A prime consideration when selecting a powder to be used as a magnetic particle medium is to select a powder That: 选择磁粉介质,主要的考虑是什么:

A、 will adhere to the surface being tested 会附着在被检表面
B、 provides a low contrast to the surface being tested 在被检测表面提供较低的对比度
C、 provides a high contrast to the surface being tested 在被检测表面提供较高对比度
D、 requires a high demagnetization current to remove it 需要退磁电流使之去除