To address the challenge of detecting subtle internal defects in ceramic sleeves, this paper integrates Phase Coherence Imaging (PCI), dB amplitude enhancement (dB), and the Total-Focusing Method (TFM) to improve image precision and enhance the detectability of subtle defects within ceramic sleeves. Initially, a model of subtle defects in the ceramic sleeve was developed in COMSOL, followed by a comparative simulation to analyze the effects of various ultrasonic phased array probe parameters-such as element count, element spacing, and element frequency-on defect detection and imaging at different positions, ultimately leading to the selection of optimal probe parameters. Subsequently, a test platform for ultrasonic total-focusing detection of ceramic sleeve defects was established, and experimental validation was performed by detecting a 1mm pore defect inside the ceramic sleeve using the optimal probe parameters. Results indicate that, when using the optimal probe parameters for detecting subtle defects in ceramic sleeves, the TFM-PCI-dB method effectively reduces noise and artifacts in the image, while enhancing the amplitude at defect locations, thus making defects easier to detect. The experimental results also validate that this method enables high-precision detection of subtle defects within ceramic sleeves.
