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本文基于超声纵波垂直入射及斜入射条件下层状介质的声压反射系数,提出了一种测量涂层弹性模量的新方法。主要原理是:在斜入射条件下,若超声波脉冲持续时间较短,通过对水/涂层/基体多界面结构上超声波传播特性分析,以及对涂层试样与块体试样回波波形的比较,可以对多界面混叠波形加以简化识别,在此基础上计算涂层的声压反射系数,并依据涂层特性参量之间的关系,计算出涂层的弹性模量。实验中首先对钢基体上均匀铝质覆层的弹性模量进行了测量,验证了本方法的可行性。然后,利用该方法测量了三种不同特性的ZrO2-7%Y2O3(YSZ)涂层的弹性模量,测量结果与已有文献报道结果相近,并与SEM观察和表面显微硬度测试结果相一致。
In this paper, a new method to measure the modulus of elasticity of coatings is proposed based on the sound pressure reflection coefficient of layered media under the condition of vertical incidence and oblique incidence of ultrasonic longitudinal waves. The main principle is: Under oblique incident conditions, if the duration of the ultrasonic pulse is short, by analyzing the ultrasonic propagation characteristics of the water / coating / matrix multi-interface structure and the waveforms of the coating sample and the bulk sample echo In comparison, the multi-interface aliasing waveform can be simplified and identified. Based on this, the sound pressure reflection coefficient of the coating can be calculated, and the elastic modulus of the coating can be calculated according to the relationship between the coating characteristic parameters. In the experiment, the elastic modulus of the uniform aluminum coating on the steel substrate was measured firstly, which verified the feasibility of the method. Then, the elastic modulus of ZrO2-7% Y2O3 (YSZ) coatings with three different properties was measured by this method. The measured results are similar to those reported in the literature and consistent with the results of SEM and surface microhardness test .