Structural and Phase Transformations on the Surface of Spark-Laser Coatings under Fretting Corrosion in AIr

Abstract

The structure and phase transformations on the surface of a ZrB₂-based combined laser-spark coating on titanium alloy are studied. The transformations are induced by triboprocesses under fretting corrosion in air. It is shown that the surface transformations result from a combination of three mechanisms: plastic strain (surface texture, fatigue, crack formation, brittle fracture); oxygen diffusion from the environment and chemical reactions of tribooxidation and diffusion of substrate elements (Al) toward the wear surface; and removal of particles from the surface. Two-phase nanostructured eutectic is found on the wear surface of the combined coating.