重载齿轮损伤原位监测智能涂层协同变形机制及使役机理

Heavy load gears which transmit large load power, will cause serious consequences once the failure occurs. However, the monitoring and diagnosis of gear damage can not realize accurate judgment of the damage process. The supersonic plasma spraying technology will be tried to prepare smart sensing composite coatings which can in-situ monitor gear damage. The coatings collaborate the stresses and strains of gears, and change the strains to measurable signals to achieve monitoring the damage evolution of gears. Firstly, the strain transmission layer will be sprayed on the gear flank, which is used as a buffer layer for the strain of the gear matrix and also plays a role of insulation and increasing the bonding strength. Then the piezoelectric ceramics (BaTiO3, PZT) coatings used as potential sensing layers will be sprayed on the strain transmission layer. The structural phase transition of the piezoelectric material will be done in the high temperature environment of the spraying process. The piezoelectric state of the sensing layer will be inspired by polarization in order to endow the special function of the force electricity transformation of the piezoelectric ceramics coatings. The damage monitoring process which includes stress, strain, synergistic strain, perception, and feedback during the service process of the gears will be done by the combined action of the piezoelectric sensing layer, strain insulating layer, and the substrate. The bonding mechanism and synergistic mechanism of the interface among the three materials will be analyzed. The damage evolution law and electric signal response mechanism will be revealed. The mapping mechanism among the dynamic parameters of gear service, the damage form, and the electrical signals will be studied. The in-situ dynamic real time monitoring of the damage of heavy load gears will be done by smart coatings.

重载齿轮是传递大载荷动力的齿轮，一旦失效将造成严重后果。目前对齿轮损伤监测诊断的手段不能实现对其损伤过程的精细准确判断。拟利用超音速等离子喷涂技术制备原位监测齿轮损伤的“智能传感”复合涂层，通过协同齿轮的应力应变，实现原位监测齿轮损伤演变的功能。首先在齿轮基体侧面喷涂应变传递层，既作为协同齿轮基体应变的缓冲层，又起到绝缘和增加结合强度的作用。然后喷涂压电陶瓷（BaTiO3、PZT等）作为潜在传感层，通过喷涂过程中高温的环境，完成压电材料的结构性相变，通过极化激发传感层的压电状态，赋予其力-电转变的特殊功能。压电传感层、应变绝缘层和基体共同作用完成齿轮服役过程损伤监测功能。通过分析三种材料间界面的结合机理与协同应变机制，探索齿轮损伤演变规律与电信号响应机制，研究齿轮服役动力学参量、损伤形式与电信号间映射机理，实现重载齿轮损伤的原位动态实时智能监测。

重载齿轮是新一代陆军机动平台高功率密度传动系统的基本单元，是决定机动平台运动性能与战场生存能力的关键构件。增强齿轮损伤的在线监测精度，提高重载传动齿轮的服役稳定性，进而优化传动性能，是我国先进制造领域重点攻关方向之一。因此，本项目针对重载齿轮侧表面损伤监测涂层的制备与使役机理进行研究。主要针对涂层成型工艺，裂纹等缺陷萌生机理及微观损伤机制进行分析，采用超音速等离子喷涂在齿轮轮齿侧面制备了BaTiO3涂层，成功开发了适合于各种尺寸齿轮侧面的原位监测智能涂层的制备方法；对压电涂层的电学性能进行优化研究，制备了感应层与基体间的应变传递层，建立了涂层与基体的协同应变模型，阐明压电传感层、应变传递层和齿轮基体的协同应变机制；通过频谱分析、小波分析、神经网络分析等信号处理手段，对整个表面损伤过程中的电信号进行了特征参量和特征波形分析，揭示齿轮齿面点蚀剥落、齿根裂纹萌生、扩展、断裂等损伤失效机理；基于压电传感技术准确监测齿轮服役全过程寿命演变实时评判，实现齿轮服役的安全验证。最终获得了介电性能稳定的PZT涂层，居里温度约为370℃，在适当的极化条件下（极化电压为4kV/mm，极化温度为120℃，极化时间为25min），PZT涂层压电常数可达72pC/N。疲劳裂纹起裂于试样次表面，并且表层形成一层约8-10μm的压缩层。样品的疲劳辉纹平行间距为0.18μm上下。齿轮接触试验中发现当循环次数达到1千万次后，齿轮齿面磨损区域不断扩展，2.5千万循环和5千万次循环后轮齿分别出现了微点蚀和点蚀失效。界面间织构能够有效提高传感涂层与基体的结合强度，当织构图案深度为75μm时，结合强度达到75MPa。结合包络功率谱确定涂层损伤过程的阶段特征频率，给出重载齿轮表面损伤过程中损伤行为与电信号的特征参量和特征波形映射关系。经过本项目的研究，获得了性能良好并适用于齿轮故障监测的智能涂层，揭示了涂层与基体间的协同应变机制，并提取了齿轮疲劳损伤各阶段的特征信号区间，保证了对齿轮疲劳损伤的准确判断。