Silicon carbide powder, complexed in metal matrix, has been widely used to manufacture various tool steels by casting and powder metallurgy as it has excellent hardness, abrasion resistance and heat resistance. However, silicon carbide powder, whose phase is like a kind of ceramic, has low wettability with metal, so when it is complexed in metal matrix, the microstructure of complex material around the particles of silicon carbide is changed, leading to the significant fall in the life of tool steels.
To overcome these disadvantages, there have been some researches to prolong the life of tool steels and to manufacture various functional complex materials by coating the surface of silicon carbide powder with metals such as nickel or copper by electroless plating based on the chemical reaction of oxidation and reduction.
However, there are no reports on the quantitative observation of nickel plating rate and the control of plating thickness on the basis of the reactions taking place during electroless plating on the surface of silicon carbide powder.
Jang Ryong, a researcher at the Faculty of Chemistry, experimentally studied the effects of amount of nickel salt and reducing agent on nickel-plating rate and thickness during the electroless nickel plating on the surface of silicon carbide powder.
He found that during electroless nickel plating on the surface of SiC powder with particle size of 42㎛ the amount of nickel salt should be as small as possible (mass of NiCl2·6H2O is 16.14g in 800mL solution) and the amount of reducing agent NaH2PO2·H2O should be more than 3 times that of nickel salt substance.
Laser Scanning Microscope (LSM) images of non-plated and plated SiC powders (0.5㎛ in thickness) showed that black metallic nickel was evenly coated on the surface of silicon carbide powders.
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