|
Ultrafine nickel powder has excellent electrical , magnetic , catalytic , and mechanical properties , are widely used in the field of catalysts , battery materials , multilayer ceramic capacitor electrode and powder metallurgy . In this thesis, the chemical vapor deposition (CVD) process conditions Preparation of ultrafine nickel powder . To design , installation , and commissioning of the complete set of chemical vapor deposition apparatus for the continuous preparation of ultrafine nickel powder , single factor conditions of the experimental method is systematic flow of carrier gas (N 2 ) , H 2 the concentration reaction temperature , H 2 flow, the structure of the reactor and the precursor (NiCl 2 ) the evaporation temperature of the process parameters studied , were characterized using X-ray diffraction , scanning electron microscopy , particle size analysis of the sample structure , morphology , particle size , and to optimize the process parameters of the preparation of powder , the optimum conditions . The results show that : NiCl 2 · 6H 2 O raw material placed in a low temperature of 135 ℃ dehydration four hours , two hours of grinding and then dehydrated in a high temperature of 250 ℃ can be completely removed 6 water of crystallization ; the carrier gas (N 2 ) flows , H , 2 concentration , reaction temperature , H , 2 flow, the structure of the reactor and the precursor body evaporation temperature powder morphology and size of the main influencing factors , and crystallization performance only with the carrier gas flow rate , reaction temperature and reactor structure ; NiCl 2 < / sub > evaporation temperature of 900 ° C , H < sub > 2 flow rate of 9.6 L / h, the carrier gas flow rate of 50 L / h H 2 concentration of 20% , the reaction temperature is 1100 ° C , the reactor without spatial confinement tube prepared under the conditions of the nickel powder , washed 5 times , dried over anhydrous ethanol, washed 3 times , and sedimentation in ethanol dispersant 2min ideal obtained powder was graded to remove large particles ; high purity of the nickel powder obtained under optimal conditions , good crystalline properties ; fine granularity , and the average particle diameter of 0.31μm , and a narrow particle size distribution ; morphology is substantially spherical or spherical ; 1.98m 2 / g specific surface area ; oxygen content of 0.33% . Prepared by chemical vapor deposition of nickel powder with high purity , large surface area , high crystallinity , narrow size distribution , controllable advantages and broad prospects for industrial application .
|