JPH06272045A - Method for heat-treating base material and production of diamond-coated member - Google Patents

Abstract

PURPOSE:To coat the base material of cemented carbide with a diamond thin film with excellent adnesion without causing the thermal deformation of the base material, at the time of forming a diamond thin film on the surface of the base material of cemented carbide by a CVD method, by placing the base material to be treated on a specified fire resistant bottom board. CONSTITUTION:The base material of cemented carbide of a sintered alloy of WC-Co series, WC-TaC-Co series, WC-TiC-Co series or the like or various cermets, etc., is charged to a vessel of BN or the like, which is placed on a bottom board made of refractories such as Al2O3, ZrO2, MgO, Si3N4. Air in the vessel is exhausted, thereafter, a mixed gas such as CO and CH4 as a carbon source forming diamond with an inert gas such as Ar and N2, is introduced into the vessel, and heating is executed, by which the base material is coated with a diamond thin film having extremely high hardness by C formed by the decomposition of CO, CH4 or the like with excellent adhesion without causing the shape change of the base material at a high temp. by the CVD method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for a base material and a method for producing a diamond-coated member, and more specifically, a heat treatment method for a base material capable of performing heat treatment without causing deformation of the base material. In addition, since the dimensional accuracy is good and the adhesion between the base material and the diamond film coating the base material is excellent, a diamond-coated member having improved wear resistance, durability, and service life is manufactured. Regarding the possible methods.

[0002]

2. Description of the Related Art Cutting tools and polishing tools that use a base material made of cemented carbide are widely used. Although such a substrate may be used as it is, in many cases, the surface is coated with a hard film such as titanium carbonitride or alumina, or the substrate surface is further coated with diamond or the like. It is often used as a tool that is coated with a substance having a high hardness to improve its performance. In particular, when coating diamonds, various pretreatments are performed to improve the adhesion of the diamond film to the substrate. As such a pretreatment, a heat treatment has a large effect of improving the adhesiveness. By the way, at the time of such heat treatment, the base material may be deformed by heat or cause dimensional change, and it is desired to prevent this.

More specifically, in heat-treating a base material made of cemented carbide, generally, a method is used in which the base material is placed in a container such as a crucible and heated in a furnace. Although various materials are used as the crucible, ceramics having high heat resistance such as boron nitride are often used. In addition, when a bottom plate on which a base material is placed and a base material are stacked in multiple layers in this container, a floor plate is often placed on each stage and the base material is placed on it. In this way, according to the material of the base material and the purpose of the heat treatment, heating is performed at a predetermined temperature and under a predetermined pressure in the presence of a predetermined atmospheric gas. It may be deformed or its dimensions may change due to.

However, since the cause of such deformation and dimensional change due to heat cannot be uniquely determined, it is the current situation that sufficient preventive measures cannot be taken.

The present invention has been completed based on the above circumstances. An object of the present invention is to provide a heat treatment method for a substrate, which can heat treat the substrate without causing deformation of the substrate or dimensional change of the substrate due to heat.

Another object of the present invention is that the dimensional accuracy is good,
It is an object of the present invention to provide a method for producing a diamond-coated member having a diamond-coated film having excellent adhesion.

[0007]

The invention according to claim 1 for solving the above-mentioned problems, comprises: alumina, zirconia, magnesia, silicon nitride, aluminum nitride, silicon carbide, boron carbide and A heat treatment method for a base material, which comprises heat-treating a base material made of a cemented carbide placed on a floor plate made of a material selected from the group consisting of carbon, and the invention according to claim 2, The heat treatment method is a heat treatment method for a base material according to claim 1, wherein the heat treatment is a treatment for heating the base material to 600 to 1,800 ° C., and the invention according to claim 3 is characterized in that the heat treatment is a nitrogen-containing gas. The heat treatment method for a base material according to claim 1 or 2, which is carried out in an atmosphere according to claim 4, wherein the invention according to claim 4 is the surface of the base material heat-treated by the heat treatment method according to claim 3. , The diamond by the vapor phase method A method for producing the diamond coating member, which comprises forming a thin film.

The method of the present invention will be described in detail below.

