JPS6148580B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a boron structural material. Structure of conventional examples and their problems Boron has a hardness second only to diamond and has very good wear resistance, so it has become a useful material for cutting tools, sliding machine parts, bearings, etc. There is. 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, materials other than boron are used to manufacture various boron-applied products. Vapor deposition method, sputtering method,
It is manufactured as a composite with a boron coating formed by chemical vapor deposition (CVD). This conventional manufacturing method depends on the hardness of boron and
When applied to products that utilize wear resistance, usually no major problems occur. However, an extremely serious problem occurs in acoustic materials such as speaker diaphragms, cartridge cantilevers, and video disk cantilevers that utilize the large specific modulus of elasticity. That is, 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 diminished. In addition, conventionally, boron (B) was added to the base of tantalum (Ta), niobium (Nb), molybdenum (Mo), and tungsten (Ta).
A method has also been developed in which boron is deposited by chemical vapor deposition and then the substrate is dissolved and removed to obtain a hollow body made of boron alone.
Different crystals are formed in the precipitated boron structural material, forming a mixed crystal, which has the disadvantage of deteriorating film quality, decreasing mechanical strength, or 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, It exhibits excellent mechanical properties without the generation of foreign crystals unlike conventional products.
It is an object of the present invention to provide a method for producing a boron structural material that also provides a product with a 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 layer and forming a boron layer by chemical vapor deposition. This is a characteristic feature. For example, the substrate is placed in a reactor, heated by infrared rays, high frequency, or electrically heated, and then raw material gas BX ₃ (where X is a halogen element such as chlorine Cl, bromine Br, or iodine I) and hydrogen H ₂ are introduced. During this process, a trace amount of argon (Ar) is added, and boron is deposited on the substrate through a reductive decomposition reaction. When this boron is deposited, a unique peeling phenomenon occurs between the base material tantalum, molybdenum, niobium, or tungsten and the chromium layer in order to facilitate the creation of boron structural materials, but when argon is not added However, this peeling phenomenon was incomplete, causing uneven heat between the peeled and non-peeled areas, and mixed crystals were generated on the surface of the deposited boron, leading to deterioration of film quality and a decrease in mechanical strength. . The addition of argon makes the peeling phenomenon complete and smooth. The amount of argon added varies depending on the amount of raw material gas flowing into the reactor and the heating temperature of the substrate, but is suitably in the range of about 0.1% to 3%. This is because if the content is less than 0.1% or more than 3%, the above-mentioned peeling phenomenon will not occur 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, an acid such as Cl ₃ , HClHF, or Br-methanol is mainly used to dissolve and remove the chromium-coated substrate from the precipitated boron to obtain a single boron structural material. Description of Examples Specific examples of the present invention will be described below. First, a tantalum wire with a diameter of 2.0 mm and a length of 100 cm was degreased and cleaned, and then coated with 0.5 μm of chromium using a sputtering method to prepare a base. Next, this substrate was heated to 1200°C by electricity, and boron trichloride was heated to 1200°C.
1 part by volume of BCl ₃ and 3 parts by volume of hydrogen H ₂ were flowed at a rate of 2 per minute for 3 minutes, and at the same time 0.1% of argon was added to the 2 parts per minute. At this time, approximately 50 μm of boron was deposited. The sample thus prepared was cut into a length of 4 cm and immersed in a solution of 50 gr of bromine dissolved in 200 ml of commercially available methanol to dissolve the tantalum of the base and the chromium coated. The time required for dissolution was 20 hours. At this time, boron was not dissolved. The following table shows samples of various hollow boron structures obtained by adding a small amount of argon, and samples of various hollow boron structures obtained by adding a small amount of argon, using the boron pipe obtained as described above as sample No. 1. The results of the anti-refractory strength measurements are shown below.

【table】

[Table] Measurements were made using a beam with a length of 3.5 cm and a load applied to the beam with both ends supported, and based on the measured value of the load when the sample broke. As a result of measuring 20 samples for sample No. 1 in the table, 19 were good, and the average strength was
It was 1.80Kgr and the etching yield was 95%. No. 2 and No. 3 are cases in which the amounts of argon added are different. No. 4 to No. 12 are the results obtained using different base materials. No. 13 to No. 17 marked with * are comparative examples in which argon was not added. In particular, No. 17 is the case where the base material was not coated with a chromium layer. The boron chemical vapor deposition (CVD) time was adjusted so that the inner and outer diameters of all samples were constant at 20 mm and 21 mm, respectively (thickness was constant at 50 μm). According to these measurement results, it is clear that simply coating the substrate with a chromium layer already significantly improves the etching yield and bending strength; however, adding a small amount of argon during the chemical vapor deposition of boron Compared to the case without addition, the etching yield was further increased by 6% (Sample No. 13).
No.1 against No.15 and No.7) to No.21 against No.15
% (No.5 against sample No.14), bending strength is 16%
(No.1 for sample No.13 and No.14 for sample No.13
No.6) to 54% (No.8 compared to sample No.15). Effects of the Invention As explained above, 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 good yield, and is of great industrial value.

Claims (1)

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