U.S. patent application number 14/654937 was filed with the patent office on 2015-12-03 for surface coated member and method for manufacturing same.
The applicant listed for this patent is SUMITOMO ELECTRIC HARDMETAL CORP.. Invention is credited to Minoru ITOH, Hideaki KANAOKA, Hiroyuki MORIMOTO, Susumu OKUNO, Anongsack PASEUTH, Kazuo YAMAGATA.
Application Number | 20150345013 14/654937 |
Document ID | / |
Family ID | 51020632 |
Filed Date | 2015-12-03 |
United States Patent
Application |
20150345013 |
Kind Code |
A1 |
PASEUTH; Anongsack ; et
al. |
December 3, 2015 |
SURFACE COATED MEMBER AND METHOD FOR MANUFACTURING SAME
Abstract
A surface coated member having improved stability and a longer
service life is provided. The surface coated member includes a base
member and a hard coating formed on a surface thereof. The hard
coating is constituted of one or more layers. At least one layer
among the layers is a layer including hard particles. The hard
particles include a multilayer structure having a first unit layer
and a second unit layer being layered alternately. The first unit
layer includes a first compound. The second unit layer includes a
second compound. The first compound and the second compound are
respectively made of one or more kind of element selected from the
group consisting of a group 4 element, a group 5 element, a group 6
element of a periodic table, and Al, and one or more kind of
element selected from the group consisting of B, C, N, and O.
Inventors: |
PASEUTH; Anongsack;
(Itami-shi, JP) ; YAMAGATA; Kazuo; (Itami-shi,
JP) ; OKUNO; Susumu; (Itami-shi, JP) ;
KANAOKA; Hideaki; (Itami-shi, JP) ; MORIMOTO;
Hiroyuki; (Itami-shi, JP) ; ITOH; Minoru;
(Sorachi-gun, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO ELECTRIC HARDMETAL CORP. |
Itami-shi, Hyogo |
|
JP |
|
|
Family ID: |
51020632 |
Appl. No.: |
14/654937 |
Filed: |
November 11, 2013 |
PCT Filed: |
November 11, 2013 |
PCT NO: |
PCT/JP2013/080395 |
371 Date: |
June 23, 2015 |
Current U.S.
Class: |
428/329 ;
427/255.394; 428/323 |
Current CPC
Class: |
Y10T 428/25 20150115;
Y10T 428/257 20150115; C23C 16/56 20130101; C23C 28/042 20130101;
C23C 28/044 20130101; C23C 16/40 20130101; C23C 16/34 20130101;
C23C 28/42 20130101 |
International
Class: |
C23C 16/34 20060101
C23C016/34; C23C 16/56 20060101 C23C016/56 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2012 |
JP |
2012-287499 |
Claims
1. A surface coated member comprising a base member and a hard
coating formed on a surface thereof, said hard coating being
constituted of one or more layers, at least one layer among said
layers being a layer including hard particles, said hard particles
including a multilayer structure having first unit layers and
second unit layers being layered alternately, said first unit layer
including a first compound, said first compound being made of one
or more kind of element selected from the group consisting of a
periodic table group 4 element, a periodic table group 5 element, a
periodic table group 6 element, and Al, and one or more kind of
element selected from the group consisting of B, C, N, and O, said
second unit layer including a second compound, said second compound
being made of one or more kind of element selected from the group
consisting of a periodic table group 4 element, a periodic table
group 5 element, a periodic table group 6 element, and Al, and one
or more kind of element selected from the group consisting of B, C,
N, and O.
2. The surface coated member according to claim 1, wherein said
surface coated member includes an intermediate layer between said
first unit layer and said second unit layer, and a composition of
said intermediate layer is changed continuously in its thickness
direction from a composition of said first compound to a
composition of said second compound.
3. The surface coated member according to claim 1, wherein said
layer including said hard particles includes a grain boundary layer
in a grain boundary of said hard particles, said grain boundary
including said first compound or said second compound.
4. A method for manufacturing a surface coated member including a
base member and a hard coating, said hard coating being formed on a
surface of said base member and constituted of one or more layers,
the method comprising: a CVD step of forming at least one layer
among said layers by a CVD method, said CVD step including: an
ejection step of ejecting a mixture gas, containing two or more
kinds of elements selected from the group consisting of a periodic
table group 4 element, a periodic table group 5 element, a periodic
table group 6 element, and Al, and one or more kind of element
selected from the group consisting of B, C, N, and O, to a surface
of said base member; and a cooling step of cooling said base member
after said ejection step.
5. The method for manufacturing a surface coated member according
to claim 4, wherein, said base member is cooled at a rate greater
than or equal to 7.degree. C./min in said cooling step.
Description
TECHNICAL FIELD
[0001] The present invention relates to a surface coated member
including a base member and a hard coating formed on a surface
thereof, and a method for manufacturing the same.
BACKGROUND ART
[0002] As a recent technical trend, producing a thinner and shorter
surface coated member for a cutting tool or the like is on the main
stream for the purpose of reducing a load on a global environment
and efficiently utilizing a resource. Accordingly, providing a
metal material having a higher strength and higher hardness used
for a surface coated member is proceeding to secure a service life
of a surface coated member and maintain its reliability. On the
other hand, at metal working sites, it has been strongly requested
to achieve improved accuracy of a worked part and reduced working
cost to compete with newly emerging countries. Further, with the
improvement in the performance of machining tools, the expectation
for further high-speed working with a surface coated member is
increasing. In the high-speed working, since a cutting edge of a
surface coated member is exposed to a high-temperature and
high-pressure environment, a surface coated member capable of
having a longer service life even under a harsh environment will be
requested in the future.
[0003] For example, Japanese Patent Laying-Open No. 7-205362 (PTD
1) discloses a hard coating which coats a surface of a base member
of a surface coated member. In the hard coating, the composition
thereof is changed continuously with nitride, carbide,
carbonitride, or boride of two or more kinds of elements selected
from group 4, 5, 6 elements, Al, and Si at a cycle of 0.4 nm to 50
nm. The above-described hard coating is formed by a PVD (Physical
Vapor Deposition) method. Specifically, TiN layers and AlN layers
are formed continuously on a base material surface with use of
solid Ti, solid Al, and N.sub.2 gas by bringing Ti ion and Al ion,
which are generated by a vacuum discharge, and N.sub.2 gas to be in
contact with a base member heated to 500.degree. C. Since the hard
coating formed by this method has a large distortion in its
structure, a surface coated member having this hard coating can
have a superior wear resistance and toughness.
[0004] Moreover, for example, Japanese National Patent Publication
No. 2008-545063 (PTD 2) discloses a member having a
Ti.sub.1-xAl.sub.xN coating as a surface coated member. This
Ti.sub.1-xAl.sub.xN coating has a single layer structure of a cubic
crystal NaCl structure having a stoichiometric coefficient of
0.75<x.ltoreq.0.93 and having a lattice constant afcc of 0.412
nm to 0.405 nm. The above-described Ti.sub.1-xAl.sub.xN coating is
formed by a CVD (Chemical Vapor Deposition) method. Specifically, a
first gas mixture constituted of AlCl.sub.3, TiCl.sub.4, H.sub.2,
and argon and a second gas mixture constituted of NH.sub.3 and
N.sub.2 as a nitrogen source are introduced into a CVD reactor
vessel of a hot wall type accommodating a base member to perform a
thermal CVD method. The above-described coating formed by this
method has a higher Al content in the coating as compared to the
Ti.sub.1-xAl.sub.xN coating produced by a generally known PVD
method. Therefore, a surface coated member having this coating has
a higher oxidation resistance and a higher hardness and can exhibit
a superior wear resistance at a high temperature.
