JPH0463606A - Diamond tool having amorphous carbon layer formed on surface - Google Patents

Abstract

PURPOSE:To provide a diamond tool which can be used for cutting of an iron material by a method wherein the surface of the diamond tool is covered in a specified thickness with glassy carbon and brought into an amorphous state down to a specified depth from a surface. CONSTITUTION:The surface of a diamond tool is covered in thickness of 0.2-100mum with glassy carbon, and a surface is modified so that the surface of the diamond tool is brought into an amorphous state down to a depth 0.01-100mum from a surface. Since, by forming an amorphous carbon layer on the surface of the diamond tool, chemical reaction between a surface carbon layer and iron is difficult to occur, the generation of wear is reduced, a cut surface is smooth, an enough life for cutting of an iron material and cutting performance are provided, and a diamond tool having an arbitrary thickness responding to a material to be cut can be easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a diamond tool having an amorphous carbon layer on its surface, which is used for cutting metal materials, particularly ferrous materials such as carbon steel.

[Prior Art] Sintered diamond or single crystal diamond is widely used as a cutting tool for various metal materials such as aluminum and copper due to its ultrahardness.

Recently, a cutting tool coated with a diamond film has been developed in which a diamond film is grown in vapor phase on a base material such as a carbide tool using the CVD method, and it is also being used for cutting soft metals.

However, these diamond tools are considered unsuitable for ferrous materials such as carbon steel. This is because diamond easily reacts chemically with iron, and when cutting iron-based materials, diamond wear increases and tool life is shortened (E, J, Duell & W, J, MacDon
ald: Wear, vol, 4. N.

5 (+961) 372’).

[Problems to be Solved by the Invention] As described above, conventional diamond tools or diamond film-coated tools tend to chemically react with iron, and are generally not used for cutting ferrous materials such as carbon steel. The present invention was made to solve these problems, and aims to provide a diamond tool that can be used for cutting ferrous materials.

[Means for Solving the Problems] The diamond tool of the present invention has an amorphous carbon layer on the surface formed by coating the surface of the diamond tool with glassy carbon with a thickness of 0.2 to 100 μl, and further is a diamond tool that has an amorphous carbon layer on its surface by subjecting the diamond tool to surface modification that makes the surface of the diamond tool amorphous over a depth of 0.01 to 100μ from the surface. shall be.

The diamond tools referred to in the present invention include natural and high-pressure diamond single stone tools, sintered diamond tools, vapor phase diamond tools, and the like.

Diamond has the highest hardness, but it has a transformation point (7
Above 23°C, it reacts rapidly and forms cementite Fe5C.
It is believed that the ease of this reaction is the main reason why diamond tools suffer significant wear and short life when cutting ferrous materials. On the other hand, graphite (gra
phHe) and amorphous carbon are far less likely to react with iron than diamond (Yasunaga et al., Precision Machinery, Vol. 38, No. 4 (1972), pp. 413-415), so diamond is the preferred choice for cutting ferrous materials. It is expected that graphite or amorphous carbon will exhibit superior properties, but the reality is that normal graphite and amorphous carbon have very low hardness and cannot be used as tools.

Figure 1 shows Raman spectra of various carbon materials. Diamond and single-crystal graphite exhibit one sharp peak, while glassy carbon, which has a structure in which graphite is disordered, exhibits the peak of graphite or one shifted to the higher wavenumber side, as well as another peak due to the vibration of the end faces of graphite crystallites. and the half-width is wide. A highly hard amorphous film, also called hard carbon, diamond-like carbon, or i-carbon, exhibits a half-width so wide that the peak position cannot be determined. Both glassy carbon and hard carbon are classified as amorphous materials, but glassy carbon is easier to produce in the form of a thin film, and
While the heat resistance temperature is 2000° C. or higher, a thin film of hard amorphous carbon must be produced by a PVD method or the like, resulting in high manufacturing costs and also has a low heat resistance temperature of about 400° C.

The first invention of the present invention is based on this knowledge and has developed a cutting tool that exhibits high wear resistance against ferrous materials by coating the surface of the diamond tool with a glassy carbon film. Furthermore, the second aspect of the present invention is to develop a cutting tool that exhibits high wear resistance against iron-based materials by modifying the surface of the diamond tool to give it an amorphous structure.

