Effect of Substrate Hardness on the Delamination Strength of WC-Co Coating Deposited by High-Velocity Flame Spraying Method
Zhang DONGKUN, Kato MASAHIKO, Nakasa KEIJIRO and Ding XIANGXIAN
Abstract:WC-Co cermet was coated on the steel substrates(JIS: SKD5, SKD62 and SS400) with different hardness by two types of spraying methods using high-velocity oxygen fuel(HVOF) and high-pressure high-velocity oxygen fuel(HP-HVOF). Tensile tests as well as Edge-indent tests were carried out to obtain interfacial fracture toughness GC12 and delamination energy Ed, respectively. The GC12 and Ed of the coatings deposited on the SS400 substrate with smaller hardness revealed larger values, and the GC12 and Ed of the coatings deposited by HP-HVOF were higher than that by HVOF with the same hardness of substrate. The reason can be that the sprayed powder with higher speed more easily shot into the soft substrate than the hard substrate so that the mechanical bond effect along interface between coating and substrate was stronger. Key Words:WC-Co coating, High-velocity flame spraying, Substrate hardness, Delamination strength