부산대학교 도서관

A Ni60/WC gradient composite coating was prepared on the surface of H13 steel by the laser cladding in situ generation method using a fibre laser. The phase composition, microstructure, microhardness and wear mechanism of the laser clad Ni60/WC gradient composite coating were analysed to reveal that it possessed few pores and cracks, the delamination phenomenon was obvious, the enhancement phase was small and uniformly distributed, and it formed a good metallurgical bond with the H13 steel substrate. In the laser clad Ni60/WC gradient composite coating the branch reinforcing phases are mainly WC, W2C, WSi2 phases, and a small amount of Cr7C3, FexC and other compounds, and the interbranch structures are mainly A-[Fe,Ni] solid solution and Cr7C3, FexC and other compounds. The Ni60+40% (W+C) and Ni60+20% (W+C) layers gradually decrease in number and size from top to bottom, while the shape gradually changes from irregular tetragonal to petal-shaped. The microhardness of the laser clad Ni60/WC gradient composite coating shows a gradient downward trend from top to bottom, and the maximum hardness can reach 1083.7 HV0.5 and the average hardness was 4.18 times that of the H13 steel substrate. The wear amount of the laser clad Ni60/WC gradient composite coating is 20.3% of the H13 steel substrate. The wear mechanism is mainly adhesive wear, brittle spalling and abrasive wear, which can prolong the service life of the mould and reduce the waste of resources. [ABSTRACT FROM AUTHOR]