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5370 |
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Thursday, June 08, 2017, Hall 26 9:00 AM Wear Protection II |
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Effect of laser treatment on plasma sprayed molybdenum coating on ET4A steel |
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MIN Yu* / Southwest Jiaotong University, P.R. China YU Min / Southwest Jiaotong University, China MA Hao/ Southwest Jiaotong University, China HUA Junwei/ Southwest Jiaotong University, China LIU Yan/ Southwest Jiaotong University, China CHEN Hui/ Southwest Jiaotong University, China |
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Towards the high-speed, heavy-duty trends of China's high-speed train, a higher requirement for the service life of the axle is put forward. The hollow structure of the high speed axle makes the relative slip amplitude of the contact surface is relatively large, and the contact between the axle and the wheel causes serious surface damage. In order to prevent the wear of the wheel seat, surface strengthening measures was usually adopted. Enhanced wear resistance of the axle by reducing the friction between the wheel and axle, thereby reducing the loss and damage due to wear, could extend the life of the axle. In this paper, Mo coating was prepared on EA4T steel substrate used for high-speed trains by plasma spray technique. A fiber Nd-YAG laser was employed on the plasma sprayed Mo coating to improve coating performance. Microstructure, microhardness and tribological property of the plasma sprayed and laser treated Mo coatings were characterized. Results showed that the Mo coating has a typical lamellar structure and low porosity. No oxide and impurity elements were found in the coatings and no diffusion and reaction occurred between the coating and the substrate, and the coating adhered well on the substrate with a mechanical anchoring way. The microhardness of the Mo coating is 514HV0.1,which is 50% higher than that of the base EA4T axle. In addition, the Mo coating showed a self-lubricating feature and both the friction coefficient and wear loss of the Mo coating were less than those of the substrate, which suggests superior wear resistance of the coating. After the wear test, friction surface morphology was observed by SEM and results show the friction mechanism is an abrasive failure, manifesting lots of debris covering on the friction track. Finally, the performance of the Mo coating was improved by laser treatment. |