Progress of Nondestructive Detection Technology on Remanufacturing Coatings

The defects of remanufacturing coatings, such as micro-cracks, micro-pores, oxide inclusion, and fatigue cracks producing in the service process have great influence on the qualities and lives of remanufacturing coatings. This paper summarizes several methods used for detecting coating defects, including ray method, ultrasonic method, eddy method, magnetic memory method, acoustic emission method. The advantages and limitations of the above methods are also discussed. The detection results by ray method are visualized, and it is easy to achieve qualitative, quantitative and locating detection, but this method has incipient fault and low detecting sensitivity. Ultrasonic detection can exactly locate defects, and it is sensitive to plane defects, but the detection has dead zones, and it is inconvenient to perform qualitative and quantitative measurement. Eddy method detects fast, but it only can detect conductive materials, and is difficult to achieve qualitative, quantitative and locating detection. Magnetic memory method is sensitive to ferromagnetic materials, but it can not detect nonferromagnetic materials and is difficult to attain quantitative measurement. Acoustic emission method has an extensive detection range and high sensitivity, but it has big noise interference, and is hard to achieve qualitative detection. In conclusion, it describes the application prospect of each method for detecting coating.