高温退火处理对ZnO压电涂层结构和性能的影响

Effect of high temperature annealing on structure and properties of ZnO piezoelectric coating

ZnO是目前压电螺栓传感器的主要涂层材料,具备优异的压电性能,表现出优异的声-电信号转换性能,但目前对其高温结构及性能稳定性研究较少。本工作利用射频磁控溅射法在(100)_(Si)和工业用钛合金螺栓上制备出可产生超声纵波的ZnO压电涂层,并对其进行不同温度和不同时长的退火处理,用扫描电子显微镜、原子力显微镜、X射线衍射和自建的WHU-US100声信号测量设备研究高温退火处理对涂层结构及性能的影响。结果表明,Si/ZnO涂层在600℃以下的退火处理不会对涂层表面微观形貌产生影响,涂层截面形貌呈现柱状晶结构,且随着温度的升高,柱状晶有合并的趋势;涂层表面粗糙度变化幅度为±4 nm;不同的退火温度对涂层的晶体结构未产生明显的影响。螺栓/ZnO涂层在500℃及以下温度的退火处理后涂层表面完整,600℃退火处理后的螺栓涂层完全脱落,超声检测表明涂层在500℃以下退火后保持稳定;在300℃下,经过长时间的退火处理后,螺栓样品可正常激发出超声波,涂层结构未被破坏,表明该ZnO涂层可以在300℃的温度范围内长期服役。

ZnO is currently the main coating material for piezoelectric bolt sensors,which exhibits excellent acoustic-electric signal conversion because of its unique piezoelectric effect,but its high-temperature structure and performance stability have been less studied.In this paper,ZnO piezoelectric coating that could generate ultrasonic longitudinal waves was prepared on(100)_(Si) and industrial titanium bolts by RF magnetron sputtering,and annealed at different temperatures and different time durations to investigate the effects of high-temperature annealing treatment on the structure and properties of the coating.The results of scanning electron microscopy show that the annealing treatment below 600℃ does not affect the microscopic morphology of the coating surface,and the cross-sectional morphology of the coating shows a columnar crystal structure,and the columnar crystals tend to merge with the temperature increased.The results of atomic force microscopy show that the surface roughness of the coating varies by±4 nm,and the X-ray diffraction results show that different annealing temperatures do not affect the crystal structure of the coating significantly.The acoustic signals of the bolt samples after annealing treatment at different temperatures and durations are examined,and the results show that the coating surface is intact after annealing treatment at 500℃ and below,and the bolt coating is completely peeled off after annealing treatment at 600℃.The ultrasonic signals characterize that the structure of coating is stable after annealing at 500℃ or below;at 300℃,after a long annealing treatment,none of the excitable ultrasonic properties of the bolt samples are destroyed,indicating that the ZnO coating can serve in the temperature range of 300℃for a long time.