Mechanical Properties and Growth Mechanism of TiB2-TiC/Fe Composite Coating Fabricated in Situ by Laser Cladding

Abstract

A TiB2-TiC/Fe composite coating was successfully produced on a Q235 substrate by laser cladding through in-situ reactions among 60TiFe, B4C, Cr, Ni, and Si preset powder mixtures. Based on the available literature, scanning electron microscopy images of the mixed precursor powder and coating layer, and corresponding electron dispersive spectroscopy and X-ray diffraction results from the produced coating, the formation mechanism of the TiC-TiB2 composite during laser cladding was determined. The results show that the coating was mainly composed of α-Fe, TiB2, TiC and (Fe, Cr)7C3, where the TiB2 had a dark grey rectangular shape and TiC had a light grey spherical shape. Most of the TiC particles were attached to the TiB2, which means that TiB2 particles were formed before the TiC. The microhardness of the composite coating approached 1260 HV0.2, which shows that the microhardness of the composite coating was more than 7 times that of the Q235 substrate. Furthermore, the wear performance of the coating was obviously improved, to approximately 15 times that of the substrate.