Subsurface damage characteristics of fused quartz glass in shear-thickening polishing

Abstract Fused quartz glass is extensively utilized in both civil and military applications due to its exceptional mechanical and optical properties. Although shear-thickening polishing (STP) method has been validated as effective for polishing hard and brittle materials like fused quartz glass, the mechanical properties and material removal characteristics of the subsurface damage in polished workpieces have not been thoroughly investigated. In this study, the depth of the crack layer in fused quartz glass before polishing was measured using the oblique polishing method. Nanoindentation and nano-scratch experiments were conducted to analyze the impact of subsurface damage on the mechanical properties and material removal characteristics of the workpieces. Additionally, the study explores the influence of polishing angle and abrasive type on the surface roughness ( S a ) and micro-scratches of fused quartz glass. The findings indicate that using 80 nm SiO₂ abrasives achieves the lowest S a , with a S a of 2.23 nm at a polishing angle of 13°. However, none of the three polishing angles were able to prevent the formation of micro-scratches in the hydrolyzed layer, and the workpiece surface exhibited crater as the angle increased to 18°. On the other hand, polishing with 500 nm CeO₂ abrasives at angles of 8°, 13°, and 18° resulted in higher S a . Nonetheless, etching experiments demonstrated that CeO₂ abrasives reduce micro-scratch formation within the hydrolyzed layer, allowing for a more homogeneous surface quality across different polishing angles. This study provides both theoretical and experimental foundations for characterizing subsurface damage in fused quartz glass following STP.