Wear Resistant Coatings on Ball Valves for Coal-Slurry Pipelines

This work deals with the selection and deposition of wear-resistant coatings for ball valves used in coal slurry pipelines. Several NiCrBSi and WC-CoCr powders were deposited on stainless steel substrates by various methods, including atmospheric plasma spraying (APS) with and without post-process fusion, plasma transferred arc (PTA) spraying, and high-velocity oxyfuel (HVOF). The HVOF deposits had very low porosity and uniform carbide distribution in the metallic matrix. WC-CoCr coatings obtained by HVOF spraying were dense and well-adhered and experienced the least amount of mass loss in wear testing. As a result, they were recommended for testing in coal-water slurry pipelines and continue to perform well after more than two years.