JPH0699197B2 - Manufacturing method for coated ceramic tools - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a coated ceramics tool, and more particularly to a method for producing a coated silicon nitride sintered body tool.

[Conventional technology]

Since the silicon nitride (Si ₃ N ₄ ) sintered body has extremely high toughness among general ceramics, it is an Al ₂ O ₃ -TiC sintered body (hereinafter referred to as a sintered ceramic for a cutting tool that has been conventionally used). It was expected to be a highly reliable dream ceramics tool material that is significantly more reliable than that of black ceramics.

However, the hardness of this silicon nitride sintered body is 1500-1700 kg / mm ^{2 in} Vickers hardness, which is softer than that of black ceramics, so that when it is actually used for high-speed cutting of castings, its wear resistance is better than that of black ceramics. Due to a shortage, the area of use was extremely limited. Therefore, Japanese Patent Publication Sho 59-1347
As disclosed in Japanese Patent Publication No. 5, a toughness-rich silicon nitride sinter resistance is used as a base material, and Al ₂ O ₃ having a high wear resistance is formed on this surface.
A coated silicon nitride member coated with a thin film of is proposed.

[Problems to be solved by the invention]

The Al ₂ O ₃ -coated silicon nitride proposed in Japanese Examined Patent Publication No. 59-13475 certainly improves the wear resistance, which is the greatest drawback of the conventional silicon nitride. However, the manufacturing method is chemical vapor deposition, the coating temperature is 1000 ° C., and there is no chemical bond between the silicon nitride sintered body and the Al ₂ O ₃ film, so it cannot be said that the adhesive strength is sufficient. On the other hand, chemical vapor deposition is usually applied to the conventional coated cemented carbide, and the cemented carbide base material and the coating film (mostly TiC) are chemically bonded, resulting in extremely strong adhesive strength. Yes, it wasn't too much of a problem.

Large that in the covering of silicon nitride member above reasons, the film thickness is at most 3μ a limit of Al ₂ O _3, when thicker than when actually cutting the Al ₂ O ₃ film at an early stage it peels There was a flaw. This is a big problem for the cutting work in which the automatic exchange system is widely used.

The present invention is intended to improve the adhesive strength between the base material of the silicon nitride tool and the coating film.

[Means for solving problems]

The present invention comprises Si ₃ N ₄ and at least one component selected from the group consisting of TiCO, Ti carbide, nitride, carbonitride, Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ and WC. While heating the sintered base material containing 5 to 70 wt% in the temperature range of 1200 to 1900 ° C, NO gas, NO ₂ gas, CO gas, CO ₂ gas, NH ₃ gas, N ₂ gas and CH
_After enriching the surface of the base material with a carbide, carbonitride and / or nitride of Si, Ti and / or Zr by holding in an atmosphere of at least one gas selected from the group consisting of ₄ gases , SiCl ₄ , TiCl ₄ and ZrCl _{4 in} the temperature range of 1200-1700 ℃
Al ₂ O in a mixed air flow of AlCl ₃ , CO ₂ and H ₂ containing one or more species
₃ and Si, Ti and / or Zr carbide, carbonitride and / or nitride mixed film or solid solution film is formed to a thickness of 0.1 to 5 μm, and subsequently coated with Al ₂ O ₃ to a thickness of 0.5 to 20 μm. Is a method for producing a coated ceramics tool.

It can be generally considered that the coating temperature in the chemical vapor deposition method may be increased in order to improve the adhesive strength between the base material of the coated silicon nitride member and the coating film. However, as a result of various studies conducted by the inventors of the present invention by increasing the coating treatment temperature, the surface of the base material is altered due to the atmosphere during film formation,
It was found that the expected effect was not always obtained.

Therefore, further research was conducted on a method for preventing the deterioration of the base material surface portion due to the film forming atmosphere, and the method of the present invention was reached. The present invention will be described in detail below in the order of steps. Si ₃ N ₄
As a pre-process of heating the sintered base material to a temperature range of 1200 to 1900 ° C and entering the coating process, a group consisting of NO gas, NO ₂ gas, CO gas, CO ₂ gas, NH ₃ gas and CH ₄ gas is selected. It is kept in an atmosphere consisting of one or more of these gases, so that S
Enrich i, Ti and / or Zr carbonitrides, carbonitrides and / or nitrides.