CITATION LIST
Patent Documents
PTD 1: Japanese Patent Laying-Open No 7-205362
PTD 2: Japanese National Patent Publication No 2008-545063
SUMMARY OF INVENTION
Technical Problem
[0005] However, as to PTD 1, there is a case where the hard coating
formed by the PVD method contains impurities such as metals of Ti,
Al, and alloy of those. Such impurities are referred to as
droplets, which inhibit formation of the hard coating and causes
falling of the hard coating during metal working. Moreover, from
the part where the hard coating has fallen as a starting point,
chipping, fracture, and the like of the hard coating is likely to
occur. Consequently, it becomes difficult to obtain a longer
service life of a surface coated member, and there is a case where
the work quality and surface roughness of the work material are
deteriorated.
[0006] Moreover, as to PTD 2, although the Ti.sub.1-xAl.sub.xN
coating has a stoichiometric coefficient of 0.75<x.ltoreq.0.93,
generally, there is a tendency to cause a large distortion in a
crystal structure when x is greater than 0.7 in this composition.
It is well known that a Ti.sub.1-xAl.sub.xN crystal of a cubic
crystal NaCl structure is modified into a hexagonal crystal wurzite
structure to mitigate the distortion. Particularly, there is a
tendency that this modification is accelerated at a high
temperature.
[0007] During the metal working, a cutting tool and a work material
repeat contact and release, and a load is applied to a surface of a
cutting edge of the surface coated member in the cycles of heating
and cooling. Therefore, a great thermal load is applied all the
time to the surface coated member during the metal working, and a
thermal fatigue occurs. This thermal fatigue accelerates the
above-described modification. Further, along with the repeated
cutting, the hard coating which has once modified is likely to
cause chipping and fracture. Therefore, also in the technique
disclosed in PTD 2, there is a limit on a longer service life of a
surface coated member in a high-speed working.
[0008] The present invention was made in view of the circumstance
described above, and its object is to provide improved stability
and a longer service life to a surface coated member and to provide
a method for manufacturing the same.
Solution to Problem
[0009] The present invention concerns a surface coated member
including a base member and a hard coating formed on a surface
thereof. The hard coating is constituted of one or more layers. At
least one layer among the above-described layers is a layer
including hard particles. The hard particles include a multilayer
structure having first unit layers and second unit layers being
layered alternately. The first unit layer includes a first
compound. The first compound is made of one or more kind of element
selected from the group consisting of a periodic table group 4
element, a periodic table group 5 element, a periodic table group 6
element, and Al, and one or more kind of element selected from the
group consisting of B, C, N, and O. The second unit layer includes
a second compound. The second compound is made of one or more kind
of element selected from the group consisting of a periodic table
group 4 element, group 5 element, group 6 element, and Al, and at
least one element selected from the group consisting of B, C, N,
and O.
[0010] Preferably, the above-described surface coated member
includes an intermediate layer between the first unit layer and the
second unit layer, and a composition of the intermediate layer is
changed continuously in its thickness direction from a composition
of the first compound to a composition of the second compound.
[0011] Preferably, in the above-described surface coated member,
the layer including hard particles includes a grain boundary layer
in a grain boundary of the hard particles, said grain boundary
layer including the first compound or the second compound.
[0012] Moreover, the present invention concerns a method for
manufacturing a surface coated member including a base member and a
hard coating. The hard coating is formed on a surface of the base
member and constituted of one or more layers. The method includes a
CVD step of forming at least one layer among the above-described
layers by a CVD method. The CVD step includes an ejection step of
ejecting a mixture gas, containing two or more kinds of elements
selected from the group consisting of a periodic table group 4
element, a periodic table group 5 element, a periodic table group 6
element, and Al, and one or more kind of element selected from the
group consisting of B, C, N, and O, to the surface of the base
member, and a cooling step of cooling the base member after the
ejection step.
[0013] Preferably, in the above-described manufacturing method, the
base member is cooled at a rate greater than or equal to 7.degree.
C./min in the cooling step.
Advantageous Effects of Invention
[0014] According to the surface coated member of the present
invention, the various characteristics such as a wear resistance
and a welding resistance are improved. Therefore, it exhibits a
superior effect of having improved stability and a longer service
life. Moreover, according to the method for manufacturing a surface
coated member of the present invention, various characteristics
such as a wear resistance and a welding resistance are improved, so
that a surface coated member having improved stability and a longer
service life can be manufactured.
BRIEF DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a schematic cross-sectional view representing a
CVD device used in a CVD step of the present invention.
DESCRIPTION OF EMBODIMENT
[0016] Hereinafter, the present invention will be described in
detail.
[0017] <Surface Coated Member>
[0018] A surface coated member of the present invention has a
configuration including a base member and a hard coating formed on
a surface thereof. Preferably, such a coating coats an entire
surface of the base member. However, even when a part of the base
member is not coated with this coating, or a configuration of the
coating is partially different, it does not depart from the scope
of the present invention.
[0019] Examples of such a surface coated member of the present
invention include a cutting tool, a wear resistant tool, a mold
component, an automobile part, and the like. Among those, the
surface coated member can be suitably used as a cutting tool such
as a drill, an end mill, a cutting edge replaceable-type cutting
tip for a drill, a cutting edge replaceable-type cutting tip for an
end mill, a cutting edge replaceable-type cutting tip for milling,
a cutting edge replaceable-type cutting tip for turning, a metal
saw, a gear cutting tool, a reamer, a tap, or the like.
[0020] <Base Member>
[0021] The base member used in the surface coated member of the
present invention can be anything as long as it has been
conventionally known as a base member of this kind. For example, it
is preferable that the base member is made of any of cemented
carbide (for example, WC-base cemented carbide or a material
containing WC and Co or carbonitride of Ti, Ta, Nb, or the like), a
cermet (mainly composed of TiC, TiN, TiCN, or the like), a
high-speed steel, a ceramic material (titanium carbide, silicon
carbide, silicon nitride, aluminum nitride, aluminum oxide, and the
like), a cubic crystal boron nitride sintered body, and a diamond
sintered body.
[0022] Among those various kinds of base members, it is
particularly preferable to select WC-based cemented carbide or a
cermet (particularly, TiCN-base cermet). This is because these base
members are particularly superior in balance between a hardness and
a strength at a high temperature and have superior characteristics
as a base member of a surface coated member for the above-described
application.
[0023] It should be noted that, when the surface coated member is a
cutting edge replaceable-type cutting tip or the like, such a base
member includes the one having a chip breaker and the one having no
chip breaker, and a cutting-edge ridgeline portion has a shape
including a sharp edge (a ridge at which a cutting face and a flank
intersect), a honing (the one having an R shape given to a sharp
edge), a negative land (the beveled one), and a combination of the
honing and negative land.
[0024] <Hard Coating>
[0025] The hard coating of the present invention is constituted of
one or more layers, and at least one among the layers is a layer
including hard particles. Preferably, the hard coating of the
present invention has a thickness of 3 to 30 .mu.m. When the
thickness is less than 3 .mu.m, there is a case where a wear
resistance is not sufficient. When the thickness exceeds 30 .mu.m,
there is a case where peeling or breaking of the hard coating
occurs frequently due to a great stress applied between the hard
coating and the base member during the intermittent working.
[0026] In the hard coating of the present invention, other layer
may be included as long as at least one layer of hard particles is
included. Other layers may include, for example, an Al.sub.2O.sub.3
layer, a TiB.sub.2 layer, a TiBN layer, an AlN layer (wurtzite
type), a TiN layer, a TiCN layer, a TiBNO layer, a TiCNO layer, a
TiAlN layer, a TiAlCN layer, a TiAlON layer, a TiAlONC layer, and
the like.
