JPH02182881A - Sintered hard alloy with diamond film - Google Patents

Abstract

PURPOSE:To provide a sintered hard alloy with a diamond film having superior adhesion by bringing gas obtd. by exciting gaseous starting material contg. a gaseous carbon source into contact with a sintered hard alloy contg. rare earth elements. CONSTITUTION:Gas obtd. by exciting gaseous starting material contg. a gaseous carbon source is brought into contact with a sintered hard alloy contg. rare earth elements such as Y and Ce to form a diamond film. Methane or CO is preferably used as the gaseous carbon source and diamond is usually synthesized under about 10<-5>-10<-3>Torr pressure. The resulting sintered hard alloy with the diamond film has advantages. For example, the diamond film does not easily exfoliate from the sintered hard alloy even when exposed to high temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cemented carbide coated with a diamond film, and more particularly to a cemented carbide coated with a diamond film having a highly adhesive diamond film.

[Issue 1 & I to be solved by the prior art and the invention] Cemented carbide is made of carbides of high-melting point metals such as tungsten and molybdenum, and is made by adding binder metals such as cobalt and sintering them densely using powder metallurgy. [``Ceramics Dictionary'' edited by Ceramics Association].

Conventionally, the cemented carbide, which is a type of ceramic, has high strength and does not deteriorate even at high temperatures; Cutting tools, grinding tools, etc., which have excellent properties with R1, 11, and are made by forming a diamond film on the surface of an a hard alloy, are known.

However, for example, by forming a diamond film on the surface of cemented carbide, which is a tungsten carbide-based sintered body containing tungsten carbide as a base material and cobalt as a binder, it is possible to create cemented carbide with a diamond film. When manufacturing, cobalt acts as a catalyst and has the effect of dissolving carbon, so there is a problem that a diamond film is difficult to form.Also, even if diamond is formed, the graphitic carbon will simultaneously dissolve the Kl length. By doing so, the diamond film has low vI:adhesion with the 111 material. There are also points 11i [Nao Otsuka, Atsuhito Sawabe Chopsticks, "Diamond Yabuhome" pp. 160-161, Sangyo Tosho 111. Published 947210 in 1988 1゜Also,
Diamond films are formed by low-pressure vapor phase growth, but it is generally said that fine diamond particles do not blend well with the surface of the underlying material, such as cemented carbide.
Id. publication, pp. 182-183].

When using a diamond-coated cemented carbide as the cutting tool or grinding tool, the diamond coating and the cemented carbide must be bonded together because such tools function by vigorously rubbing against the workpiece. The adhesion of the film is considered to be i?(22), and various studies have been made to improve the adhesion.

For example, after selecting a base material that facilitates the formation of carbide-based compounds and growing a diamond film on its surface, heat treatment is performed at a high temperature to form a carbide layer at the interface with the base.
There is a method to increase the density strength [Ibid. Publication, No. 18]
pages 2-183].

Specifically, the diamond film-coated cemented carbide (Japanese Patent Application Laid-Open No. 2003-130002) is a diamond film-coated cemented carbide in which a diamond film is formed on the surface of the cemented carbide through an intermediate layer consisting of carbides, nitrides, borides, oxides, etc. of Na and Valia group metals. 58-126972)),
A cemented carbide with a diamond film formed by forming diamonds on a tungsten R-based Ijfl hard alloy (containing a specific amount of CO and consisting of tungsten carbide with a specific particle size) (see Publication No.) has been reported.

However, such a method does not guarantee that a carbide layer will be uniformly formed at the interface between the base and the diamond film [
It is unclear whether the 182nd item 183 can be reliably formed.

The present invention is based on the above! This was done based on IG information.

An object of the present invention is to provide a diamond film-coated cemented carbide having a diamond film with excellent adhesion to the cemented carbide.

r +W+ +iL! [Means for Solving the Problems] The present invention for solving the above problems is a method of forming a cemented carbide containing a rare earth element by contacting a gas obtained by exciting a raw material gas containing a carbon source gas. This is a cemented carbide with a diamond film, which is characterized by having a diamond film.

The present invention will be explained in detail below.

