The effect of co-deposition of SiC sub-micron particles and heat treatment on wear behaviour of Ni–P coatings

The purpose of the study is to assess the influence of SiC particles and heat treatment onthe wear behaviour of Ni–P coatings when in contact with a 100Cr6 steel. Addition of reinforcingparticles and heat treatment are two common methods to increase Ni–P hardness. Ball-on-disc weartests coupled with SEM investigations were used to compare as-plated and heat-treated coatings,both pure and composite ones, and to evaluate the wear mechanisms. In the as-plated coatings,the presence of SiC particles determined higher friction coefficient and wear rate than the pureNi–P coatings, despite the limited increase in hardness, of about 15%. The effect of SiC particleswas shown in combination with heat treatment. The maximum hardness in pure Ni–P coatingwas achieved by heating at 400◦C for 1 h while for composite coatings heating for 2 h at 360◦Cwas sufficient to obtain the maximum hardness. The difference between the friction coefficient ofcomposite and pure coatings was disclosed by heating at 300◦C for 2 h. In other cases, the coefficientof friction (COF) stabilised at similar values. The wear mechanisms involved were mainly abrasionand tribo-oxidation, with the formation of lubricant Fe oxides produced at the counterpart.