JPH0733569B2 - Ni-TiC composite coating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for coating a Ni—TiC composite coating. More specifically, Ni that is useful for imparting wear resistance to tools, molds, etc.
-A method for coating a TiC composite coating with good adhesion.

(Prior Art) Conventionally, in order to impart wear resistance to a tool, a mold, etc., a method of coating a ceramic film such as titanium nitride or titanium carbide by a chemical vapor deposition method or a physical vapor deposition method has been performed.

However, the coating film obtained by this method has poor adhesion to the substrate, and particularly when the film is thicker than 5 μm, the film tends to peel off.

(Object of the invention) The present invention has been made to solve the drawbacks of the conventional method, and the object thereof is a wear-resistant Ni-TiC composite film which has strong adhesion and is difficult to peel even in a thick film. Another object of the present invention is to provide a method which can be easily coated with a simple operation.

(Structure of the Invention) As a result of intensive research to achieve the object of the first aspect, the present inventors have found that when a plasma is generated in a gas phase in which a hydrocarbon gas is mixed with a mixed vapor of nickel vapor and titanium vapor, the hydrocarbon gas Decomposes into carbon and hydrogen in plasma. Ni is difficult to form carbides, whereas Ti is easy to form carbides, it was found that Ni-TiC composites in which Ni crystal grains and TiC crystal grains are finely and uniformly mixed can be formed. The present invention has been completed in view of the fact that the composite is extremely hard and has excellent toughness.

The gist of the present invention is characterized by causing a plasma chemical reaction in a gas phase in which a hydrocarbon gas is mixed in a mixed vapor of nickel, vapor, and titanium vapor to deposit a Ni-TiC composite coating on a substrate. -It is in the coating method of TiC composite coating.

In the present invention, as a method of producing a mixed vapor of nickel vapor and titanium vapor, nickel and titanium metal may be vaporized separately or a nickel-titanium alloy may be vaporized. The hydrocarbon gas mixed with this mixed vapor may be any gas that decomposes into carbon and hydrogen by plasma. However, lower hydrocarbons such as acetylene and methane that are easily decomposed and easily available at low cost are preferable.

Any method may be used as a method of generating plasma that causes a plasma chemical reaction. Explaining based on the ion plating method below, Ni and Ti are melted and vaporized by an electron beam, while hydrocarbon gas such as acetylene is mixed at 10 ^-3 To
It is introduced into the device until stable glow discharge occurs at rr pressure. At this time, applying a positive bias voltage of 50 to 100 V to the probe electrode is effective for promoting the refinement of crystal grains and, as a result, for improving the hardness. It is desirable to heat the substrate in order to improve the adhesion with the composite film. For example, heating to about 400 ° C can be considered, but if it is too high, coarsening of crystal grains will occur and Is TiC dispersed in coarse Ni crystal, or TiC
The Ni particles are dispersed in the crystal, which deteriorates the characteristics of the film. Therefore, it is desirable to keep the temperature of the substrate at about 600 ° C. or lower.

Example 1 As a substrate, 10 m from a 0.8 mm thick SUS304 stainless steel plate
A plate that first appeared in m square was used. The surface of the substrate was polished with emery paper, puffed, and then ultrasonically cleaned in acetone. Immediately before coating, the Ar pressure was set to 1 Pa and a voltage of -4 kV was applied to the substrate to perform argon bombardment for 10 minutes to clean the surface.

The Ni-TiC composite coating was applied to the substrate using a Bunshan type ion plating device. As a mixed vapor source, 25% Ti-Ni 50% Ti-Ni, 75% Ti-Ni, as a comparative example
Four kinds of 100% Ti were used, and these raw materials were heated and evaporated by an electron beam having a filament current of 0.70 A and an acceleration voltage of 10 kV. As the carbon source, a C ₂ H ₂ gas stream having a pressure of 0.11 Pa was supplied. Ionization of gas particles is
Promoted by applying a positive voltage up to 0 V, the ionized gas particles were accelerated towards the substrate by a negative voltage of 2 kV. The substrate was heated and held at 400 ° C. by a Ta heater. Ion brating time is 20 minutes,
A film having a thickness of about 5 μm was obtained. The adhesion and hardness of those films were measured. The hardness was as shown in FIG. According to this, when a Ni-Ti alloy containing 50% or more of Ti is used, a Ni-TiC composite coating having the same hardness as the TiC coating can be obtained. Further, the adhesion of the coating was measured by a heat cycle test. Thermal cycle test is 8 × 10 ^-5 Torr
In the vacuum, the sample was moved from the low temperature part kept at room temperature to the high temperature part kept at 900 ° C to perform rapid heating and quenching. As the results show, many fine cracks were generated on the surface of the TiC film, whereas no cracks were observed in the Ni-TiC film. From this, Ni-TiC
It can be seen that the film has excellent adhesion to thermal cycling.

Example 2 A SUS304 sample coated with the Ni-TiC composite coating of Example 1 using a 50% Ti-Ni vapor source and an uncoated SUS304 sample.
A TiC film was coated on the sample.

The same apparatus as in Example 1 was used for coating TiC. Ti was evaporated by heating with an electron beam having a filament current of 0.20 A and an acceleration voltage of 10 kV. On the other hand, carbon is C _{2 at} a pressure of 0.11 Pa.
Supplied from a H ₂ gas stream. Ionization of gas particles was promoted by applying a positive electrode up to 50 V to the probe electrode, and the ionized gas particles were accelerated toward the substrate by a negative voltage of 2 kV. The substrate was heated and held at 400 ° C. by a Ta heater. 2 during ion plating
At 0 minutes, a TiC film having a thickness of about 5 μm was coated. The adhesion thus obtained was evaluated for the samples thus obtained. The evaluation of adhesion was performed by a scratch test. As a result, the TiC film coated on SUS304 peels off under a load of 6N, but the TiC film coated on Ni-TiC does not peel off up to a load of 16N. From this, it is understood that when the Ti-TiC composite coating produced by the method of the present invention is used as the undercoating, the adhesion of the TiC coating can be improved.

(Effect of the Invention) According to the method of the present invention, it is possible to coat a Ni-TiC composite film having excellent adhesion. In addition, when this Ni-TiC composite coating is used as an undercoating for the TiC coating, it has an excellent effect of enhancing the adhesion of the TiC coating.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the composition of the vapor sources of Ni and Ti and the hardness of the resulting coating.

Claims (1)

[Claims] 1. A Ni-TiC composite film is deposited on a substrate by causing a plasma chemical reaction in a gas phase in which a hydrocarbon gas is mixed with a mixed vapor of nickel vapor and titanium vapor. TiC composite coating method.