JPH09295224A - Method for coating super hard tool with diamond film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesive force between a surface of a super hard tool base material and a diamond film by applying voltage to the material to be etched, and performing the etching to the surface of a super hard tool base material with NaOH or KOH solution, and thereafter, coating the surface with a diamond film. SOLUTION: Electrolytic etching is performed to a super hard tool by using NaOH or KOH solution. Furthermore, etching is performed to the super hard tool, to which the electrolytic etching is already performed, by using a mixture solution of H2 SO4 +H2 O2 so as to form a cobalt binder phase. Sheeting treatment is performed to this etched super hard tool with the diamond powder slurry. A diamond film is deposited to the super hard tool, to which sheeting treatment is performed. A carbide phase of the super hard tool is irregularly etched so as to increase the surface roughness of the super hard tool by performing etching to the surface of the super hard tool. The surface of the super hard tool, in which roughness is increased, shows the mechanical binding effect with the diamond film, and binding force between the phases can be increased.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for depositing and coating a diamond film on a cemented carbide tool.
Electrolytically etched in H or KOH aqueous solution or K
The present invention relates to a method for coating a diamond film of a cemented carbide tool in which the adhesion between the diamond film and the cemented carbide base material is improved by chemical etching with an aqueous solution of MnO ₄ + KOH.

[0002]

2. Description of the Related Art It is known that a cemented carbide tool whose surface is coated with a diamond film is remarkably superior in performance to general cemented carbide tools.

However, a cemented carbide tool coated with such a diamond film loses its function when the coated diamond film is peeled off from the tool.

Since such a peeling phenomenon occurs when the adhesive force between the surface of the cemented carbide tool and the diamond film is insufficient, research for increasing the adhesive force has been vigorously conducted.
As one of the methods, there is a method of etching the surface of the cemented carbide tool with a chemical solution.

Further, such an etching treatment method includes a method of dissolving the binder phase on the surface of the cemented carbide tool with an acid,
The method of melting the carbide phase is mainly used.

In the former method, cobalt in the binder phase weakens the adhesive force by forming a non-diamond phase between the diamond film and the surface of the cemented carbide tool due to the catalytic action.
This is a method of removing the cobalt phase to a predetermined depth, and this method has a disadvantage that it cannot maintain sufficient adhesive strength.

On the other hand, the latter method is a method in which the carbide phase is etched using a Murakami solution and then the cobalt phase is etched again using the former method, as described in US Pat. No. 5,236,740. The surface of the cemented carbide tool was etched for 2 minutes or more using a solution of potassium ferricyanide 10 g + potassium hydroxide 10 g + water 100 g, and then again etched for 5 seconds or more with a sulfuric acid-hydrogen peroxide solution to be coated with a diamond film. It manufactures cemented carbide tools.

In the method using such Murakami solution, as shown in the following formula, potassium ferricyanide in the Murakami solution reacts with KOH to generate nascent oxygen, and potassium ferricyanide acts as an oxidizing agent. It is possible to remove the component that oxidizes in a general chemical etching solution and obtain the same effect as adding an electrical potential to the sample to be etched [Metallography
Principles and practice by George F. Vader Voort,
See MacGraw-Hill Book Co. 1984].

2K ₃ Fe (CN) ₆ + 2KOH → 2K ₄ F
_{e (CN) 6 + H 2} O + 1/2 O 2

However, not only is the price of potassium ferricyanide in the constituents of the Murakami solution about 10 times more expensive than that of the other component, potassium ferricyanide, but the potassium ferricyanide is either heated or exposed to acid and acid vapors. On contact, it is extremely dangerous as it can generate a very toxic cyanide gas, causing suffocation.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to use an aqueous solution that is harmless to the human body to ensure work safety when etching the surface of a cemented carbide tool, and to use an inexpensive aqueous solution to reduce manufacturing costs. The present invention provides a method for coating a diamond film of a cemented carbide tool.

[0012]

In order to achieve the above object of the present invention, in the method for coating a diamond film of a cemented carbide tool according to the present invention, a carbide of a cemented carbide tool base material is formed by the etching solution of the present invention. The phase is etched to increase the surface roughness, improve the mechanical coupling effect between the diamond film and the surface of the cemented carbide tool base material, and improve the adhesive force of the film.

