JPH0674497B2 - Ceramic hard film coating method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for coating a ceramics hard film on the surface of a substrate such as a tool or a mold, and more specifically, it has excellent adhesion to the substrate and is dense. The present invention relates to a method of coating a hard film having a film quality on the surface of a substrate.

[Prior Art] The surface of a cutting tool made of high speed tool steel or cemented carbide has TiN,
A technique has been proposed for coating a hard film such as TiC or Al ₂ O ₃ to improve wear resistance, and has dramatically improved the performance of cutting tools. As the above-mentioned hard film coating method, there are a CVD method and a PVD method. Among them, the CVD method has a high substrate temperature, so that the film has good adhesiveness to the substrate, and a hard film can be uniformly coated on a three-dimensional shape. However, on the other hand, there is a drawback that the base metal deteriorates in strength under high temperature conditions and a brittle decarburized layer is formed between the coating layer and the base.
In particular, it is difficult to apply to high-speed tool steel, which often suffers strength deterioration at 500 to 600 ° C.

Therefore, the PVD method, which can be processed at a lower temperature than the CVD method, is attracting attention, especially the ion plating method, but it is one of the problems to be solved in the ion plating method that is not as good as the CVD method in terms of adhesion to the substrate. Has become.

[Problems to be Solved by the Invention] The ion plating method is a method of causing vaporized substance ions and reactive gas ions to collide with the surface of a substrate to deposit a vaporized substance or a compound thereof. Various methods have been proposed depending on differences.

For example, in the arc evaporation type ion plating method, as shown in FIG. 3, a reactive gas is introduced from the gas inlet 9 and an arc is generated between the evaporation source 2a to which a negative voltage is applied and the positive voltage trigger 3. , A hard film is coated and formed on a substrate W to which a negative bias voltage is applied. In the arc evaporation method, sputter cleaning by metal bombardment is performed prior to the hard coating in order to enhance the adhesion between the substrate and the hard film. To remove impurities on the surface of the substrate,
After that, a hard film is formed by arc vapor deposition.

However, in the above-mentioned method, a large cleaning effect can be obtained by the metal bombardment, and therefore a sufficient adhesion of the coating film to the substrate can be obtained, but large particles of about 1 to 5 μm are contained in the formed coating film. Since they are mixed, the coating film lacks in fineness and pinholes are easily generated, resulting in poor wear resistance.

Other ion plating methods include DC glow method, high-frequency excitation method, multi-cathode method, and hollow cathode (HCD
The discharge method, or a combination of these methods, has been proposed. Regarding the adhesion, the arc vapor deposition method of forming a film by arc vapor deposition after performing sputter cleaning with a metal bombardment is the most excellent. However, none of the above methods is superior to this.

The applicant of the present invention first applied for a method of coating by the arc vapor deposition method and then by the melt vapor deposition method (Japanese Patent Application No.
61-169183), this method has the effect of improving the surface condition, but the pinholes of the underlayer arc-deposited film that have been formed are not completely covered with the melt-deposited film.

The present invention has been made in view of these circumstances, and provides a hard film coating method capable of forming a hard film having excellent adhesion to a substrate, a dense surface structure, and excellent wear resistance. It is the one we are trying to provide.

[Means for Solving Problems] The method of the present invention which has achieved the above object, however, is characterized in that after the work surface is cleaned by an arc evaporation type metal bombardment, a hard film is formed on the surface by a melt evaporation method. Is to have.

[Operation] None of the coating films formed by the ion plating method other than the above-mentioned arc vapor deposition method is superior to the arc vapor deposition method in terms of adhesion to the substrate, but they have their respective characteristics. is doing. Among them, in the case of HCD discharge type ion plating method which is one of the melt vapor deposition methods, sputter cleaning by Ar bombarding is performed prior to hard film coating, but the cleaning effect is small, so the substrate and coating film The adhesion of is unstable. However, HCD discharge itself is more stable than arc discharge, and the state of particle evaporation from the evaporation source is uniform and gentle, so a very smooth and dense coating film can be obtained.

The present invention pays attention to the features of such HCD method, and thinks that the above object can be achieved by combining with the metal bombardment cleaning in the arc vapor deposition method excellent in cleaning effect, and as a result of various studies, a result of the invention It has reached completion.

That is, the method of the present invention is, for example, as shown in FIG. 2, an arc generating mechanism composed of a Ti cathode 2 and a trigger 3 in a vacuum container 1 and an HCD composed of an HCD gun 4 and a hearth 5 containing an evaporation source metal M. It is carried out by using an apparatus (both an arc vapor deposition method and an HCD vapor deposition method can be implemented) in which an evaporation mechanism is installed and a work W connected to the DC bias power source 6 is arranged so as to face them. is there. First, an arc is generated between the Ti cathode 2 and the trigger 3 using the arc generating mechanism to evaporate Ti from the Ti cathode 2, and the evaporated particles are ionized in the arc discharge atmosphere to collide with the surface of the work W. As a result, the work W is caused by the ion impact.
Impurities are removed from the surface and the surface of the work W is cleaned. When the cleaning process is completed, the arc generating mechanism is stopped and the HCD mechanism is operated instead. Ie Ar
The thermoelectrons generated by the bombardment of ions are emitted from the HCD gun and applied to the evaporation source M in the hearth 5, and the evaporated particles are further activated by collision with electrons and vaporized on the surface of the work W together with the reactive gas ions. Let Work W in this way
It is possible to obtain a work which is excellent in adhesiveness with and is coated with a hard film having a dense film structure.

