Abstract: In order to detect thermal barrier coating(TBC) using microwave non-destructive detection technique in the low frequency, the detection sensitivity, optimization of detection parameters is carried out detecting thickness and porosity of thermal barrier coating, and detecting crack of metal substrate, using coaxial probe which frequency is 0-17 GHz. The influence of the coaxial probe size, standoff distance, thickness and porosity of top coating(TC) is suited using CST-microwave studio. The results of detecting TC thickness show that the smaller the probe or the smaller the TC dielectric constant, the higher the frequency when phase difference equal to zero, and the smaller the standoff distance, the higher the detection sensitivity. The results of detecting TC porosity show that the higher the detection sensitivity, the larger the TC thickness. The results of detecting crack of metal substrate show that in order to prevent un-detection, the scanning length should be less than the radius of the probe. Therefore, it is feasible to detect TBC using microwave in low frequency, when coaxial was used a sensor.

Key words: coaxial probe;top coating thickness;top coating porosity;crack of substrate;microwave detection