Study On Ultrafine Nickel Powders And Composites

This thesis investigated firstly the synthesis of ultrafine nickel powders by liquidphase reduction method. The influences of PH value, Ni²⁺ concentration,polyvinylpyrrolidone (PVP) concentration, SDS concentration and reactiontemperature on particle diameter, morphology of nickel powders were investigatedrespectively by X-ray, image analysis meter and laser granularity analysis meter. Theresults showed PH value affected the velocity of reaction and purity of nickelpowders; Both SDS and PVP retarded the velocity of reaction greatly, and properconcentration of them could control nickel powders granularity; The polygonal, gooddispersibility and the average particle diameter aroundlμm ultrafine nickel powderscould be synthesized with 85℃, PH=13, both Ni²⁺ and SDS concentration is0.125g/ml. Through study on the course products of reaction, The results showed[Ni²⁺]/[N₂H₄] could directly affect reaction mechanism.Secondly, Nickel powders composites with ethoxyline is prepared and nickelpowders is prepared by previous method. Study on its properties showed theencapsulation materials soft magnetism performance became better with more nickelpowders. In low frequency, self-inductance(L) decrease obviously. Q-factor hasalmost linearity relationship with frequency. When mass ratio of acetone toethoxyline is0.2 and 0.4 respectively, the encapsulation materials L value and Q valuedecrease with more PA650.But when mass ratio of acetone to ethoxyline is 0.6, the Lvalue and Q value increase with more PA650. Through study on composite metallicphase by metallographic microscope, the results showed when mass ratio of nickelpowders to ethoxyline is 0.25, nickel powders is not aggregation, but when mass ratioof nickel powders to ethoxyline is bigger than 0.25,there is lots of aggregation.Annealing had little influence on metallic phase microscopic structure. Through studyon annealing treatment of composite, the results showed the optimal time andtemperature of annealing is 1h and 80℃respectively.and proper annealing treatmentcould increase Composite magnetoconductivity is 268.33nH/m with f is 500k whenmass ratio of ethoxyline, PA650, acetone and nickel powders is1,1,0.6,1.