JPS6340800A - Method for synthesizing high-hardness boron nitride - Google Patents

Abstract

PURPOSE:To form a BN coated layer having extremely high hardness by forming a diamond coated layer on the surface of a substrate, then supplying a mixture obtained by mixing a B material and an N material in a specified ratio, and forming BN by microwave plasma CVD, etc. CONSTITUTION:A diamond intermediate layer 2 is formed in 0.01-100mum thickness by microwave plasma CVD on a substrate 1 for a silicon wafer, an Mo material, a W material, a carbide tool, etc. The substrate is placed in a reaction chamber 5. The B material such as gaseous diborane (B2H6) and the N material such as gaseous N2 and gaseous NH3 are introduced from a gaseous reactant feeder 7, and mixed so that the atomic ratio of B/N is controlled to 1-10. A microwave from a microwave generator 12 is simultaneously introduced into the reaction chamber 5 through a waveguide 13 to keep a substrate 4 at >=800 deg.C. As a result, a cubic BN layer 3 having extremely high hardness, excellent thermal conductivity, and chemical stability is formed on the surface of the diamond coated layer 2 of the substrate 1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention not only has extremely high hardness, but also has excellent thermal conductivity and is chemically stable. This relates to a method for depositing cubic boron nitride, which has excellent resistance to metals and is used as tool materials such as cutting tools and wear-resistant tools, as well as electronic materials such as heat sinks, on the surface of substrates from the gas phase. It is.

[Conventional technology]

Conventionally, methods for producing cubic boron nitride have been known, such as the following methods (1) to (2).

■ As shown in Japanese Patent Publication No. 60-181262, boron is evaporated onto the substrate from an evaporation source containing boron, and at the same time, the ion species are deposited onto the substrate from an ion source that generates ionic species containing at least nitrogen. A method for producing a boron nitride film, which comprises irradiating the substrate with boron nitride to produce boron nitride on the substrate.

■ “Journal of Materials Science Letters”
Ience 1etters), 4 (1985) 51
54, a method for producing cubic boron nitride by chemically transporting boron using Ht + N and plasma.

■ [9th Ion Engineering (Ion 5ourceIon
As shown in the proceedings of the Assisted Technology Symposium (Tokyo, 1985), ``Ion Sources and Ion-Based Applied Technologies'', N2 was evaporated from the hollow anode while boron was evaporated with an HCD gun.
This method generates cubic boron nitride by ionizing and irradiating it to the substrate, applying high frequency to the substrate, and creating a self-bias effect.

■ [Miscellaneous Waves; "Vacuum" Vol. 28, No. 27 (1985)
29-34], boron is evaporated by applying an electron beam (EB) to a boron-containing solid, and a nitrogen-containing gas is poured into it to simultaneously ionize boron and nitrogen. A method of producing cubic boron nitride on the surface.

[Problems to be Solved by the Invention] However, the method (2) has a drawback in that the ion beam generating device and its focusing device are expensive.

The method (2) uses high-power RF plasma for film formation and is discussed under low pressure, so impurities from the reaction system are likely to mix in.

Like method (2), method (2) has the disadvantages that the ion beam generating device and its focusing device are expensive, and that the atoms of the inert gas are incorporated into the precipitated cubic boron nitride.

In the method (2) above, since boron has a relatively low melting point, boron tends to cause bumping, and therefore it is difficult to control the film thickness by EB.

As mentioned above, all methods ① to ③ have various drawbacks, but the biggest drawback is that cubic boron nitride itself can be deposited to a satisfactory degree, but hexagonal boron nitride or amorphous boron nitride cannot be used. are present in the film, large thermal stress is generated within the film, and if the film exceeds a certain thickness, it will peel off.

The object of the present invention is to provide a novel method for producing cubic boron nitride that solves the drawbacks and difficulties of the conventional methods, and allows hard boron nitride to be deposited stably on the surface of a substrate, such as The object of the present invention is to provide a method for producing hard boron nitride that can be coated on tools and the like to provide excellent machinability, wear resistance, and chipping resistance.

[Means for solving problems]

This is a method for synthesizing high-hardness boron nitride, which is characterized by precipitating high-hardness boron nitride from system raw materials.

In the above, the boron-to-nitrogen atomic ratio B/N of the boron-based raw material and the nitrogen-based raw material is Q, in the range of 1 to 10, and the thickness of the diamond coating layer is 101 μm to 100 μm.
A particularly preferred embodiment is a range of m.

