Influence of Oxides on the Performance of Cylinder Bore Coatings of Engine Blocks

The performance of thermally sprayed coatings such as for the inner surface of combustion engines depends on the microstructure and phase composition of the coatings after deposition. These can be varied in a targeted manner to reach the desired coating behavior. One approach might be altering the atomization gas in order to influence the oxide content in the coating. A former study of the authors already showed that the oxide content in the coatings can be influenced effectively by simply changing the atomization gas in case of Plasma Transferred Arc Spray technology. In this study, a systematic approach is followed in order to investigate the effect of oxides on the tribological performance and the corrosion behavior. For this purpose, coatings with different oxide contents were manufactured by taking advantage of different atomization gases. The results of this study confirm that coatings with pronounced oxide‐rich phases exhibit lower friction coefficients and less sever outbreaks in comparison to those without distinctive oxide‐rich phase. The presence of oxide‐rich phases does not influence the corrosion behavior of the coatings significantly, although some minor effects are observed along phase boundaries. As shown in this manuscript, oxides in thermal spray coatings can exhibit friction‐reducing properties. Since the oxide content can be influenced by the process parameters, thermal spraying coatings are suitable to optimize different applications.