Research on terahertz non-destructive testing technology for internal defects of insulation layer

In this study, terahertz non-destructive testing technology was used to insulation materials. The terahertz wave non-destructive testing was carried out to test the thickness of the layer, the air hole in the insulation layer and the defect of adiabatic structure. The refraction and absorption coefficients of terahertz wave in asbestos-filled nitrile rubber, aramid fiber-filled ethylene propylene diene monomer(EPDM) and silica-filled polyurethane rubber were studied. Two terahertz wave scanning imaging results were compared. Terahertz wave has a good penetrating ability to the insulation material and can be used to test the insulation layer thickness. At the same time, quality defects such as stratification and porosity of samples with a thickness of 2 mm can be identified. It is proved that terahertz technology can be applied to the detection of insulation materials and internal defects.