Influence of Critical Plasma Spray Parameter on Microstructural and Tribological Characteristics of Nanostructured Tungsten Carbide-Cobalt Coatings

摘要

Nanostructured tungsten carbide-cobalt coatings were deposited by air plasma spraying (APS) technique, using nitrogen as primary plasma gas. The characteristics of nanostructured coatings are typically affected by the percentage of unmelted/partially-melted regions present in the coatings. Hence, the coatings were obtained as a function of critical plasma spray parameter (CPSP), which is defined as the ratio of arc power to the primary plasma gas flow rate. It was observed that tungsten (W) rather than tungsten carbide (WC) was the dominant phase in nanostructured coatings due to decarburization. CPSP was found to have a significant effect on wear performance of APS nano-structured coatings. Wear resistance was highest for coatings deposited at lowest CPSP. Flaking was more prevalent in nanostructured coatings deposited at the highest CPSP.