JPH07109572A - Production of coating body excellent in adhesion - Google Patents

Abstract

PURPOSE:To enhance the adhesive strength between a substrate and a coating film and the peeling resistance and to provide a highly reliable coating body reduced in variance by pretreating the surface of a substrate with a gas and then forming a coating film by CVD. CONSTITUTION:The surface of a substrate of the metal, alloy or ceramic sintered compact is coated with a film. In this case, the substrate is heated as the pretreatment in a pretreating gas consisting of a gaseous halogen and/or a gaseous halogen compd. contg. halogen element or a mixture of the pretreating gas with dilution gas, and then the substrate surface is coated with the film. Consequently, the adhesive strength between the substrate and coating film is increased by about 5-10 times as compared with the conventional production of the coating body by CVD, the variance is reduced, and the quality of the coating body is remarkably improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a chemical vapor deposition method (CVD) on a surface of a base material of a metal, alloy or ceramics sintered body.
Method) for producing a coated object for coating a coating film, specifically, after subjecting a surface of a substrate in a reaction vessel to a pretreatment with a gas, the coating film is coated to form a cutting tool and an abrasion resistant tool. The present invention relates to a method of manufacturing a coated object having excellent adhesiveness for optimizing a tool such as.

[0002]

2. Description of the Related Art Generally, thermal CVD is known as a method for coating a film on a surface of a substrate by a gas phase-gas phase reaction.
The method, plasma CVD method or laser CVD method includes solid phase diffusion reaction, thermal decomposition reaction, hydrogen reduction reaction, complex reaction, hydrogen reduction complex reaction, substitution reaction and the like depending on the reaction mode.

In the coating process performed by these reaction modes, a substrate whose surface has been washed with water, an organic solvent or the like is placed in a reaction vessel, and the inside of the reaction vessel is evacuated or filled with hydrogen gas or an inert gas atmosphere. After that, a first step of raising the temperature and a gas phase containing an element to be a constituent of the coating or an excitation gas addition for exciting the gas phase and an excitation mechanism are provided, and the material is heated and held, and the surface of the substrate is heated. It can be roughly divided into a second step of coating a film and a third step of cooling the inside of the reaction vessel.

The coated article produced through these steps has the problems of poor adhesion between the coating and the substrate, poor adhesion between different coatings, and large variations in adhesion strength.

Many investigations have been made to solve this problem. One of the methods is to clean the surface of the substrate with water or an organic solvent before placing the substrate in the reaction vessel. Typical ones that have attempted to solve the problem of adhesion between different coatings, such as cleaning the substrate surface with ultrasonic waves or etching the substrate surface with an acid or alkaline solvent.
There is JP-A-59-219477.

[0006]

SUMMARY OF THE INVENTION Japanese Patent Laid-Open No. 219477/1984 proposes a method for joining or joining coatings on a coated object, and a cutting plant made of hard metal represented by cemented carbide. Coating the substrate surface of the blade with a thin layer of a refractory metal carbide, nitride or carbonitride, and exposing the thin layer to an oxidizing atmosphere to form an oxide having a hardness higher than that of the refractory metal monoxide; Advanced oxide layer is TiCl ₄ , HfC
l ₄ , ZrCl ₄ One compound of H ₂ and a mixture gas of H ₂ are reduced to form a monoxide on the surface, and then a hard wear-resistant aluminum oxide is coated on the surface of the monoxide. A method for manufacturing a characteristic hard metal cutting tool planting blade is described.

The manufacturing method described in the publication is a method of strengthening the bonding or bonding between a thin layer of a refractory metal carbide, nitride or carbonitride and a hard layer of aluminum oxide. The adhesion between the material and the thin layer has not been improved, and particularly in the case of the base material of the ceramics sintered body, there is a problem that the peeling between the base material and the thin layer shortens the service life.

The present invention solves the above-mentioned problems, and specifically, a halogen compound containing a halogen gas and / or a halogen element is formed before the surface of a substrate is coated with a film by a CVD method. Manufacture to obtain a highly reliable coated object with little variation while increasing the adhesion strength and peeling resistance between the coating and the substrate by performing a pretreatment step of heating the substrate in an atmosphere containing gas. The purpose is to provide a method.

[0009]

Means for Solving the Problems When the coated object is used as a cutting tool, the inventors of the present invention have developed a ceramic sintered body, in which the surface of the substrate is coated with a hard coating, and As a result of studying how to increase the adhesive strength, when coating a film on the surface of a substrate, the adhesiveness between the substrate and the film depends on the consistency of the respective materials, the film thickness,
It is greatly affected by the surface condition of the base material and the coating conditions, but it is necessary to adjust the surface condition of the base material before coating the coating, especially after the base material is placed in the reaction vessel for coating the coating. It was found that it was greatly affected by the surface condition of the base material just before coating, and that heating the base material surface in an atmosphere containing halogen gas or a halogen compound gas containing a halogen element had a greater effect. The invention has been completed.