First, the first invention will be explained. The thickness of the glassy carbon film to be coated on the surface of the diamond tool is 0.2
~100 μm is desirable. If the thickness of the glassy carbon film is less than 0.2μ1, the anti-wear effect will be low due to abrasion and pinhole formation, and if it exceeds 100uI11, the film will easily peel off from the diamond tool surface due to the internal stress of the film. It cannot demonstrate sufficient performance as a cutting tool. Desirably, a coating thickness of 2 to 1 Oum allows cutting with a sufficient tool life.

The method for forming a glassy carbon film is to use known organic polymers such as vinyl chloride resin, vinyl acetate resin, and phenolic resin as raw materials. In the case of phenolic resin, it is diluted with an organic solvent and then coated with graphite or ceramics by spraying or coating. A method of coating the surface of the metal and then heating it in an inert atmosphere, or
When vinyl chloride resin, vinyl acetate resin, etc. are used as raw materials, the incomplete thermal decomposition products obtained by heating at -degrees are dissolved in an organic solvent, and then the solution is coated on graphite or ceramics and placed in an inert atmosphere. Use the method of lowering and heating.

Although it varies depending on the manufacturing method, the hardness of glassy carbon equivalent to HvlO00 (silicon single crystal with HvlOOO can be scratched, but silicon nitride with Hv1300 cannot be scratched) is formed. .

In order to improve the adhesion of glassy carbon to diamond, it may be effective in some cases to modify the surface of the diamond tool to make it amorphous, then coat it with the above-mentioned resin and sinter it.

Since sintered diamond tools and vapor phase polycrystalline diamond tools have fine holes, it is also possible to form a surface layer of glassy carbon by impregnating them with the above resin or solution and then heating them.

Next, the second invention will be explained. The thickness of the amorphous carbon layer to be modified on the surface of the diamond tool is 0.01 to 10
0 μm is desirable. If the thickness of the modified layer is less than 0,019 m, it is too thin and has little wear-resistant effect, and if it exceeds 100 microns, the outermost surface becomes brittle and the wear-resistant effect is reduced, making it unusable as a cutting tool. Preferably 0.05um-10μm
The surface modified layer enables cutting with sufficient tool life. As a diamond surface modification method, a known method of heating diamond in a trace oxygen atmosphere (fl:, Ph
aal:Ind, Diamond Rev.

25.300. (1965) 486) and a method of surface modification by implanting atoms such as hydrogen and argon into diamond (Kaida et al.: Abstracts of the 15th Annual Meeting of the Carbon Materials Society, (1988) pp. 142-143). This surface modification method makes it possible to cover the diamond surface with amorphous carbon. For example, using a Kaufmann type ion source for a diamond single crystal, the pressure is 5 x 1O-5 Torr.
, acceleration voltage], 200V, ion current density 1 mA/
cm2, when irradiated with hydrogen ions for 2 hours, the color turned slightly brown to the naked eye, and the presence of an amorphous layer on the surface was confirmed by Raman spectroscopy, and analysis by nitrogen isotope resonance nuclear reaction method. It can be confirmed that hydrogen atoms exist from the surface to a depth of 0.06 um.

A conical slider made of single crystal diamond, a slider whose surface is coated with glassy carbon to a thickness of 2JJ111, and a surface layer of the slider modified to a depth of 0.06um by hydrogen ion irradiation. Slider 3
Comparing the wear resistance of two sliders, for example, 535C
When friction is applied to carbon steel in a vacuum with a load of 2.0 kg and a friction speed of 1130 m/min, the diamond single crystal slider wears out! is 13X 10-'mm3
/km, whereas the wear amount of the glassy carbon coated slider is 1.2 x ICl-'mm3/km,
That of the surface modified slider is 5 x 10-'mm'/k
m, and about 10 m for the glassy carbon coated slider.
It can be said that the surface-modified slider has twice as good wear resistance.

In addition, under the above friction conditions, a slider made of sintered diamond having the same shape as the single crystal diamond slider, a slider whose surface was coated with glassy carbon with a thickness of 2 μm, and a slider whose surface was coated with glassy carbon with a thickness of 2 μm; Comparing the wear resistance of three sliders whose layers were modified by hydrogen ion irradiation to a depth of 0.06 μm, the wear resistance of the sintered diamond slider was 23 x 10
-'mm3/km, whereas the wear amount of the glassy carbon coated slider is 1.6 x 10-'mm"/km
and that of the surface-modified slider is 10x 10-'m
m3/km, and it can be said that the glassy carbon-coated slider has about 14 times better wear resistance, and the surface-modified slider has about twice the wear resistance.

