JPH01316460A - Production of cubic b-c-n crystal - Google Patents

Abstract

PURPOSE:To produce cubic B-C-N crystals under mild conditions of high temp. and pressure by bringing Co, Fe or Ni into contact with hexagonal BC2N synthesized by chemical vapor deposition with BCl3 and CH3CN and by heating them under specified conditions. CONSTITUTION:A film or powder of hexagonal BC2N having the regular compsn. is synthesized by chemical vapor deposition with BCl3 and CH3CN. One or more kinds of metals selected among Co, Fe, Ni and alloys thereof are brought into contact with the film or powder and they are heated at >=1,360 deg.C within the range in which diamond is stable. Extremely high pressure is not required and insulating cubic B-C-N crystals having high hardness are easily obtd. under mild conditions of temp. and pressure at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to high hardness, insulating cubic B-C-N (hereinafter referred to as cB
-C-N)) relates to a method for producing crystals. cB-C
-N crystal, like diamond and cubic boron nitride (hereinafter abbreviated as cBN), has high hardness and wear resistance, so it is a substance with suitable properties as grinding abrasive grains, cutting tool materials, etc. This is something that is attracting attention.

Prior Art and Its Problems Diamond is the best known material in terms of hardness. However, there are stability problems when used at high temperatures. - On the other hand, cBN is the second hardest substance after diamond. Furthermore, its high-temperature stability is far superior to that of diamond. However, the hardness of cBN crystal is about half that of diamond crystal. On the other hand, cB-C-N crystal has a hardness close to that of a diamond crystal and has excellent high temperature stability, making it an extremely promising material as a highly hard and wear-resistant material.

As a conventional method for producing cB-C-N solid solution, (+)
Andrzej R. Badzian, Materials Research Paperback (Mat, Res, Bull
), vol, 16+ρρ1385-1393.1
In 1981, the synthesis of cB-C-N solid solution was reported. According to the paper, a hexagonal B-C-N solid solution (hB-C-N solid solution) synthesized by chemical vapor deposition was heated to a very high pressure of 14 GPa, about 3,600 psi using a static high-temperature and high-pressure apparatus. reported that cB-C-N solid solution could be synthesized under temperature conditions. In addition, in the same paper, hB-C-N solid solutions synthesized in the same manner were used as diamond synthesis catalysts (Co, Ni) and cBN synthesis catalysts (Li).
It is reported that the cB-C-N solid solution could not be synthesized even though it was treated under high-temperature and high-pressure conditions similar to those used for synthesizing ordinary diamond and cBN.

(2) Nobuo Setaka, Research Report No. 39 of the Institute of Inorganic Materials, Science and Technology Agency (research on diamonds).

pp. 59-61, 1984), the possibility of synthesizing cB-C-N solid solution using high impact pressure was reported. The method uses a carbon precursor (6
Hexagonal BN (hBN, ) synthesized from NaBH, -NH, CI (00''
This is to synthesize a solid solution.

Both of the above two methods, which are said to be able to synthesize cB-C-N solid solution under very high pressure conditions, regardless of static or dynamic high pressure, are difficult to put into practical use as an industrial process. difficult. Furthermore, it is based on the fact that the lattice constants are between those of cBN and that of cBN.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of conventional cB-C-N solid solution production methods and provides a method for producing cB-C-N crystals under mild high temperature and high pressure conditions without requiring very high pressure conditions. The purpose is to provide.

Structure of the Invention The present inventors achieved the above object (as a result of intensive research, the above-mentioned A. R. Baclzian report states that in order to produce hB-C-N solid solution, BCIs, CCl4.Na,
A chemical vapor deposition method (hereinafter referred to as CVD method) is performed using Hz gas.

However, since this method uses different raw material gases for B, C, and N raw materials, hBN or a heterogeneous mixture of B, N, and C tends to be selectively formed rather than a homogeneous -C-N solid solution. , It is also difficult to control the composition ratio of 1 ethylene oxide and C.

The present inventors used both boron trichloride (BCIs) and acetonitrile (CIlICN) gases and a CVD reaction to produce a solid solution at 750 to 900°C.

As a result, a black film-like deposit was observed on the substrate from 750°C. As a result of electron beam diffraction and powder X-ray diffraction of the deposit, the lattice constants are a = 2.44 and C = 3.4.
There were 0 people. These values are very close to the lattice constant values of graphite and hBN.

