Friction and wear behaviour of BN(h) and Ag incorporated nickel phosphorous coatings under dry reciprocating sliding conditions

ABSTRACT Ni–P–BN(h)–Ag hybrid composite coatings were fabricated on the steel substrate by a scalable electroless deposition process. The optimum bath composition and operating conditions were selected to obtain defect-free composite coatings with ∼50 μm thickness. Further, to enhance the hardness, as-deposited coatings were subjected to heat treatment in a tubular furnace at 400°C for 1 h. The dry sliding wear behaviour of the as-deposited (AD) and heat-treated (HT400) composite coatings was evaluated using a linear reciprocating tribometer. The average friction coefficient of the hybrid coating was ∼0.14 (in as-deposited condition) and ∼0.16 (in heat-treated condition); these values represent 51.72% and 52.94% reduction over non-hybrid Ni-P coatings. The specific wear rate of the as-deposited and heattreated composite coatings was found to be 50% and 43% lower, respectively, than that of conventional Ni–P coatings. Detailed wear track analysis was carried out to identify underlying wear mechanisms and tribochemical interactions. GRAPHICAL ABSTRACT