Technological Justification of the Possibility of Applying Wear-Resistant Coatings to Strengthen Machine Parts

Abstract

The technology of restoring worn-out engine parts using modern techniques for applying wear-resistant diamond-like (DLC) coatings has been analyzed. To simplify the coating technology and reduce the wear of the highly adhesive deposited layer, applying metal-containing adhesive undercoats has been proposed. The camshaft surface wear types have been studied.The dependence of the change in the oil film thickness in the camshaft -follower contact zone on the cam rotation angle at a rotation frequency of 1,500 rpm is given. The contact causes an unsteady friction surface lubrication mode and intensive wear of the material in the contact zone.To apply a wear-resistant coating, ion etching has been proposed, followed by spattering a tungsten layer with a thickness of up to 10 μm on the product surface with subsequent 20 μm thick tungsten carbide-based coating using microwave plasma. Such a gradient structure over the cross-section of the wear-resistant coating allows achieving the best product performance.The values ​​for the change in surface temperature in the cam-follower friction pair contact zone are given. Nitride, carbonitride, and other types of wear-resistant coatings, their recommended thicknesses, and maximum allowable operating temperatures are given. The hardness of various coatings and possible types of their destruction are shown.The reasons for adhesive and cohesive delamination of wear-resistant coatings are shown, and ways to eliminate this phenomenon are proposed.