From these facts, it is considered that the product has a well-defined layered structure. Moreover, the crystallinity of the product was better as the gas partial pressure was lower and the CVD reaction temperature was higher.

I investigated by doing this. As a result, BC! It was revealed that it has a chemical composition of H. The hB-C-N solid solution with the stoichiometric composition can be synthesized in this way because the C and N sources are supplied from acetonitrile and the B source is supplied from boron trichloride, which suppresses the selective formation of hBN. This is thought to be because a deposit in which B, C, and N are homogeneously distributed is obtained. In this respect, it was found that it is significantly different from existing hB-C-N solid solutions. The reaction is as follows.

BClz(g) 10CHsCN(g)-BC*N(s
) +38C1(g) BCla and CI(,CV of CN
The electrical resistance of the film-like hB-C-N solid solution obtained by the D reaction was measured by the four-probe method, and the specific resistance was 0.05 to 0.
It was 1Ω1. This value belongs to the semiconductor region and is located between graphite, which behaves like a semimetal, and hBN, which is an insulator.In terms of electrical properties, the film-like hB-CN solid solution has hB
It was found that this substance exhibits properties closer to graphite than to N.

The hB-C-N solid solution synthesized by CVD reaction of Bcts, CIl, and CN was heated at 7.7 GPa, 2000
Although the treatment was carried out under the conditions of ``C'', the presence of any cB-C-N solid solution was not observed by X-ray diffraction.It is believed that the formation of cB-C-N solid solution was not observed due to the low temperature of the above synthesis conditions. Thoughts, higher temperature synthesis conditions, 7.7
The hB-C-N solid solution was processed at 2200'C, GPa. As a result of X-ray diffraction of the obtained sample, it was found that it was partially converted into a cubic crystal system substance. Judging from these lattice constant values, it is not a cB-C-N solid solution, but a cB-C-N solid solution.
It is thought that BN was partially generated. ? , 7 GP
a. Under high temperature and high pressure conditions of 2200°C, hB-C-Nil! It is considered that the il solution was not directly converted to a cB-C-N solid solution, but decomposed and a part of it was converted to cBN.

Under the above pressure and temperature conditions, synthesis of cB-C-N solid solution is very difficult.

Therefore, metals or alloys of Co, Ni, and Fe, which are well known as diamond synthesis catalysts, and hB-C-N
The solid solution was laminated and treated under conditions of approximately 6 GPa and 1500°C. The obtained sample was treated with hot concentrated hydrochloric acid, washed with water, dried, and examined by X-ray diffraction. As a result, the lattice constant of the sample was clearly smaller than that of cBN and larger than that of diamond. These results indicate that cB-C
This strongly suggests the possibility of -N solid-thin synthesis. The results of examining the sample using scanning Auger electron spectroscopy (SAM) are B and C.

Three elements, N, could be clearly detected. Moreover, as a result of 38M observation of the sample, it was also revealed that the cB-C-N solid solution was a microcrystal with an euhedral surface.

It was also found that cB-C-N crystals could not be obtained if the treatment temperature was lower than 1360°C. The present invention was completed based on these findings.

The gist of the present invention is that hexagonal BC,N
A cubic crystal characterized by contacting the film or powder with one or more metals selected from cobalt iron, nickel, and their alloys, and heat-treating the film or powder at a temperature of 1360°C or higher in the diamond stability range. It is in the manufacturing method of B-CN crystal.

A schematic diagram of the CVD reactor used in the method of the present invention is shown in FIG. 1, where 1 is a helium cylinder, 2 is a boron trichloride cylinder, 3 is a common bubbler for boron trichloride, 4 is an acetonitrile distillation device, and 5 is for acetonitrile. 6 is an electric furnace, 7 is a trap, 8 is a vacuum line, and 9 is a mercury bubbler.

EXAMPLE Using the CVD reactor shown in FIG. 1 and using helium gas as a carrier gas, a thickness of O
, we were able to synthesize a black film about 1 m long.

As a result of X-ray diffraction of the obtained film, the sample belonged to a hexagonal crystal system, with lattice constants of m-2,44 and c-3,40. Figure 2 shows a 38M image of the cross section of the sample.

