JPH0468388B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical field The present invention relates to a method for producing a coated hard member with excellent heat resistance. (b) Conventional background TiC, which has excellent wear resistance, is applied to the surface of cemented carbide.
Coated cemented carbide parts coated with one or more layers of hard substances such as TiN, Al ₂ O ₃ , etc. are widely used as cutting tool materials that are superior to conventional cemented carbides. It is offered to Among them, double coated cemented carbide parts using Al ₂ O ₃ are
Due to the excellent heat resistance and oxidation resistance of Al ₂ O ₃ ,
It is known as a particularly excellent cutting tool material. In recent years, the cutting conditions required for cutting tool materials have become more severe year by year, and cutting speeds are often exceeding 300 m/min, creating a demand for cutting tool materials with greater wear resistance. . In order to meet these demands, it is known to increase the thickness of the Al ₂ O ₃ coating layer. However, the _CVD method (chemical vapor _deposition method.
It is called CVD method. ), the growth rate of Al ₂ O ₃ is extremely slow at 1/10 to 1/5 compared to TiC and TiN, making it extremely difficult to thicken the film in terms of industrial production. Also, since the growth rate of Al ₂ O ₃ is extremely slow, the reaction atmosphere is usually 10 Torr or more, preferably
It is carried out at 20 Torr to 60 Torr, and if it is lower than that, a sufficient growth rate for industrial purposes cannot be obtained. CVD
It is known that the higher the vacuum in the reaction atmosphere, the more uniform the film thickness becomes.
In the case of Al ₂ O ₃ , due to its growth rate, coating cannot be carried out under a sufficiently high vacuum, resulting in large variations in film thickness and a significant drop in yield, which is undesirable in industrial production. (C) Disclosure of the Invention The present invention provides a method for producing a thick Al ₂ O ₃ coating film, which is preferable for industrial production, has an improved growth rate, and has a significantly improved yield. As a method for obtaining an Al ₂ O ₃ coating film with improved growth rate using the conventional CVD method, Japanese Patent Application Laid-open No. 10314/1983 describes
Reactive gas of CVD method (Al ₂ O ₃ , CO ₂ and/or
CO, H ₂ ) with 0.08% Ti, Zr and/or Hf ions
A method of adding ~0.5% by volume is disclosed. However, although this method certainly improves the growth rate of the Al ₂ O ₃ coating film, it does not bring about any improvement in the variation in film thickness. The features of the present invention are summarized as follows. (1) Generate an Al ₂ O ₃ film using the so-called plasma CVD method activated by plasma. (2) AlCl ₃ and TiCl ₄ are used as reaction gases in a ratio of 0.2 to 30 by volume. Plasma CVD activated by plasma
In this method, the reaction rate is said to depend not so much on the temperature of the base material as on the electron temperature of the plasma (usually said to be several thousand degrees), and compared to the conventional CVD method, it is significantly slower at the same base material temperature. It is known that its growth rate is improved. In addition
When Ti ions were added to the reaction gas, the
The Ti oxide forms a solid solution in Al ₂ O ₃ and improves the surface diffusion rate of Al ions, further improving the growth rate. In addition, in the present invention, the growth rate of Al ₂ O ₃ has been sufficiently improved, so even if the reaction atmosphere is set to a high vacuum, a growth rate suitable for industrial production can be obtained, and the variation in film thickness can be significantly reduced. It can be improved. The raw material gas for Al ₂ O ₃ is a mixed gas of H ₂ , CO and/or CO ₂ and AlCl ₃ , TiCl ₄ titanium, with a titanium tetrachloride/aluminum trichloride ratio of 0.2 to 30.
However, it is preferably 0.2 to 20. If it is less than 0.2, it will not have much effect on improving the growth rate, and if it exceeds 30,
Ti oxides are not preferred because they produce Ti oxide precipitates and have inferior wear resistance compared to Al ₂ O ₃ . (The pressure inside the reactor is 0.1 to 10 Torr, preferably 0.1 to 10 Torr.
It is 2 Torr. ) Below 0.1 Torr, plasma generation is unstable, and above 10 Torr, there is no effect on film thickness uniformity. To generate plasma, 13,
Naturally, the effect is the same even if microwaves are used in addition to 56MHz high-frequency power. Another feature of using the plasma CVD method is that the quality of the Al ₂ O ₃ film can be controlled. That is, with the conventional technology, only α and κ type crystalline products can be produced, but according to the present invention, amorphous and non-crystalline products can be adjusted by controlling the temperature and the magnitude of high-frequency power. I can do it. 13.When using 56MHz high frequency power, 100W~3KW at 500~800℃, 800~
200~1000W between 1000℃, 1000℃~1200℃
A power of 500W or less is preferred. The characteristics of the precipitated Al ₂ O ₃ film change as the reaction temperature and high frequency power decrease.
Amorphous amorphous or a mixed phase with crystalline material can be obtained, and as the power and temperature increase, amorphous amorphous, κ-, and α-Al ₂ O ₃ can be obtained.
The mixed phase of Al ₂ O ₃ has slightly inferior wear resistance, but has good opacity, so by selecting the high frequency power and reaction temperature, it is possible to obtain any desired film quality depending on whether it is a single crystalline substance or a mixed phase. It will be done. Outside these conditions, the grains become coarse when the temperature and high frequency power are high, and a sufficient growth rate cannot be obtained when the temperature and high frequency power are low. As mentioned above, in the present invention, a film quality with higher toughness than that of the conventional Al ₂ O ₃ alone can be obtained, so the substrate can be made of carbides, nitrides, and carbides of group IVa, Va, and VIa elements in addition to cemented carbide. It can also be applied to substrates with low toughness such as cermets made of hard phases such as nitrides, ceramics mainly composed of Al ₂ O ₃ , or ceramics of SiC and Si ₃ N ₄ . Naturally, it can also be applied to base materials with high toughness such as high-speed steel. This will be explained below using examples. Example 1 Commercially available TiC coating chip (product name
AC720) Model number SNMN432 coated with aluminum oxide. The conditions for coating aluminum oxide were as follows. Reaction gas composition H ₂ 90% by volume Al ₂ Cl ₃ 3 〃 CO ₂ 6 〃 TiCl ₄ 0.5 〃 CO 0.5 〃 Reaction gas flow rate 2m/sec Reaction gas pressure 2Torr Temperature 900, 1000℃ Reaction time 5 to 10 hours 13, 56MHz high frequency power under conditions
Coated with Al ₂ O ₃ at 500W. From these results, the growth rate per unit time is shown in FIG. The activation energy in the conventional method is
32 kcal/mol, 7 kcal/mol in the present invention,
Variations in film thickness distribution due to temperature changes are reduced. Under these conditions, at 0.1 Torr, the plasma was unstable, and when the temperature exceeded 10 Torr, the film thickness distribution became large. Example 2 Commercially available TiC coating chip, model number
Al ₂ O ₃ coating was performed using SNMN432 under the following conditions. Note that the conditions other than the composition of the reaction gas were the same as in Example 1 (high-frequency power 500 W). (reaction time
3Hr)