(1) Heat Treatment Method for Substrate-Substrate-The substrate in the present invention is made of cemented carbide.

The cemented carbide is not particularly limited,
Various commonly known types and compositions can be used, such as W, Mo, Cr, Co, Ni,
Fe, Ti, Zr, Hf, Nb, Ta, Al, B, G
a, Si, etc. cemented carbides made of one or more metals, cemented carbides of various compositions made of one or more of these metals and carbon, nitrogen, oxygen and / or boron ( Specifically, for example, WC, W-WC,
WC-C, W-WC-C, etc. WC system, Co-C system, C
o-WC, Co-W-WC, Co-WC-C, Co-W
-WC-C, etc. Co-W-C system, TaC etc. TaC _x
System, TiC system such as TiC, MoC _x, Mo-MoC
_x , MoC _x- C system or other Mo-C system, SiC or other Si-
C system, Fe-FeC _x system, etc. FeC system, Al ₂ O ₃ -
Al-Fe-O system such as Fe, Ti-N such as TiC-Ni
i-C system, Ti-Co-C system such as TiC-Co, BN
System, B ₄ C-Fe or the like of Fe-B-C system, Ti such as TiN
-N system, such as AlN _x AlN system, such as TaN _x Ta-
N-based, W-Ta-Co-C such as WC-TaC-Co-C
System, W-Ti-Co-C such as WC-TiC-Co-C
System, W-Ti-T such as WC-TiC-TaC-Co-C
a-Co-C system, W-Ti-C-N system, W-Co-Ti
-C-N system, W-Nb-Co-C system, W-Nb-Ti-
A wide variety of cemented carbides such as Ta-Co-C series) can be mentioned.

Among these, as particularly preferable examples,
For example, a WC-based cemented carbide suitable for cutting tools and the like (specifically, for example, JIS B 4053 uses classification symbols P01, P10, P20, P30, P40,
P series such as P50, M10, M20, M30, M4
M series such as 0, K01, K10, K20, K30,
WC-Co, such as cemented carbide chips for cutting tools such as K series such as K40, for drawing dies such as V series such as V1, V2, V3, etc., cemented carbide chips for centers, cutting tools, etc. W-Co-C cemented carbide, WC-TiC
W-Ti-Ta-Co-C type cemented carbide such as -TaC-Co, or those in which a part of Ta is changed to Nb).

It should be noted that these may contain elements other than the above and additional components. The material and shape of the cemented carbide used may be appropriately selected depending on the purpose of use and the like.

In the present invention, among the tungsten carbide type cemented carbides used as the base material, as a concrete example of a preferable composition, for example, in the cemented carbide having a composition of WC-TiC-Co, tungsten carbide 50-95. By weight, preferably 70-94% by weight, titanium carbide 1-30% by weight, preferably 2-20% by weight, and cobalt 2-20% by weight, preferably 4-10% by weight. You can

Further, in a cemented carbide having a composition of WC-TaC-Co, 80 to 93% by weight of tungsten carbide, preferably 85 to 92% by weight, and 1 to 20% by weight of tantalum carbide, preferably 2 to 10% by weight. %, Cobalt 3-10
% By weight, preferably 4 to 6% by weight.

Further, as a cemented carbide having a composition of WC-Co, 90 to 98% by weight of tungsten carbide, preferably 94 to 97% by weight, and 2 to 10% by weight of cobalt,
Preferable examples thereof include those having 3 to 6% by weight.

The tungsten carbide, the titanium carbide,
The tantalum carbide and the cobalt do not have to be particularly pure, and may contain inevitable impurities as long as the objects of the present invention are not impaired.

For example, the tungsten carbide may contain a trace amount of excess carbon, excess metal, impurities such as oxides, and the like.

The cemented carbide in the present invention is understood as a concept including cermet.

As the cermet, for example, Ti,
Examples include cermet materials containing carbides and nitrides such as W, Mo, Cr, Ta, Nb, V, Zr, and Hf, and metals such as Co, Ni, Cr, Mo, and Fe as sintering aids. It can be used without particular limitation as long as it is generally known as a cermet material.