Therefore, the first method for coating a diamond film on a cemented carbide tool according to the present invention is to apply a voltage to the material to be etched and etch the surface of the cemented carbide tool base material using an aqueous NaOH or KOH solution. After that, the surface is coated with a diamond film to improve the adhesive force between the surface of the cemented carbide tool base material and the diamond film.

A second method for coating a diamond film on a cemented carbide tool according to the present invention is a method of using an aqueous solution of KMn ₄ O + KOH as an etching solution, in which KMnO ₄ is used instead of toxic potassium ferricyanide. After performing etching by using it, a diamond film is coated on the surface to improve the adhesive force between the surface of the cemented carbide tool base material and the diamond film.

The method for coating the diamond film on the cemented carbide tool according to the present invention will be described below.

First, the first method is NaOH or KOH.
This is a method of performing electrolytic etching using an aqueous solution as an etching solution. At this time, the concentration of KOH or NaOH is 5
-50% is desirable, and the cemented carbide tool is mounted on the anode. The voltage and current are adjusted appropriately according to the concentration of KOH or NaOH.

In the second method, chemical etching is carried out using an aqueous solution of KMnO ₄ + KOH. At this time, the composition of the etching solution is KMnO ₄ 5-30%, KOH 1-1.
5%, H ₂ O 55 to 94%, and the treatment time is 1 minute or more.

In such an etching method, it is desirable to first wash the cemented carbide tool with distilled water and trichlorethylene. When the surface of the cemented carbide tool is etched according to the present invention, the carbide phase of the cemented carbide tool is irregularly etched to increase the surface roughness of the cemented carbide tool, thus increasing the roughness of the cemented carbide tool. The surface exerts a mechanical bonding effect with the diamond film, increasing the bonding force between them.

The thus-etched cemented carbide tool is washed again with distilled water and acetone, and H ₂ SO ₄ -H ₂ O _{2 is} added.
Etching is performed for 5 seconds or more using the mixed solution to remove the cobalt binder phase.

Thereafter, this cemented carbide tool is washed again with distilled water and acetone, seeded with an ultrasonic cleaner using a diamond powder slurry solution, and then ultrasonically cleaned with distilled water and acetone.

Then, the treated cemented carbide tool is coated with a diamond film by a general diamond coating means.

Embodiments of the present invention will be described below.

[0023]

【Example】

Example 1 A K20 SPGN 120308 cemented carbide tool was ultrasonically cleaned with distilled water and acetone. A sample is 20%
The sample B was etched for 30 seconds using a sulfuric acid-80% hydrogen peroxide solution, and the sample B was subjected to electrolytic etching for 15 minutes under the conditions of 8V and 10A using a 10% KOH aqueous solution as an electrolytic solution, and then the sample A was used. Etching was carried out using the same H ₂ SO ₄ + H ₂ O ₂ mixed solution as described above.

After that, all the A and B specimens were washed again with distilled water and acetone, sonicated with a solution of 0.5 μm diamond powder dispersed in ethyl alcohol for 2 minutes, and then distilled water and acetone. Washed again with.

Microwave chemical vapor deposition (CVD) was applied to these two test pieces to obtain methane 5% and pressure 110.
A diamond film was deposited to a thickness of 50 μm under the conditions of torr and substrate temperature of 960 ° C.

The film of A test piece was peeled from the substrate when it was cooled to room temperature after vapor deposition, but the B test piece was not peeled off and maintained a good adhesion state.

Example 2 As an electrolytic solution for treating the B sample, a 10% NaOH aqueous solution was used instead of the 10% KOH aqueous solution, and the same experiment as in Example 1 was carried out. As a result, the same results as in Example 1 were obtained.

Example 3 A K20 SPGN 120308 cemented carbide tool was ultrasonically cleaned with distilled water and acetone, and then the A sample was not subjected to any treatment and the B sample was etched with a Murakami solution for 2 hours. The test piece was etched with a solution of 5 g of KMnO ₄ and 10 g of KOH in 100 ml of distilled water for 2 hours.

Next, the B and C test pieces were washed with distilled water and then etched with a 20% sulfuric acid-80% hydrogen peroxide solution for 30 seconds.