[0027] For example, adhesion between the base member and the hard
coating can be improved by including the TiN layer, TiC layer, TiCN
layer, or TiBN layer as a base layer directly above the base
member. Moreover, the oxidation resistance of the hard coating can
be improved by including the Al.sub.2O.sub.3 layer. Moreover,
including an outermost layer made of the TiN layer, TiC layer, TiCN
layer, TiBN layer, or the like can provide a distinctive
characteristic on whether or not the cutting edge of the surface
coated member is used. It should be noted that other layer may be
typically formed to have a thickness of 0.1 to 10 .mu.m.
[0028] It should be noted that, in the present invention, when the
composition of each layer constituting the hard coating is
expressed by the chemical formula such as "TiN" and "TiCN," the
chemical formula not particularly specifying an atomic ratio does
not indicate that the atomic ratio of each element is only "1" but
includes all of the conventionally known atomic ratio.
[0029] Moreover, the hard coating of the present invention can have
an indentation hardness greater than or equal to 3000 kgf/mm.sup.2.
It should be noted that the indentation hardness can be measured by
cutting a sample along a flat plane including a normal line with
respect to the surface of the hard coating of the cutting tool and
pressing an indentor at a load of 25 gmHv with respect to a hard
particle layer in a direction perpendicular to the cut plane.
[0030] <Layer Including Hard Particles>
[0031] The hard coating of the present invention is constituted of
one or more layers, and at least one layer among the layers is a
layer including hard particles (hereinafter, also referred to as
"hard particle layer"). The hard particle layer of the present
invention suitably has a thickness greater than or equal to 1 .mu.m
and less than or equal to 20 .mu.m, more preferably greater than or
equal to 1 .mu.m and less than or equal to 15 .mu.m. When the
thickness is less than 1 .mu.m, there is a case where the wear
resistance is insufficient. When the thickness exceeds 20 .mu.m,
there is a case where peeling or breaking of the hard coating
frequently occurs due to a great stress applied to the hard coating
and the base member during the intermittent working. It should be
noted that, even when the hard particle layer of the present
invention partially includes the configuration other than the hard
particles, for example, includes an amorphous phase or a wurtzite
hard phase, it does not depart from the scope of the present
invention as long as the effect of the present invention is
exhibited.
[0032] <Hard Particles>
[0033] The hard particles of the present invention include a
multilayer structure having the first unit layers and the second
unit layers being layered alternately. It should be noted that,
even when the hard particles of the present invention partially
include the configuration other than the multilayer structure, for
example, include an amorphous phase or a wurtzite hard phase, it
does not depart from the scope of the present invention as long as
the effect of the present invention is exhibited.
[0034] The above-described first unit layer includes a first
compound made of one or more kind of element selected from the
group consisting of a periodic table group 4 element, a periodic
table group 5 element, a periodic table group 6 element, and Al,
and one or more kind of element selected from the group consisting
of B, C, N, and O. The above-described second unit layer includes a
second compound made of one or more kind of element selected from
the group consisting of a periodic table group 4 element, a
periodic table group 5 element, a periodic table group 6 element,
and Al, and one ore more kind of element selected from the group
consisting of B, C, N, and O. It goes without saying that the
composition of the first compound and the composition of the second
compound are different.
[0035] The first compound and second compound made of one or more
kind of element selected from the group consisting of a periodic
table group 4 element, a periodic table group 5 element, a periodic
table group 6 element, and Al, and one or more kind of element
selected from the group consisting of B, C, N, and O respectively
include TiC, TiN, TiCN, TiNO, TiCNO, TiB.sub.2, TiO.sub.2, TiBN,
TiBNO, TiCBN, ZrC, ZrO.sub.2, HfC, HfN, TiAlN, TiAlCrN, TiZrN,
TiCrN, AlCrN, CrN, VN, N, AlTiCrN, TiAlCN, ZrCN, ZrCNO,
Al.sub.2O.sub.3, AlN, AlCN, ZrN, TiAlC, NbC, NbN, NbCN, Mo.sub.2C,
WC, W.sub.2C and the like. It should be noted that even when
inevitable impurities are included in the first compound and second
compound, it does not depart from the scope of the present
invention.
[0036] The first unit layer and second unit layer of the present
invention may have a configuration of a single composition or a
configuration in which respective compositions are changed in the
respective thickness directions. Such a configuration in which the
composition is changed will be described for easy understanding by
referring to the case where the composition at a midpoint in the
thickness direction of the first unit layer is
Al.sub.0.9Ti.sub.0.1N and where the composition at a midpoint in
the thickness direction of the second unit layer is
Al.sub.0.1Ti.sub.0.9N.
[0037] In the above-described case, the first unit layer, as to its
composition in the thickness direction, contains
Al.sub.0.9Ti.sub.0.1N at the midpoint, and the composition can be
changed, from the midpoint to the side in contact with the adjacent
second unit layer, into the composition having the atomic ratio of
Al being gradually reduced from Al.sub.0.9Ti.sub.0.1N. Moreover,
the second unit layer, as to its composition in the thickness
direction, contains Al.sub.0.1Ti.sub.0.9N at the midpoint, and the
composition can be changed, from the midpoint to the side in
contact with the adjacent first layer, into the composition having
the atomic ratio of Ti being gradually reduced from
Al.sub.0.1Ti.sub.0.9N. In other words, in this case, there is no
clear boundary in the composition between the first unit layer and
the second unit layer.
[0038] Moreover, in the above-described multilayer structure, the
thickness in the layer cycle is preferably greater than or equal to
0.5 nm and less than or equal to 20 nm. It is difficult to set the
layer cycle to be less than 0.5 nm in the sense of manufacturing
technique. This is because, when the layer cycle exceeds 20 nm, the
distortion between the unit layers is alleviated, and the superior
characteristic as the hard phase is deteriorated. Herein, the
thickness of the layer cycle represents a distance from one first
unit layer to other adjacent first unit layer across the second
unit layer adjacent to the one first unit layer (when an
intermediate layer described later is included between the first
unit layer and the second unit layer, the intermediate layer
adjacent to the second unit layer is included). It should be noted
that this distance is a distance connecting midpoints of each of
the first unit layer and the other first unit layer in the
thickness direction of each layer.
[0039] The number of layers (the total number of layers)
constituting this multilayer structure layer is not particularly
limited but is preferably greater than or equal to 10 layers and
less than or equal to 1000 layers. This is because, when the number
of layers is less than 10 layers, the crystal grains in each layer
become coarse and large, so that there is a case where the hardness
of the hard panicles is lowered, and it shows a tendency that each
unit layer becomes thinner when the number exceeds 1000 layers and
each of the layers is mixed.
[0040] It should be noted that the multilayer structure and the
particle diameter of the hard particles can be confirmed by means
of a scanning electron microscope (SEM), a transmission electron
microscope (TEM), a scanning electron microscope energy dispersive
X-ray spectroscopy (EDX), an X-ray diffraction method, and the
like. Since it is difficult to obtain hard particles having a
particle diameter of less than 10 nm in the sense of manufacturing
technique, and the particles having a particle diameter larger than
1000 nm causes falling and chipping, the particle diameter of hard
particles is preferably greater than or equal to 10 nm and less
than or equal to 1000 nm.