Specific examples include WC, Mo ₂ C, Cr ₃
C ₂ , TaC, NbC, VC, TiC, ZrC, Hf
C, TaN, NbN, VN, TiN, ZrN, HfN,
Ta (C, O), Ti (C, O), Ti (N, O),
(W, Ti) C, (W, Ta, Ti) C, (W, Ta,
Nb, Ti) C, Ti (C, N), Ti (C, N,
O), (Ti, Zr) C, (Ti, Zr) (C, N), etc., contains Co and / or Ni as a sintering aid, and Cr, Mo, Fe, etc. in addition to Co and / or Ni. You can list the things that you did.

If the cermet is expressed differently from the above, the following expressions are also possible.

As the cermet which can be used in the present invention, WC, TaC and TiN are added to TiC,
It means that Ni or Mo is added as a binder phase, for example, TiC-TaC-Ni, TiC-TaC-Mo, TiC.
-TaC-Ni-Mo, TiC-TiN-Ni, TiC
-TiN-Mo, TiC-TiN-Ni-Mo, TiC
-TiN-TaC-WC-Ni, TiC-TiN-Ta
C-WC-Mo, TiC-TiN-TaC-WC-Ni
-Mo, TiN-TaN-Ni, TiN-TaN-M
o, TiN-TaN-Ni-Mo, TiC-TaN-N
i, TiC-TaN-Mo, TiC-TaN-Ni-M
o, TiC-Ni, TiC-Mo, TiC-Ni-M
o, TiC-Ni, TiC-Mo, TiC-Ni-M
o, TiC-TaN-Ni, TiC-TaN-Mo, T
iC-TaN-Ni-Mo etc. can be mentioned. Note that these may contain other elements or their carbides and / or nitrides.

Regarding the shape of the substrate in the present invention,
There is no particular limitation.

The base material can be, for example, formed into a desired shape in advance during the sintering, and then can be sintered, or after the sintering, the base material can be processed into a desired shape if necessary, and then variously processed. Can be used as a base material for the diamond-coated member of the present invention.

-Floor Plate- The material of the floor plate in the present invention is selected from the group consisting of alumina, zirconia, magnesia, silicon nitride, aluminum nitride, silicon carbide, boron carbide and carbon.
When using a floor board of the above material, the clear reason is not clear, but the cobalt removal phenomenon and coarsening of crystal grains during heat treatment,
Deformation and dimensional change that are considered to be caused by phenomena such as relaxation of internal strain or generation of strain are extremely small. However, when a floor plate made of h-BN is used, the base material is significantly deformed and the dimensions are changed, and the object of the present invention cannot be achieved.

Of these, the alumina is α-
Alumina, γ-alumina, θ-alumina, χ-alumina, κ-alumina, ρ-alumina and the like can be mentioned. The silicon nitride may be either α-type or β-type, and sialon may be used as the silicon nitride. Examples of the carbon include graphite such as artificial graphite and natural graphite, carbon black, and a carbon fiber composite material.

The shape of the floor plate is not particularly limited, and is designed according to the shape of the container that contains the base material. For example, when the container has a bottomed cylindrical shape with an open top, this floor plate is disk-shaped so that it can be placed on the bottom of the container, and the container is a bottomed bat with an open top. At one time, the floor is rectangular or rectangular so that it can be placed on the bottom of the container.

The thickness of the floor plate can be appropriately selected in consideration of easiness of handling or strength thereof, but in many cases, it is appropriately selected from the range of 1 to 10 mm.

-Heat Treatment Conditions- In the method of the present invention, a substrate is placed on the floor plate and heat treatment is performed.

As the heat treatment conditions, the heating temperature range is usually selected from the range of 600 to 1800 ° C., preferably 1,000 to 1600 ° C. When the heating temperature range is within the above range, the modification of the substrate surface is sufficiently promoted. The heating temperature range is 1,80
If the temperature is higher than 0 ° C, the modification of the substrate, which is the object of the present invention, can be achieved for the time being, but the effect of modifying the substrate commensurate with increasing the temperature may not be observed.

The pressure during heat treatment of the substrate is usually 1
The pressure is 0 ^-3 Torr to 2,000 atm (gauge pressure), preferably 1 Torr to 100 atm (gauge pressure).
When the pressure is within the above range, the effect of modifying the base material can be achieved much better.

