# A Through-Transmission Ultrasonic Method for the Detection of Ferrite Tile Defects
1  
[PERSON]  
1 Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; [EMAIL_ADDRESS] (K.H. ); [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Q. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (X.L.) 1  
[PERSON]  
1 Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; [EMAIL_ADDRESS] (K.H. ); [EMAIL_ADDRESS] (K.Z. ); [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Q. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (X.L.) 1  
[PERSON]  
1 Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; [EMAIL_ADDRESS] (K.H. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Q. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (X.L.) 1  
[PERSON]  
1 Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; [EMAIL_ADDRESS] (X.H. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Q. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (X.L.) 1  
[PERSON]  
1 Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; [EMAIL_ADDRESS] (X.H. ); [EMAIL_ADDRESS] (X.Z. ); [EMAIL_ADDRESS] (B.C. ); [EMAIL_ADDRESS] (X.Q. ); [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (X.L.) 1  
[PERSON]  
1 Shenzhenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; [EMAIL_ADDRESS] (X.H. ); zkx1 conducted time-domain analysis of the weld defect echo signal of stainless steel pipes according to the weld defect echo signal of stainless steel pipes, compared and analyzed the amplitude changes of different types of weld defect signals, and realized the detection of weld defects. Typically, ultrasonic pulse-echo methods detect sample defects by analyzing the time and frequency domain characteristics of echo signals. For defect detection in ferrite tiles, [PERSON] et al. [12] developed a pulse-echo-based approach that improved the B-scan (Brightness Scan) imaging and accurate localization of internal defects in the tiles. However, when defects are located near or at the surface of the sample, the impedance mismatch between the probe, sample, and coupling agent leads to strong surface echoes, making defect detection challenging [13; 14]. As a result, ultrasonic pulse-echo methods have limitations in terms of detection accuracy and sample structures [15]. In the realm of ultrasonic testing (UT), ultrasonic transmission emerges as a defect detection technique that overcomes the limitations of traditional methods, allowing for the inspection of near-surface and surface defects and the measurement of various material properties. Several studies both domestically and internationally have utilized ultrasonic transmission methods for defect detection and measurement [16; 17; 18; 19; 20; 21]. For instance, [PERSON] [22] employed ultrasonic transmission for defect detection in complex curved resin-based composite materials, demonstrating the capability of the ultrasonic transmission method to detect bending composite parts with the aid of an automatic robot inspection system. These research outcomes suggest that ultrasonic transmission method has the potential for comprehensive defect inspection of both internal and external defects in ferrite tiles. The ultrasonic echo test of ferrite tiles posed several challenges during the experiments. These challenges included the high damping attenuation in ferrite tiles, leading to weak echo signals and a low signal-to-noise ratio in the pulse-echo method. Moreover, the pulse-echo method exhibited more pronounced blind zones in small-sized ferrite tile samples, making defect detection difficult. Additionally, the detection of common longitudinal cracks in ferrite tiles was hindered by the influence of defect orientation. To address these difficulties, a water-immersion ultrasonic transmission method for ferrite tiles is proposed. The effectiveness of this method is validated through finite element simulation, test system design, and experimental verification.