Microstructure of Fe-Cr-Si-B coating prepared by plasma cladding on cast iron

A wear-resistant coating was prepared on cast iron using Fe-Cr-Si-B elemental powder blends by plasma cladding.The microstructure and properties of the coating were investigated by optical microscope(OM),scanning electron microscopy(SEM) with energy dispersive spectroscopy(EDS), X-Ray diffractometer(XRD) and microhardness tester.The results show that the microstructure of the clad layer consists of primary phase of(Cr,Fe)_7C_3,eutectic carbide(Cr,Fe)_7C_3,α-(Fe,Cr) solid solution and Fe_3C.Primary phase(Cr,Fe)_7C_3 exhibits hexagon,U,L or H shape and eutectic carbide(Cr,Fe)_7C_3 presents the shape of short bar or small block.The fine eutectic ledeburite is formed at the interface between cladding and substrate.Alloy elements in cladding and substrate near the interface diffuse each other to produce the coating with metallurgically bonded to substrate.The microhardness of the clad layer reachs 600～1200HV0.2.