Use of electrothermal alloy in six-side top high-temperature high-pressure synthetic cavity

Abstract

The invention more particularly relates to an electric heating element that uses an electrothermal alloy containing iron, chrome, aluminum, columbium, tantalum and molybdenum as an electric heating element and is applied to a cubic multi-anvil high pressure apparatus for a technique of indirect heating and synthesizing a diamond at high pressure and high temperature. The alloy can also be applied to the growth of cubic boron nitride, carborundum monocrystal and gallium nitride monocrystal. The heating element rolls the electrothermal alloy with the components of 65 to 80 percent of iron, 13 to 27 percent of chrome, 4 to 7 percent of aluminum and 0.5 to 1 percent of the mixture composed of one or more of columbium, tantalum and molybdenum, into a pellicle with a thickness of 0.05 to 0.3mm, while the pellicle is cut with a certain width and length so as to take the place of a graphite heating pipe in the assembly of indirect heating and synthesizing the diamond. The element of the invention has the advantages that: (1) the machine shaping difficulty is greatly reduced and the yield of the element production is improved; (2) the better tenacity of the element leads the structure of the indirectly heating assembly to be more compact and the transport performance of the indirect heating assembled products is improved, while the damage ratio is reduced; (3) compared with the graphite-pipe, the electrothermal alloy tube further decreases the volume, the effective utilization of a synthesizing cavity is improved and the yield per unit can be further improved.

Description

Technical field [0001] The present invention specifically refers to electric heating alloys containing iron, chromium, aluminum, niobium, tantalum, and molybdenum as electric heating elements, which are applied to indirectly heating high-pressure high-temperature synthetic diamond heating elements in a six-side top press. The alloy can also be applied to the growth of cubic boron nitride, silicon carbide single crystal and gallium nitride single crystal. Background technique [0002] The industrial production of synthetic diamond generally uses high-purity graphite as raw material and adds alloy catalysts (such as alloys formed by Fe, Ni, Mn, Co, etc.) to partially convert the graphite into diamond at high temperature and high pressure. According to the heating method, the synthesis process is divided into direct heating and indirect heating. Before 2005, the synthesis process basically used the direct heating process, that is, the graphite rod was directly passed through the gra...

AI Technical Summary

Problems solved by technology

However, the indirect processing technology has the following disadvantages: (1) thermal assembly is quite complicated; (2) insulating sleeves and thin-walled graphite heating tubes are difficult to process, have low strength, and are easily damaged during assembly and transportation

(3) Since almost all key components in the indirect heating assembly are brittle materials, there are deformation, fragmentation and fluidity under high pressure, and a short circuit is easily generated between the graphite tube and the graphite synthesis rod, which makes the synthesis invalid

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