Visualization of Subsurface Damage in Silicon Nitride from Grinding by a Plasma Etching and Dye Impregnation Method

Abstract

In order to develop a spatial morphology model of subsurface damage in grinding of hot‐pressed silicon nitride, the damage has been investigated using visualization techniques, plasma etching, and a dye impregnation method developed in our previous work. The plasma etching technique resolved subsurface damage formed by a single abrasive grit on a grinding wheel surface. The damage consists of a grain‐released area, which has an overall shape approximately that of a blade like a willow leaf, and a series of bow‐like crack series that appear repeatedly along the grit‐scratching direction. By coupling these results with previous conclusions about the geometry of the strength‐controlling cracks in a flexural test specimen, we were able to develop a spatial model of subsurface damage morphology. The most distinctive feature of the model is the absence of a transverse crack, whose presence is commonly accepted in existing work on subsurface damage by grinding. The applicability of the model to the fracture behavior of a longitudinally ground flexural test specimen was verified by fractography and dye impregnation.

Methods for Detection of Subsurface Damage: A Review

“…However, since the width of a subsurface crack is normally less than one micron, the slurry is prevented from wetting the tip of the crack because of the surface tension of the slurry. Therefore, the measurement result of SSD is typically smaller than the real depth of the subsurface crack, which is also a problem with the dye penetration method [13,101].…”

“…Hard and brittle materials are widely used because of their excellent physical and mechanical properties, such as high hardness and strength at elevated temperatures, wear and corrosion resistances, etc. Among hard and brittle materials, single crystalline silicon is the predominant substrate material for integrated circuits (IC) [1][2][3][4][5]; optical glasses are for optical windows and lens [6][7][8][9][10][11] as well as high-power laser components [12]; ceramic materials are commonly used for bearings, cutting tools and machine parts [13][14][15][16]. However, these materials are also difficult to machine due to their hard and brittle nature.…”