多元共渗FGM涂层齿轮性能分布调控及服役行为研究

The academic thought was put forward that FGM coating gear is made with multicomponent infiltration process according to performance requirement of the high-end gear. High current pulsed electron beam technology is used to clean gear surface and improve performancement, while gear surface is activated. A variety of elements are diffused into gear surface with vacuum thermal diffusion process. Then FGM coating is prepared on gear, which has the characteristics of high hardness, large depth, reasonable gradient distribution with performance and alloying connection. Studies focus as follows. The performance gradient requirements are put forward according to the gear service conditions and the stress characteristics. The physical characteristics and distribution function of component are studied. Multicomponent infiltration process, element diffusion and micro structure characteristics are analysed, then inner link is discussed between the process, composition, inter organization. Gear performance is studied with multicomponent permeation FGM coating, and relationship is gained between element distribution, organizational structure and binding force of FGM coating. The bending and contact fatigue strength are tested. The gear design method and evaluation principle of FGM coating are explained through the research projects. The multicomponent infiltration and layer formation mechanisms are illuminated. The problem of multicomponent infiltration structure and properties of FGM coating regulation are solved. Multicomponent infiltration coating FGM gear service behavior and failure mechanisms are acquired. The scientific theoretical basis, experimental data and design method are provided for new gear manufacturing process with high hardness, high wear resistance and high toughness.

针对高端齿轮性能要求，提出多元共渗FGM涂层齿轮的学术思想，利用强流脉冲电子束清洁齿轮表面、改善表层性能，采用真空热扩渗工艺制备齿轮表面多元FGM涂层，获得硬度高、层深大、性能梯度分布合理、合金化连接的涂层。重点开展以下研究：根据齿轮服役条件和受力特性提出性能梯度要求，研究组元渗层的物理特性和组元分布函数；分析多元共渗工艺、组元扩散及微组织特征，获得工艺、成分、组织间的内在联系；研究齿轮表面多元共渗FGM涂层的性能、FGM涂层组元分布、组织结构与结合力的关系；开展多元共渗FGM涂层齿轮的弯曲、接触疲劳实验研究。通过项目研究，建立FGM涂层齿轮设计方法及性能评价系统，阐明多元共渗FGM涂层组元扩散机制及渗层形成机理，解决多元共渗FGM涂层结构及性能调控问题，获得多元共渗FGM涂层齿轮的服役行为及失效机理。为新型高硬度、高耐磨性和高韧性的齿轮制造技术提供科学的理论依据、实验数据和设计方法。

齿轮是现代机械装备中应用领域最广、用量最大的机械传动件，齿轮及齿轮传动装置的设计、制造水平直接影响机械产品的性能和质量，是我国发展战略性新兴产业的重要支撑和从制造大国向制造强国转变的重要产业标志。齿轮失效多从表面开始，表面工程成为改善齿轮等机械零件表面性能的重要技术，项目提出了“齿轮表面多元共渗FGM涂层”研究思路。.根据齿轮受力特性，提出了界面性能梯度要求，利用有限元分析进行了梯度渗层齿轮设计。对齿轮电子束预处理工艺进行了组织表征，完成多元梯度涂层的合金组元匹配研究，完成Cr、B、Si等单元渗层特性试验。进行了Cr-Mo、B-Cr、Si-Cr、Cr-C多元扩渗工艺，研究扩渗过程成分对组织的影响，研究了齿轮表面多元共渗渗层的硬度、结合力、耐腐蚀、摩擦磨损等性能，建立模型解释了其机理。开展多元共渗FGM涂层齿轮弯曲疲劳强度和接触疲劳性能试验，分析讨论了疲劳失效行为和机理。.有限元分析参数敏感性分析发现，同样载荷条件下，接触压强主要受到最外层涂层厚度影响最大。不同温度扩渗下，1000℃渗Cr层组织为合金渗碳体，1300℃渗Cr层组织为固溶体，均能达到外硬内韧的效果。预渗B可以有效解决渗Cr处理亚表面的贫碳问题，感应加热渗Cr效率更高，硼铬富集涂层的形成能够很好地改善40Cr钢的耐磨性和耐蚀性,在感应加热渗Cr早期界面反应促进了渗层生长，后期原子的扩散逐渐控制了渗层的生长。随着渗Cr时间的延长，渗层的平均硬度呈现增加的趋势，耐磨性也显著改善。以硅铁粉为供硅剂进行Si-Cr共渗后,渗层不存在贫碳层，耐磨性也更好。.经过本研究的开展，获得硬度高、层深大、性能梯度分布合理、合金化连接的涂层，建立FGM涂层齿轮设计方法及性能评价系统，阐明多元共渗FGM涂层组元扩散机制及渗层形成机理，解决多元共渗FGM涂层结构及性能调控问题，获得多元共渗FGM涂层齿轮的服役行为及失效机理,为新型高硬度、高耐磨性和高韧性的齿轮制造技术提供科学的理论依据和实验数据。

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