Tribological characterization of WC-Co plasma sprayed coatings

TitleTribological characterization of WC-Co plasma sprayed coatings
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2009
AuthorsDi Girolamo, G., Pilloni L., Pulci G., and Marra F.
JournalJournal of the American Ceramic Society
KeywordsAmorphous phasis, Atmospheric plasma spraying, Cermet coatings, Comparative studies, Dissolution, Dry sliding frictions, Enhanced hardness, Experimental datum, Helium, Helium flow rates, High qualities, High temperatures, High velocity oxygen fuels, Mechanical properties, Micro-structural, Oxidizing atmospheres, Oxygen, Plasma jets, Plasma spraying, Plasma-sprayed coatings, Plasmas, Protective coatings, Scanning electron microscopy, Sodium compounds, Spray conditions, Sprayed coatings, Sprayed particles, Tribological characterizations, Tungsten alloys, Tungsten carbide, Wear resistance, Wear tests

Atmospheric plasma spraying of WC coatings is typically characterized by increased decarburization, with a consequent reduction of their wear resistance. Indeed, high temperature and oxidizing atmosphere promote the appearance of brittle crystalline and amorphous phases. However, by using a high helium flow rate in a process gas mixture, plasma spraying may easily be optimized by increasing the velocity of sprayed particles and by reducing the degree of WC dissolution. To this purpose, a comparative study was performed at different spray conditions. Both WC-Co powder and coating phases were characterized by X-ray difraction. Their microstructure was investigated by scanning electron microscopy. Mechanical, dry sliding friction, and wear tests were also performed. The wear resistance was highly related to both microstructural and mechanical properties. The experimental data confirmed that high-quality cermet coatings could be manufactured by using optimized Ar-He mixtures. Their enhanced hardness, toughness, and wear resistance resulted in coatings comparable to those sprayed by high velocity oxygen-fuel. © 2009 The American Ceramic Society.


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