[0041] In the present invention, the cause of improvement in the
various characteristics such as the wear resistance and the welding
resistance of the surface coated member by coating the base member
with hard coating including a hard particle layer is unknown, but
the following cause is presumed. In other words, among the
plurality of layers constituting the hard coating, at least one of
the layers is constituted of a hard particle layer, so that the
hard coating can have a region of a granular structure in its
thickness direction. Accordingly, the toughness of the hard coating
is improved. Moreover, even when a crack occurs on the surface of
the hard coating, development of the crack into the base member can
be suppressed effectively. Then, this effect is particularly
fostered when each particle in the granular structure has a
multilayer structure.
[0042] <Intermediate Layer>
[0043] The hard coating of the present invention can include an
intermediate layer between the first unit layer and the second unit
layer. The composition of this intermediate layer is changed
continuously in its thickness direction from the composition of the
first compound to the composition of the second compound from the
side in contact with the first unit layer to the side in contact
with the second unit layer. For example, in the case where the
composition of the first compound is TiN and where the composition
of the second compound is AlN, the intermediate layer can have the
configuration having an atomic ratio of Ti reduced and an atomic
ratio of Al increased from the side in contact with the first unit
layer to the side in contact with the second unit layer. Moreover,
for example, in the case where the first compound is TiAlN and
where the second compound is AlN, the intermediate layer can have
the configuration having an tomic ratio of at least Ti reduced
continuously from the side in contact with the first unit layer to
the side in contact with the second unit layer.
[0044] Moreover, the thickness of the intermediate layer is not
particularly limited. For example, the thickness of the
intermediate layer may be substantially equal to or smaller than
the thickness of the first unit layer or second unit layer.
Moreover, the thickness of the intermediate layer may be
exceedingly greater than the respective thickness of the first unit
layer or second unit layer. In other words, the thickness of the
first unit layer and second unit layer may be exceedingly smaller
than the intermediate layer.
[0045] In the present invention, the hard particle layer includes
the intermediate layer between the first unit layer and the second
unit layer, so that various characteristics such as the wear
resistance and chipping resistance of the surface coated member
further improves. However, the cause is not clear. For example, it
is considered that the cause is related to the fact that a large
distortion is accumulated in the hard particle layer since
providing the intermediate layer changes the composition
continuously between the first unit layer and the second unit
layer. Moreover, it is considered that the cause is related to the
fact that, since the layer becomes more thermally stable, the
modification due to a thermal shock becomes more unlikely to occur,
and the adhesion strength with the first unit layer and the second
unit layer becomes higher due to the presence of the intermediate
layer.
[0046] Moreover, the intermediate layer can be recognized as the
first unit layer and/or second unit layer. For example, the case is
assumed where the first compound is TiN, and the second compound is
AlN, and the composition of the intermediate layer is
Ti.sub.xAl.sub.yN, and the atomic ratio x of Ti decreases
continuously from 1 to 0 and the atomic ratio y of Al continuously
increases from 0 to 1 from the side in contact with the first unit
layer to the side in contact with the second unit layer. In this
case, for example, in the intermediate layer, the region having the
atomic ratio x/y of Ti and Al is greater than or equal to 1 can be
recognized as the first unit layer, and the region having the
atomic ratio x/y of less than 1 can be considered as the second
unit layer. In this case, the first unit layer and second unit
layer have no clear boundary. It should be noted that, when the
thickness of the first unit layer and/or second unit layer is
exceedingly smaller than the intermediate layer, the region
including the first compound in the first unit layer becomes a
maximum point of the Ti concentration in the thickness direction of
the layer cycle, and the region including the second compound in
the second unit layer becomes a maximum point of the Al
concentration in the thickness direction of the layer cycle.
[0047] <Preferable Structure of Hard Particle Layer>
[0048] Moreover, in the hard particle layer of the present
invention, preferably, the first compound and second compound are
Ti.sub.xAl.sub.yN respectively (however, the values of x and y are
different respectively in the first compound and second compound),
and more preferably, TiN and AlN. Although the cause of this is not
clear, the following cause is presumed. In other words, in this
case, the first compound and second compound can be TiN having an
fcc crystal structure (in the following, also referred to as
"fcc-TiN") and AlN having an fcc crystal structure (in the
following, also referred to as "fcc-AlN"), and the intermediate
layer can change the composition in its thickness direction
significantly. In such a configuration, being different from the
layer such as fcc-Ti.sub.0.1Al.sub.0.9N having an even composition,
distortion caused by the difference in the thermal expansion
coefficient is present in the layer. With the presence of this
distortion, a shift from the fcc crystal structure to an hcp
crystal structure caused by a thermal load becomes particularly
unlikely to occur Consequently, the various characteristics such as
the wear resistance and welding resistance improve.
[0049] The matter which should be focused is that, when the
thickness of the layer cycle exceeds 100 nm, AlN of the
mechanically stable hexagonal crystal wurtzite structure is
precipitated, and the above-described superior characteristics are
deteriorated
[0050] <Grain Boundary Layer>
[0051] The hard particle layer of the present invention can have a
grain boundary layer constituted of the first compound or second
compound at the grain boundary between the hard particles, in other
words, at the upper most surface of the hard particles. For
example, in the case where the first compound and second compound
are TiN and AlN respectively, the composition of the grain boundary
layer is TiN or AlN. Having this grain boundary layer further
improves the various characteristics such as the wear resistance
and chipping resistance of the surface coated member. However, the
cause of it is not clear. For example, it is surmised that the
presence of the grain boundary layer improves the heat resistance
of the hard particles, or the excessive particle growth of the hard
particles is suppressed. It should be noted that, as to the grain
boundary layer, the thickness thereof is preferably greater than or
equal to 10 nm and less than or equal to 100 nm in view of the
balance between the strength and toughness.
[0052] As described above in detail, according to the surface
coated member of the present invention, the base member is coated
with a hard coating including the hard particle layer, so that the
various characteristics such as the wear resistance and welding
resistance of the surface coated member improves. Thus, the present
invention can provide a surface coated member having improved
stability and a longer service life
[0053] <Method for Manufacturing Surface Coated Member>
[0054] A method for manufacturing a surface coated member according
to the present invention is a method for manufacturing a surface
coated member including a base member and a hard coating formed on
a surface thereof and constituted of one or more layers. The method
includes a CVD step of forming at least one layer among the layers
by a CVD method. The CVD step includes an ejection step of ejecting
a mixture gas, which contains two or more kinds of elements
selected from the group consisting of a periodic table group 4
element, a periodic table group 5 element, a periodic table group 6
element, and Al, and one or more element selected from the group
consisting of B, C, N, and O, to the surface of the base member,
and a cooling step of cooling the base member after the ejection
step. It should be noted that, the method for manufacturing a
surface coated member of the present invention can include other
step as long as the above-described CVD step is performed. Other
step may include, for example, a thermal treatment step such as
annealing, a surface preparation step such as a surface grinding or
a shot blasting, and a CVD step for providing another hard layer.
In the following, each step of the present invention will be
described in detail.
[0055] <CVD Step>
[0056] The CVD step of the present invention is a step of forming
at least one layer among the layers constituting the hard coating
of the present invention by the CVD method. In this CVD step, the
CVD device shown in FIG. 1 can be used.
[0057] Referring to FIG. 1, a plurality of base member setting jigs
3 retaining base members 2 can be provided in a CVD device 1, and
these are covered in a reactor vessel 4 made of heat-resistant
alloy steel. Moreover, a temperature-adjusting device 5 is arranged
around reactor vessel 4, and the temperature in reactor vessel 4
can be controlled by this temperature-adjusting device 5.
