超高速下干滑动摩擦磨损特性

Hypervelocity test track is a very important test platform for national defense construction. However, serious sliding friction and wear during the unlubricated sliding process have an abominable impact on service performance, security and lifetime of the test track. In order to improve tribological properties of the test track, FeAl intermetallic compound coating is selected as friction pair (slipper) to the track. This is because the FeAl coating possesses excellent corrosion and wear resistance at high temperature. Then the unlubricated high-speed sliding tribological behaviors of the coating material are systematically investigated. The main study of the project includes five aspects as follows: (1) to study the influence laws of load, speed, temperature, surface roughness on the high-speed sliding friction and wear characteristics; (2) To study the intrinsic material mechanism of the sliding friction coefficient with the change of sliding speed; (3) to study the influences of aerodynamic heat and friction heat on the sliding tribological properties of the test track at high speed; (4) to study on the transition mechanism from mechanical wear to melt wear, and the tribological properties of melt wear; (5) to establish the wear-transition and wear-mechanism maps for the high-speed sliding process. Through these studies, it is expected that the nature of high-speed slide friction and wear behaviors will be revealed. Finally, a high-speed unlubricated sliding experiment will be performed, in which the maximum sliding speed will be at Mach 5, to verify the correctness of ours research works. This project should be helpful to ensure the safety, reliability and long-lifetime operation of ours high-speed test track, and improve the performance property to reach and/or close to that of the Holloman High Speed Test Track (HHSTT) facility at Holloman Air Force Base, New Mexico, USA.

超高速测试平台在国防建设中占有举足轻重的地位，但严重的滑动摩擦磨损现象直接影响着平台的安全性、使役性能和寿命。因此，本项目首先选用具有良好高温耐磨耐蚀性能的FeAl涂层做为运动副。其次，从摩擦学机理方面对超高速测试平台的滑动摩擦磨损现象进行系统的研究,主要研究了:1）载荷、速度、温度、接触表面粗糙度对超高速滑动摩擦磨损特性影响规律；2）滑动摩擦因数随速度等变化的内在机理；3）超高速滑动下，气动热、摩擦热对摩擦磨损特性的影响；4）机械磨损-熔融磨损的转变机制及熔融磨损摩擦学特性表征；5）构建超高速滑动磨损机理图和磨损率图。通过这些研究工作，本项目希望深入、全面理解超高速滑动摩擦磨损现象，阐明超高速滑动摩擦磨损现象的本质机理。最后，通过最高速度5马赫滑动试验验证本项目研究工作的正确性。最终实现超高速测试平台的安全、可靠、长寿命运行，使役性能接近或达到美国霍洛曼空军基地高速实验轨道的现有水平。

高超声速火箭橇在国防建设中占有举足轻重的地位，但严重的滑动摩擦磨损现象直接影响着平台的安全性、使役性能和寿命。因此，开展滑靴与轨道之间的摩擦磨损研究对提高我国国防综合实力具有重大意义，同样具有重大的科学意义和工程应用价值。本项目首先从高速滑动耐磨材料选择开始，研究了新一代火箭橇滑靴材料18Ni(300)马氏体时效钢制备和热处理工艺，使其性能指标与美国8马赫火箭橇滑靴材料VascoMax300钢性能指标相似，此研究工作为本项目后续高超声速干滑动摩擦磨损特性研究提供了物质基础。其次，从摩擦学机理方面对超高速测试平台的干滑动摩擦磨损现象进行系统的研究,主要包括: 1）载荷、速度、温度、接触表面粗糙度对超高速滑动摩擦磨损特性及机理影响规律研究。采用分型模型描述真实粗糙表面，通过有限元模拟获得了载荷、速度、接触表面粗糙度与火箭橇滑靴轨道间摩擦系数数学模型。进而研究了摩擦热和气动热耦合作用下火箭橇滑靴温升问题。2）研究了高速、大冲击下材料失效准则，高速干滑动过程中磨损机理及其磨损率计算方法，构建了高超声速火箭橇滑靴磨损量预测模型。3）根据现有高超声速火箭橇系统，研究并建立了火箭橇-轨道系统非线性耦合的动力学方程；建立了火箭橇试验过程中滑靴-轨道接触压力（载荷）-时间等关系，为高速干滑动摩擦系数以及摩擦磨损量的有限元计算提供了真实的边界条件。最后，通过4马赫高超声速火箭橇试验验证本项目研究成果的可靠性。火箭橇试验结果表明本项目的火箭橇滑靴高速摩擦磨损特性研究与试验结果相符，火箭橇滑靴典型部位的磨损量预测值与实际磨损测量值误差小于30%。由此可见，项目的研究能够为高超声速火箭橇试验的安全运行提供技术保障，为高超声速火箭橇滑靴结构设计等方面提供科学依据，为我国超高速测试火箭橇平台使役性能接近或达到美国HHSTT的现有水平提供理论和技术支持。

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