RESUMO
Ultrasonic-assisted glass molding (UGM) has recently gained a promising start in fast replication of tailored functional structures onto glasses; however, the underlying mechanisms of the unique thermomechanical and micro-filling behaviors of glasses in UGM remain largely unrevealed. This study presents a full demonstration and elucidation of the ultrasonic-induced thermal/tribological effects on viscoelastic responses and filling capacity of the typical optical glass L-BAL42. First, conventional precision glass molding (PGM) and UGM experiments with partial-filling settings are implemented, whereby glass arrays with surface protrusions of varied depths (460-780 µm) are directly formed. Subsequently, the molding force, forming time and filling depth of the glass under varying pressing speeds/loads are comparatively evaluated. Furthermore, experimental quantifications of ultrasonic-induced heat increment and friction reduction are performed to account for the differentiated molding effects in UGM and PGM. The results indicate that compared with PGM, the molding force and forming time in UGM are greatly reduced, while the average filling depth of the UGM-formed glass array is effectively improved. This overall enhancement can be attributed to the ultrasonic-induced thermal softening, friction reduction and stress superposition effects, among which the thermal contribution is dominant. The findings in this study will provide new references for ultrasonic-assisted precision molding of glass-based micro/meso components.