The conclusion of the X-ray diffraction pattern and SEM observation was that the stacked state of the product was composed of homogeneous particles having a disordered turbostratic structure.

Electron energy loss spectrum (EELS) of product
is shown in Figure 3, energy loss 180-450 eV
Three peaks appeared in the range.

These peaks are due to the excitation of shell electrons.

They were assigned to C and N, respectively. Since no other peaks are observed, it is clear that the product is composed of 3 elements: B, C, and N. By comparing the area of each peak with the calculated value of the ionization cross section of each element, the mol% of B, C, and N is 24.7±4.
1%, 52.6±5.8%, and 22.7±3.6%. These results revealed that the chemical composition of the product was BC,N. It was also confirmed by Auger electron spectroscopy that the chemical compositions were the same.

5. The obtained hB-C-N solid solution was laminated on a metal Co plate.
The treatment was carried out under conditions of 8 GPa and 1500° C. for 1 hour.

The obtained sample was treated with hot hydrochloric acid and hot concentrated sulfuric acid, washed with water, dried, and examined by X-ray diffraction. The X-ray diffraction pattern (Fig. 4) showed a cubic pattern, and the lattice constant was a-3.60. This lattice constant was between the lattice constants of cBN and diamond. A 38M image of the sample is shown in Figure 5. This sample consists of microcrystalline particles of submicron to several micron size with euhedral surfaces. is clear.

In order to clarify the constituent elements of this sample, we investigated it using SAM (Figure 6). Since this sample is an insulator, the apparent energy value shifted, but B, C, and N were clearly detected. . Auger spectra at many points were investigated, and at every point a spectrum consisting of B, C, and N was obtained.

Estimating the composition from the intensity of each peak, it is clear that it is a B, C, N crystal containing about 15% carbon.

From the measurement results of X-ray diffraction, SEM image observation, and Auger electron spectrum, it was found that hB-C-N solid solution was laminated on a metal Co plate and treated at 5.8 GPa and 1500°C, resulting in cB-C of about several microns. -N crystals were found to be obtained.

Effects of the Invention According to the method of the present invention, cB-C-N crystals can be easily produced under mild pressure and temperature conditions without requiring extremely high pressure in conventional methods for producing cB-C-N crystals. It will be done. Therefore, the equipment becomes simple and industrial production can be facilitated.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the CVD reactor, Figure 2 is an SEM image of the cross section of hB-C-N solid solution obtained by the method of the present invention, and Figure 3 is
The diagram is BC! Electron beam energy loss spectrum of N, 4th
The figure shows cB-C-N crystal powder X obtained by the method of the present invention.
A line diffraction diagram, FIG. 5 shows an SEM image of the crystal, and FIG. 6 shows an Auger electron spectrum of the crystal. ■ = Helium cylinder, 2: Boron trichloride cylinder, 3
: Common bubbler for boron trichloride, 4 Niacetonitrile distillation equipment, 5 Niani heptonitrile bubbler, 6; Electric furnace, 7: Trap, 8: Vacuum line, 9: Mercury bubbler. Factor l Factor 2 Intensity Figure 5 Figure b Kinetic energy (ev) Procedural correction written by Mr. 4) 1ilj<':. Yoshi, Director General of the Japan Patent Office, January 1, 1983/% Date 1) Tsuyoshi Moon, 1988 Patent Application No. 149133 Z Name of Invention Method for Manufacturing Cubic B-C-N Crystal 3, Case of Person Who Makes Amendment Related Patent Applicant■ Nobuo Setaka 4.1iif□, Dyoio;
1 Completion --- September 27, 1988 5. Number of inventions increased due to amendment No. 1) In the second line of page 12 of the specification, after "solid solution cross-section", "indicates particle structure" is added. insert. (2) On page 12, line 6, insert ``Show structure'' next to ``J'' for crystal. that's all

Claims (1)

[Claims] One or more metals selected from cobalt, iron, nickel, and their alloys are added to a hexagonal BC_2N film or powder with a stoichiometric composition synthesized by chemical vapor deposition of boron trichloride and acetonitrile. 1. A method for producing cubic B-C-N crystals, which comprises bringing them into contact with each other and heat-treating them at a temperature of 1360° C. or higher in the diamond stability region.