Multi-layer structure improves wear and corrosion resistance of chromium

Abstract

Electrodeposited hard chromium coatings have been proven to significantly improve the friction and wear properties of matrix metallic materials. Due to the presence of microcracks, there is an inverse relationship between the friction and corrosion properties of hard chromium coatings. In this work, we designed and successfully prepared chromium coatings with alternating soft and hard chromium by pulse and direct current processes. The experimental results show that the multilayer structure can significantly reduce the microcrack density of the surface hard chromium coating. The wear rate and corrosion potential of the multi-layer Cr coating with five layers are 3.48 × 10⁻⁵·mm³·N⁻¹·m⁻¹ and −524 mV, respectively. Compared with the single hard/soft chromium coating, the multilayer structure achieves a good synergy of wear resistance and corrosion performance. This is attributed to the multi-layer structure can effectively reduce the generation and propagation of microcracks. In the multi-layer structure, each layer can play a buffering role, reduce the brittleness of the overall coating, improve the wear resistance, and at the same time, in the multi-layer coating, more interfaces are formed, which prevent the further penetration of corrosive media to a certain extent.