The present inventors have solved the above problem by first forming a diamond thin film as an intermediate layer on the surface of the substrate, and then depositing cubic boron nitride on the diamond thin film. Boron nitride can be produced without cracking or peeling, so if it is used to coat tools, etc., it has excellent machinability and wear resistance.

It has been found that a tool that is resistant to charcoal damage can be obtained.

The reason for using a diamond thin film as an intermediate layer in the present invention is that diamond and cubic boron nitride have very similar properties as shown in Table 1 below, and cracks due to differences in coefficient of thermal expansion and internal stress are not caused. This is because gouging is less likely to occur and the adhesion between diamond and cubic boron nitride is good.

Table 1 Furthermore, the crystal structures of diamond and cubic boron nitride are diamond-type structure and zincblende-type structure, respectively.
The latter structure has B and N for every other carbon atom in the former.
Since this is a replacement, the former and latter have the same structure. Therefore, it was discovered that boron nitride can grow on a diamond thin film in a manner similar to the diamond structure, so that pure cubic boron nitride can be produced.

In the present invention, first, a diamond thin film is formed as an intermediate layer on the surface of a base material, but this film forming method is particularly limited.
Alternatively, known methods such as microwave plasma CVD1 can be used.
, a thermal filament CVD method, an ion beam mini method, an ionization vapor deposition method, a direct current plasma CVD method, a high frequency plasma CVD method, a sputtering method, a chemical transport method, and the like.

The I thickness of the diamond coating layer is preferably in the range α01 μm to 100 μm.

If the thickness of the diamond coating 1 ii is thinner than CLol μm, the diamond coating layer will be too thin, and the thickness of the diamond coating layer will be uneven, and some parts will not be covered. Therefore, some portions appear where cubic boron nitride does not precipitate. Further, if the thickness of the diamond coating layer is greater than 100 μm, the internal stress of the diamond coating layer becomes large, and peeling between the base material and the diamond coating layer is likely to occur, which is not preferable.

Next, a cubic boron nitride film is formed on the surface of the diamond inspection layer, but the method for forming this film is not particularly limited, and may be any known method such as ion blating method or ion beam evaporation method. , Ionization vapor deposition method, Pulsed plasma CVD method, Laser CVD method, Plasma chemical transport method, Activated reaction vapor deposition method, Hollow Cando ARE method, Electron beam-ARE method, Dual beam sputtering method, Reactive sputtering method, C○, Laser A vapor deposition method or the like is used.

The thickness of the cubic boron nitride coating layer is Q, 01 to 10
A range of 0 μm is preferred. If it is less than 0.01 μm, the film thickness will be too thin and the film thickness will be non-uniform, and some portions will not be covered with the cubic boron nitride layer. Moreover, if it exceeds 100 μm, the internal stress of the cubic boron nitride layer becomes large and peeling easily occurs between the cubic boron nitride and the diamond layer.

In the present invention, as a raw material for synthesizing a boron nitride film,
The ratio B/N of the number of boron atoms in the boron-based raw material to the number of nitrogen atoms in the nitrogen-based raw material is preferably in the range of 11 to 10. This is because boron nitride is likely to be precipitated, and when B/N) is 10, boron is excessive and amorphous boron is likely to be formed.

Examples of boron-based raw materials that can be used in the present invention include solid boron, solid boron nitride (BN), diborane (BtHa
) gas, boron bromide gas, boron chloride gas, etc., and examples of the nitrogen-based raw material include Hz*NHs.

Figure 2g1 is a cross-sectional view illustrating the high hardness boron nitride coating obtained by the present invention, in which 1 is the base material, 2 is the diamond coating layer, and 3 is the high hardness boron nitride coating layer.

Note that the base material used in the present invention includes, for example, crystalline silicon,
Applications such as molybdenum plates, tungsten plates, carbide tools, etc., and other materials that take advantage of the characteristics of high-hardness boron nitride coatings can be considered, and materials that can be used as base materials for diamond and hard boron nitride synthesis methods can be used.

