In the search for newer distributed phases that can be used in Ni-composite coatings, inexpensive and naturallyudavailable pumice has been identified as a potential candidate material. The composition of the pumice mineral asuddetermined by Rietveld analysis shows the presence of corundum, quartz, mulllite, moganite and coesite phases.udPumice stone is crushed, ball-milled, dried and dispersed in a nickel sulfamate bath and Ni–pumice coatings areudelectrodeposited at different current densities and magnetic agitation speeds. Pumice particles are uniformlyudincorporated in the nickel matrix and Ni–pumice composite coatings with microhardness as high as 540 HK are obtained at the lowest applied current density. In the electrodeposited Ni–pumice coatings, the grain size of Ni increaseswith the applied current density. The overall intensity of texture development is slightly strongerudfor the Ni–pumice composite coating compared to plain Ni coating and the texture evolution is possibly not theudstrongest deciding factor for the enhanced properties of Ni–pumice coatings. The wear and oxidation resistancesudof Ni-pumice coating are commensurate with that of Ni-SiC coating electrodeposited under similar conditions.
展开▼
