JPS59110773A - Manufacturing method of boron structural material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for manufacturing a boron structural material.

Structure of conventional examples and their problems Boron has a strength second only to diamond and has very good wear resistance, so it is a useful material for cutting tools, sliding machine parts, bearings, etc. (1) Yes. In addition, the specific elastic modulus (elastic modulus/density) is the highest among currently known materials. This property means that the propagation speed of sound waves is the highest among existing materials, making it particularly valuable for applications as acoustic materials. Since it is difficult to obtain such boron-applied products in the form of dense blocks by methods such as casting or rolling, in most cases, when manufacturing various boron-applied products, we use a substrate made of a material other than boron. Then, it is manufactured as a composite body with a boron coating formed thereon by a vapor deposition method, a sputtering method, a chemical vapor deposition method (CVD method), or the like.

Such conventional manufacturing methods usually do not cause any major problems when applied to products that utilize the hardness and wear resistance of boron. However, extremely serious problems occur in acoustic materials such as speaker diaphragms, cartridge cantilevers, and video disc cantilevers that utilize the magnitude of specific elastic modulus. In other words, the density and elastic modulus of the composite are greatly influenced by the properties of the substrate and the process of vapor deposition, and the inherent properties of boron may be significantly reduced(2). In addition, conventional tantalum (Ta)
), niobium (Nl)), molybdenum (Mo), and tungsten (Ta) by chemical vapor deposition, these substrates are dissolved and removed to obtain a hollow body made solely of boron. Methods have also been developed, but in particular for relatively large objects such as diaphragms and video disk cantilevers, different crystals are generated in the precipitated boron structural phase.
It has the form of a mixed crystal, which has the drawbacks of deteriorating film quality, decreasing mechanical strength, and inhibiting the propagation of sound waves.

Purpose of the Invention The present inventor considered coating the substrate with a chromium layer in order to eliminate the drawbacks of the conventional example, but by adding a small amount of argon during the chemical vapor deposition process, The present invention aims to provide a method for manufacturing boron structural materials that does not generate foreign crystals as in conventional methods, exhibits excellent mechanical properties, and provides products with good appearance.

Structure of the Invention The method for producing a boron structural material according to the present invention involves adding a small amount of argon to a base of tantalum, molybdenum, niobium, or tungsten coated with a chromium (3) layer to form a boron layer by chemical vapor deposition. It is characterized by: For example, the substrate is housed in a reactor, heated by infrared rays, high frequency, or electrically heated, and the raw material gas BX is heated.
3 (where X is a halogen element such as chlorine C/, bromine Br, iodine I, etc.) and hydrogen H2 are introduced, and in this process, a trace amount of argon 1ffAr is added, and boron is deposited on the substrate by a reductive decomposition reaction. During this boron precipitation,
Tantalum as a base material, to facilitate the creation of boron structural materials
A unique peeling phenomenon occurs between molybdenum, niobium or tungsten and the chromium layer, but if argon is not added, this peeling phenomenon is incomplete and
Heat unevenness occurs between the peeled portion and the non-peeled portion, and mixed crystals are generated on the surface of the precipitated boron, which may lead to deterioration of film quality and reduction in mechanical strength. The addition of argon makes the peeling phenomenon complete and smooth. The amount of argon added depends on the amount of raw material gas flowing into the reactor and the heating temperature of the substrate (4
), but a range of approximately 0.1% to 3% is appropriate. This is because if the content is less than 0.1% or more than 3%, the above-mentioned peeling phenomenon will not proceed smoothly and it will be difficult to achieve a sufficient effect. Methods for coating the substrate with chromium include sputtering, vacuum deposition, and plating.

Next, in order to obtain a single boron structural material by dissolving and removing the chromium-coated substrate from the precipitated boron, mainly C13,
Acids such as HC/, HF, Br-methanol are used.

Description of examples Specific examples of the present invention will be described below.

First, a tantalum wire with a diameter of 20 mm and a length of 100 mm was degreased and cleaned, and then coated with 0.51 gn of chromium by sputtering to prepare a base. Then, by energizing the entire base, 1
Heating to 200°C, flowing boron trichloride BClal volume and hydrogen I (23 parts by volume) at a rate of 21! per minute for 3 minutes,
At the same time, 01% of argon was added to the above 21-.

In this case, boron having a thickness of about 50 μm was precipitated. The thus prepared sample was cut into a length of 411 m and immersed in a solution of 50 fr of bromine dissolved in 200 ml of commercially available methanol (5) to dissolve the tantalum of the base and the coated chromium. The time required for dissolution was 20 hours.

At this time, boron was not dissolved.

The following table lists the boron pipe obtained as described above as sample No. 1, and the following table shows various hollow boron structure samples obtained by adding a small amount of argon and samples obtained without adding argon. The results of measuring the bending strength of the same sample are shown below.

Margins below (6) (7) Measurements were made using a beam with a total length of 35 mm, and a load was applied to the beam with both ends supported, and the measured value of the load was used when the sample broke. As a result of measuring 20 samples for samples No. 1 in the table, 19 pieces were found to be of good quality, and the average strength was 1.80 Kgr. The yield by etching was 95%. No, 2, no
, 3 are cases in which the amounts of argon added are different.

Similarly, No. 4 to No. 12 are results obtained using different base materials. Items marked with * in No. 13 to No. 17 are A with argon k i% not added as a comparative example. In particular, No. 17 is the case where the base material was not coated with a chromium layer. All samples were subjected to boron chemical vapor deposition (CVD) so that the inner and outer diameters were constant at 208M and 21M respectively (thickness was constant at 50μm).
) was fully adjusted. According to the results, it is clear that simply coating the base material with a chromium layer can significantly improve the etching yield and bending strength.
If a small amount of argon kW is added during chemical vapor deposition of boron, the etching yield on the length is 6% compared to when no argon is added (No. 1 and No. 1 for samples N, o, 13).
(7) to 21% (Sample No. 14, No. 5), (8) flexural strength is 16% (Sample No. 13, No. 1 and No. 14, No. 6) to 54%. (Sample No. 15 vs. No. 8) It can be seen that there is an increase.

As described in detail of the invention, according to the method for manufacturing a boron structural material according to the present invention, when forming a boron layer on a substrate coated with a chromium layer by chemical vapor deposition, by adding a small amount of argon. , a high-strength boron structural material with excellent film quality can be obtained at a high yield, and is of great industrial value.

Agent Hiroshi Mori (9)

Claims (1)

[Claims] 1. A method for producing a boron structural material, which comprises forming a boron layer by chemical vapor deposition using tantalum, molybdenum, niobium, or tungsten JILFK coated with a chromium layer and adding a trace amount of argon. . 2. The method for producing a boron structural material according to claim 1, wherein the amount of argon added is 0.1% to 3%.