Failure analysis of the outside coating on the process roller

Abstract

Abstract A failure case of the outside coating on the process roller is presented in this study. The coating consists of WC-Co, which is deposited on 45 steel by High Velocity Oxygen Fuel (HVOF) spraying. The spalling of coatings has been found in the middle of the roller. Rust was also observed on the coatings of the roller. The failure analysis of the coating was performed in terms of composition analysis, and microstructure observation etc. In addition, the effects of sandblasting post-treatments were compared on the residual sand on the interface between the coating and substrate. And the effect of substrate material is investigated on the corrosion of coatings. It was concluded that the sandblasting particles remained on the substrate surface have effects on the failure of the coating. The peeling-off coating on the roller is also related with the formation of iron oxides. Less sand can be remained on the substrate surface when air purging and brushing is used after the sand-blasting compared with only air purging or non-treatment is applied. The stainless steel shows excellent corrosion resistance than the low carbon steel when they are used as substrate for WC-Co coatings during the wet/dry cyclic corrosion tests.