关键词: 陶瓷基复合材料, 太赫兹波谱, 缺陷检测, 零相位滤波, 融合成像

Abstract: Ceramic matrix composites (CMC) have a series of advantages such as low density and high temperature resistance, and are widely used in components such as the leading edge of aircraft wings and advanced gas turbine engines. Due to factors such as diversified manufacturing processes and complicated manufacturing steps in the production process, defects inevitably remain in the material, which has a non-negligible impact on the stability and reliability of the material. In response to the urgent need for internal defect detection, based on the advantages of rich information and high time resolution of terahertz time-domain spectroscopy (THz-TDS) technology, a terahertz detection method for non-destructive detection of internal defects of CMC is proposed. First, the reflective THz-TDS system is used to perform non-contact non-destructive testing on the prefabricated CMC sample, and point-by-point scanning detection signals are obtained in the sample. Then, in view of the obvious phase delay phenomenon that often occurs in the high-frequency signal after high-order filtering, a zero-phase filtering method is proposed, which eliminates the phase delay and accurately extracts information such as peak value, phase and time-of-flight. On this basis, the multi-feature weighted fusion imaging method is used to draw the two-dimensional surface imaging results of the material defect, and the corresponding three-dimensional defect topography is reconstructed, and the defect topography position information is visually displayed, and the location and quantitative evaluation of the defects in the CMC sample are achieved.

Key words: ceramic matrix composite, terahertz spectroscopy, defect detection, zero phase filtering, fusion imaging