Note as Si ₃ N ₄ sintered body base material in the present invention, Si ₃ N
₄ and TiCO, Ti carbide, nitride, carbonitride, Al ₂ O ₃ , ZrO
It is preferable to contain 5 to 70% by weight of at least one component selected from the group consisting of ₂ , Y ₂ O ₃ and WC.

When the SiN ₄ sintered body base material is heated to 1200 to 1900 ° C. in a vacuum or kept heated, nitrogen gas is dispersed and released, and an impure phase such as a sintering aid is precipitated at the grain boundary, Or Si ₃ N ₄ , A
As a result of mutual reaction with l ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ or WC, a bore is generated in the surface portion or the surface structure becomes nonuniform. Means pursuant to Al ₂ O ₃ coating in such a surface is also not able to be Al ₂ O ₃ uniformly nucleation, adhesion of the Al ₂ O ₃ film is inferior to this.

In the present invention, CO gas, CO ₂ gas, NO
Gas, NO ₂ gas, NH ₃ , N ₂ and CH ₄ gas in an atmosphere of at least one gas selected from the group consisting of at least 1,200 ~ 1900 ℃ by heating or holding the base material surface Is enriched with SiTi and / or Zr carbonitrides, carbonitrides and / or nitrides, thereby making the base material surface composition uniform. Here, "enrichment" means that, on the surface of a sintered body containing Si ₃ N ₄ as a main component, the proportion of carbonitrides, carbonitrides and / or nitrides of Si, Ti and / or Zr in the surface is More than that, or the disappearance of the Si ₃ N ₄ phase. ,
After the above steps, subsequently, at a temperature of 1200 to 1700 ° C., a mixed gas stream containing Al ₂ Cl ₃ , CO ₂ and H ₂ containing one or more of SiCl ₄ , TiCl ₄ and ZrCl ₄ as a dopant was applied to the surface of the base material. Introduced, 0.1 ~ 5μm thick Al ₂ O ₃ and Si, Ti and Zr
A mixture or solid solution film with one or more of the above-mentioned carbides, carbonitrides and / or nitrides.

SiCl ₄ , TiCl ₄ and Z in the Al ₂ O ₃ coating material gas
One or more of the rCl ₄ dopant gases are added, and the Ti, Si and / or Zr carbonitride, carbonitride and / or nitride enriched in the Ti, Si and / or Zr formed on the surface of the base material by the above process are added. C, N diffused from the oxide layer reacts with Si, Ti and / or
A Zr carbide, carbonitride and / or nitride is obtained, and this film and the Al ₂ O ₃ film react with each other to form a mixed film of Al ₂ O ₃ and a solid solution film. As a result, an intermediate layer that is extremely strongly adhered to the surface of the base material is formed.

The thickness of the intermediate layer is preferably in the range of 0.1 to 5 μm. Film thickness
If it is less than 0.1 μm, the adhesive effect is not sufficient, and if it exceeds 5 μm, the amount of strain in the film increases and peeling easily occurs.

Then, as a final step, a mixed air stream composed of AlCl ₃ , CO ₂ and H ₂ was introduced into the intermediate layer obtained in the above step, and Al ₂ O ₃ was added.
To cover. The thickness of the Al ₂ O ₃ layer is preferably in the range of 0.5 to 20 μm, and if the thickness is less than 0.5 μm, the effect of improving wear resistance cannot be obtained, and if it exceeds 20 μm, the wear resistance decreases. .

As the Al ₂ O ₃ production process, SiCl ₄ , TiCl ₄ , and ZrCl ₄ may be sequentially reduced from the conditions of the above process.

In the above steps, the temperature for forming the enriched layer is 1200
~ 1900 ℃ is preferable, and the coating temperature and the temperature for heating and holding are
The range of 1200 to 1700 ° C is preferred. In the latter case, if the temperature is less than 1200 ° C., the reaction between the films is unlikely to occur, and if it exceeds 1700 ° C., if the reaction time is long, the particles in the base material become coarse and the strength is lowered, which is not preferable.

Hereinafter, a specific description will be given with reference to examples.

