Microstructure and Properties of Electroless Ni-P/Si(3)N(4) Nanocomposite Coatings Deposited on the AW-7075 Aluminum Alloy

The article presents the results of mechanical and tribological tests of Ni-P/Si(3)N(4) nanocomposite coatings deposited on the AW-7075 aluminum alloy using the chemical reduction method. The influence of the chemical composition on the Vickers microhardness determined by the DSI method was examined. The nanocomposite layers were made of Si(3)N(4) silicon nitride in a polydisperse powder with a particle size ranging from 20 to 25 nm. The influence of the content of the dispersion layer material on the adhesion to the substrate was analyzed. The abrasive wear was tested and determined in the reciprocating motion using the “ball-on-flat” method. The surface topography was examined by the contact method with the use of a profilometer. Based on the obtained test results, it was found that the Ni-P/Si(3)N(4) layers produced in the bath with the Si(3)N(4) nanoparticle content in the amount of 2 g/dm(3) are more resistant to wear and show greater adhesion than the Ni-P/Si(3)N(4) layers deposited in the bath with 5 g/dm(3) of the dispersion phase. NiP/Si(3)N(4) layers provide protection against abrasive wear under various loads and environmental conditions.