Furthermore, under the above friction conditions, a slider made of vapor-grown polycrystalline diamond having the same shape as the single-crystal diamond slider, a slider whose surface was coated with glassy carbon with a thickness of 2 μm, Comparing the wear resistance of three sliders whose surface layer has been modified to a depth of 0.061 μm by hydrogen ion irradiation, the wear resistance of the vapor phase diamond slider is 20x10-'mm3/km. On the other hand, the wear amount of the glassy carbon coated slider is 1.3 x 10-
'mm3/km, and that of the surface modified slider is 7X
10 to 411IID37kIII, and it can be said that the glassy carbon-coated slider has about 15 times better wear resistance, and the surface-modified slider has about 3 times better wear resistance.

[Function] When using the above-mentioned diamond tool with an amorphous carbon layer on its surface, chemical reaction between the surface carbon layer and iron is less likely to occur, so wear is lower than with a diamond tool without an amorphous carbon layer. It also has a smooth cutting surface and exhibits sufficient life and cutting performance for cutting ferrous materials. When coating with glassy carbon, it can be easily manufactured to any thickness depending on the material to be cut. When the surface is modified, there is no risk of peeling of the modified layer, and if the thickness is the same, it is stronger than a glassy carbon coated tool.

[Example] Diamond tools include a single-crystal diamond tool (manufactured by Asahi Diamond Industries) and a sintered diamond tool (Crys
The amorphous carbon layer on the surface was formed using two methods: coating with glassy carbon and surface modification by hydrogen ion irradiation. did. Using such a diamond tool, cut into a rigid material 545G with a diameter of 75 mm (1,511101, feed (1,] Omm/rev
1. The flank wear amount was measured when the cutting speed was 400 m/m and the cutting speed was 0. The hardness of a diamond tool is load 10
The micro Vickers hardness of gf was measured. Glassy carbon was coated by the following method. 5% by weight of phenolic resin
After coating a diamond tool with a solution dissolved in acetone to a thickness of just under 3 μm, the tool was placed in a heating furnace and heated under the following conditions in an air atmosphere.

Room temperature ~ 150℃ 5℃/l1in J50~270℃ 0.08℃/1lin270
The temperature was maintained at 0.degree. C. for 5 hours, and then the atmosphere was replaced with argon gas, and the temperature was increased under the following conditions.

270~350℃ 15℃/m1n350~550
℃ 2℃/win 550 ~990℃ 15℃/win990℃
Holding for 30 minutes As a result, a diamond tool having a 2 μm thick glassy carbon layer on the surface was obtained. The surface modification was performed by irradiating the diamond tool with hydrogen ions for 2 hours using a Kauffman type ion source at a pressure of 5 x 1O-5 Torr, an acceleration voltage of 1200 V, and an ion current density of 1 mA/cm2.

Raman spectroscopy confirmed the presence of an amorphous layer on the surface, and analysis using nitrogen isotope resonance nuclear reaction confirmed the presence of hydrogen atoms at a depth of 0.06 to 0.07 μm from the surface. did. In this way, about 0.06 μm on the surface
A diamond tool with a thick amorphous carbon layer was obtained.

The above results are shown in Table 1. For single-crystal diamond bits, sintered diamond bits, and vapor-phase diamond bits, those coated with glassy carbon show less than one-tenth the wear amount compared to untreated ones, and the surface is modified by hydrogen ion irradiation. The ones tested showed less than half the amount of wear.

[Effects of the Invention] The present invention has an amorphous carbon layer formed on the surface of a tire mont tool, which makes it difficult to cause a chemical reaction with iron, making it possible to use diamond for cutting ferrous materials, which conventional tire mont tools have difficulty with. It is expected that it will greatly contribute to improving the productivity and quality of cutting of ferrous materials, which account for the largest market for metal materials.

[Brief explanation of the drawing]

Figure 1 shows Raman spectra of various carbon materials.

Claims (1)

[Claims] 1. A diamond tool having an amorphous carbon layer on the surface, which is formed by coating the surface of the diamond tool with glassy carbon having a thickness of 0.2 to 100 μm. 2. 0.01 to 100 μm from the surface of the diamond tool
A diamond tool having an amorphous carbon layer on its surface, which is subjected to surface modification to make the surface of the diamond tool amorphous over a depth of .