[0058] In CVD device 1, a teed pipe 8 having two feed ports 6, 7 is
arranged. Feed pipe 8 is arranged so as to pass through the region
having base member setting jigs 3 arranged therein, and a plurality
of through holes are formed in the portion near base member setting
jigs 3. In feed pipe 8, each gas introduced into the pipe from feed
ports 6, 7 are not mixed in feed pipe 8 and are introduced into
reactive vessel 4 through different through holes. Feed pipe 8 can
rotate its axis as a center axis. Moreover, an exhaust pipe 9 is
arranged in CVD device 1, and exhaust gas can be discharged from an
exhaust port 10 of exhaust pipe 9 to outside. It should be noted
that, the jigs in reactor vessel 4 are typically made of black
lead.
[0059] In this step, the CVD device shown in FIG. 1 is used to
perform the ejection step and cooling step described below, so that
the above-described hard particle layers can be formed.
[0060] <Ejection Step>
[0061] In this step, with use of the above-described CVD device,
mixture gas containing two or more kinds of elements selected from
the group consisting of a periodic table group 4 element, a
periodic table group 5 element, a periodic table group 6 element,
and Al, and one or more kind of element selected from the group
consisting of B, C, N, and O is ejected to the surface of the base
member.
[0062] Specifically, for example, first gas containing two or more
kinds of elements selected from the group consisting of a periodic
table group 4 element, a periodic table group 5 element, a periodic
table group 6 element, and Al is introduced from feed pipe 6 to
feed pipe 8, and second gas containing one or more kind of element
selected from the group consisting of B, C, N, and O are introduced
from feed port 7 to feed pipe 8. It should be noted that the first
gas may be mixture gas, for example, first mixture gas of source
gas containing the group 4 element, source gas containing the group
5 element, and carrier gas. The second gas may also be mixture gas,
for example, second mixture gas of source gas containing B, source
gas containing C, and carrier gas.
[0063] Since a plurality of through holes are formed in feed pipe 8
on the upper side of the drawing, the introduced first gas (or
first mixture gas) and second gas (or second mixture gas) are
ejected to reactor vessel 4 from different through holes. At this
time, feed pipe 8 is rotated about its axis as indicated by the
rotating arrow in the drawing. Therefore, the first gas (or first
mixture gas) and second gas (or second mixture gas), as evenly
mixture gas, are ejected to the surfaces of base members 2 set on
base member setting jigs 3.
[0064] As the gas containing two or more kinds of elements selected
from the group consisting of a periodic table group 4 element, a
periodic group 5 element, a periodic table group 6 element, or Al,
chloride gas of these can be favorably used. Moreover, boron
chloride gas such as BCl.sub.3 gas can be used as gas containing B.
Hydrocarbon gas such as CH.sub.4 can be used as gas containing C.
Gas containing nitrogen such as ammonia or N.sub.2 can be used as
gas containing N. H.sub.2O (vapor) can be used as gas containing O.
It should be noted that the hydrocarbon gas is preferably
unsaturated hydrocarbon.
[0065] Moreover, in this step, the temperature in reactor vessel 4
is preferably within the range of 700 to 900.degree. C., and the
pressure in reactor vessel 4 is preferably 0.1 to 13 kPa. Moreover,
H.sub.2 gas, N.sub.2 gas, and Ar gas can be used as carrier gas. It
should be noted that the composition of the first unit layer,
second unit layer, intermediate layer, grain boundary layer, and
the like can be controlled by a mixing ratio of the source gas. The
thickness of the hard particle layer can be controlled by adjusting
a flow of the source gas and a film-forming time. The respective
thicknesses and layer cycles of the first unit layer, the second
unit layer, and the intermediate layer can be controlled by
adjusting the film-forming time and the cooling rate. The number of
layers of the hard particle layers can be controlled by adjusting
the rotating speed of feed pipe 8 and the film-forming time.
[0066] <Cooling Step>
[0067] Next, in this step, base members 2 are cooled after the
ejection step. For example, base members 2 set on base member
setting jigs 3 can be cooled by temperature-adjusting device 5.
Typically, base members 2 subjected to the thermal CVD treatment in
a CVD furnace are cooled naturally by leaving. In this case, the
cooling rate does not exceed 5.degree. C./min, and the cooling rate
becomes lower as the temperature of base members 2 is lowered. On
the other hand, according to the present invention, base members 2
are cooled at a rate which is at least higher than the natural
cooling, in other words, cooled at a rate higher than or equal to
5.degree. C./min. More preferably, base members 2 are cooled at a
rate higher than or equal to 7.degree. C./m. Moreover, in this
cooling step, it is preferable to cool base members 2 at least to
the temperature lower than or equal to 300.degree. C. Accordingly,
more even hard particle layers can be formed.
[0068] The above-described hard particle layers can be formed by
the method described above in detail. Therefore, by forming the
hard coating with use of the manufacturing method, a surface coated
member having improved characteristics such as the wear resistance
and welding resistance can be manufactured. Thus, the present
invention can provide a surface coated member having improved
stability and a longer service life.
EXAMPLES
[0069] In the following, examples of the present invention will be
described in detail. However, the present invention is not limited
to the examples.
[0070] <Preparation of Base Member>
[0071] A base member A and a base member B described in the Table 1
below were prepared. Specifically, the material powders of the
blend compositions described in Table 1 were evenly mixed and
press-formed into a predetermined shape, and thereafter sintered at
1300 to 1500.degree. C. for one to two hours, so that base members
made of cemented carbide having two kinds of shapes including
CNMG120408NUX and SEET13T3AGSN-G were obtained. In other words, two
different kinds of shapes were provided for each base member.
[0072] Both of the two kinds of shapes described above are
manufactured by Sumitomo Electric Hardmetal Division. CNMG120408NUX
is a shape of a cutting edge replaceable-type cutting tip for
turning, and SEET13T3AGSN-G is a shape of a cutting edge
replaceable-type cutting tip for rotary cutting (milling).
TABLE-US-00001 TABLE 1 Blend Composition (Mass %) Co
Cr.sub.3C.sub.2 TaC WC Super Hard A 5.2 0.5 -- Remainder Base
Members B 10.0 -- 2.0 Remainder
[0073] <Formation of Hard Coating>
[0074] A hard coating was formed on the surface of each base member
obtained as described above. Specifically, the CVD) device shown in
FIG. 1 was used, and the base members were set on base member
setting jigs 3, and a thermal CVD method was conducted to form the
hard coating on the base members. The conditions for forming each
hard coating were as described in Table 2 and Table 3, and a flow
of source gas, a mixing ratio of source gas, a film-forming time,
and a cooling rate were adjusted so as to obtain each thickness
described in Table 4. It should be noted that Table 2A shows
forming conditions for hard particle layers, and Table 2B shows
forming conditions for conventional hard layers, and Table 3 shows
forming conditions for other layers.
[0075] As shown in Table 2A, there were seven forming conditions a
to g for the hard particle layers. As shown in FIG. 2B, x and y
were conditions for Comparative Examples (Conventional Art). In the
forming conditions a to g, AlCl.sub.3 gas was used as source gas
containing Al, and TiCl.sub.4 gas was used as source gas containing
Ti, and these source gases were introduced from feed port 6 to feed
pipe 8 as first mixture gas together with the carrier gas
constituted of H.sub.2 gas and N.sub.2 gas. Moreover, with use of
NH.sub.3 gas as source gas containing N, the source gas together
with carrier gas constituted of N.sub.2 gas were introduced from
feed port 7 to feed pipe 8 as the second mixture gas. Then, feed
pipe 8 was rotated to allow the first mixture gas and second
mixture gas to be ejected from the through holes of feed pipe 8 to
thereby eject the mixture gas evenly containing the first mixture
gas and second mixture gas toward the surfaces of the base members.
