Research On The Preparation, Microstructure And Properties Of Nickel-coated Titanium Carbide Particulates Reinforced Steel Matrix Composites

Ni-coated titanium carbide composite powders were prepared by electroless plating. Further, using hot isostatic pressing, iron matrix composites reinforced with TiC particulates were prepared. And TiC particulates reinforced steel matrix composites were prepared by vacuum sintering method. The microstructure and properties of composites were investigated by scanning electron microscope, differential scanning calorimeter, X-ray diffraction instrument, microhardness tester and electronic universal testing machine. The main conclusions are as followed:(1) The optimum technical parameters could be obtained when the TiC powder load was10g/L, the plating temperature was70℃,the pH=10and the hydrazine concentration was100ml/L. The mean reaction speed and plating mass of per gram TiC were13mg/min and0.26g, the reaction time was60min with the optimum parameters, and the mean thickness of Ni coating is0.2μm. The coating turned to loose porous spongiform structure from compact cellular when the plating temperature varied from70℃to95℃.(2) Iron matrix composites reinforced with TiC particulates were prepared by hot isostatic pressing method in1200℃and150MPa. The TiC particles were distributed uniformly in the matrix and were free of segregation or coarsening. The density, hardness, tensile strength, and elongation were enhanced to99.96%,243HV,565MPa, and11.7%, respectively in composites containing Ni-coated TiC particles from99.70%,210HV,514MPa, and10.3%, respectively in composites without Ni coating. In addition, the mass losses in the composites containing the Ni-coated particles were reduced by32-75%in the abrasive wear test with30-70N loads.(3) Steel matrix composites reinforced with TiC particulates were prepared by vacuum sintering method in1380℃and the sintering time was4h. TiC particles appeared to be slight segregation. Compared with the sintered H13steel, the hardness and tensile strength were enhanced to 482HV and1337MPa from462HV and1069MPa respectively when1wt%Ni-coated TiC particles were added while the elongation and the impact toughness were decreased to5.0%and9.6J/cm2from8.2%and13.4J/cm2.When the content of added Ni-coated TiC particles increased to2wt%, the hardness of the composite further increased to496HV while the tensile strength, elongation and impact toughness decreased to1011MPa,3.4%and4.7J/cm2, respectively. When the added2wt%TiC particles were free of Ni coating, the tensile strength, hardness, elongation and impact toughness of the composite decreased to848MPa、463HV、3.0%and4.5J/cm2.