Temperature effect on pulsed eddy current measurements

• Main Authors: Wei Lin, 林威
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/31323872985901721558

碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程所 === 93 === Pulse Eddy Current Technology is a widely used nondestructive corrosion monitoring method that estimates the thickness of a surface based on the decay of the eddy current. The eddy current is proportional to the product of two temperature-dependent properties, the electric conductivity and the magnetic permeability. Therefore, the measurement will be inaccurate, when the surface temperature is inhomogeneous. This research first investigated the temperature effects on the electric conductivity and the magnetic permeability of ferrous materials, developed empirical relationship, and finally applied the empirical relationship for the correction of the field data. Experimental results showed that the product of the electric conductivity and the magnetic permeability was linearly proportional to the temperature, when the temperature is between ambient temperature and 280 oC. The product was almost a constant when the temperature was between 280 oC and 450 oC. The product increased nonlinearly with the temperature, when the temperature was between 450 oC and the Curie temperature. By using the empirical relationship developed in this work to the field data, we were able to reduce the error within 5%.