Although the basic configuration of the method of the present invention is as described above, the metal collided in the bombardment by the arc vapor deposition method is not limited to Ti and may be another metal, but if possible, try to coat it. It is preferable to sputter the constituent metals of the film. However, the sputter of a metal of a different type from the constituent metal is not excluded.
On the other hand, for reactive gas, N ₂ , O
_{2. It} is sufficient to introduce a hydrocarbon gas or the like, but it is not always necessary to use a reactive gas when preparing a compound evaporation source in the hearth. In addition to the HCD method, an ARE method, a hot cathode method, or the like can be used as a method for heating and evaporating the evaporation source metal in the hearth, and these can be collectively defined as a melt evaporation method. Further, the Ti bombardment is sufficient for cleaning before vapor deposition, but Ar bombardment may be performed prior to the Ti bombardment.

[Example] Using the apparatus illustrated in Fig. 2, the surface of the HSS drill was coated with a TiN film by the following procedure.

After evacuating the inside of the vacuum container 1 to 1 × 10 ⁻⁴ Torr or less, the work W was heated to 400 to 500 ° C. using the heater 8 and kept at the same temperature for 30 to 90 minutes. After the heating by the heater 8 was stopped, the trigger 3 was actuated to generate arc discharge with the Ti cathode 2. At this time, on the work W- (600
˜1000) V bias voltage was applied and the work W was rotated. As a result of continuing the sputter cleaning of the surface of the work W for 30 seconds to 2 minutes, the arc power supply was stopped.
Next, the heater 8 is activated again to set the work W to 400 to 500.
After heating and holding at ℃, the HCD gun was started and the Ti in the hearth 5 was melted. Further, N ₂ gas was introduced up to (1 to 3) × 10 ⁻³ Torr from the reactive gas pipe 9, and the work W-
A bias voltage of (50-100) V was applied. Thus HCD
When the vapor deposition is ready, the shutter 10 is opened and the work W
The TiN film coating on top was started. After continuing vapor deposition for a predetermined time, the HCD gun was stopped, the work was taken out after cooling to 100 to 130 ° C.

The TiN film coated drill (A) thus obtained, the drill coated with the TiN film by the conventional arc vapor deposition method (C), the drill coated with the TiN film by the conventional HCD method (B), and both arc vapor deposition and HCD vapor deposition When the surface condition and wear resistance of the drills (D) were compared, the results were as follows.

Regarding the surface state, the film surface states of the example drill (A) and the comparative example drill (B) were dense, whereas the large diameter particles were mixed on the film surface of the comparative example drill (C) and the homogeneity was observed. Was lacking in. Further, the comparative drill (D) was improved as compared with the comparative drill (C), but was inferior to (A).

On the other hand, when the drill wear characteristics of the drills (A) to (D) were drilled and compared, the results were as follows:
The results shown in the figure were obtained.

As shown in FIG. 1, the drill (B) is most easily worn, and then the drill (C), the drill (D), and the drill (A).
The wear resistance showed a high value in the order of. That is, although the drill (B) had a fine film surface state as described above, the adhesion between the base and the film was low and the wear resistance was low. On the other hand, the drill (C) showed higher wear resistance than the drill (B) because the adhesion between the base material and the film was strong, but as described above, it is a heterogeneous film structure in which large-diameter particles are mixed. In addition, the abrasion started to come off due to the large-diameter particles, and sufficient abrasion resistance could not be obtained. And the drill (D) showed higher wear resistance than the drill (C) because the adhesion was strong and the surface condition was improved to some extent. However, since large-diameter particles are mixed together, sufficient wear resistance is obtained. I couldn't do that. On the other hand, the coating film of the drill (A) has strong adhesion to the base material, and the film structure is uniform and dense.
It exhibited higher wear resistance than (C) and (D).

EFFECTS OF THE INVENTION The present invention is configured as described above and can coat the surface of a substrate with a dense hard film having excellent adhesion to the substrate. Thus, by coating a tool made of high-speed steel or the like with a hard film according to the method of the present invention, it was possible to provide a tool having better wear resistance than before.

[Brief description of drawings]

FIG. 1 is a wear resistance comparison graph of a drill coated with a TiN film by the method of the present invention and a conventional drill, and FIG. 2 is a schematic diagram showing an example of a hard film coating device applied to the practice of the present invention.
FIG. 3 is a schematic diagram for explaining the arc vapor deposition method. 1 ... Vacuum container, 2 ... Ti cathode 3 ... Trigger, 4 ... Holocathode gun 5 ... Haas, 6 ... Bias power supply 8 ... Heater, 9 ... Reactive gas pipe 10 ... Shutter W ... Work, M ... Evaporation source metal

Claims (1)

[Claims] 1. A method for coating a ceramics hard film, which comprises cleaning the surface of a work by an arc evaporation type metal bombardment and then forming a ceramics hard film by a melt evaporation method.