Properties and microstructures of ultra-thick gradient TiC/Ni coating by plasma cladding

By plasma cladding technology and appropriate cladding parameter, an ultra-thick gradient TiC/Ni composite cladding layer was synthesized on Q235 steel.Composition, microstructures and performance were analyzed by scanning electron microscope, X-ray diffraction, optical microscopy and microhardness tester.The cladding coating was about 2.7 mm in thickness and without any crack and gas pore.TiC particles exhibit a continuous increase both in volume fraction and size from the bottom of the coating to the top surface;the microstructures of the coating matrix present distribution from planar to cellular to dendrite crystal.Fe decreases and Ni, Cr, Si increase gradually from the substrate to the cladding coating.TiC particles distributes in dispersivity within the coating matrix.The maximal microhardness value of the plasma cladding coating is about 800 HV and 4-5 times of the substrate (Q235).