Preparation And Tribological Mechanism Of TiAl Based Self-lubrication Joint Bearing

As aerospace and automobile industry rapid development, this requires joint bearing with the safety under the complex environment of high temperature and overloading. New style solid self-lubricating composites are needed, which can work at high temperature to prevent wearing and failure of joint bearing. TiAl alloy with low specific weight, high strength, maintaining high enough strength and stiffness at high temperature, good creep resistance and oxidation resistance, is the ideal substrate material. CaF2 and BaF2 from the beginning of the 500 degree of lubrication, and high temperature oxidation resistance, can be used to 900 degrees and not due to oxidation failure. 62%BaF2-38%CaF2 eutectic has a lower melting point and shear stress, therefore it is better lubrication properties than single CaF2 or BaF2.In this article, TiAl self-lubricating composites is fabricated by powder metallurgy, during which the Ti44Al2Cr8Nb3V0.5B0.5Al2O3 powder was used as original materials, and 62%BaF2-38%CaF2 powder was added as solid lubricant. The worn surfaces of TiAl self-lubricating Composites is by SEM and EDS. Effect of 62%BaF2-38%CaF2 eutectic content on tribological and dynamics properties of TiAl based self-lubricating Composites is analyzed. The study shows: With increasing 62%BaF2-38%CaF2 content,relative density, tensile strength, impact toughness, hardness, elongation and friction coefficient tend to decrease, while wear rate decreases firstly, and then increases. The material with 11% 62%BaF2-38%CaF2 content has the minimal wear rate, and perfect mechanical properties, is a new style self-lubricating composites. The reason is that a layer of solid lubrication film can be formed on the friction surface in the process of sliding friction, the existence of solid lubrication film makes it have good wear and friction reducing properties.Effects of temperature on tribological property of TiAl self-lubricating composites are studied. The study shows: with increasing temperature, Friction coefficient and wear rate of TiAl based self-lubrication composites decrease, but the friction coefficient is relatively large at below the temperature of 100℃. The reason is that 62% BaF2-38%CaF2 does not play the role of lubrication at temperatures below 100℃.Preparation of self-lubricating joint bearing by the material with 11% 62%BaF2-38%CaF2 content, the TiAl based self- lubricating joint bearing of high temperature friction and wear experiment and finite element simulation of friction and wear are studied. The study shows: the temperature of test point increases with the increasing time in the same condition of pv value, but increased gently, and as the friction on both the temperature error is bigger and bigger.