JPS5832013A - Preparation of boron structural material - Google Patents

Abstract

PURPOSE:To prepare a boron structural material useful as a high strength acoustic material, etc., at a low cost, by evaporating and depositing amorphous boron on a W substrate, forming a crystalline layer by heat-treatment, depositing boron on the crystalline layer, and removing the substrate. CONSTITUTION:A Cr-coated W substrate is heated at 700-800 deg.C, and amorphous boron is deposited thereon by the chemical evaporation under reduced pressure. The amorphous boron is diffused by heat-treatment, and a crystalline layer of CrB2, WB2, W2B5, etc. is formed on the surface of the substrate at a thickness of 20-200mum. Boron is deposited on the crystalline layer at a desired thickness by e.g. evaporation. Thereafter, the substrate is removed by chemical or mechanical means. A boron structural material having improved film quality of boron and mechanical properties can be obtained by this method in high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a boron structure (A),
(t'Jl element) 1° #I structure 14 Plans for the film quality and mechanical properties of the boron IL'f - l: :l'r, 1: Boron structure (Aimed at cost reduction of A) It is.

Boron (Bl has hardness A: 'P!I' second only to diamond)
I>, and its wear resistance is also very high.
(In order to cut, j, lJ cutting tools and Ji'l moving machine parts,
It's 1-month 1fr, mouth i1. The cow rate (1 instant 111 rate/1.64 degrees) is 1.
31j〆1The largest known substance (that is, 1°d
-:/i ta'l! +r modified 4 has it. This game 1. Is the quality 51′? His (]-16;
ll'l+shi (as the old Pa1, it is especially for If).

Is it possible to cast boron applied products? :'
It is d-■In+ that can be obtained in the form of a dense lump in a month, and (for the second time 5)
．． In most cases, 4′A″4′:1 or C
) is used as a composite formed of boron IEi4 by vapor deposition method, sputtering method, chemical vapor deposition method (CVN method), etc.

Such conventional methods have been used to
Excellent aspect 1. Vl: h: Use (-) The product you are trying to use has a large support 1 (+:'j 7.

This is a very serious problem in acoustic materials such as the 3-beam diaphragm of a speaker, the cantilever of a cartridge, or the cantilever of a video disc, etc., which utilizes the large specific bullet ratio. In other words, the density and elastic modulus of the composite are greatly influenced by the properties of the substrate, and the inherent properties of boron are thereby greatly reduced.

Dota. In addition to the methods described above, tantalum (Ta).

Niobium (Nb), molybdenum (Mo"), tungsten (W), etc. are deposited on wires (0.2 to 0.4 mmφ) using the 1 element-4C VD method, and then these core wires are completely dissolved and removed. It is now possible to obtain m-boron bodies using these methods, but it is difficult to produce large-sized objects such as diaphragms and video disc cantilevers with a good yield using these core wires and substrates due to the difference in thermal expansion from single-round bodies. It was difficult due to the internal stress of the deposited boron.In particular, it was a regression process to create a large structural material of boron+1j with a good overall yield using an inexpensive core material such as MO or W.

The present invention has been made to eliminate such conventional drawbacks.
Boron was deposited on a chromium-coated W substrate by VC low-pressure chemical vapor deposition (LP-IVD method), and then subjected to heat treatment. , CrB2 on the human face. W
B2. By fully forming a crystalline layer consisting of at least one of W2B5 and fully precipitating a boron layer on this soil, a boron structure 4A with mechanical strength and a good yield V can be provided. Therefore, the manufacturing method of the present invention will be specifically explained.

Boron 'fr: LP-GvD method J: S, No 1 (The method for forming it on the body is, for example, under reduced pressure: infrared heating, high frequency heating of the substrate placed in the vessel) 10 It is heated with an electric current, etc., and the boron is completely precipitated by the reduction T1 reaction as shown in the following formula.

2BXs4-3H2-p 2B16HX (Tatashi,
is a hydrogen element such as Cr, Br, I, etc.) As the raw f'1 gas used in the CVD method, there are boron hydride and the like in addition to Q and BI3. It's a descendant, this 1'111 element, I1111m
For heating temperature, reduced usage status, and gas use.

When the raw material gas flows into the reactor, a crystal form of Nili species is obtained. In particular, under reduced pressure conditions, the above reaction may be in an amorphous state at ○○°C to 1000°C.
,, -1. β-07 bohedral boron is obtained at 1000°C to 130°C. In particular, for normal pressure CVD method,
The L P-CV D method produces amorphous boron and β at low temperatures.
-Since rhombohedral boron is precipitated, it is advantageous that there is less thermal strain between the substrate and the deposited boron.