The diamond film-coated cemented carbide of the present invention is formed by forming a diamond film on a cemented carbide containing 16 earth elements.

The cemented carbide according to the present invention mainly consists of rare elements and cemented carbide components.

Examples of the rare earth elements include scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

These may be used alone or in combination of two or more.

Among these, yttrium is preferred.

It is cerium.

The content of the above elements in cemented carbide is usually 0.
．． 01-10%, preferably 0.02-3%, more preferably 0.02-1lj
It is 1%.

When the content of the above-mentioned stacked elements is less than 0.01% by weight, the effect of adding rare earth elements is small, and there is a tendency that there is almost no difference between the addition of rare earth elements and the case of no addition.
If it exceeds 5%, the strength of the cemented carbide may decrease, and the production cost may increase due to the high price of rare earth elements.

When the content of the Moeki Fuku earth elements is within the range of 0.02 to 1% by weight, not only does it have excellent adhesion to diamond, but it also improves the adhesion of the diamond crystals that make up the diamond film, although the reason is not clear. There is a tendency for the grain size to become smaller, which makes it possible to form a diamond into a Q film, and has the excellent advantage of reducing the surface roughness of the diamond film.

The hard alloy component a may include a carbide of a high melting point metal or a carbide with a high melting point and a binder. As such a cemented carbide, a known cemented carbide can be suitably used, such as a WC-Co alloy, a We-Tie-Go alloy, or a We-Tie-Go alloy.
DingaCJl: o-based alloy, We-Tag-Go-based alloy W
C-TiN-Co alloy, WC-〒1e-Tie-G
o series alloys can be mentioned.

The blending ratio of each component constituting the cemented carbide component to the rare earth element depends on the type of cemented carbide component selected. When using Co, the Co
It is preferable that the amount is 1 to 30% (the remainder being wC).

The method for producing the cemented carbide is not particularly limited as long as it can produce a cemented carbide containing at least the rare earth element and the cemented carbide component in the proportions shown above; For example, the cemented carbide of the present invention containing stacked elements can be produced by mixing the powdered cemented carbide component and the powdered rare earth element by employing a known method for producing cemented carbide. , can be formed by sintering.

More specifically, for example, WC-
When using a Co-based alloy, after pulverizing a raw material consisting of tungsten carbide, cobalt, and the rare earth element,
Auxiliary binders [ethylene glycol, EVA (ethylene-donyl acrylate).

Polybutylene methacrylate, a substance whose main component is adamantane, etc.] are mixed, press-formed, pre-sintered if necessary, then sintered, and processed if necessary to produce cemented carbide products, etc. For example, a manufacturing method can be mentioned.

The average particle size of both the rare earth element and the cemented carbide component is 0.1 to IOpm, preferably 0.
．． It is desirable that it is 5 to 5 Bm.

In addition, the strength of cemented carbide increases as the cemented carbide component and the accumulated grain size become finer. may be impractical in terms of manufacturing method and cost; on the other hand, if the average particle size exceeds lOJLm, it may become brittle.

When sintering a mixture of cemented carbide components and rare earth elements,
The sintering temperature is usually 1350 to 1550°C.

Note that the cemented carbide in the present invention may contain at least the nine earth elements and the cemented carbide component in the ratio shown in +iiij, and in addition to the rare earth element and the cemented carbide component, For example, it may contain free carbon or the like.

The diamond film-coated cemented carbide of the present invention is obtained by forming a diamond film on such a cemented carbide.

The thickness of the diamond film is usually (1,1~
1 (10 ILm, preferably 0.2 to 30 μm.

Note that if the film thickness is less than 0.11 Lm, the surface of the cemented carbide may not be sufficiently covered;
On the other hand, if the length exceeds 1004 m, the diamond film may form a 1q layer due to the difference in thermal expansion between the cemented carbide and the diamond film.

Such a diamond-coated cemented carbide can be manufactured by the method shown below.

In the cemented carbide with a diamond film of the present invention, a diamond film is formed on the cemented carbide by contacting the cemented carbide with a gas obtained by exciting a raw material gas containing a carbon source gas.

