Improvements of commercial chromium coatings wear resistance by means of electro-co-deposition with Graphite, TiN, and w-BN

Composite coatings were obtained by electro-co-deposition of chromium with Graphite, TiN or wurtzite-like BN (w-BN). The content (vol.%) of the dispersed phase in the electrodeposits was equal to: Cr–Graphite – 10, Cr–TiN – 4, Cr–w-BN – 1. Cr-Graphite coatings showed no increase in the microhardness (HV), while their fracture toughness (K1c) and wear characteristics were better as compared to Cr deposits. The coefficient of friction in the tribopair “coating– steel” decreased from 0.32 (Cr) to 0.19 (Cr–Graphite) under conditions of dry friction and from 0.05 (Cr) to 0.03 (Cr–Graphite) in the presence of a lubricant. The inclusion of TiN particles into a Cr-matrix resulted in an improvement in both HV and wear resistance (WR) of the coatings. A significant increase in WR (70–170 %) was obtained for Cr–w-BN coatings with small content of the dispersed phase. Therefore, Cr–Graphite, Cr–TiN, Cr–w-BN electrodeposits may be considered as promising wear-resistant materials.