Microstructure and properties of cold sprayed multimodal WC–17Co deposits

• Multimodal WC–17Co deposits with nano and micro WC were fabricated by cold spraying.
• The cold sprayed deposits presented dense microstructure with somewhat wavy stripes.
• There occur some rearrangement of WC and deformation of Co during deposition process.
• The properties of deposits were influenced by content of nano WC particles.
• The wear of deposits was dominated by the cutting of Co and peel-off of WC particles.

In the present paper, three multimodal WC–17Co deposits with different content of nano-sized WC (10%, 30% and 50%, in wt.%) were prepared by cold spraying process. The effect of micro/nano ratio of WC particles on the microstructure, phase composition and properties such as microhardness, fracture toughness and wear performance of cold-sprayed multimodal WC–12Co coating was investigated. The experimental results demonstrated that the cold-sprayed multimodal WC–17Co deposits exhibited dense microstructure with some stripes composing of Co and nano WC, and their phase structures were similar to that of feedstock. The microhardness and fracture toughness of cold sprayed multimodal WC–17Co deposits respectively increased and decreased with increasing the content of nano-sized WC. The obtained multimodal WC–17Co deposits had both a high hardness and high fracture toughness and exhibited a greatly enhanced wear resistance in comparison to the conventional high-velocity oxy-fuel (HVOF) sprayed WC–12Co coating. The abrasive wear behavior of cold sprayed multimodal WC–17Co deposits was mainly dominated by cutting or gouging related to the preferential wear of Co and the fracture and the peel-off of WC particle.