Amorphous [11
The appropriate temperature for precipitating CrB2.1 is 700 to 80°C. At temperatures lower than 700°C, the precipitation rate is very slow and it precipitates in powder form. WB2. W2B5 f is produced by recirculation, and at temperatures exceeding 80°C, strain is likely to be introduced between the body (W) and the amorphous boron. hand,
The temperature at which the entire crystal layer consisting of at least one of CrBz, WB2, and W2B5 is formed is 860 to 125
0'C is suitable, 850℃! l lJk in!
At +1L degree, CrB 2 , WB 2 , W2B5
When the temperature exceeds 12tso'C-r, thermal stress tends to occur. Also, as a boride of W, 5WB2. W2B5 or this r-, noil+'
The reason why these crystal systems have a coefficient of thermal expansion closer to that of boron than W2B and WB is 1. ′-Li, therefore, the boron film has an O concentration of /1
: 7 chiru for Jinigume.

In addition, when WB<, the bonding force between boron and WB4 becomes too strong, making it difficult to etch.
ing. CrB2. WB2. The thickness of the crystal layer consisting of at least one of W2B5 is 20~2oool1m is 1"-<
, 20 ltm! When it becomes thinner, it becomes a boron layer (w)
, the thermal strain of the q-body cannot be completely relaxed, and Doda200
If it is thicker than 71 m, the base itself becomes brittle and the 1V shape is difficult to break.

Full coating of Or on a small W substrate depends on the adhesion between boron and WB2 or W2B5, chemical, and I.) Rui it.
To make it easier to mechanically remove the entire base (1), in this moving table, Cr reacts with boron to become CrB2,
The effect of weakening the adhesion between boron and WB2 or W2B5 is to improve the etching yield.
It has the effect of 1-. The film thickness of Or is several 1 tm.
It is desirable that the Next, this 1111 compound was subjected to full-phase deposition techniques such as boron total evaporation, CVD/71, etc.
i7! 1! , (-7, -1 Karuno also removed the entire substrate chemically or mechanically.

A structure consisting of boron j1i is obtained.

An embodiment of the present invention will be described below.

All W wires with a diameter of 2.0 mm and a length of 100 mm are prepared and degreased.

Wl: Coated with about 1 micron thick C.rf by sputtering/; f7 on rJ+. Next, insert this wire into the CVD furnace. Then, all the air in the furnace was removed using an O-tally pump, and the furnace was heated to 7 oO'G by electricity. Next, 1 volume part of boron trichloride (B(7Jx)) and 3 volume parts of hydrogen (R2) were flowed at a rate of 2e per minute for 4 minutes. At this time, the reduced pressure was maintained at 100 Torr using a rotary pump and a valve. Thereafter, only BC7!s gas was introduced, and heat treatment was performed at 850° C. for 3 minutes.

Amorphous 17111 element fully diffused 20μm thick WB
2 (results of X-ray analysis). Next, BCβ3 gas was flowed again (the body core line was kept at 1000°C, and the gas was flowed for 6 minutes. As a result, 5071 m of amorphous boron was deposited on WB2. The sample was cut into lengths of 4 (m) and immersed in a mixture of Br and methanol to completely dissolve the sample.

Next, the length of the beam is 3.5 teeth in total, and the beam is supported at both ends.
Adding weight, the pipe broke by 1' from the load of lL7
The uniform strength was determined. As a result, it was clear that 17 pieces of ~tazambul 2° water were of good quality, and the ~IL average jj・n degree was 1.s5.
It was at 2. As a result, I was ranked No. 1 in the test of Katsujii γ'L.
I...

Hereinafter, each condition was changed and an R111 raw structural material was obtained in the same manner as in Example 17. The results are shown in the table below. Tatami sample number No. 'O-No, 15 f':1: Comparison'l
I/lI Thea Z). All samples had inner and outer diameters of JOlnm, respectively.

so that it is a constant value of 2.1 mm (thickness is 50 lt)
(constant at m) Precipitation of boron ii.

The following margin is 0. It is clear from the table that the test FL within the scope of the present invention has a high bending strength and a good yield, and has extremely superior characteristics as a γ6 sound 4A advantage.

1 = As explained above, the manufacturing method of the present invention is based on the LP-IVD method on a W substrate.
Precipitation (1, then heat treatment with 1.k expansion 1
1 (l-sa flooded GrB2.WB2.W2B5 f produced → ↓, boron was deposited on the substrate in 18)J, and then the substrate was removed to obtain boron rl'l. Yes, this J: The method of the present invention can produce high-strength boron structural materials at a higher overall yield than conventional methods.
i) It has great industrial value because it can

Claims (1)

[Claims] Tungsten L” body coated with 11 mm e7oo~
Vacuum chemical vaporization is performed on this substrate at 1υ1 at each time of 800°C using the j':f method? i: A first step of precipitating amorphous boron using the method, and heat treatment at 1111 V degrees of the substrate f85o'0 to 1250''Q on which the amorphous boron has been precipitated. jI (on the body surface: CrB2, WB2, W2B5) A second crystal formed with a thickness of 20 to 200 μm
A third step of depositing boron on the crystal layer; and a fourth step of removing the substrate by chemical means (a) and mechanical means. -to do”;j:
1:1'L method for manufacturing boron structural material with 'l'l feature.