Koutsomichalis et al (2008) discussed that having high hardness and good adhesion with the substrate the sprayed coating exhibited satisfactory wear resistance. Tungsten carbide is an advanced ceramic material combining a unique set of properties such as high hardness, high melting point, wear resistance, good thermal shock resistance, thermal conductivity and good resistance against oxidation. They can be applied as coatings by thermal spraying processes such as plasma-spraying, high-velocity oxy-fuel spraying and detonation gun methods [1].
Bell and Sun (2002) discussed that a low temperature plasma carburizing technique has recently been developed to engineer the surfaces of austenitic stainless steels to achieve combined improvement in …show more content…
However, carbon loss (decarburization) of WC–Co powders during thermal spraying reduced the efficiency of the coatings against abrasive wear. Results showed that the rapid SPS technique was successful in supplying superfluous carbon for the restoration of WC in the coating through phase transformation from W2C or reaction with W. Predominant presence of WC was revealed in the coatings treated with SPS at 800 jC and up to 6 min. Furthermore, changes in microstructure was made and found that the SPS-induced WC reconstruction can apparently be achieved within the coating surface with limited thickness. Transmission electron microscopy (TEM) results also showed the evidence of supplementary reaction between Co and WC/W2C to form Co3W3C during the SPS processing. Microhardness values obtained on the surface of SPS-treated coating showed 40% enhancement over as-sprayed surface …show more content…
X-ray diffraction and backscattered electron analysis showed that H2 gas produced a greater decarburization of the WC phase. The dissolution and decomposition of the WC phase during the process produced a Co+W+C solid solution as binder phase and the formation of W2C and W as secondary phases. The Nano hardness (H) and Young's modulus (E) resulting from a grid of 300 indentations performed at 50 nm in depth identified the characteristics of each phase in the heterogeneous structure produced by decarburization. Statistical study by a CDF fit and Gaussian simulated distributions showed that the mechanical properties of the coatings were governed by the binder phase content, which decreased the possible hardening effect of the arising hardest phases
Bell and Sun (2002) discussed that a low temperature plasma carburizing technique has recently been developed to engineer the surfaces of austenitic stainless steels to achieve combined improvement in …show more content…
However, carbon loss (decarburization) of WC–Co powders during thermal spraying reduced the efficiency of the coatings against abrasive wear. Results showed that the rapid SPS technique was successful in supplying superfluous carbon for the restoration of WC in the coating through phase transformation from W2C or reaction with W. Predominant presence of WC was revealed in the coatings treated with SPS at 800 jC and up to 6 min. Furthermore, changes in microstructure was made and found that the SPS-induced WC reconstruction can apparently be achieved within the coating surface with limited thickness. Transmission electron microscopy (TEM) results also showed the evidence of supplementary reaction between Co and WC/W2C to form Co3W3C during the SPS processing. Microhardness values obtained on the surface of SPS-treated coating showed 40% enhancement over as-sprayed surface …show more content…
X-ray diffraction and backscattered electron analysis showed that H2 gas produced a greater decarburization of the WC phase. The dissolution and decomposition of the WC phase during the process produced a Co+W+C solid solution as binder phase and the formation of W2C and W as secondary phases. The Nano hardness (H) and Young's modulus (E) resulting from a grid of 300 indentations performed at 50 nm in depth identified the characteristics of each phase in the heterogeneous structure produced by decarburization. Statistical study by a CDF fit and Gaussian simulated distributions showed that the mechanical properties of the coatings were governed by the binder phase content, which decreased the possible hardening effect of the arising hardest phases