Adhesion strength measurement of nickel layer on the iron-based P/M parts influenced by different surface pre-treatment operations

The adhesion of the coated layer to the substrate in powder metallurgy (P/M) parts is of major concern due to the presence of surface porosities. In the present study, electroplated nickel layer was applied on the pre-treated surfaces. Pre-treatments were performed through three different operations including copper infiltration, resin impregnation and steam treatment in order to close the open surface pores of the iron-based substrates and subsequently to improve the adhesion of coating to the surface. Beside the microstructural analyses, heating–quenching procedures and tensile tests were carried out to measure the adhesion strength of nickel layer to the substrate. Based on the achievements, all pre-treated specimens exhibited better adhesion strength compared to the non-treated ones. Furthermore, the maximum layer adhesion was obtained from the copper infiltration process.