Deposition patterns and mechanisms of PVD plasma erosion-resistant coatings based on boundary constraint conditions

When immersed in sand and dust environment, aero-engine blades are exposed to harsh erosion which may lead to failure if erosion is severe. Using Physical Vapor Deposition (PVD) to prepare hard ceramic coatings can greatly enhance the operational capabilities of aero-engine. However, due to the “line-of-sight” processing characteristic of PVD process, uneven coating deposition rates occur when preparing coatings on obstructed areas such as blisks. Quantitative research on such phenomena is few, and it is even rarer in the study of aero-engine coatings. Based on the analyses and considerations of the geometric shape of blade surfaces and the influence of both deposition and re-sputtering effect, an ideal model is established to analyze the deposition rate variation along blocked region in complex self-shadowing boundaries. The relative deposition rates at various locations on the blade surface within the inter-blade gaps are quantitatively calculated and experimentally validated. Furthermore, differences in erosion resistance of the coatings are tested. The conclusions are drawn as follows: the geometric configuration of the obstructed shape and re-sputtering phenomenon significantly influence the deposition rates within the inner wall of blade gaps. Taking the structural configuration as an example, in a 25 mm × 60 mm × 15 mm gap, the coating thickness can vary more than 252% from the thickest to the thinnest location. The deposition rates of various locations are proportional to the solid angle of incident ion in more obstructed regions, and the re-sputtering is more prominent in open regions. Obstructive boundaries directly affect the erosion resistance at various locations within the gaps, with erosion failure time decreasing by 40% in heavily blocked region compared to open region.