Influence of micromachining on strength degradation of silicon nitride

In recent years, much research has been devoted to the development of micromachining technologies for ceramic materials. This paper investigates two kinds of machining methods capable of dimpling a ceramic surface with highly controlled precision: abrasive jet machining (AJM) and laser beam machining (LBM). A comparative discussion of the geometrical and topographical characteristics of microdimples machined on to an Si3N4 surface is first presented, followed by the main topic, an examination of the effects of micromachining on the strength degradation of ceramics. Dimpling by LBM cannot be prevented from forming a sharp edge around the dimple bottom face, which may degrade the flexural strength of the ceramic considerably. In contrast, the AJM dimple has a smooth-faced rounded shape, and only negligible deterioration of the strength takes place.