Onset of selective laser flash sintering in 8YSZ

Flash sintering of ceramics is distinguished by rapid sintering during simultaneous application of electric field and heat. Previous studies of flash sintering have been conducted in furnace environments, where sample temperatures are approximately uniform. Selective Laser Flash Sintering (SLFS) combines the highly dynamic heating of a scanning laser with an electric field to selectively initiate flash sintering, only where the laser heats the ceramic. The evidence that flash sintering has been initiated is a measurable increase in current through the sample. Our results show that flash sintering can be initiated by laser heating, as evidenced by measured current in 8YSZ. At low-to-moderate laser energies and applied electric field, measured current rises slightly when the laser is scanned completely across the specimen from one electrode to the other. Microstructures for these samples show that powder consolidation is minimal in this regime, and thus the measured current is likely due to the formation and growth of necks between powder particles rather than densification. At higher laser energies, current rises steeply and microstructures show significant consolidation and localized melting. The SLFS process is targeted at the lower laser energy region to reduce the risk of cracking. Selective Laser Flash Sintering uses low to moderate laser energies and controlled current to form and grow strong necks between ceramic particles without using polymer binders. Using the combination of electric field and selective heating, SLFS has promise as an additive manufacturing process for direct sintering of ceramic preforms.Mechanical Engineerin