Characterization of Defects in Mn-Zn Ferrites by Scanning Laser Acoustic Microscopy (SLAM)

摘要

A scanning laser acoustic microscope (SLAM) has been used to evaluate the integrity of Mn-Zn ferrite ceramic components which comprise part of the magnetic circuit in an electromechanical code interrogation device. Cracking of the ferrites during processing and assembly emerged as a significant manufacturing problem. Operations such as grinding, metallization, joining, and welding were suspected of causing damage, and acoustic microscopy was used to monitor these processes. Parts which produced suspicious acoustic images were dismantled and destructively sectioned to identify specific physical defects. Correlations between the defects and their acoustic signatures were established. This procedure has provided the basis for several process modifications and improvements which have resulted in acceptable production yields. The SLAM is used as an engineering tool for the detection and characterization of defects and is presently being used routinely to inspect production ferrite components. (ERA citation 12:039437)