As an atmosphere when the substrate is heat-treated,
It may be under high vacuum, but it should be performed under reduced pressure with a small amount of nitrogen gas, or under a mixed gas atmosphere of nitrogen gas and an inert gas such as argon so that the partial pressure of nitrogen gas is low. This is preferable because the effect of modifying the surface of the base material is large, especially when the thin film of diamond or the like is formed on the base material after the heat treatment to improve the adhesion between them.

The amount of nitrogen gas that contributes to the improvement of the adhesion between the substrate and the thin film such as diamond varies depending on the type of substrate, the heating temperature, the treatment time, etc., so it cannot be uniquely determined. No, but usually 1 to 760 Torr
Is appropriately selected from the range of 1 to 200 To
rr.

The heat treatment time for the substrate is usually 30 minutes to 5 minutes.
Although it is about time, it is not limited to this and may be appropriately determined according to the type, size, etc. of the base material.

When the base material is placed on a floor plate made of a specific material and heat-treated by the method of the present invention, the reason for this is not clear, but the diamond itself is not deformed or dimensionally changed. Adhesion with a thin film such as is improved.

(2) Method for producing diamond-coated member In the present invention, the surface of the substrate heat-treated as described above is coated with a thin layer of diamonds.

The diamonds referred to here include, in addition to diamond, diamond partially containing diamond-like carbon and diamond-like carbon.

Various methods have been conventionally known as a method for forming a thin layer of diamonds, and there is no particular limitation. However, in the method of the present invention, a carbon source gas is used as shown below. The vapor phase synthesis method can be preferably adopted.

Examples of the carbon source gas include paraffinic hydrocarbons such as methane, ethane, propane and butane; olefinic hydrocarbons such as ethylene, propylene and butylene; acetylene hydrocarbons such as acetylene and allylene; and butadiene. Diolefin hydrocarbons such as allene; cyclopropane, cyclobutane, cyclopentane,
Alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as cyclobutadiene, benzene, toluene, xylene, naphthalene; ketones such as acetone, diethyl ketone, benzophenone; alcohols such as methanol and ethanol; other oxygen-containing compounds Hydrocarbons; amines such as trimethylamine and triethylamine; other nitrogen-containing hydrocarbons; carbon dioxide gas, carbon monoxide, carbon peroxide and the like. Further, the above various compounds may be mixed and used.

Among these, preferred are paraffinic hydrocarbons such as methane, ethane and propane, alcohols such as ethanol and methanol, ketones such as acetone and benzophenone, amines such as trimethylamine and triethylamine, carbon dioxide, and It is carbon oxide, and carbon monoxide is particularly preferable.

Incidentally, these may be used alone,
You may use together 2 or more types as mixed gas.

Further, these may be used as a mixture with an active gas such as hydrogen or an inert gas such as helium, argon, neon, xenon or nitrogen.

A known method for forming the thin layer of diamonds, for example, a CVD method, a PVD method, a PCVD method,
Alternatively, various diamond thin-layer vapor phase synthesis methods such as a combination thereof can be used. Among them, various hot filament methods including EACVD method and various methods including thermal plasma method are usually used. DC plasma CV
Microwave plasma CVD including D method and thermal plasma method
The method etc. can be used conveniently.

The conditions for forming a thin layer of diamonds are not particularly limited, and the reaction conditions usually used in the above vapor phase synthesis method can be applied.

For example, the reaction pressure is usually 10 ^-6
-10 ³ Torr is preferable, and especially 1-800 Torr
It is preferably within the range.

When the reaction pressure is lower than 10 ^-6 Torr, the formation rate of a thin layer of diamonds may be slow. If it is higher than 10 ³ Torr, 10
There is no more effect than that obtained at ³ Torr.

The surface temperature of the base material cannot be unconditionally specified because it depends on the means for activating the raw material gas and the like, but it is usually 300 to 1,000 ° C., preferably 450 to 950 ° C. It should be within the range.

If this temperature is lower than 300 ° C.,
Formation of a thin layer of crystalline diamonds may be inadequate. Further, when the temperature exceeds 1,000 ° C., etching of the formed thin layer of diamonds and graphitization of diamond are likely to occur.

