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摘要
The electroless pretreatment of SiC ceramic powders through a specific chemical activation pretreatment method and room temperature ultrasonic auxiliary chemical deposition method can result in Ni layers on the surface of SiC ceramic powder. The growth mechanism of Ni layers and the surface morphologies and composition of initial SiC powders, pretreated SiC powders, and Ni-coated SiC powders were analyzed by field emission scanning electron microscopy (FE-SEM) and energy dispersion spectrometry (EDS). The results show that the uniformly Ni-coated SiC composite powders are successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The Ni layers on the powders have cell structures with dense uniform distribution. The growth process of Ni is as follows: the reactants in the chemical deposition solution absorb near the surface defects of SiC powder and the particles of Ni stick to the nucleation of surface defects of SiC powder through redox reaction. The Ni nucleus grows in three-dimensional direction to form cellular 'Ni' particles that accumulate into a film. On the surface of the Ni layer film, the Ni layer grows by superposition type.
