In-situ synthesis of Fe-based ZrC-ZrB₂ composite coating produced by GTAW

A Fe-based composite coating reinforced by ZrC-ZrB₂ particles has been successfully fabricated on Q235 steel by gas tungsten arc welding(GTAW) cladding process utilizing the in situ reaction of pre-placed Zr, B4 C and Fe powders. The microstructure of the coating was analyzed by scanning electron microscopy(SEM), X-ray diffraction(XRD), energy-dispersive spectrum(EDS), and the growth mechanism of the ZrC-ZrB₂ reinforcement was discussed. Meantime, the microhardness and the wear resistance of the composite coating were examined by means of microhardness tester and wear tester at room temperature, respectively. The results show that the coating that has excellent metallurgical bonding with substrate can be obtained. The main phases of coating are ZrC, ZrB₂ and α-Fe, in which the ZrC phase exhibits hexahedron and petalled shapes and the ZrC-ZrB₂ compound presents acicular and rod shape. The microhardness of coating is up to 1 200 MPa, and the wear resistance is about twenty times higher than that of the Q235 steel.