The reaction time is not particularly limited, and it is preferable to appropriately set the reaction time according to the formation rate of the diamond thin layer so that the diamond thin layer has a desired thickness.

The thickness of the thin layer of diamonds formed on the surface of the base material cannot be uniformly set because it depends on the purpose of use of the diamond-coated member and the like, but in the case of tools, it is usually 5 μm or more, preferably , 10 to 50
A value of μm or more is suitable. If the thin layer of diamonds is too thin, it may not be possible to sufficiently coat the surface of the substrate. In this way, when a diamond thin layer is formed on the surface of the heat-treated substrate, formation of fine irregularities on the substrate surface layer portion due to heat treatment, reduction of cobalt content of the substrate surface layer portion, cobalt Adhesion between the substrate surface and the thin layer of diamonds is improved due to various factors such as the formation of a modified layer that prevents the diffusion of diamond.

As described above, according to the method of the present invention,
A diamond coated member can be manufactured.

[0052]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Examples 1 to 5) Length 12.7 mm, width 1
A substrate having dimensions of 2.7 mm and a thickness of 3.18 mm (JIS B4120 nominal code; SPGN12030
8, composition: WC5%, Co2.5%, TiC92.
5%) and a rhombus with a side length of 15.5 mm, a long angle of 35 degrees, and a wall thickness of 4.76 mm (JIS B41).
20 number code: VNGA150408, composition: W
C5%, Co2.5%, TiC92.5%) was used as the base material for the cutting tip.

Table 1 is attached to the bottom of a bottomed cylindrical crucible made of boron nitride.
A base plate made of the material shown in 1 was laid, and the base material was placed directly on the base plate.

Then, heat treatment was performed under the heat treatment conditions shown in Table 1. The warp of the substrate after the heat treatment was evaluated by using a surface shape measuring instrument and a dial gauge together. The results are shown in Table 1.

Next, this heat-treated substrate is placed on a substrate support in a diamond synthesis reaction tube, and a mixed gas of carbon monoxide gas containing 15% by volume of carbon monoxide gas and hydrogen gas is introduced into the reaction tube. Distributed. Then frequency 2.4
A microwave of 5 GHz was introduced to form diamond by the plasma CVD method.

The pressure in the reaction tube was 40 Torr, the temperature of the substrate was 900 ° C., and the reaction was carried out for 10 hours. As a result, a diamond film was formed on the surface of the base material.

The diamond-coated member thus obtained was subjected to an indentation test with a Rockwell tester under a load of 100 kgf to evaluate the adhesion of the diamond film to the substrate. As a result, the peeled area on the surface of the base material by the indentation test was 0.1 mm ² or less, and the adhesion was good.

(Comparative Examples 1 to 4) Heat treatment was performed under the heat treatment conditions shown in Table 1 using the same base material as in the above example except that the floor plate was not used. The warpage of the substrate after the heat treatment was evaluated in the same manner as in Example 1 above. The results are shown in Table 1.

[0060]

[Table 1]

[0061]

According to the method of the present invention, it is possible to provide a method for heating a base material which does not cause warpage or dimensional change in the base material even if heat treatment is performed. Further, by using such a heat-treated base material, it is possible to provide a method for manufacturing a diamond-coated member having a diamond film having good dimensional accuracy and good adhesion.

Claims (4)

[Claims] 1. A cemented carbide placed on a floor plate made of a material selected from the group consisting of alumina, zirconia, magnesia, silicon nitride, aluminum nitride, silicon carbide, boron carbide and carbon, which is placed in a container. A heat treatment method for a base material, which comprises heat-treating a base material made of metal. 2. The base material subjected to the heat treatment is 600 to 1,80.
The heat treatment method for a substrate according to claim 1, wherein the heat treatment is performed at 0 ° C. 3. The heat treatment method for a substrate according to claim 1, wherein the heat treatment is performed in a nitrogen-containing gas atmosphere. 4. A method for producing a diamond-coated member, which comprises forming a diamond thin film on the surface of a substrate heat-treated by the heat treatment method according to claim 3 by a vapor phase method.