After that, the surface roughness of the A, B and C test pieces was measured by a profilometer having a tip radius of a stylus of 12 μm. The measured surface roughness was Ra 0.08 μm for the A sample, Ra 0.4 μm for the B sample, and Ra 2.0 μm for the C sample.

Using these three test pieces, a diamond film was deposited to a thickness of about 50 μm under the same conditions as in Example 1.

As a result, the diamond films of the A and B test pieces were peeled off after cooling, but the C test piece was not peeled off.

Example 4 A K20 SPGN 120308 cemented carbide tool was ultrasonically cleaned with distilled water and acetone, the A sample was treated in the same manner as the A sample of Example 1, and the B sample was KMnO ₄ 5 g and KOH 1.
It was immersed in a solution of 0 g in 100 ml of distilled water for etching for 1 hour. After that, the A and B test pieces were washed with distilled water and acetone, and then ultrasonically treated for 2 minutes with a solution in which 0.5 μm diamond powder was dispersed in ethanol.
It was washed again with distilled water and acetone. A diamond film of 50 μm was formed from these two test pieces under the same conditions as in Example 1.
Evaporated to a thickness of m. As a result, the same results as in Example 1 were obtained.

Example 5 A K20 SPGN 120308 cemented carbide tool was ultrasonically cleaned with distilled water and acetone, the A specimen was treated in the same manner as the A specimen of Example 1, and the B specimen was KMnO ₄ 5 g and KOH 1.
It was immersed in a solution of 0 g in 100 ml of distilled water for etching for 1 hour. After that, the A and B test pieces were washed with distilled water and acetone, then subjected to ultrasonic treatment for 2 minutes with a solution in which 0.5 μm diamond powder was dispersed in ethanol, and washed again with distilled water and acetone. A diamond film having a thickness of 20 μm was vapor-deposited on these two test pieces under the same conditions as in Example 1.

Then, using these two test pieces, A1
A cutting experiment was performed using −18% Si alloy as a material to be cut. The cutting conditions are cutting speed = 700 m / min, feed = 0.
25 mm / rev, depth of cut = 1 mm, the size of the material to be cut was 120 mm and the length was 120 mm, and the material to be cut was cut to a diameter of 60 mm.

As a result, in the B sample, the diamond film was gradually worn without peeling of the diamond film, and the diamond film was 4 to 5 times.
After machining the individual work pieces, a portion of the cemented carbide tool base material appeared.

However, in the sample A, the diamond film was suddenly peeled off during the processing of one material to be cut, and the cutting operation became impossible.

[0038]

In the method for coating a diamond film of a cemented carbide tool according to the present invention, the etching solution used has a greater etching effect than the conventional Murakami solution and is harmless to the human body because it does not contain toxic potassium ferricyanide. There is an effect that waste treatment is easy.
And the price of KMnO ₄ is 30 for potassium ferricyanide.
%, The manufacturing cost is low.

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Claims (4)

[Claims] 1. A step of electrolytically etching a cemented carbide tool using an aqueous solution of NaOH or KOH, wherein the electrolytically etched cemented carbide tool is H ₂ SO ₄ + H.
A step of etching a cobalt binder phase using a ₂ O ₂ mixed solution; a step of seeding the etched cemented carbide tool with a diamond powder slurry; and a step of depositing a diamond film on the seeded cemented carbide tool. A method for coating a diamond film of a cemented carbide tool, which is sequentially performed. 2. The method for coating a diamond film on a cemented carbide tool according to claim 1, wherein the concentration of the aqueous solution of NaOH or KOH in the electrolytic etching step is 5 to 50%. 3. A step of chemically etching a cemented carbide tool using an aqueous solution of KMnO ₄ + KOH, the cemented carbide tool being chemically etched being H ₂ SO ₄ + H
A step of etching a cobalt binder phase using a ₂ O ₂ mixed solution; a step of seeding the etched cemented carbide tool with a diamond powder slurry; a step of depositing a diamond film on the seeded cemented carbide tool A method for coating a diamond film of a cemented carbide tool, which is sequentially performed. 4. The composition of the KMnO ₄ + KOH aqueous solution is such that KMnO _{4 is} 5 to 30%, KOH is 1 to 15%, and H _{2 is 2.}
The method for coating a diamond film of a cemented carbide tool according to claim 3, wherein O is 55 to 94%.