Mechanical and tribological properties of Ni-W-TiB2 composite coatings

Pure Ni, Ni-W alloy, and Ni-W-TiB2 composite coatings were prepared on the copper substrate by electrodeposition technique. Surface morphology and elemental composition of as prepared samples were observed and analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) technique was used to analyze the crystallinity and phase composition of the samples. XRD patterns show a typical FCC Ni-W alloy phase of the Ni-W-TiB2 composite coating. Vickers microhardness of Ni-W-TiB2 composite coating is significantly improved as compared to pure Ni and Ni-W alloy coatings. Wear and coefficient of friction of the Ni-W-TiB2 composite coating are found to be improved. Adhesive wear is found to be predominant in pure Ni, and Ni-W coating whereas abrasive nature of wear is obtained in Ni-W-TiB2 composite coating. The Ni-W-TiB2 composite coating exhibited improved scratch resistance over pure nickel and Ni-W coatings. The scratch resistance of the composite coating is influenced by W alloying and TiB2 incorporation to the nickel matrix.