〔Example〕

Example 1 A silicon urethane substrate was used, and the surface thereof was coated with a diamond intermediate layer to a thickness of approximately 5 μm by microwave plasma CVD, and then a boron nitride film was coated using a microwave plasma CVD apparatus as shown in FIG. was formed. The diamond-coated plate 4 was placed on the substrate support stand B in the reaction chamber 5, and Cibolaf 5Cr:,/- and nitrogen 1occ/- were flowed into the reaction chamber 5 from the reaction gas supply device 7 via the cock 8. . The pressure inside the reaction chamber 5 is controlled by a cock 9. Exhaust device 10
．． The temperature was adjusted to 50 Tarr using the exhaust port 11, and the temperature of the substrate 4 was adjusted to 800° C. by adjusting the microwave plasma. The output of the microwave oscillator 12 was set to 400 W, and the microwave was guided into the reaction chamber 5 by the wave guide 13, and film formation was performed at 5 o'clock under these conditions.

As a result, a boron nitride film with a thickness of about 4 μm was formed on the diamond-coated silicon wafer, and when this film was analyzed by X-ray diffraction, a sharp peak was detected near 2θ = 4 & 2°. The boron nitride film was identified as cubic boron nitride.

Example 2 Using a molybdenum substrate as a substrate, thermal filament CV
After coating diamond to a thickness of about 10 μm to form an intermediate layer using the D method, a boron nitride film was formed using the microwave plasma CVD apparatus shown in FIG. The reaction gases are boron bromide 4Ct:,/- and ammonia a CC/
= was allowed to flow, the reaction chamber pressure was 10 Torr, and the substrate temperature was 900°C. As a result of opening the film at 8 o'clock with a microwave output of 400 W, a thickness of 6 μm was formed on the surface of the diamond-coated substrate.
A boron nitride film with a thickness of 100 m was produced. When this film was analyzed by X-ray diffraction, a sharp peak was detected near 2θ=452°, so it was identified as a cubic boron nitride film.

Example 5 A silicon wafer was used as a substrate, and diamond was coated to a thickness of about .mu.m to form an intermediate layer by a chemical transport method, and then a boron nitride film was formed using a tungsten filament apparatus as shown in FIG. A diamond-coated substrate 4 is placed on a substrate support 6 in a reaction chamber 5, and 6 cc/=+ of boron chloride and 8 cc of ammonia are supplied as reaction gases into the reaction chamber 5 from a reaction gas supply device 7 via a cock 8.
The cr-7 layer was run. The pressure inside the reaction tube 5 is controlled by the cock 9.
Exhaust device 10. The exhaust port 11 adjusts the temperature to 5° Torr, and the heater inside the substrate support table raises the temperature of the substrate 4 to 100° Torr.
0℃ [, the temperature of the tungsten filament 14 is 200℃
The temperature was 0°C.

Director 12 is a reactor. As a result of applying acid and film for 6 hours under the above conditions, a thickness of 4 μm was formed on the surface of the diamond-coated substrate.
A boron nitride film of about 100% was formed.

When this film was subjected to X-ray diffraction, it was identified as cubic boron nitride, as in Example 1.2.

As described above, it was confirmed that cubic boron nitride films could be produced in all cases under the conditions of Examples 1 to 5 of the present invention, and therefore, using these conditions, a chip was coated with the boron nitride of the present invention. (Examples, 1 to 3)
A cutting test was conducted on the

For comparison purposes, cutting tests were also conducted on an uncoated chip (Comparative Example 2) and a chip of the same type coated with TiN by ion blating (Comparative Example 1). The chip used as the base material is a we-based cemented carbide, Ni-10 cemented carbide TNMG35.
2 [manufactured by Sumitomo Electric ■] was used.

Note that the thickness of the cubic boron nitride coating layer and the TiN coating layer were both 5 μm.

Table 2 shows the conditions for the chip cutting test.

Table 2 Table 3 shows the results of the cutting test. Note that the abbreviation CBN hereinafter means cubic boron nitride.

Table 5 From the above results, it is clear that the chips coated with cubic boron nitride using the diamond coating layer as an intermediate layer according to the present invention have excellent wear resistance.

