Thermal treatment effect on the mechanical, tribological and corrosion properties of Ni-W alloy obtained by direct and pulse plating electrodeposition

Abstract

Ni-W electrodeposits have emerged as one of the most suitable alternatives to hard chromium mainly owing to their remarkable mechanical and tribological properties. Additionally, advanced technologies that require materials resistant to high temperatures could benefit from the use of Ni-W coatings. In this work, the effect of thermal treatment at different temperatures (300, 500, 700°C) on the characteristics of Ni-W coatings obtained by direct and pulse plating (PP) was studied. The morphology, composition, crystalline structure, hardness, wear rate, friction coefficient and corrosion resistance of the thermally treated coatings were analysed and compared with the performance of hard chromium coatings. The results indicate that the pulse-plated Ni-W coatings show better mechanical and tribological properties than the ones obtained by direct current. A significant improvement in hardness in Ni-W layers was achieved by thermal treatment, mainly in the films grown by PP, with minor changes in wear resistance and corrosion performance.