Examples of the carbon source gas include paraffinic hydrocarbons such as methane, ethane, propane, and butane; ethylene;
Olefin hydrocarbons such as propylene and butylene; Acetylene hydrocarbons such as acetylene and arylene; Diolefin hydrocarbons such as butadiene; Alicyclic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, and cyclohexane; cyclobutadiene, Aromatic hydrocarbons such as benzene, toluene, xylene and naphthalene; ketones such as diethyl ketone and benzophenone; alcohols such as methanol and ethanol; trimethylamine,
Amines such as triethylamine: phosphoric acid gas, -carbon oxide, carbon peroxide; In addition, although not individual substances, fire service law dangerous substances class 4 and class 1 such as gasoline, kerosene, turpentine oil, ginger oil 2nd petroleum such as, 3rd petroleum such as heavy oil,
Quaternary petroleum oils such as gear oil and cylinder oil can also be used. It is also possible to use a mixture of the various carbon compounds mentioned above.

Among these, preferred are paraffinic compounds such as methane, ethane, and propane, alcohols such as methanol and ethanol, ketones such as acetone and benzophenone, amines such as trimethylamine, carbon dioxide, and -oxidation. It is carbon.

Further, methane and carbon oxide are more preferred, and carbon monoxide and carbon oxide are particularly preferred.

When using methane gas as the carbon source gas, the content of methane gas in the raw material gas is usually less than 5 mol%, preferably less than 1 mol%.

Note that -carbon oxide is particularly preferred because it allows carbon monoxide to be contained in the raw material gas at a high concentration of 1 to 80 mol%, thereby further improving the diamond synthesis rate. .

Furthermore, -carbon oxide is preferably combined with hydrogen gas, and by combining -carbon oxide and hydrogen gas, the growth rate of diamond can be further increased.

In addition, - the combination of carbon oxide and hydrogen gas.

Under the same reaction conditions, a growth rate 2 to 1θ times faster than the combination of methane and hydrogen gas can be expected.

The carbon oxide is not particularly limited, for example, stone 1
5. Sufficiently purified generator gas or water gas obtained by hot reaction of coke or the like with air or steam can be used.

The hydrogen gas is not particularly limited, and may be used, for example, in gasification of petroleum, metamorphosis of natural gas, water gas, etc., electrolysis of wood, etc.
It is possible to use sufficiently refined materials obtained by the reaction of iron with thin water, complete gasification of coal, etc.

In addition, when using a mixed gas consisting of such a combination of hydrogen gas and carbon monoxide as the raw material gas, the content of -carbon oxide gas is usually 0.2 to 80 mol%, preferably 1. The raw material gas is prepared at a ratio of 1 to 60 mol%.

If the content of carbon monoxide gas in the mixed gas is less than 0.2 mol%, the diamond film formation rate will decrease and it may become impossible to form a diamond film on the cemented carbide. be.

On the other hand, if the content of La in the carbon oxide gas exceeds 80 mol %, the purity of the diamond component in the deposited diamond film may decrease.

In addition,! ! An inert gas may be mixed into the X source gas, and the inert gas can be used as a carrier gas for the carbon source gas.

The inert gas is, for example, nitrogen gas.

Examples include argon gas, neon gas, and xenon gas.

As the excitation means for the raw material gas, any method can be used from among the various methods conventionally used for diamond synthesis.

Specifically, for example, plasma decomposition is performed by applying direct current, plasma decomposition is performed by applying high frequency, plasma decomposition is performed by microwave unauthorized discharge, or plasma decomposition is performed in an ion chamber or an ion gun. Examples include various plasma decomposition methods such as an ion beam method in which ions are extracted using an electric field, and thermal decomposition methods in which thermal decomposition is performed by heating with a hot filament. Among these, various plasma decomposition methods are preferred, and decomposition by microwave plasma is the most preferred.

In the present invention, a diamond film is usually formed on the cemented carbide under the reaction conditions shown below.

The reaction pressure when synthesizing diamond is usually 1
0-5 to 103 torr, preferably 10-3 to
It is 103 torr.

In addition, if the reaction pressure is lower than 1O-5 torr, the formation rate of the diamond film may be slowed down.
Even if it is made higher than 0' torr, a corresponding effect may not be expected in some cases.