〔Example〕

Example 1 TiCO 2%, TiCN 3%, Al ₂ O ₃ 10%, ZrO ₂ 5%, WC 1%, Y ₂
Sintered body (model number SNG120408) consisting of O ₃ 1% and balance Si ₃ N ₄ (above wt%) was placed in an internal heat type chemical vapor deposition device in a carbon reactor in a vacuum atmosphere from room temperature to 1200 ° C. At 1200 ° C to 1800 ° C, CH ₄ atmosphere (100
Torr) heated in, CH ₄ 5% at 1800 ℃, NO 5%, balance N ₂
Heated in gas (above volume%, 100 Torr) for 30 minutes. At further _{1500 ℃, AlCl 3 5%,} CO 2 10%, TiCl 4 5%, the balance
Al ₂ O containing Ti at 30 Torr in H ₂ gas (more than volume%)
₃ was produced to a thickness of 1 μm. Next, TiCl _{4 is set} to 0% and Al ₂ O is added.
₃ was coated to a thickness of 2 μm. As described above, the coated sintered body (A) of the present invention was obtained.

For comparison, 1500 in a vacuum atmosphere in the above example.
After the temperature was raised to 0 ° C, Al ₂ O ₃ alone was coated to a thickness of 3 μm,
It was used as a comparative product (B).

A cutting test was performed on (A) and (B) under the following conditions. In addition, when observing the cross-sectional structure of both, (A)
TiCN was enriched in the surface of the base metal, and a large number of pores were present in (B).

Cutting conditions Work material: FC25 Cutting speed (V): 500m / min Feed (f): 0.36mm / rev Depth of cut (d): 2mm Cutting time: 10 minutes Dry type As a result of the above test, the product of the present invention (A) The flank wear amount (V _B ) was 0.23 mm, while the comparative product (B) was not cut due to wear in 3 minutes.

Example 2 Using the same base material as in Example 1, under the conditions shown in Table 1, 1600 ° C.
The temperature was raised to 100 ° C. to form a coating.

The coated sintered body obtained above was subjected to a cutting test under the same conditions as in Example 1, and as a result, (C), (D), (E)
And the flank wear amount (V _B ) of (F) is 0.20,
It was 0.24, 0.27 and 0.25 mm.

Example 3 Under the conditions of C of Example 2, the temperature was raised and the first layer was heated.
An Al ₂ O ₃ coating containing SiCl ₄ to a film thickness of 3 μm was used as (G), and ZrCl ₄ 1% was added to a film thickness of 3 μm to be used as (H). _{A 2} O ₃ layer was coated to a thickness of 4 μm. The obtained coated sintered body was subjected to a cutting test under the same conditions as in Example 1, and as a result, V _B of (G) and (H) was 0.29 and 0.31 mm.

From the above, it is understood that all of the products of the present invention are Al ₂ O ₃ -coated Si ₃ N ₄ sintered body tools having excellent toughness and wear resistance. It is also clear that the product of the present invention does not cause peeling during cutting even when the outermost layer of Al ₂ O ₃ is 4 μm. This fact indicates that the coating is firmly bonded to the sintered base metal due to the presence of the intermediate layer.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The method of the present invention can provide a coated ceramics tool in which a coating containing Al ₂ O ₃ as a main component, which has excellent wear resistance, is firmly bonded to a Si ₃ N ₄ sintered body having excellent toughness.

Claims (1)

[Claims] 1. At least one component selected from the group consisting of Si ₃ N ₄ and TiCO, Ti carbide, nitride, carbonitride, Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ and WC. While heating the sintered base material containing 5 to 70% by weight to a temperature range of 1200 to 1900 ° C,
Gas, NO ₂ gas, CO gas, CO ₂ gas, NH ₃ gas, N ₂ gas and
The surface of the base material was enriched with carbides, carbonitrides and / or nitrides of Si, Ti and / or Zr by being kept in an atmosphere of at least one gas selected from the group consisting of CH ₄ gas. rear,
Al in a mixed air flow of AlCl ₃ , CO ₂ and H ₂ containing at least one of SiCl ₄ , TiCl ₄ and ZrCl _{4 in} a temperature range of 1200 to 1700 ° C.
₂ O ₃ and Si, Ti and / or Zr carbide, nitride and / or nitride mixed film or solid solution film is formed with a thickness of 0.1-5 μm, and subsequently coated with Al ₂ O ₃ with a thickness of 0.5-20 μm A method for producing a coated ceramics tool characterized by the above.