低温重载工况下自润滑材料摩擦磨损机理和轴承服役性能研究

The project focuses closely on the national strategic requirement “Design and construction of large cryogenic high reynolds number (Re) wind tunnel”, aiming at solving the key challenge of preserving low friction under extreme conditions, e.g. low temperature and its large variation (110-323K) in nitrogen gas and in ambient air and heavy load, etc., suffered by the key tribopairs in the wind tunnel such as the spherical plain bearings for driving and support of flexible steel plate in wind tunnel nozzle and the heavy load sliding support for the internal segment. The project plans to develop technologies of on-line monitoring of friction and wear of self-lubricating materials across the length scales, and on-line monitoring of friction-induced transfer film thickness and chemical compositions in microdomains on the outer surface of inner ring of the spherical plain bearing with only half-outer ring. This will help to unravel new laws and mechanisms involving the tribochemistry and the formation and evolution of the transfer film, and help to establish the structure-property relationship between microstructure and tribological performance of self-lubricating materials. To develop the preparation scheme of polymer-based self-lubricating material with the construction of "surface lubricating layer-composite fiber fabric-adhesive resin" with low friction and high strength, as well as to develop the preparation method of strong and tough diamond-like carbon composite coatings with multi-phase and heterogeneous structures, modulated by using synergistic high-energy ion beam deposition and ion implantation. To carry out the service performance test in cryogenic wind tunnel on-site, aiming at achieving stable friction coefficient lower than 0.1 in full working temperature range of spherical plain bearings, and to provide theoretical guidance and technical support for the design and preparation of self-lubricating materials and upgrading the performance of key tribopairs in large cryogenic wind tunnel in our country.

本项目紧密围绕“大型低温高雷诺数风洞设计建设”国家战略需求，针对其中喷管段柔板支撑用关节轴承和内部部段支撑用重载球形支座等关键摩擦副，为解决其低温/大温变（110-323K）氮气、常温空气环境及重载等工况下实现稳定低摩擦的关键技术挑战，本项目拟发展自润滑材料摩擦磨损宏微观多尺度在线观测技术，发展基于傅里叶变换显微红外光谱法的半外圈结构轴承表面微区转移膜厚度和化学组分的在线监测方法，深入揭示自润滑材料摩擦化学和转移膜形成演化的新规律和新机理，建立自润滑材料微观结构和摩擦特性构效关系；发展“表面润滑膜—复合纤维织物—胶粘剂”低摩擦高强度聚合物基自润滑材料制备技术，及高能离子束沉积和离子注入协同调控的类金刚石多相异质复合强韧化涂层制备技术；通过低温风洞现场服役性能测试，实现关节轴承全温域摩擦系数稳定低于0.1，为我国大型低温风洞中关键摩擦副自润滑材料设计制备及性能提升提供理论指导与技术支撑。

本项目紧密围绕“大型低温高雷诺数风洞设计建设”国家战略需求，解决大型低温风洞核心部段关节轴承关键摩擦副低温/大温变（-163~50℃）工况下实现稳定低摩擦的关键技术挑战，开展了系统的理论研究与技术攻关。.在低温摩擦机理方面，开发了描述聚合物摩擦化学作用的反应粗粒化力场，首次能够精确预测分子链与对偶面之间化学锚定键的形成/断裂、分子链解缠结和有序化取向等微观过程，发现低温下分子链冻结、摩擦化学被抑制，而引入化学活性聚醚醚酮分子可激活低温摩擦化学反应，有效促进分子链有序化取向和低剪切滑移界面形成，从而大幅降低摩擦；通过单粗糙峰级微观摩擦试验结合原子级分辨率转移膜表征，揭示了类金刚石膜摩擦演化至超滑态的过程与摩擦界面结构有序化转变之间的强相关性，发现了类金刚石膜低温下摩擦演化的亚Arrhenius规律，揭示了氢转移量子隧穿效应促进摩擦相变的类金刚石膜低温超滑机制。.在低温轴承测试装备和低温轴承润滑规律方面，自主设计/研制了低温/大温变关节轴承摩擦测试装置，为大型低温风洞核心部段运动机构轴承研制提供了测试平台支撑；提出了关节轴承摩擦转移膜成分演化的红外光谱原位观测方法，避免了样品所处测量环境改变带来的误差，发现室温下衬垫摩擦表面润滑分子链呈现明显取向行为，在轴承内圈外表面形成“薄且均匀”的材料转移；随着温度降低衬垫摩擦表面分子链取向变差，转移膜迅速减少；继续降低温度，材料发生脆性转变，形成碎片状转移膜，摩擦不变或略有降低。该规律的揭示为低温润滑材料设计提供理论依据。.在低温自润滑关节轴承设计与应用方面，采用热塑性聚醚酰亚胺浸渍液替代传统树脂，通过高化学活性磺化聚醚醚酮强化纤维织物促进全温域稳定转移膜形成，构建梯度复合结构，研制出兼具低温韧性/润滑性的织物衬垫型关节轴承，与国外产品相比，该轴承低温摩擦系数可降低30%以上，并通过了-163℃环境3万摆次轴承寿命测试、0.3m小型低温风洞测试等，已应用于大型低温风洞喷管段柔板机构和第二喉道中心体调节机构，并通过了风洞低温标模试验。

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