涂层强化齿轮传动接触机理与承载性能研究

The coating technology is employed to strengthen the gear surface, and it offers a possibility for the lightweight gear to realize the high performance requirements, such as large fatigue limit, long endurance lifetime, and optimum friction coefficient, etc. The challenge is that how the coating can bear heavy load as well as strong impact, and how the coating-substrate system can still keep undamaged, under severe operating conditions. In order to solve the problem, it is urgent to explore the contact mechanism and surface/interface damage evolution rule of the coated gear. Firstly, utilizing the surface engineering technology, the functional gradient multilayer construction of carbon-based composite coating and the surface texture coating are respectively deposited on the gear, and hard/tough characteristic and tribological performance are evaluated. Secondly, according to research method of gear transmission, the new contact/interface, tribological, and dynamics model of coating-substrate system coupling the real surface/interface morphology, diffusion layer, and residual stress is established, that can be used to explore mechanisms of the enhanced load carrying capacity of the coated gear. Finally, based on the damage/fracture mechanics, the surface/interface damage evolution mechanism of the coated gear is studied, and laws of the initiation and fatigue propagation of the coating crack and interfacial delamination are revealed, coupling preparation and service situations of the coating, which can optimize the load carrying performance of coated gear surface. The surface strengthening design theory and method on coating for high performance gear are created, that lays a sound basis for its application on the heavy-duty transmission.

表面涂层强化为轻量化齿轮高疲劳极限、长耐久寿命和最佳摩擦系数等高性能要求的实现提供了可能性。其所面临的难题是涂层在苛刻的齿轮工况下如何实现其高负荷、强冲击承载且能保持自身及膜基界面的无损、可靠。而探究涂层强化齿面接触机理及覆膜齿轮表界面损伤演化规律是解决该难题的当务之需。本项目首先采用表面工程技术，在齿面生成功能化梯度多层构筑碳基复合涂层和表面织构化涂层，评价其硬韧协调、减摩擦、耐磨损、抗点蚀、抗胶合性能。其次，耦合真实表界面形貌、渗层、残余应力，利用齿轮传动学的研究方法，建立评价承载能力的膜基系统接触/界面力学-摩擦学-动力学新模型，诠释覆膜齿面承载能力提高原理。最后，综合考虑涂层制备与服役情况，基于损伤/断裂力学理论，揭示微尺度下齿轮涂层裂纹萌生-疲劳扩展及界面分层演化规律，优化齿面承载性能。由此创成高性能齿轮传动表面涂层强化的设计理论与方法，为涂层在重载传动领域的应用创造基础。

本项目以提高重载齿轮承载能力并延长其使用寿命为方向，在齿面生成具有良好硬韧及摩擦学特性的复合涂层。项目首先在研究高性能齿轮传动对齿面材料特性要求的基础上，建立了齿面的梯度多层构筑碳基复合涂层和表面织构化涂层的基本模型，获得了制备该涂层的相关技术。其次，探究了微观形貌-渗层-残余应力耦合的覆膜齿轮传动接触机理，构建了评价涂层齿面承载能力的模型，使得涂层改性后的齿轮表面接触疲劳寿命和抗胶合强度显著提高，实现了齿面涂层强化的设计理论与方法。最后，从理论和实验上诠释了涂层-齿轮基体系统表界面损伤演化规律，实现了对齿轮膜基系统失效演化过程的科学预测，提高了涂层硬韧特性以及界面结合性能，进一步优化齿面承载性能。项目研究成果一方面探究了涂层强化齿面接触机理，明晰了薄膜涂层对齿面起到强化作用的原因；一方面揭示了覆膜齿轮表界面损伤演化规律，提升了齿面承载性能。上述研究为高性能齿轮涂层的设计奠定理论基础，也为齿面完整性制造提供工程实用价值。