超高真空环境钛合金钻具表界面减阻防护机理研究

The realistic and practicable drilling technology and automated drilling sampler are the key techniques for achieving the aim of the third phase of China Lunar Exploration Project. However, the basic experimental data, corresponding failure mechanisms and wear protection mechanisms for the ultrahigh vacuum tribological behaviors of the drilling tools have not been obtained and understood in China. As a result, the deep cognition of the lunar soil drilling technology and the optimal design of the lunar soil automated drilling sampler would be restricted or prevented by the above knowledge lack. This proposal aims at achieving the friction reducing and anti-wear properties of Titanium alloy drilling tools under ultrahigh vacuum conditions. Based on this idea, we proposed a method for the ultrahigh vacuum tribological evaluation in laboratory and a novel surface treatment technique for the preparation of the friction reducing and anti-wear ultra-thick and hard ceramic layers by the surface nanocrystallizition and the plasma nitriding composite process. Several series of vacuum tribotests under different parameters would be carried out, such as vacuum degrees, simulated lunar soils, the materials of counter balls, velocities and loads ect. Moreover, the microanalyses for detail microstructures and mechanical properties would be performed. Next, the intrinsic interactions among the parameters of the surface modified process - microstructures - mechanical properties - tribological behaviors - wear failures will be revealed. Finally, the surface and interface friction reducing and anti-wear protection mechanisms of Titanium alloy drilling tools under ultrahigh vacuum conditions will be deeply discussed and illuminated. The implementation of the project will provide a theoretical and practical guidance to the design of the Titanium alloy drilling tools and the selection of the relative applied surface modified techniques for the demand working under ultrahigh vacuum conditions.

切实可行的钻探工艺技术和自动钻探取样机具是实现我国探月工程三期科学目标的关键技术，然而我国尚无超高真空环境钻具表面摩擦损伤基础实验数据积累、相应损伤机理模型和防护机理模型，这必将制约我国对月壤取样钻探工艺的深入认知和取样钻具的优化设计。以实现钛合金钻具在超高真空下的减阻抗磨作用效果为目标，本项目提出在实验室实现超高真空环境下摩擦磨损行为的评价方法，并提出表面纳米化和离子氮化复合的新型表面处理工艺，制备超厚减阻抗磨的硬质陶瓷层。通过多工况的真空摩擦磨损性能评价如改变真空度、模拟月壤条件、对磨副材料、转速和载荷等参数，结合深入的微观结构性能分析，揭示钛合金的表面处理工艺参数——组织结构——力学性能——摩擦学性能——磨损失效的内在关系，最终阐明超高真空环境下钛合金钻具表界面减阻防护机理。本项目的实施为超高真空下钛合金钻具设计和表面处理工艺选择提供技术支撑和理论指导。

为保障“三深一土”和“探月工程”国家重大战略工程的实施，为苛刻太空环境的取样钻具设计和表面处理工艺选择提供技术支撑和理论指导，本项目优化设计了模拟月球极端工况下（高真空6.67×10-4 Pa和月壤环境）钻探实验装置，实现了极端工况下钛合金钻具的减摩抗磨实验室评价。探索了钛合金钻具在超高真空下的减阻抗磨技术，开发了表面纳米化预处理、离子渗氮和表面微织构制备复合表面强化技术，在钛合金表面制备了减阻抗磨的硬质陶瓷层，为钻具披上了“铠甲”。此外，还优化了钛合金空间取样钻具减阻耐磨防护工艺，阐明了超高真空环境下钛合金钻具表界面减阻防护机理。.通过复合表面强化技术在钛合金表面成功制备厚度约500 μm厚的金属氮化物硬质陶瓷增强/耐磨结构功能一体化涂层，使空间取样钻具硬度提升7倍（提高至1500HV以上）。在真空条件下，可使钛合金摩擦系数降低30%（降低到0.55左右），磨损率降低86%（耐磨寿命提升7倍多）。在月壤环境下，能使钛合金摩擦系数降低10%（降低至~0.45），磨损率降低83%（耐磨寿命提升6倍多）。.本项目发表学术论文19篇（其中SCI论文14篇，EI论文4篇），授权国家发明专利1项，培养了博士研究生3名，硕士研究生22名。项目相关成果分别荣获2018年度和2019年度国土资源科学技术奖二等奖各1项，2017年度和2019年度中国有色金属工业科学技术奖（发明奖）各1项，已经中国地质学会第十六届青年地质科技奖（银锤奖）等奖项。

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