SBIR Phase I: Eddy Current Condition Monitoring of Metallic Flaws Under Surface Coatings Using Giant Magnetoresistance (GMR) Sensors

这个小型企业创新研究第一阶段项目提出使用巨磁阻（GMR）磁传感器和涡流技术来检测绝缘涂层下金属部件的缺陷。表面处理的创新和改进，如涂层和喷涂，包括热障涂层，是无用的，除非降解，磨损，腐蚀和氧化，由于热和机械应力可以监测这些表面处理。使用GMR传感器进行条件监测具有以下优点：（1）改进现有传感器技术将使涡流传感器的制造具有非常高的灵敏度，从而增加允许的提离. (2)与超声波方法不同，磁场不会受到电绝缘涂层的显著影响。 (3)基于GMR传感器的方向灵敏度允许检测边缘附近的缺陷，这些缺陷更容易引发裂纹。该项目将证明使用GMR传感器和涡流技术检测涂层下缺陷的可行性。高灵敏度的GMR传感器将允许设计小型、易拆卸、便携式NDE装置，可用于结构监测、监视、关键部件监测和设备准备。

This Small Business Innovation Research Phase I project proposes to use giant magnetoresistance (GMR) magnetic sensors and eddy current techniques to detect flaws in metallic components under insulative coatings. Innovations and improvements in surface treatments such as coatings and sprayings including thermal barrier coatings are useless unless degradation, wear, corrosion and oxidization due to thermal and mechanical stresses can be monitored under these surface treatments. Conditional monitoring using GMR sensors has the following advantages: (1) Refinement of present sensor technology will enable themanufacture of eddy current sensors of very high sensitivity thereby increasing the permissible lift-off. (2) Unlike ultrasonic methods, magnetic fields are not significantly affected by the presence of electrical insulating coatings. (3) The directional sensitivity of GMR based sensors allows detection of flaws near edges where cracks are more likely to initiate.This project will prove the feasibility of using GMR sensors and eddy current techniques to detect flaws under coatings. High sensitivity GMR sensors will allow the design of small, easily maneuvered, portable NDE units which can be used for structure monitoring, surveillance, critical component monitoring and equipment preparedness.