Comparison of Microstructure, Microhardness, Fracture Toughness, and Abrasive Wear of WC-17Co Coatings Formed in Various Spraying Ways

Abstract

WC-Co cermet materials serving as protective coatings are widely used in many fields. Conventional WC-17Co coatings were formed in high-velocity oxygen-fuel (HVOF), warm spraying (WS), and cold spraying (CS), respectively. Deposition behavior of a single WC-17Co particle, as well as the microstructure, microhardness, fracture toughness, and abrasive wear of WC-17Co coatings formed in various spraying ways were investigated. The results show that the deposition behavior of a single WC-17Co particle was different after it was deposited onto a Q235 steel substrate in various spraying ways. The WC-17Co splat deposited by HVOF showed a center hump and some molten areas, as well as some radial splashes presented at the edge of the splat. The WC-17Co splat deposited by WS presented a flattened morphology with no molten areas. However, the WC-17Co splat deposited by CS remained nearly spherical in shape and embedded into the substrate to a certain depth. All the WC-17Co coatings had the same phase compositions with that of feedstock. The microstructure of all the WC-17Co coatings was dense with no cracks or abscission phenomena between the coatings and substrate. Moreover, fine WC particles were formed in the coatings due to the fracture of coarse WC particles, and the content of fine WC particles in the cold-sprayed coating was significantly more than the other coatings. A stripe structure was formed by the slippage of fine WC particles with a plastic flow of Co binder in the warm-sprayed and cold-sprayed coatings. More fine WC particles, as well as the stripe structure, in the coatings were conducive to improve the microhardness and fracture toughness of the coating. The microhardness and fracture toughness of the cold-sprayed WC-17Co coating were the highest among the coatings. The main wear mechanism of all coatings was the groove and some peel-offs. The cold-sprayed WC-17Co coating with the lowest wear loss presented the highest wear resistance among the coatings.

Investigation of the Influence of Powder Fraction on Tribological and Corrosion Characteristics of 86WC-10Co-4Cr Coating Obtained by HVOF Method

“…It is possible that the lower tungsten carbide W2C (light gray) may be dispersed in this cobalt binder as shown in Figure 2b (the same characteristics are repeated in the remaining Figures 2d,f,h). This assumption is consistent with numerous literatures that a ribute the formation of W2C around WC to the decarburization process of WC during the HVOF process [48][49][50].…”

Numerical and Experimental Investigation Gas-Particle Two Phase Flow in Cold Spraying Nanostructured HA/Ti Composite Particle

“…The deposition of single HA/Ti particles was carried out by a CS system (CS-2000, Xi'an Jiaotong University, Xi'an, China). The schematic diagram of CS system can be found in the literature [48]. Detailed CS parameters of single HA/Ti particle deposition are listed in Table 2.…”

Effect of Cobalt and Chromium Content on Microstructure and Properties of WC-Co-Cr Coatings Prepared by High-Velocity Oxy-Fuel Spraying

“…In addition, the inserted high magnification image in Figure 3e,f shows that a circle of white phase surrounds WC particles. According to numerous pieces of the literature, the generation of the W 2 C around WC is attributed to the decarbonization of WC during the HVOF process [4,13,14]. Some researchers proposed that the decarbonization of WC caused by the diffusion of C in WC to the surrounding liquid-phase Co is the most crucial decarbonization form in the HVOF process, called indirect decarbonization [15][16][17].…”