This study presents a comparative analysis of the water droplet erosion resistance of three compressor wheels coated with Ni-P and Si-P layers. The tests were conducted using a custom-developed experimental apparatus in accordance with the ASTM G73-10 standard. The degree of erosion was monitored through continuous precision mass measurements, and structural changes on the surfaces of both the base materials and the coatings were examined using a Zeiss Crossbeam 350 scanning electron microscope (SEM). Hardness values were determined using a Vickers KB 30 hardness tester, while the chemical composition was analysed using a WAS Foundry Master optical emission spectrometer. Significant differences in erosion resistance were observed among the various compressor wheels, which can be attributed to differences in coating hardness values, as well as to the detachment of the Ni-P layer from the base material under continuous erosion. In all cases, water droplet erosion led to a reduction in the isentropic efficiency of the compressor—measured using a hot gas turbocharger testbench—with the extent of efficiency loss depending upon the type of coating applied. Although blade protection technologies for turbocharger compressor impellers used in the automotive industry have been the subject of only a limited number of studies, modern technologies, such as the application of certain alternative fuels and exhaust gas recirculation, have increased water droplet formation, thereby accelerating the erosion rate of the impeller. The aim of this study is to evaluate the resistance of three different coating layers to water droplet erosion through standardized tests conducted using a custom-designed experimental apparatus.

Erosion caused by water droplet impact in high peripheral velocity rotating machinery is an area that is widely researched today. Newer and newer blade protection solutions are being developed for wind power plants, gas turbines, and jet engines to reduce erosion and maintain efficient power generation. However, this phenomenon on turbochargers used in the automotive industry has been the subject of a limited number of studies, despite advanced technologies such as alternative fuels and exhaust gas recirculation increasing the water droplet formation and thus increasing the erosion rate of the impeller. This study investigated the resistance to erosion of three different compressor wheel coatings. Tests were carried out according to the ASTM-G73-10 standard using a custom-developed test apparatus. The degree of erosion was measured by continuous precision mass measurement. Electron microscopy was used to detect structural changes on the surface, both on the base material and on the coating. Significant differences in the extent of erosion were observed for the different coatings. As a result, the isentropic efficiency of the compressor decreased in all cases but varied depending on the type of coating.