also prepared using the same
formulation as detailed in Table 4. However, the BCP abrasive
article includes the addition of a block copolymer, as described
herein, to the standard bond material. The block copolymer includes
a binder immiscible block and a binder miscible block. Further, the
block copolymer includes a PMMA block copolymer. Specifically, the
block copolymer includes polystyrene-b-polybutadiene-b-syndiotactic
poly methyl methacrylate.
[0057] Specifically, the block copolymer is blended with the
standard bond at a ratio of 1:99 (block copolymer to standard
bond). Moreover, the block copolymer is in a solid, powder form to
facilitate thorough mixing and substantially uniform dispersion, as
described herein. Dispersion is determined by taking various
micrographs of the completed BCP abrasive article and determining
the associated dispersion of the toughening domains formed by the
immiscible portion of the block copolymer.
TABLE-US-00004 TABLE 4 Grinding Wheel Formulation. Vol. Type Vol. %
Fract. Wt. % Abr. Alumina- 25.00 1.145 69.58 Zirconia Bond standard
42.10 0.922 29.00 Furf 3.90 0.045 1.42
TABLE-US-00005 TABLE 5 Standard bond. weight % 32% Phenolic Resin
37% Iron Pyrites 21% Potassium Sulfate 2% Alcohol, Tridecyl 8%
Lime
[0058] Once the mixture for each wheel is blended, the powder blend
is pressed into a mold and heated to a temperature of 200.degree.
C. for 1 hour. After the abrasive articles are made, each abrasive
article is placed in a burst testing apparatus. Each abrasive
article is freely spun, or rotated, until each wheel fails
catastrophically, i.e., until it bursts. The speed at which the
abrasive article fails is recorded as the burst speed.
[0059] FIG. 5 shows the results of the burst testing as a simple
bar graph. The standard abrasive article provides a burst speed of
approximately 6800 RPM. The BCP abrasive article constructed using
the block copolymer as described herein provides a burst speed of
approximately 7100 RPM. Accordingly, the BCP abrasive article
constructed using the block copolymer provides a burst speed that
is approximately 4.4% higher than the burst speed of the standard
abrasive articles as given by the formula:
[BS.sub.BCPBS.sub.ST]/BS.sub.ST.times.100%, wherein BS.sub.BCP is
the burst speed of the BCP abrasive article and BS.sub.ST is the
burst speed of the standard abrasive article.
[0060] The above-disclosed subject matter is to be considered
illustrative, and not restrictive, and the appended claims are
intended to cover all such modifications, enhancements, and other
embodiments, which fall within the true scope of the present
invention. Thus, to the maximum extent allowed by law, the scope of
the present invention is to be determined by the broadest
permissible interpretation of the following claims and their
equivalents, and shall not be restricted or limited by the
foregoing detailed description.
[0061] 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.
* * * * *