论文部分内容阅读
用超音速等离子喷涂设备在45钢基体上制备了铁基合金涂层。以球盘式疲劳试验机为平台,研究了涂层的接触疲劳损伤行为,探测并分析了涂层在不同应力水平下疲劳损伤的声发射反馈信号。结果表明,涂层的接触疲劳损伤过程主要包括弹塑性变形、裂纹萌生和缓慢扩展、裂纹亚临界扩展、裂纹失稳扩展4个阶段。裂纹萌生和缓慢扩展阶段是决定疲劳寿命长短的主要阶段。接触应力越大,裂纹亚临界扩展时间和失稳扩展时间越短。涂层的最终失效模式可以根据裂纹失稳扩展阶段声发射幅值的最大值来判断,发生点蚀失效时幅值最大值约为82.4 dB,剥落失效时幅值最大值约为90.2 dB,分层失效时幅值最大值约为91.3 dB。
An iron-based alloy coating was prepared on a 45 steel substrate using a supersonic plasma spray apparatus. The ball-type fatigue testing machine is used as the platform to study the contact fatigue damage behavior of the coating, and to detect and analyze the acoustic emission feedback signals of the coating under different stress levels. The results show that the contact fatigue damage process of the coating mainly includes four stages: elastoplastic deformation, crack initiation and slow propagation, crack subcritical expansion and crack instability propagation. Crack initiation and slow expansion phase is to determine the main stage of fatigue life. The larger the contact stress is, the shorter the subcritical crack propagation time and instability propagation time are. The final failure mode of the coating can be judged according to the maximum value of acoustic emission amplitude in the phase of crack instability expansion. The maximum value of the amplitude of the pitting corrosion failure is about 82.4 dB and the maximum value of the failure amplitude is about 90.2 dB. The maximum amplitude at layer failure is approximately 91.3 dB.