Study On Wear Characteristics Of TiN/Al₂O₃/Ti（C,N） Series Tool Coatings In Repairing Of CL65 Wheel Steel

With the increase of axle load in heavy-haul trains,it is necessary to equip CL65 heavy-haul wheels with higher hardness and strength.But the severe wear problem of the tool is brought to the wheel repairing,which will affect the efficiency and quality of wheel repairing.Precisely wheel repairing to maintain the profile of tread is one of the key factors to ensure the stable running of the train.At present,few attention attach to the wear characteristics of coating tools for wheel repairing,and an effective tool wear model is lacking in the wheel repairing process.To optimize coating preparation technology and prolong the service life of the repairing tool,the wear characteristics of the coating tool for wheel repairing were studied and the wear prediction model of the coating tool was established.It is of great guidance and economic value to improve the turning efficiency and machining quality of the wheel.The thesis adopts the research method of combining experiment and simulation.Firstly three kinds of TiN/Al₂O₃/Ti（C,N）series multi-layer coatings were prepared by chemical vapor deposition（CVD）technology on the surface of cemented carbide tool material pinball.The tribological conditions in the wheel repairing for CL65 rail steel were simulated on the high-temperature tribometer,which takes into account effect of rates,temperatures,and load.The relationship between coating microstructure and wear behavior was revealed,and the wear prediction model of the coating tool under the thermal-mechanical field was established by using ABAQUS secondary development technology.The main conclusions are as follows:The thickness of the three TiN/Al₂O₃/Ti（C,N）coatings ranges from 8.9 to 15μm,the hardness ranges from 1692 to 1752HV,and the microstructure of the coatings is mainly composed of granularα-Al₂O₃ and columnar Ti（C,N）;However,the coatings are different in the preferred growth orientations of Al₂O₃ and Ti（C,N）and the microstructures.The wear characteristics of TiN/Al₂O₃/Ti（C,N）series coatings are related to the microstructure of the coatings.The granular structure of TiN on the surface of 01 coating makes it shows the best adhesion resistance at 350°C and below;The 56 coating with high Ti（C,N）content in columnar structure has a long service life under the condition of high load and high speed;and the granularα-Al₂O₃ structure makes the coating have excellent wear resistance at high temperature（around 350°C）.In comparison,better wear resistance and best coating structure make the 01 coating the best coating to match the CL65 wheel repair.The Usui wear model under the fiction of three TiN/Al₂O₃/Ti（C,N）coatings and wheel steel was fitted,ABAQUS secondary development technology was used to simulate and predict the wear of the coating tool.The accuracy of the wear model was verified by the friction and wear test.The results of the tool wear simulation show that the tool with a larger rake angle for low-speed cutting improves the service life of the repair tool.