With increasing of immersion time, when the potential of thin oil film reached most positive value, it began to shift negatively.
当浸泡一段时间后,薄层油膜的电位开始随时间变化发生负移。
2
By oilimmersion coupling. the system can be used to detect near surface defects with focussing probe. find surface cracks with surface wave probe and determine defect size with computerized C-scan.