In-situ TiC/Ni Coating Controlled By Plasma Cladding

TiC/Ni composite coating had been in-situ synthesized on 45 steel controlled by plasma cladding technology after the [Ti+C] powders precoated on the substrate were activated by high energy ball milling. The ball milled powders' activation and the formation pattern of TiC in cladding were studied by X-Ray Diffraction(XRD), Optical Microscopy(OM), Scanning Electron Microscopy(SEM) and Transmission Electron Microscopy(TEM). Through the study on microstructures and properties of plasma cladding, the processing parameter of plasma cladding was optimized. By using finite element software Ansys, the temperature field and residual stress field of the clad were simulated.The results showed that the grain size of milled [Ti+C] powders, which had their fresh surface, was decreased. The milled powders' activity was of advantage to the formation of TiC in the cladding.The ceramic reinforced phase in-situ synthesized in the cladding cluster around by several single TiC, which were lumpish, group and radiation in shapes. The dimension of single TiC grain was less than 1μm, and the group of TiC was about 2-2.5μm. The TiC in-situ synthesized had regular shapes, clean surface, and without any product of interface reaction.There were primary phaseγ-Ni, M₂₃C₆, TiC and CrB in the cladding and the TiC/Ni cladding's microstructures include planar at interface, celluar and dendrite whose growth direction was perpendicular to the interface. Through the study on the influence of processing parameter toward the apparent pattern, microstructures and performance of the cladding and orthogonal method, the preferable parameter of plasma cladding was obtained: the working current was 140A; the scanning speed was 13cm/min; the milling time was 8h.The result of simulation of temperature field and residual stress field was that there was residual tress at interface between clad and substrate, and at both ends of clad existed stress concentration.