After that, with temperature-adjusting device 5, the base member
was cooled after the ejection step
[0076] Specifically, in the forming condition a for example, the
first mixture gas was obtained by mixing AlCl.sub.3 gas of 0.065
mol/min, TiCl.sub.4 gas of 0.025 mol/min, and Hz gas and N.sub.2
gas of 2.9 mol/min and 1.0 mol/min, and the first mixture gas was
introduced from feed pipe 6 into reactor vessel 4. Thus, the atomic
ratio of Al/Ti in the first mixture gas was 2.6. Moreover, the
second mixture gas was obtained by mixing NH.sub.3 gas of 0.09
mol/min and N.sub.2 gas of 0.9 mol/min, and the second mixture gas
was introduced from feed pipe 7 into reactor vessel 4. Reactor
vessel 4 at this time was retained in the condition with the
pressure of 1.3 kPa and the temperature of 800.degree. C. Then, the
first mixture gas and second mixture gas were ejected from the
through holes of feed pipe 3 by the rotation of feed pipe 8, so
that mixture gas constituted of evenly mixed first mixture gas and
second mixture gas was ejected to the surface of the base member.
After that, reactor vessel 4 was cooled at a cooling rate of
10.degree. C./min until the temperature of the base member after
the heat ejection step reached 200.degree. C.
[0077] Moreover, referring to Table 2A, the forming condition a
provides "TiN (2 nm)/AlN (6 nm)." This indicates that the thickness
of the TiN layer as the first unit layer was 2 nm, and the
thickness of the AlN layer as the second unit layer was 6 nm, and
the layers were layered alternately. The "layer cycle" indicates a
distance from a midpoint in the thickness direction of TiN layer to
a midpoint in the thickness direction of an adjacent TiN layer
through one AlN layer, in other words, a sum of the thickness of
one TiN layer and the thickness of one AlN layer. It should be
noted that the thickness of the hard particle layer was controlled
by the film-forming time, and the layer cycle of TiN and AlN in the
hard particle layer was controlled by the cooling rate of feed pipe
8.
[0078] Moreover, each layer other than the hard particle layers
described in Table 3 were also formed in a similar manner except
for that all of the gases such as source gas and carrier gas were
introduced from feed port 6 and that the base member was cooled by
the natural cooling after the thermal CVD treatment. It should be
noted that the "Remainder" in Table 3 indicates that H.sub.2 takes
up the remainder of the source gas (reaction gas). Moreover. "Total
Gas Amount" indicates a total amount of flow introduced into the
CVD furnace per unit time with gas in the reference condition
(0.degree. C., 1 atmospheric pressure) as ideal gas.
[0079] In the forming condition x, the hard coating was formed with
use of the PVD method disclosed in PTD 1, and the hard coating was
formed with use of the CVD method disclosed in PTD 2 in the forming
condition y. It should be noted that, in the forming condition x, a
layer (AlN/TiN layer) of a layered structure in which the TiN layer
having a thickness of 4 nm and the AlN layer having a thickness of
4 nm were alternately layered was formed. In the forming condition
y, a layer constituted mainly of the composition of
Ti.sub.0.1Al.sub.0.9N (Ti.sub.0.1 Al.sub.0.9N layer) was
formed.
TABLE-US-00002 TABLE 2A Characteristics of Layers Film-Forming
Conditions Layer Thickness Al/Ti Ratio Pressure in Temperature in
Cooling and Cycle First Mixed Gas Second Mixed in Raw Furnance
Furnance Rate Forming Method Thickness (nm) (mol/min) Gas(mol/min)
Material (kPa) (.degree. C.) (.degree. C./min) Examples a CVD TiN
(2)/AlN (6) AlCl.sub.3(0.065) NH.sub.3(0.09) 2.6 1.3 800 10.0 Layer
Cycle (8) TiCl.sub.4(0.025) N.sub.2(0.9) H.sub.2(2.9), N.sub.2(1.0)
b CVD TiN (1)/AlN (3.5) AlCl.sub.3(0.065) NH.sub.3(0.09) 2.6 1.3
800 15.0 Layer Cycle (4.5) TiCl.sub.4(0.025) N.sub.2(0.9)
H.sub.2(2.9), N.sub.2(1.0) c CVD TiN (10)/AlN (10)
AlCl.sub.3(0.058) NH.sub.3(0.09) 1.8 2.6 830 7.0 Layer Cycle (20)
TiCl.sub.4(0.032) N.sub.2(0.9) H.sub.2(2.9), N.sub.2(1.0) d CVD TiN
(6)/AlN (3) AlCl.sub.3(0.028) NH.sub.3(0.09) 0.45 1.3 800 10.0
Layer Cycle (9) TiCl.sub.4(0.062) N.sub.2(0.9) H.sub.2(2.9),
N.sub.2(1.0) e CVD TiN (12)/AlN (8) AlCl.sub.3(0.034)
NH.sub.3(0.09) 0.6 2.6 850 7.0 Layer Cycle (20) TiCl.sub.4(0.056)
N.sub.2(0.9) H.sub.2(2.9), N.sub.2(1.0) f CVD TiN (2)/AlN (1)
AlCl.sub.3(0.028) NH.sub.3(0.09) 0.45 1.3 800 15.0 Layer Cycle (3)
TiCl.sub.4(0.062) N.sub.2(0.9) H.sub.2(2.9), N.sub.2(1.0) g CVD TiN
(0.5)/AlN AlCl.sub.3(0.065) NH.sub.3(0.09) 2.6 1.3 780 20.0 (1)
TiCl.sub.4(0.025) N.sub.2(0.9) Layer Cycle (1.5) H.sub.2(2.9),
N.sub.2(1.0)
TABLE-US-00003 TABLE 2B Characteristics of Layers Film-Forming
Conditions Layer Thickness Second Al/Ti Ratio Pressure in
Temperature Cooling Forming and Cycle First Mixed Mixed Gas in Raw
Furnance in Furnance Rate Method Thickness (nm) Gas(mol/min)
(mol/min) Material (kPa) (.degree. C.) (.degree. C./min)
Conventional x PVD TiN (4)/AlN (4) -- Art Layer Cycle (8) y CVD
Ti.sub.0.1Al.sub.0.9N AlCl.sub.3(0.009) NH.sub.3(0.09) 6.0 1 800
3.5 TiCl.sub.4(0.00015) N.sub.2(0.9) (Natural H.sub.2(2.9),
N.sub.2(1.0) Cooling)
TABLE-US-00004 TABLE 3 Configuration of Reaction Atmosphere Cover
Film-Forming Conditions Pressure Temperature Total Gas Composition
Reaction Gas Composition (Volume %) (kPa) (.degree. C.) Amount
(L/min) TiN (Base Layer) TiCl.sub.4 = 2.0%, N.sub.2 = 39.7%,
H.sub.2 = Remainder 6.7 915 63.8 TiN (Outermost TiCl.sub.4 = 0.5%,
N.sub.2 = 41.2%, H.sub.2 = Remainder 79.8 980 45.9 layer) TiCN
TiCl.sub.4 = 2.0%, CH.sub.3CN = 0.7%, H.sub.2 = Remainder 9 860
50.5 TiBNO TiCl.sub.4 = 36.7%, BCl.sub.3 = 0.1%, CO = 1.6%,
CO.sub.2 = 1.7%, N.sub.2 = 61.7%, 6.7 980 80.3 H.sub.2 = Remainder
TiCNO TiCl.sub.4 = 2.1%, CO = 3.2%, CH4 = 2.8%, N.sub.2 = 23.7%,
H.sub.2 = Remainder 16.0 1030 70.5 Al.sub.2O.sub.3 AlCl.sub.3 =
1.6%, CO.sub.2 = 4.5%, H.sub.2S = 0.2%, HCl = 3.5%, H.sub.2 =
Remainder 6.7 1000 46.2
[0080] <Production of Surface Coated Member>
[0081] A hard coating was formed on the base member in accordance
with the above-described conditions of Table 2 and Table 3 to
produce a cutting tool as surface coated members of Examples 1 to
15 and Comparative Examples 1 to 6 shown in following Table 4.
