等离子喷涂WC-Co涂层的超声波评价

为了解决目前等离子喷涂涂层制备中的质量检测问题及为在役涂层质量评价提供无损评价技术,研究了一种新的涂层超声无损检测方法.该方法考虑超声波在涂层中传播时,不同界面的回波信号相互叠加并发生多重反射的传播特性,运用功率谱分析及互相关函数分析方法,提出了由涂层引起的群速度延迟时间及涂层密度的求解方法,建立了适于涂层材料评价的超声无损检测系统.对等离子喷涂铁基上的WC-Co涂层进行了密度测试,测试结果与质量差法测量结果误差3.7%.对不同厚度的涂层进行了测试,证明延迟时间与涂层厚度成比例,并与最小二乘法吻合.

Evaluation on the plasma-sprayed WC-Co coating using ultrasonic wave technology

The ultrasonic nondestructive(NDT) testing method was applied to evaluate the quality of plasma-sprayed coatings.The overlay and multi-reflection propagation of ultrasonic wave within the coatings were taken into account.A power spectrum analysis and analytical cross-correlation function(ACCF) were applied to obtain the group delay time cased by coatings and coating density and thus an ultrasonic NDT system was built up for evaluating layered materials.The test density gained for the iron-based coatings by using the proposed testing method has 3.7% error compared with the results obtained by density difference method.The tested results show that the delay time is proportional to coating thickness and matches well with least-squares method.