FIG. 4 is a graph showing the wear resistance test results of cemented carbide tips in steel turning in terms of the relationship between the cutting time (cutting time) and the amount of wear on the exposed surface (-). A in Figure 4 is a cemented carbide tip,
Diamond coating (thermal filament CVD1.CH) manufactured by Sumitomo Electric Co., Ltd., using 5NG432 as a base material
410a/m, H, 10QCt/m, filament temperature 2000℃, substrate temperature 800℃, pressure 100 Torr
) and cubic boron nitride coating (microwave plasma CVD method, 5 CC/-+ N210 CC
/ Agony, substrate temperature 900℃, pressure 50 Torr)
The product of the present invention is coated with TiC using the reactive ion blating method on the same base material.
Here are the test results for a comparative product, which is an uncoated base chip. The test conditions were: work material S CM 415;
The cutting speed was xoom/=+.

FIG. 5 is a graph showing the cutting performance test results for cast iron turning using cemented carbide tips in terms of the relationship between cutting speed (m/-m) and life time (-).

The second part in Figure 5 is a cemented carbide tip, manufactured by Sumitomo Electric, TM0.
Diamond coating (microwave plasma CVD method, CH420Cr:, 7 m
, H, 100Cr, 7m, pressure 20Torr, substrate temperature 800°C) and cubic boron nitride coating (thermal filament CVD method, ]31FIs 4 CC/-.

NH3b cr, /= , H,10o a,, /=
, filament temperature 2200°C, substrate temperature 900°C, pressure 40 Torr).
Here are the test results for the conventional coated product and the comparative product, which is an uncoated chip of the same material. In addition, if the work material is FCD
I went at 30.

FIG. 6 is a graph showing the fracture resistance test results of cemented carbide tips in cutting cast iron in terms of the relationship between the number of impacts and the time until fracture (-). Figure 6 shows a cemented carbide chip, manufactured by Sumitomo Electric, 5NG432'fl material coated with diamond according to the present invention (microwave plasma CVD method, CH
410a:, /x*, H, so cr,, /-,
Substrate temperature 1000℃.

pressure s OTarr ) and cubic boron nitride coating (
Ion blating method, B-based raw material, solid boron.

N, 2occ/=, substrate temperature 500℃, pressure 1X10-
"Pa,)" is the present invention's product, "H" is a conventional product in which the same base material is coated with TiN using the ion blating method, "R" is a conventional product in which the same base material is coated with TiC using the CVD method,
Here are the test results for a comparative product, which is a base material chip with a coating. The work material is FCD45. Cutting speed zso
I went with m/-.

From the results shown in Figures 4 to 6 above, the insert coated with cubic boron nitride according to the present invention has excellent cutting performance, wear resistance, and chipping resistance compared to conventional and comparative products. It is clearly seen that In addition to the above tests, it was also found to have excellent thermal shock resistance, thermal conductivity, hardness, and resistance to iron group metals at high temperatures.

〔Effect of the invention〕

As explained above, the present invention first forms a diamond coating on the surface of a base material, and then roughly forms a cubic boron nitride film on the diamond layer, thereby eliminating the problem of amorphous boron nitride being mixed in or peeling off of the film. Hard boron nitride can be stably precipitated.

The coated tools and the like according to the present invention have excellent machinability, wear resistance, chipping resistance, thermal shock resistance, thermal conductivity, hardness, and resistance to ferrous metals at high temperatures, so cutting members,
It is very effective when used as a coating film for wear-resistant members and heat-resistant members.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a substrate coated with high hardness boron nitride according to the present invention. 2 and 5 are schematic cross-sectional views for explaining embodiments of the present invention, and FIG. 2 is a plasma CVD
Figure 3 shows the case of the tungsten filament method. Figures 4 to 6 are graphical representations of performance comparison tests of a product of the present invention coated with a cemented carbide chip as a base material, a conventional product, and a comparative product without coating. Fig. 5 shows the results of a wear resistance test in turning, and Fig. 6 shows the results of a cutting performance test in cast iron turning, and Fig. 6 shows the results of a fracture resistance test of cast iron.

Claims (3)

[Claims] (1) A method for synthesizing high-hardness boron nitride, which comprises forming a diamond coating layer on the surface of a base material, and then precipitating high-hardness boron nitride from a boron-based raw material and a nitrogen-based raw material on the surface of the coating layer. (2) The method for synthesizing high hardness boron nitride according to claim (1), wherein the boron-to-nitrogen atomic ratio B/N of the boron-based raw material and the nitrogen-based raw material is in the range of 0.1 to 10. (3) The thickness of the diamond coating layer is 0.01 μm to 100 μm.
A method for synthesizing high hardness boron nitride according to claim (1), wherein the hardness is in the μm range.