Abstract
Ni-coated Cr 3C 2 powder was prepared by ultrasonic-assisted electroless plating process without conventional sensitization and activation treatments at room temperature. The growth mechanism of Ni layers and the effects of Cr 3C 2 powder concentration on plating rate and coating quality were studied. Surface morphologies and composition of initial Cr 3C 2 powder, pre-treatment Cr 3C 2 powder and Ni-coated Cr 3C 2 powder were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the Ni layers on the Cr 3C 2 powder had cell structure with dense and uniform distribution. The growth mechanism of Ni layers appears as follows: the pretreated surfaces of Cr 3C 2 powder act as activated sites, nucleation and the growth of nickel grains take place on the powder surfaces, and the process repeats continuously on the lath particles with reticulate structure on the as-coated surfaces of previously deposited Ni-cells, finally Ni cells grow up and merge into a layer. With the increase of Cr 3C 2 powder concentration, the plating time becomes shorter accordingly and the optimal powder concentration is 40 g L −1.
Published Version
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