Research Of Inorganic Powders Electroless-plating Technology

In this paper, we study the technology of electroless silver and nickel plating on iron oxide, hollow micro-spheres and carbon spheres and use the resistance probe to test the conductive properties of the products of. From the result we gained the best electroless plating process of various inorganic powders and its conductivity. Combined with recent research we analyzed the maybe used field and its prospected application.For the experiments we used ultrasonic to stir and studied the influence factors of different temperature, PH value and reaction time on the inorganic power electroless plating. It was found that iron oxide at a temperature of 55-60℃, PH = 9.5-10.5, after acted about 70 minutes get a composite powder whose content of silver up to 90%, fully covering the surface of iron oxide to get a gray with a metallic luster power, have excellent magnetic and conductive properties of composite powders; at a temperature of 65℃, under the conditions of PH = 11-12, reaction time is 80 minutes, yielded a power whose nickel content is more than 86%. The color of nickel-Fe3O4 was light black, with an average conductivity was 1.37cm.The best conditions of silver electroless plating on hollow spheres were: temperature is 55-60℃, PH = 10-12, the reaction time is 80 minutes. Under this condition we got an composite powders which contained about 70% silver. For this power its electrical conductivity is weaker than the Ag-Fe₃O₄ power, its average conductivity is only 0.0218? ? cm. But with a lower density, there are applied prospects in many fields; to the electroless nickel plating its best process is as follows: temperature between 65-70℃, PH = 11-12, the reaction time was 80 minutes. It can come to a result of about 70% nickel in weight and the conductivity was about 5.301 cm.It was also studied the preparation of carbon spheres. According to the literature prepared: two small modifications to prepare a uniform carbon spheres, one of which particle size is about 0.1-2μm, and the other is 5μm. The prepared carbon spheres were quite different with the purchase carbon particles; it has a narrow size distribution coefficient, with some hydrophilic groups, carboxyl groups and carbonyl groups, which can let the electro-less plating carry easier. Carbon spheres were made at a temperature about 50℃, PH = 10-11. After 70 minutes reaction, the carbon spheres were covered with silver completely, silver content up to 91%, and the content can be achieved higher by continuing reaction. The average conductivity of silver-carbon spheres was 1.16×10-4? ? cm; at a temperature of 67℃, PH = 11-12, the reaction time was 70 minutes, we reached a nickel composite power completely covered with nickel , its average conductivity reached 0.038? ? cm.