Preparation method of nano-coated composite powder

Abstract

The invention discloses a preparation method of nano-coated composite powder, and belongs to the technical field of material preparation. According to the preparation method of the nano-coated composite powder, in the preparation process, a precipitant is added into an organic solution containing powder particles and metal compounds, a nano-precursor wrapping the surfaces of the powder particles is obtained, the nano-coated composite powder of a nucleus-shell structure is obtained through reduction, through a solvation effect of the metal compounds in the organic solution and the weak electrolyte property of the precipitant in the organic solution, the defects of too high local concentration, too long reaction time and large particle size of reaction products during the precipitation reaction are overcome, the average particle size of the prepared metal precursor is smaller than 200 nm, the metal precursor wraps the surfaces of the powder particles in a colloidal state, after low temperature reduction, nano metal or alloy particles adhere to the surfaces of the powder particles, and a nano-coating layer with highly uniform phase distribution is formed.

Description

technical field [0001] The invention belongs to the technical field of material preparation, and relates to a preparation method of nano-coated composite powder. Background technique [0002] Due to their excellent structure, physical and mechanical properties, nano-powders and coatings are the hotspots in current materials research. Usually, refractory metal alloys (such as alloys based on tungsten, molybdenum, tantalum, niobium, rhenium, etc.) and hard materials (such as WC, TiC, TiN, Ti(C, N), TaC, NbC, Mo 2 C. TiB 2 , B 4 C, etc. are cemented carbide or ceramic materials of the hard phase) produced or prepared by powder metallurgy. Its production process mainly includes: mixing the refractory metal matrix and additive elements (such as Co, Cu, Ti, etc.), hard phase and binder metal (such as Mn, Fe, Co, Ni, Cu, etc.) by ball milling to obtain a powder mixture ; After further pressing and sintering, refractory metal alloys (such as W-Cu, Mo-Ti-Zr alloys), hard material...

AI Technical Summary

Problems solved by technology

Usually, the ball milling time is more than 15 hours, which takes a long time and the production efficiency is low

Other defects are: (1) The wear of the tank body and the grinding balls may cause pollution; (2) When the ball milling time is insufficient or the process is not good, the WC and Co phases in the WC-Co mixture are not uniformly distributed, and after compression molding , the probability of direct contact between WC particles increases, resulting in the merging and growth of WC grains during the sintering process; (3) Due to the crushing effect of ball milling, the WC particle size distribution in the obtained WC-Co mixture is wide, which leads to the hardness after sintering. The WC grain size distribution of the cemented carbide is wide, that is, the cemented carbide is "thick and thin". According to the "Ostwald ripening" aging mechanism, during the sintering process, the fine WC particles are preferentially dissolved quickly, and at the same time they are precipitated on the original coarse WC surface. resulting in unusually large WC grains in the alloy

However, the metal salt precursor prepared by chemical precipitation in aqueous solution generally has a large particle size, and the shape is difficult to control. It is difficult to prepare a nano-coated composite powder with a uniform phase and a special shape.

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