[Table] For comparison with the cutting tips above, commercially available
6μTiC coated with 5μAl ₂ O ₃ (No.
5) A cutting test was conducted under the following conditions. Work material SCM435 Cutting conditions V=400m/min f=0.3mm/rev d=1.5mm After cutting for 3 minutes, No. 1 to No. 3 could be cut with flank wear of 0.25 to 0.28 mm. No.
4. No. 5 was 0.39mm and 0.31mm. Example 3 10% by volume binder phase (Co, Ni) and 60% hard phase
Using a cermet with a composition of TiC, 8% TiN, 2% Mo ₂ C, and residual WC as a base and a 95% Al ₂ O ₃ -5% TiC ceramic as a substrate, the reaction gas composition was the same as in Example 1 and under the conditions shown in Table 2. Coated with 5 μ of Al ₂ O ₃ .

[Table] For comparison, cermet (No. 12) and ceramic (No. 13) coated with 5 μAl ₂ O ₃ using the conventional CVD method.
A cutting test was conducted under the cutting conditions of Example 2 (cutting time: 5 minutes), and flank wear was measured.
The results in the table were obtained.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 shows the effect of reaction temperature on the Al ₂ O ₃ coating rate, with A showing the effect of the present invention and B showing the effect of conventional doping alone.

Claims (1)

[Claims] 1. A mixed gas of hydrogen, aluminum trichloride, carbon monoxide and/or carbon dioxide and titanium tetrachloride is applied to a base material of cemented carbide, high speed steel, ceramic or cermet. and the ratio (volume) of titanium tetrachloride and aluminum trichloride is 0.2 to 30.
Flow the mixed gas, and generate plasma in the atmosphere.
Characterized by coating Al ₂ O ₃ film by CVD method
A method for manufacturing a cutting tool with an Al ₂ O ₃ coating film. 2. In claim 1, the pressure in the atmosphere is 0.1 to 10 torr.
A method for manufacturing a cutting tool with an Al ₂ O ₃ coating film. 3 In claim 1 or 2, the plasma CVD method is performed using high frequency power of 13.56MHz, and when the reaction temperature is 500 to 800℃, the power is 100W to 3KW, and 800 to 1000℃. Well then,
A method for producing a cutting tool having an Al ₂ O ₃ coating film, characterized in that the Al ₂ O ₃ film is coated under conditions of 200 W to 1000 W, 1000° C. to 1200° C., and a high frequency power of 500 W or less.