Method for preparing nano diamonds by using direct-current arc process

Abstract

The invention discloses a method for preparing nano diamonds by using a direct-current arc process, belonging to the technical field of preparation of carbon-related nano materials. The method is characterized in that direct-current arc hydrogen plasma is used as a heat source, graphite is used as a carbon source, nickel is used as a catalyst and silicon is used as a nucleation substance to synthesize diamond nano-particles. High-temperature hydrogen plasma is used for evaporating a block composite target material to form atomic and ionic states of raw material components, a silicon carbide cluster crystal nucleus is formed and atoms are induced to form a diamond phase during condensation, carbon atoms separated out from a supersaturated nickel-carbon solid solution become growth substances for the diamond phase, and a nano diamond blank is obtained through passivation. The remaining impurities including metals, graphite, amorphous carbon, silicon carbide and the like are removed through purification processes including acid treatment, high-temperature oxidation, rinsing and the like so as to obtain high-purity diamond nano-particles. The method disclosed by the invention has the effects and benefits that the preparation process is simple, the synthesis is performed under a normal pressure condition, and the low cost, low energy consumption and large-scale production of the diamond nano-particles are realized.

Description

technical field [0001] The invention belongs to the technical field of carbon-related nanometer material preparation. In particular, it relates to a method for synthesizing diamond nano-particles under high temperature and normal pressure conditions by using graphite as a carbon source, nickel as a catalyst, and silicon as a nucleation substance, using DC arc plasma as a heat source. Background technique [0002] Due to its unique physical and chemical properties, diamond is widely used in the fields of science and technology and chemical industry. In addition to the basic properties of diamond, nano-diamond also has the characteristics of nano-materials, and its application prospects are very broad. [0003] The main preparation methods of nano-diamonds are: high-pressure high-temperature synthesis method, that is, direct current or alternating current is used to generate continuous high temperature through graphite, the reaction temperature is usually 2300-2500 ° C, and t...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a method for preparing nano-diamond by direct current arc method, using automatic control direct current plasma equipment (Chinese patent number: 200410021190.1), using graphite as carbon source, and utilizing high temperature (about 3000K) formed by ionized hydrogen Hydrogen plasma is used as a heat source to evaporate the anode graphite into atomic and ionic carbon components. Under the action of catalyst, crystal nucleus and condensation atmosphere, after nucleation and growth process, diamond nanoparticles are finally formed to solve the problem of existing diamond The disadvantages in the preparation technology are that the reaction conditions are difficult to achieve, the reaction process is complicated, the yield of diamond is low, and the purity is low.

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