Study On Properties Of Reactive Plasma Synthesis Ti-Si Carbide Composite Coating

In this paper,Ti-Si-C cermet composite coatings with different Cr or Mo content were prepared by reactive plasma spraying technology.Scanning electron microscope,X-ray diffractometer and other experimental equipment are used to observe and characterize the surface morphology and composition changes of the coating,and to test the mechanical properties of the coating by instruments such as hardness testers and friction and wear testers.Finally,the performance comparison and analysis of metal-ceramic composite coatings at different ratios were performed to obtain the most comprehensive composition ratio.The effects of metal additives Cr and Mo on the performance of Ti-Si-C coatings were mainly studied.The test results of the composite coating under different composition ratios show that the Ti-Si-C coating is composed of TiC,Ti₃SiC₂,Ti₅Si₃ and residual graphite phase.After Cr or Mo elements are added,the overall density of the coating increases.A small amount of Si and Cr elements appear in the Ti-Si-C-Cr composite coating.As the Cr element content increases,the proportion of Ti₃SiC₂ composition increases relatively.After adding Mo element,in addition to TiC,Ti₃SiC₂ and Ti₅Si₃ phases,Mo elementary phase and Mo₅Si₃ phase appeared in the coating,while the proportion of Ti₃SiC₂ and Ti₅Si₃ phases decreased relatively.The test results of the mechanical properties of the composite coating show that the microhardness of the Ti-Si-C coating is 1200±145 HV0.2.After adding Cr element,the hardness of the composite coating showed a slight downward trend,and it dropped to 1070±95 HV0.2 when the Cr content was 1.5 moles.After the addition of Mo element,the hardness of the composite coating increased significantly,and the maximum hardness of the coating reached 1400±162 HV0.2 when the Mo element reached 1.5mol.The elastic modulus of the two cermet composite coatings reached the maximum at 1.0Cr and 1.0Mo,which were 187GPa and 204 GPa.The fracture toughness of the composite coating increases significantly with the addition of metal elements.The Ti-Si-C-Cr composite coating has the highest fracture toughness when the Cr element content is 1.0mol,reaching 2.654MPa·m^1/2.The Ti-Si-C-Mo composite coating also reached a maximum of 3.35MPa·m^1/2 when the Mo element content was 1.0 mol.As the content of metal elements increases,the amount of wear after friction and wear of the coating decreases first and then increases.When the Cr element is 0.2mol,the wear of the coating is 0.7×10^-3g,and the wear of the coating has a slight increase at the ratio of 1.0Cr,which is 1.112×10^-3g.The minimum wear of 1.0Mo coating is0.3×10^-3g.The wear of the Ti-Si-C-Cr and Ti-Si-C-Mo composite coatings is the wear of adhesive wear and abrasive wear composite mechanism.