Tribological characteristics of chromium carbide -based coatings with varying binder content deposited by HVOF and HVAF spray processes

Premature wear within gas turbine engines can significantly reduce the lifespan of critical components and increase the overall cost of the machinery. This concern raised the need to develop advanced materials that can resist surface degradation due to wear, corrosion and erosion in severe environments, especially at extreme temperatures. Chromium carbide – based coatings offer a sustainable solution for reducing wear in harsh environments, where corrosion and high temperatures are prevalent. In addition, chromium carbide and nickel-chromium binders are chemically stable and provide better resistance to degradation when sprayed on components by high-velocity oxygen fuel (HVOF) and high-velocity air fuel (HVAF) process. It is worth stating that the composition of carbides, the ratio of binder, and the process parameters have a significant effect on the performance of coated components. In this study, chromium carbide coatings with different NiCr binder content were deposited by means of HVOF and HVAF processes. Subsequently, tribological behavior of the coatings were evaluated at a wide range of contact and environmental conditions. Ex situ analysis was performed on the worn surfaces by SEM and micro-Raman for better understanding of the interfacial processes. Observations were correlated to the differences in friction and wear of the various systems.