氢诱导作用下的钢铁表面原位生成纳米复合涂层高温超滑行为及机制研究

Due to super low coefficient of friction, superlubricity which has important applications for energy saving has recently attracted enormous attentions. However, until now, superlubricity was achieved at or near room temperature mostly, which restricts the development of superlubricity technology and its practical applications under high temperature conditions. Our earlier research has found that nanocomposite coatings are generated by oxidation from hydrogenated amorphous silicon coatings on the steel at the temperature of 600 oC and hydrogen are liberated from diamond like carbon films of the friction pair in the process of high temperature friction tests, which can lead to high temperature superlubricity (coefficient of friction is 0.005). These findings shed light on a new principle of high temperature superlubricity design based on hydrogen inductive effect. Therefore, the application proposed a scientific problem of “hydrogen-induced high-temperature superlubricity mechanism”, and will carry out researches in following steps, starting with the preparation, structure characterization, annealing and high temperature oxidation of hydrogenated amorphous silicon coatings, focusing on high temperature in-situ generated nano composite coatings from hydrogenated amorphous silicon coatings on steel and hydrogen induced high temperature superlubricity due to hydrogen interactions with the friction interface, and finally aiming to the development of high temperature superlubricity coatings with self-lubricating property under a wide operating temperature range based on the above fundamentals. The research outcomes will beneficial to exploring the application of superlubricity coatings in key mechanical parts such as roller bearing at elevated temperature, and have major significances on enriching traditional superlubricity and opening up the high temperature superlubricity.

近年来，超滑因具有超低摩擦系数可最大程度地实现能源节约而受到广泛的关注。然而，目前有关超滑的报道均在室温附近实现的，这在很大程度上限制了超滑技术在高温下的应用。申请人前期研究发现，氢化非晶硅膜在高温下与氧、水蒸汽发生化学反应，在钢铁基体表面原位生成纳米复合涂层；在摩擦配副类金刚石膜逸出的氢诱导作用下产生了高温超滑（摩擦系数为0.005），这为基于氢诱导作用下的固体润滑涂层高温超滑设计提供了新思路。为此，本项目提出以氢诱导作用下的高温超滑机理为核心科学问题，以氢化非晶硅膜的制备、结构表征、退火处理和高温氧化为基础，以钢铁表面高温原位生成纳米复合涂层和氢与摩擦表面相互作用产生高温超滑为原理支撑，以宽温域环境下连续自润滑的高温超滑涂层研发为目标开展研究。研究结果对于拓展超滑涂层在轴承等高端装备关键零部件高温领域的应用有巨大的实用价值，对于丰富传统的超滑与开拓新兴高温超滑研究具有重要的科学意义。

本项目运用表面涂层技术制备了类金刚石（DLC）膜、氢化非晶硅（a-Si:H）膜和纳米复合涂层，获得了纳米复合涂层在宽温域工况下的超滑行为并揭示了其超滑机理。具体研究内容包括：研究了轴承材料高温摩擦的规律与机制，钢摩擦系数随温度的升高而降低，而Inconel-X750合金摩擦系数随温度的升高而增加，其高温摩擦机制分别为钢摩擦氧化与合金高温软化；研究了DLC膜在不同气氛和温度下的摩擦学性能及高温退火处理对其摩擦学性能的影响规律，获得了大气环境下DLC膜摩擦系数低至0.008的高温超滑行为，揭示了DLC膜中氢屏蔽作用以及配副表面转移膜协同作用的超滑机理；研究了a-Si:H的热稳定性及高温摩擦学性能，结果显示a-Si:H膜具有良好的热稳定性能、摩擦系数随温度的升高而降低，高温600oC下的超低摩擦归因于钢及a-Si:H膜发生高温摩擦氧化原位形成主要成分为SiO2、α-Fe2O3及Fe3O4纳米复合涂层；构建了DLC膜模拟体系，研究了大气环境中氧气、水分子与DLC膜摩擦过程的相互作用机制，分析了DLC膜的石墨化及其对DLC膜摩擦学行为的影响规律，仿真分析了a-Si:H膜的高温氧化过程，探讨了高温氧化过程在超低摩擦中的作用；研制了非晶包裹纳米晶的核壳结构的γ-Fe2O3@SiO2纳米复合涂层，考察了中低温相Ag、韧性相CeO2掺杂含量等制备参数对纳米复合涂层微结构及摩擦学性能的影响规律，探究了纳米复合涂层中纳米非晶SiO2四面体包裹纳晶γ-Fe2O3的核壳结构可抑制γ-Fe2O3向α-Fe2O3相变、高温塑形优异的γ-Fe2O3易剪切的高温超滑机理，揭示了中低温相Ag、韧性相CeO2与高温润滑相γ-Fe2O3的协同润滑机制，实现了γ-Fe2O3@SiO2纳米复合涂层的高温超滑行为及其在宽温域下的连续润滑；构筑了弥散非晶相与纳米晶润滑相结合的复合结构的WSN纳米复合涂层，并实现了宽温域下的超滑行为。研究结果对于拓展超滑涂层在轴承等高端装备关键零部件高温领域的应用具有巨大的实用价值，对于丰富传统的超滑与开拓新兴高温超滑研究具有重要的科学意义。