Erosion behavior of Cr/Cr₂N alternating coating and uncoated steel substrate under propellant gas

Chromium-based alternating coatings, renowned for their exceptional overall performance, hold promise for application in barrel protection. Nonetheless, a notable discrepancy persists between standard thermal shock techniques and actual operational conditions. This study employs a high-pressure propellant gas erosion experimental apparatus to conduct a comparative investigation into the multifactorial damage behaviors of Cr/Cr₂N alternating coatings and the substrate material. Utilizing hardness testers, scanning electron microscopes (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD) techniques, we analyzed the eroded surfaces and cross-sections. The research findings indicate that damage observed in uncoated samples is attributed to a multi-faceted coupling damage mechanism, encompassing gas mechanical impact, chemical corrosion, and thermal stress. The damage mechanisms of Cr/Cr₂N alternating coatings primarily due to thermal stress induced by differences in thermal expansion coefficients. The impacts of substrate oxidation-related expansion and thermochemical corrosion are largely negligible. Notably, the presence of a crack network with optimal spacing enhances the coating's adhesion strength. This research endeavor is anticipated to provide novel insights into the design and fabrication of coatings to extend barrel lifespan.