Vacuum Evaporation Method Experimental Study Of The New Technology Of Ultra-fine Copper Powder

Superfine copper powder has been used in powder metallurgy, catalyst, medicine and other fields for its novel physical and chemical properties. With the development of science and technology, the demand for superfine copper power in industry is increasing, so it is an eager project to prepare superfine copper powders. In this thesis a novel preparation approach of evaporation and condensation was proposed based on the research on other preparation techniques and equipments. The superfine copper powders were characterized by laser particle size analyzer (LS), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), glow discharge mass spectrometer (GDMS), and differential scanning calorimetry (DSC). The results revealed that the mean particle diameter of spherical copper powder was less 2μm, and the mean particle diameter of flake powder was 10-30μm with a thickness of 1～2μm, both copper powders had narrow size distribution with controllable size, and high dispersity and purity.The superfine copper powders were collected by two novel self-designed condensaters, one was plumbaginous of 3 layers, and the other is water-cooling steel plate. The influencing factors of both condensaters were investigated. The effect of technique parameters on the evaporating rate, morphology of the copper particles, mean particle diameter, size distribution and product rate was systematically investigated, and the mechanism of evaporation and condensation method was discussed in the thesis. At last the conclusions were drawn as follows:1. The evaporating rate and the yield increased with the evaporating temperature T, the vacuum degree P, the area of the melt surface, and the depth of the copper melt surface.2. The optimum condition was gotten from the single factor experiment for both condensaters. The results showed that the evaporating temperature, vacuum degree, and the holding time had the similar effect on the morphology, mean particle diameter and size distribution of the copper powders, which were the main factors. For glumbaginous condensater, the optimum condition was evaporating temperature of 1673K, vacuum degree of 10Pa, holding time of 70min and the best condensation location of the second layer, while for water-cooling steel plate one, that was evaporating temperature of 1673K, vacuum degree of 10Pa, cooling water flux of 160L/h and the height for condensation of 7cm.3. The morphology of the copper powder depended on the particle size. The powders of small sizes formed into a sphere, while the large ones took on plate-like with smooth surface. The mean particle diameter, size distribution and morphology could be controllable by the technique parameters.