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Four WC-12wt.%Co Powders from Different Powder Suppliers and Their (powders) Effect on the As-Sprayed WC-Co Coatings Microstructure and Average Surface Roughness (Ra)

Four tungsten carbide-cobalt powders were HVOF sprayed. All the powders were sprayed with same parameters and condition, using ASB Paramaeters as the reference.  Powder 1 showed the highest deposition efficiency (DE), lowest average surface roughness and highest coating thickness than the other as-sprayed coatings. These observations could be related to the range of particle size distribution (PSD) which has strong effect on the DE of the powders.

Particle size distribution of powder 1 is the lowest compared to that of other powders. Powder 1 gives the best microstructure, with powder 3 having the next acceptable microstructure. Since, uniform distribution of fine carbides is required for high hardness values, it is anticipated that the powder 1 coating presents best hardness value. Powder 4 had the worst microstructure, with most of the carbides forming clusters. Powder 2 coating also show considerable clustering. Considering the DE values, surface roughness, hardness, uniform distribution of fine carbides, coating thickness, the Powder 1 was considered to be the best material for production of WC-Co protective and wear resistant coatings in this study.