That is, the method for producing a coated article according to the present invention is a method of coating a film on the surface of a base material of a metal, alloy or ceramics sintered body by a CVD method, which is a halogen compound containing a halogen gas and / or a halogen element. In a pretreatment gas consisting of a gas, or in a mixed gas of the pretreatment gas and a diluent gas (excluding the combination of the treatment gas and the diluent gas such that a film is formed on the surface of the substrate). The method is characterized in that the surface of the substrate is coated with the coating after a pretreatment step of heating the substrate.

The base material in the method for producing a coated article of the present invention is, for example, a metal of group 4a, 5a, 6a of the periodic table, tool steel such as stainless steel, die steel, high speed steel, Al, etc. Alloy, Ti alloy or cemented carbide, sintered alloy such as cermet or silicon nitride ceramics sintered body,
Examples thereof include silicon carbide-based ceramics sintered bodies, aluminum oxide-based ceramics sintered bodies, aluminum nitride-based ceramics sintered bodies, and zirconium oxide-based ceramics sintered bodies.

It is preferable that the surface of these base materials is subjected to conventional cleaning treatment (including ultrasonic cleaning) with water, an organic solvent, an acid solution, an alkaline solution or the like. Then, the substrate is placed in a reaction vessel of an apparatus capable of performing various CVD methods that have been conventionally used, and a halogen gas and / or a halogen element-containing halogen is applied before the surface of the substrate is coated with a coating film. In a pretreatment gas consisting of a compound gas, or in a mixed gas of the pretreatment gas and a diluent gas (excluding the combination of the treatment gas and the diluent gas such that a film is formed on the surface of the base material) A major feature of the production method of the present invention is to perform a pretreatment step of heating the substrate.

The pretreatment gas in the method for producing a coated article of the present invention is, for example, a halogen gas of fluorine, chlorine, bromine, iodine, CCl ₄ , CF ₄ , C ₂ F ₆ , C.
₃ F ₈ , CCl ₂ F ₂ , CBrF ₃ , HF, HCl, CH
F ₃ , WF ₆ , MoF ₆ , TiCl ₄ , AlCl ₃ , Si
Examples include F ₄ , SiCl ₄ , MoO ₂ Cl ₂ , and CrO ₂ Cl ₂ halogenated carbon gas, hydrogen halide gas, halogenated hydrocarbon gas, silicon halide gas, and metal halogenated gas.

In a gas atmosphere of at least one of these pretreatment gases or with the pretreatment gas such as hydrogen, oxygen,
After modifying the surface of the base material by subjecting the base material surface to a pretreatment step of heating the base material to about 400 ° C. or higher in a mixed gas of carbon monoxide and at least one diluent gas among inert gases, the base material This is a method of coating a film on the surface.

It is also preferable to add another step before and after this pretreatment step. In particular, a base material is placed in a reaction vessel, and then the reaction vessel is subjected to a vacuum atmosphere or a non-oxidizing gas atmosphere. It is preferable from the standpoint of adhesion strength between the base material and the coating film to raise the temperature of the base material and then perform the pretreatment step and then coat the surface of the base material with the coating film. It is also preferable that after the above steps, the coating film is further coated by a physical vapor deposition method (PVD method) to form a multilayer film.

The coating used in the method for producing a coated article of the present invention must be selected depending on the application and the material of the base material.
The film is not limited as long as it is a film coated by a conventional CVD method, and specifically, for example, metals of groups 4a, 5a and 6a of the periodic table, their carbides, nitrides, carbonates, oxynitrides and sulfides. , Boride, Al oxides, nitrides, Si carbides, nitrides and mutual solid solutions thereof, or at least one monolayer or multilayer of cubic boron nitride, diamond and diamond-like carbon. it can.

[0017]

The method for producing a coated object according to the present invention comprises a pretreatment gas,
Alternatively, the mixed gas of the pretreatment gas and the diluent gas removes the oxides or impurities that have adhered or oxidized on the surface of the base material to increase the surface roughness, and the film is attached like wedges in the large surface roughness. This has the effect of increasing the adhesive strength between the base material and the coating film, or widens the substantial surface area of the base material surface and allows the coating material to adhere to a large surface area, thereby adhering the base material to the coating film. It has the effect of increasing the strength, and further, when the base material surface is polished, it acts to reduce or eliminate microcracks on the base material surface caused by polishing, resulting in the generation of microcracks. It has an indirect effect of suppressing peeling of the coating film.

