Measurement and Control of Subsurface Damages

Subsurface damage is easily induced during the processing of hard and brittle materials, and has a significant impact on the lifetime, secular stability, coating quality, transmission performance, and laser-induced damage threshold of a machined part. To realize high quality manufacturing, it is necessary to detect the subsurface damages and remove them in the subsequent processes. However, subsurface damage is rather difficult to detect directly since it is often covered with a smearing layer. This chapter introduces the formation mechanism, measurement methods, and control strategies of subsurface damage. Firstly, the theoretical model and mechanism of subsurface damage formation based on the indentation fracture mechanics of hard and brittle material is discussed. Then, the detection methods of subsurface damage including both destructive and non-destructive are reviewed, and their principles, characteristics, research progresses, and applications are illustrated. In comparison, destructive methods can provide quantitative and reliable information; non-destructive methods have the advantages of fast and convenient operation and can realize in-process detection to meet the growing demand on high quality manufacturing. Finally, the control strategies for subsurface damage are summarized and the future development trend is prospected.