[0082] For example, the cutting tool of Example 13 employs base
member B described in Table 1 as a base member. A TiN layer (base
layer) having a thickness of 1.0 .mu.m was formed as a base layer
on the surface of base member B in the condition of Table 3. A TiCN
layer having a thickness of 3.0 .mu.m was formed on the TiN layer
(base layer) in the condition of Table 3. A hard particle layer
having a thickness of 5.0 .mu.m was formed on the TiCN layer in the
forming condition f of Table 2. A TiN layer (outermost layer)
having a thickness of 0.5 .mu.m was formed on the hard particle
layer in the condition of Table 3. Accordingly, a hard coating
having a total thickness of 9.0 .mu.m was formed on the base
member. The blank (hyphen) in Table 4 indicates that the
corresponding layer is not formed.
[0083] It should be noted that, as to the base layer and the layer
including a multilayer structure, there is a layer which has the
same composition but different thickness. For example, although the
hard particle layer of Example 1 is a layer having a thickness of 5
.mu.m formed by the forming condition a, the hard particle layer of
Example 6 is a layer having a thickness of 8 .mu.m formed in
forming condition a. The difference in the thicknesses of these
layers was controlled by adjusting a forming time of a layer, in
other words, a total time of ejecting the first gas and second gas
alternately onto the surface of the base member.
TABLE-US-00005 TABLE 4 Layer Configuration and Thickness of Each
Layer Kind Hard Particle Total Layer of Base Layer Layer Outermost
Layer Thickness Base (.mu.m) (.mu.m) (.mu.m) (.mu.m) Example 1 A
TiN (0.5)--TiCN (2.5) a (5.0) -- 8.0 Example 2 A TiN (0.5)--TiCN
(2.5) b (3.0) -- 6.0 Example 3 A TiN (0.5)--TiCN (2.5) d (7.5) --
10.5 Example 4 A TiN (0.5)--TiCN (2.5) f (12.0) -- 15.0 Example 5 A
TiN (1.5) c (10.0) -- 11.5 Example 6 A TiN (1.5) a (8.0) -- 9.5
Example 7 A TiN (1.5) g (3.7) -- 5.2 Example 8 A TiN (1.5) e (15.0)
-- 16.5 Example 9 A TiN (0.5)--TiCN (5.0) d (6.0) -- 11.5 Example
10 B TiN (1.0) a (5.0) TiN (1.0) 6.0 Example 11 B TiN (1.0) d (6.5)
-- 7.5 Example 12 B TiN (1.0) g (5.5) -- 6.5 Example 13 B TiN
(1.0)--TiCN (3.0) f (5.0) TiN (0.5) 9.0 Example 14 B TiN
(1.0)--TiCN (3.0) a (4.0) -- 8.0 Example 15 B TiN (1.0)--TiCN (3.0)
b (2.5) TiBN (0.3)--Al.sub.2O.sub.3 (1.0) 7.8 Comparative A -- x
(10.0) -- 10.0 Example 1 Comparative A TiN (0.5)--TiCN (2.5) x
(5.0) -- 8.0 Example 2 Comparative B TiN (1.0) x (5.0) TiN (1.0)
7.0 Example 3 Comparative A TiN (0.5)--TiCN (2.5) y (5.0) -- 8.0
Example 4 Comparative A TiN (1.5) y (10.0) TiN (0.5) 11.5 Example 5
Comparative B TiN (1.0)--TiCN (3.0) y (5.0) -- 9 Example 6
[0084] <Observation of Hard Particle Layer>
[0085] When the coated hard coating was observed with use of a
transmission electron microscope and an X-ray diffraction method, a
granular structure constituted of hard particles was observed in
the hard particle layer formed in each condition shown in Table 2A.
Moreover, each hard particle had a layered structure in which the
fcc-TiN and fcc-AlN are alternately layered. Further, a layer made
of fine fcc-TiN was present in the grain boundary of each hard
particles. On the other hand, in each layer formed in each
condition shown in Table 2B, the granular structure was not
observed.
[0086] It should be noted that, although the respective thicknesses
of layers constituted of fcc-TiN and layers constituted of fcc-AlN
are shown in Table 2A based on the above-described observation,
this is based on that, in the microscope observation, in the region
where the layer structure is observed, the region having a higher
atomic ratio in Ti than Al is considered as TiN, and the region
having a higher atomic ratio in Al than Ti is considered as AlN. In
other words, the layer constituted of fcc-TiN is changed in its
composition from TiN to AlN continuously as it came closer to the
adjacent layer constituted of fcc-AlN, and the layer constituted of
fcc-AlN was continuously changed in its composition from AlN to TiN
as it came closer to the adjacent layer constituted of fcc-TiN. In
this case, in the thickness direction of the hard particle layer,
the region having the highest atomic ratio in Ti can be considered
as the first unit layer, and the region having the highest atomic
ratio in Al can be considered as the second unit layer, and the
region therebetween having its composition changed can be
considered as the intermediate layer.
[0087] <Cutting Experiment>
[0088] With use of the cutting tool obtained as described above,
the following five kinds of cutting experiments were conducted.
[0089] <Cutting Experiment 1>
[0090] As to the cutting tools of Examples and Comparative Examples
described in the following Table 5 (the base member having a shape
of CNMG120408NUX was used), the machining time to obtain the flank
wear amount (Vb) of 0.20 mm under the following cutting condition
was measured, and the final damage form of the cutting edge was
observed. The result is shown in Table 5. It indicates that, as the
machining time is longer, the wear resistance is superior.
Moreover, it indicates that, as the final damage form is closer to
the normal wear, the welding resistance is superior.
[0091] <Cutting Conditions>
[0092] Work Material: SUS316 round bar outer periphery cutting
[0093] Peripheral Speed: 200 m/min
[0094] Feed Rate: 0.15 mm/rev
[0095] Cutting Amount: 1.0 mm
[0096] Cutting Liquid: Present
TABLE-US-00006 TABLE 5 Cutting Time (min) Final Damage Form Example
1 17.0 Normal Wear Example 3 15.0 Normal Wear Example 7 19.0 Normal
Wear Example 9 20.0 Normal Wear Comparative 7.0 Normal Wear Example
1 Comparative 6.0 Fracture Example 2 Comparative 13.0 Normal Wear
Example 4
[0097] As is clear from Table 5, the cutting tools of the Examples
according to the present invention were, as compared to the cutting
tools of Comparative Examples, superior in both the wear resistance
and welding resistance, and had improved stability and a longer
service life. It should be noted that, in the final damage form of
Table 5, the "Normal Wear" indicates a damage form constituted of
only wear without occurrence of chipping or loss (having a smooth
worn surface), and the "Fracture" indicates a large loss occurred
in the cutting edge.
