Y2O3改性石墨/CaF2/TiC/镍基合金复合涂层微观组织与摩擦学性能研究

为提高石墨/CaF₂/TiC/镍基合金（GCTN）复合涂层的力学性能和摩擦学性能，运用等离子喷涂技术在45钢表面制备了Y₂O₃改性GCTN复合涂层，研究了Y₂O₃对复合涂层的微观组织、显微硬度、断裂韧性和摩擦磨损性能的影响。结果表明：Y₂O₃改性GCTN复合涂层主要由γ-Ni、CrB、Cr7C₃、TiC、CaF₂和石墨等物相组成。Y₂O₃在等离子火焰加热作用下与C元素反应生成活性元素Y，Y净化了复合涂层的微观组织，并细化了CrB、Cr₃C7等硬质相晶粒，提高了其致密性。当Y₂O₃质量分数为0.5%时，复合涂层的显微硬度和断裂韧性分别为593.3MPa和6.82MPa·m^1/2，比不含Y₂O₃的复合涂层分别增大了8%和22%，其机理主要是Y₂O₃细化了CrB、Cr₃C₇等硬质相晶粒，起到了细化强化作用。由于GCTN-0.5Y₂O₃复合涂层的显微硬度和断裂韧性显著提高，减少了其黏着磨损和微观断裂磨损，因而GCTN-0.5Y₂O₃复合涂层的摩擦因数和磨损率最小，分别为0.085和0.39×10-3mm3/m。

Study on Microstructure and Tribological Properties of Y2 O3 Modified Graphite/CaF2/TiC/Ni-base Alloy Composite Coatings

In order to improve the friction and wear properties, the graphite/CaF₂/TiC/Ni-base alloy(GCTN) composite coatings were modified Y₂O₃ and prepared by plasma spray on the surface of 45 carbon steel. The microstructure, microhardness, fracture toughness and tribological properties of the composite coatings were researched. The results show that the Y₂O₃ modified GCTN composite coatings are mainly composed of γ-Ni, CrB, Cr₇C₃, TiC, CaF₂ and graphite. Y₂O₃  reacts with C and produces active element Y by the heat of plasma flame. Y can purify the γ-Ni structure, refine the grain size of CrB and Cr₃C₇, and improve the density of the composite coating. When Y₂O₃  is 0.5wt%, the microhardness and fracture toughness of the composite coating are 593.3MPa and 6.82MPa·m^1/2 respectively, which are increased by 8% and 22% than those of the composite coating without Y₂O₃ , because of the refining strengthening effort of CrB and Cr₃C₇. The improvement of microhardness and fracture toughness of the GCTN-0.5Y₂O₃  composite coating reduces the adhesive wear and micro fracture wear, so it presents the lowest friction coefficient and wear rate, which are 0.085 and 0.39×10-3mm3/m respectively.