Microstructure and Properties of TiC-Reinforced Nickel-Based Gradient Coatings Generated in Situ
TiC-reinforced Ni-based single coatings and gradient coatings were generated in situ on the sur-face of H13 steel by laser cladding technology.The micromorphology,composition distribution,phase com-position,microhardness and frictional wear resistance of the coatings were analyzed and compared by scan-ning electron microscope,energy spectrometer,X-ray diffractometer,microhardness tester and universal friction and wear testing machine.The results show that the single coating is prone to macroscopic pores,cracks,poor bonding with the matrix and other defects,while the gradient coating can realize the gradient change of composition,microstructure and properties,and form a good metallurgical bonding with the ma-trix.Fe-Cr,TiC and other reinforcing phases generate in the gradient coating,which significantly improves the surface hardness and wear resistance of the steel.The average hardness of the gradient coating is about 1.44 times that of the single coating and about 2.58 times that of the matrix.The average wear loss of the gradient coating is 45.6%of that of single coating and 32.4%of that of the matrix.The wear mechanism of the gradient coating is mainly abrasive wear and adhesive wear.
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