[0018]

Example 1 92% Si ₃ N ₄ -5% Y ₂ O ₃ -3% Al ₂
A commercially available silicon nitride-based sintered body having an O ₃ (wt%) composition is JIS
A base material having a standard shape SNMN120412 and having its surface mirror-polished to have a surface roughness Ra of 0.005 μm or less according to JIS standard B0601 was prepared. After cleaning and drying the surface of the base material, the base material was mounted in a reaction vessel of a chemical vapor deposition apparatus, and the temperature was raised according to the conditions of the temperature raising step in Table 1.
The temperature was raised to 00 ° C., and then the pretreatment step, the first coating step, the second coating step, the third coating step and the cooling step shown in Table 1 were sequentially performed to obtain a coated object by the method of the present invention.
At this time, when moving from one step to the next step, the supply of gas was always stopped, and the gas remaining in the reaction vessel was evacuated to 5 Torr or more by an ejector pump.

For comparison, only the pretreatment steps shown in Table 1 were not carried out, and the other steps were all carried out in the same steps as described above to obtain coated objects by the method of comparison.

In order to evaluate the adhesion strength of the coating of the coated article obtained by the method of the present invention and the coated article obtained by the comparative method, a scratch test using a Rockwell diamond indenter was carried out. As a result, the coating produced by the method of the present invention was used. The object did not peel off the coating even under a load of 10 Kgf, whereas the coated article according to the comparative method caused peeling of the film under a load of 1 Kgf.

Among the above-described method of the present invention and the comparative method, only the surface of the substrate is a surface ground with a # 400 grindstone,
Using coated objects obtained by performing the other respectively in the same manner,
Work Material: FC350 (HB208), Cutting Time: 20
Min, cutting speed: 200 m / min, feed: 0.3 mm /
rev, depth of cut: 1.5 mm, as a result of a dry cutting test, the coated object produced by the method of the present invention had an average flank wear amount (V _B ) = 0.19, and no peeling of the coating occurred. On the other hand, in the case of the coated article prepared by the comparative method, the peeling of the coating occurred at the average flank wear amount (V _B ) = 0.52.

[0022]

[Table 1]

[0023]

Example 2 A commercially available cemented carbide having a composition of 92% WC-8% Co (% by weight) was formed into a shape according to JIS standard SNMN12041.
A base material molded into 2 was prepared. This substrate was heated to 1100 ° C. under the conditions of the temperature raising step of Table 2 in the same manner as in Example 1, and then the pretreatment step, first coating step, second coating step, The 3 coating step, the 4th coating step and the cooling step were sequentially performed to obtain a coated object by the method of the present invention.

For comparison, only the pretreatment steps shown in Table 2 were not performed, and the other steps were all performed in the same steps as described above to obtain coated objects by the method of comparison.

As a result of evaluating the adhesion strength of the coating film of the thus-obtained coated article by the method of the present invention and the coated article by the comparative method in the same manner as in Example 1, the coated article by the method of the present invention was subjected to a load of 10 Kgf. No peeling of the coating occurs, whereas the coated object produced by the comparative method has 5 Kgf
The peeling of the coating film occurred under the load of.

[0026]

[Table 2]

[0027]

EFFECTS OF THE INVENTION The method for producing a coated article according to the present invention is remarkably superior in adhesion strength between the substrate and the coating by about 5 to 10 times as compared with the conventional method for producing a coated article by the CVD method. effective.

Claims (2)

[Claims] 1. A method of coating a film on a surface of a base material of a metal, alloy or ceramics sintered body by a chemical vapor deposition method, in a pretreatment gas comprising a halogen gas and / or a halogen compound gas containing a halogen element, Alternatively, a pretreatment step of heating the base material in a mixed gas of the pretreatment gas and a diluting gas (excluding the combination of the treatment gas and the diluting gas such that a film is formed on the surface of the base material). After applying
A method for producing a coated article having excellent adhesion, which comprises coating the surface of the substrate with the coating. 2. A method of coating a film on the surface of a base material of a metal, alloy or ceramics sintered body by a chemical vapor deposition method, which comprises heating the base material in a vacuum or an atmosphere of a non-oxidizing gas. In a pretreatment gas consisting of a halogen gas and / or a halogen compound gas containing a halogen element, or a mixed gas of the pretreatment gas and a diluting gas (provided that a treatment gas for forming a film on the surface of the base material is used). A pretreatment step of heating the base material in (excluding a combination with a diluting gas), and then coating the coating on the surface of the base material. Production method.