The surface temperature of the cemented carbide cannot be determined generally since it varies depending on the activation means of the raw material gas, but it is usually room temperature to 1,200°C, preferably 65°C.
The temperature is 0 to 1,100°C.

Note that if the surface temperature is lower than room temperature, the formation of a diamond film may be insufficient and the precipitation of ff1 may increase; on the other hand, if the surface temperature exceeds 1,200°C, The diamond film formed thereon may easily peel off.

The reaction time can be appropriately set depending on the formation rate of the diamond film so as to achieve the diamond film thickness shown above.

Under the above conditions, diamond crystals grow on the cemented carbide to form a diamond film.

The thus obtained diamond-coated cemented carbide has much greater adhesion than conventional ones, so it can be particularly suited for use as various tools such as bits, cutters, and end mills. can.

[Example] (Examples 1 to 6. Comparative Example 1) In this example, tungsten carbide (+L average particle size 2 #Lm) and cobalt (f, average particle size 2 pm) in the amounts shown in Table 1 were used. A raw material powder consisting of 6 frju% and a rare earth element (average particle size 2 gm) of the type and composition h1 shown in Table 1 was pulverized, and then an auxiliary binder was mixed therein and press-molded.

Then, this was pre-sintered (900°C, 1 hour).

Then, main sintering (1,450℃, 2 hours) was performed to obtain JI.
15) A cutting tip made of cemented carbide having a shape conforming to S K 105 PGN422 was prepared.

A cutting tip made of this cemented carbide was cut into Wrangell E (10
Double-fold dilution solution, liquid temperature 50℃, Nikkasei T■) once, pure water once
Then, the surface was washed with CFC (R113) three times to remove dirt, oil components, etc. from the surface. Note that each cleaning operation was for 60 seconds, and among the three Freon cleanings, the second cleaning n1 used ultrasonic treatment, and the third cleaning was steam cleaning.

Next, this cutting chip was placed as a base material in a reaction chamber, and a reaction was carried out under conditions of a base material temperature of 900° C. and a pressure inside the reaction chamber of 50 torr.

In addition, in the above reaction, a mixed gas containing 20 mol % of -carbon oxide gas and hydrogen gas was supplied into the reaction chamber at a rate of 100 scc as a raw material gas, and the frequency was 2, 45 GH.
The output of the microwave power source of z was set to 350W.

The reaction was carried out for 2 hours under these conditions, and the reaction described in 7.
A deposit was obtained on the lli material.

When the obtained deposits were subjected to Raman spectroscopic analysis, it was found that the deposits obtained in Examples 1 to 6 and Comparative Example 1 were diamonds.

Note that the film thickness of the obtained diamond is shown in Table 1.

Further, in this example, a cutting test was conducted on the obtained cutting tip with a diamond film under the following conditions.

Wave cutting material: Al-8 weight% Si alloy Cutting speed: 800m/sec Feed: 0.1mm/ray.

νJ included; 0.25s layer.

Cutting time: 10 minutes, 100 minutes, 1,000 minutes after testing,
Rarely 11 pieces of workpiece material welded to a cutting tip with a diamond film! The state of the cutting edge of the cutting tip was removed with acid and examined using a scanning electron microscope *btru J5M840 manufactured by Hondenshi Co., Ltd.
] The adhesion of the diamond film was evaluated by observation.

The results are shown in Table 1.

The meanings of the symbols in the column of adhesion in Table 1 are shown below.

○: There is no peeling of the diamond film.

Δ・Red・Diamond film partially peeled off.

X: The diamond film was significantly peeled off.

[Effects of the Invention] According to the present invention, (1) Excellent adhesion between the M1 hard alloy and the diamond film.

(2) The diamond film does not easily peel off from the cemented carbide even when exposed to high temperatures.

It is possible to provide a diamond-coated cemented carbide having the following advantages.

Claims (1)

[Claims] (1) Cemented carbide with a diamond film, characterized in that it has a diamond film formed by contacting a cemented carbide containing a rare earth element with a gas obtained by exciting a raw material gas containing a carbon source gas. .