[0098] <Cutting Experiment 2>
[0099] As to the cutting tools of the Examples and Comparative
Examples described in the following Table 6 (the base member having
a shape of CNMG120408NUX is used), the machining time to obtain the
flank wear amount (Vb) of 0.20 mm under the following cutting
condition was measured, and the final damage form of the cutting
edge was observed. The result is shown in Table 6. It indicates
that, as the machining time is longer, the wear resistance is
superior. Moreover, it indicates that, as the final damage form is
closer to the normal wear, the welding resistance is superior.
[0100] <Cutting Conditions>
[0101] Work Material: FCD700 round bar outer periphery cutting
[0102] Peripheral Speed. 150 m/min
[0103] Feed Rate: 0.15 mm/rev
[0104] Cutting Amount: 1.0 mm
[0105] Cutting Liquid: Present
TABLE-US-00007 TABLE 6 Cutting Time (min) Final Damage Form Example
1 18.0 Normal Wear Example 4 23.0 Normal Wear Example 5 20.0 Normal
Wear Example 8 17.0 Normal Wear Comparative 9.0 Fracture Example 2
Comparative 13.0 Front Boundary Fine Example 4 Chipping
[0106] As is clear from Table 6, the cutting tools of the Examples
according to the present invention were, as compared to the cutting
tools of Comparative Examples, superior in both the wear resistance
and welding resistance, and had improved stability and a longer
service life. It should be noted that, in the final damage form of
Table 6, the "Normal Wear" indicates a damage form constituted of
only wear without occurrence of chipping or loss (having a smooth
worn surface), and the "Fracture" indicates a large loss occurred
in the cutting edge, and the "Front Boundary Fine Chipping"
indicates fine chipping occurred in the cutting edge part forming
the machined surface.
[0107] <Cutting Experiment 3>
[0108] As to the cutting tools of Examples and Comparative Examples
described in the following Table 7 (the base member having a shape
of CNMG120408NUX was used), the machining time (minute) to
occurrence of fracture or chipping in the tool cutting edge under
the following cutting condition was measured. The result is shown
in Table 7. It indicates that, as the machining time is longer, the
fatigue resistant toughness is superior.
[0109] <Cutting Conditions>
[0110] Work Material: SCM435 groove material
[0111] Cutting Speed: 200 m/min
[0112] Feed Rate: 0.3 mm/s
[0113] Cutting Amount: 1.0 mm
[0114] Cutting Liquid: Present
TABLE-US-00008 TABLE 7 Cutting Time (min) Example 1 6.0 Example 2
7.0 Example 3 4.0 Example 5 4.0 Example 6 4.5 Comparative 5.0
Example 2 Comparative 3.0 Example 4 Comparative 1.0 Example 5
[0115] As is clear from Table 7, the cutting tools of the Examples
according to the present invention were, as compared to the cutting
tools having hard coating formed by the conventional CVD method,
superior in the fatigue resistant toughness, and therefore were had
improved stability and a longer service life.
[0116] <Cutting Experiment 4>
[0117] As to the cutting tools of the Examples and Comparative
Examples described in the following Table 8 (the base member having
the shape of ET13T3AGSN-G was used), the path number and cutting
distance to obtain the cutting or flank wear amount (Vb) of 0.20 mm
under the following cutting condition was measured, and the final
damage form of the cutting edge was observed. The result is shown
in Table 8. It indicates that, as the path number is larger (as the
cutting distance is longer), the wear resistance is superior.
Moreover, it indicates that, as the final damage form is closer to
the normal wear, the shock resistance is superior.
[0118] It should be noted that the path number is obtained by
repeatedly performing the rotational cutting with use of a cutter
having one cutting tool (a cutting edge replaceable-type cutting
tip) from one end to the other end of one side surface (the surface
of 300 mm.times.80 mm) of the following work material (shape: a
block-like shape of 300 mm.times.100 mm.times.80 mm) and obtaining
the frequency of repetition (the path number with a value after the
decimal point indicates that the above-described condition is
obtained on the way from one end to the other end). The cutting
distance indicates a total distance of the work material cut before
reaching the above-described condition and corresponds to a product
of the path number and the die length (300 mm) of the
above-described side surface
[0119] <Cutting Conditions>
[0120] Work Material: FC250 block material
[0121] Peripheral Speed: 300 m/min
[0122] Feed Rate 0.3 mm/s
[0123] Cutting Amount: 2.0 mm
[0124] Cutting Liquid: Present
[0125] Cutter: WGC4160R (manufactured by Sumitomo Electric
Hardmetal Division)
TABLE-US-00009 TABLE 8 Cutting Final Damage Path Number Distance
(m) Form Example 10 12.6 3.8 Normal Wear Example 11 11.5 3.5 Normal
Wear Example 13 14.0 4.2 Normal Wear Example 15 15.0 4.5 Normal
Wear Comparative 6.0 1.8 Normal Wear Example 3 Comparative 8.0 2.4
Normal Wear Example 6
[0126] As is clear from Table 8, the cutting tools of the example
according to the present invention were, as compared to the cutting
tools of the Comparative Examples, superior in the wear resistance,
and therefore had improved stability and a longer service life. It
should be noted that, in the final damage form of Table 8, the
"Normal Wear" indicates a damage form constituted only of wear
without chipping or loss (having a smooth worn surface).
[0127] <Cutting Experiment 5>
[0128] As to the cutting tools of the Examples and Comparative
Examples described in the following Table 9 (the cutting tool
having the shape of SEET13T3AGSN-G was used), the path number and
cutting distance to obtain the cutting or flank wear amount (Vb) of
0.20 mm under the following cutting condition was measured, and the
final damage form of the cutting edge was observed. The result is
shown in Table 9. It indicates that, as the path number is larger
(in other words, the cutting distance is longer), the wear
resistance is superior. Moreover, it indicates that, as the final
damage form is closer to the normal wear, the shock resistance is
superior.
[0129] <Cutting Condition>
[0130] Work Material: SUS304 block material
[0131] Peripheral Speed: 160 m/min
[0132] Feed Rate: 0.3 mm/s
[0133] Cutting Amount. 2.0 mm
[0134] Cutting Liquid: Absent
[0135] Cutter: WGC4160R (manufactured by Sumitomo Electric
Hardmetal Division)
TABLE-US-00010 TABLE 9 Path Number Cutting Distance (m) Final
Damage Form Example 10 7.0 2.1 Normal Wear Example 12 8.0 2.4
Normal Wear Example 13 10.0 3.0 Normal Wear Example 14 11.0 33
Normal Wear Comparative 2.5 0.8 Chipping Example 3 Comparative 3.5
1.7 Chipping Example 6
[0136] As is clear from Table 9, the cutting tools of the Examples
according to the present invention were, as compared to the cutting
tools of the Comparative Examples, were superior in both the wear
resistance and shock resistance, and had improved stability and a
longer service life. It should be noted that, in the final damage
form of Table 9, the "Normal Wear" indicates a damage form
constituted of only wear without occurrence of chipping or loss,
and the "chipping" indicates a small loss occurred in the cutting
edge part.
[0137] As described above, the embodiment and examples of the
present invention were described. However, the appropriate
combinations of each embodiment and example described above was
expected from the original.
[0138] It is to be understood that the embodiments and examples
disclosed herein are only by way of example in all aspects, and not
to be taken by way of limitation. The scope of the present
invention is not limited by the description above, but rather by
the terms of the appended claims, and is intended to include any
modifications within the scope and meaning equivalent to the terms
of the claims
REFERENCE SIGNS LIST
[0139] 1 CVD device; 2 base member; 3 base member setting jig; 4
reactor vessel; 5 temperature-adjusting device, 6, 7 feed port, 8
feed pipe, 9 exhaust pipe; 10 exhaust port.
* * * * *