Mechanism of huge void generation in laser-melted Al2O3

• Published in: Optics and laser technology Vol. 75; pp. 13 - 15
• Main Authors: Honma, Takuya, Tatami, Junichi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2015
• Subjects: Al2O3 sintered ceramic; Aluminum oxide; Capillarity; Formations; Laser melting; Lasers; Metal sealing; Niobium; Sealing; Void formation; Voids; Wire; Void formation; Al2O3 sintered ceramic; Metal sealing; Laser melting
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2015.06.012

The sealing of sintered ceramics with metal often results in the formation of huge voids that reduce the strength of the final structure. This study therefore investigates the mechanism of void formation during Nb-sealing of an Al2O3 capillary using Nd:YAG laser irradiation. It is found that during the initial stages of cooling the outer surface of the Al2O3 capillary solidifies rapidly, but the Nb wire used as the heat source remains at a higher temperature for longer. This causes any gases emitted from the sealing section at the time of melting to be constrained within the capillary, which eventually leads to the formation of huge voids. •We studied Nb-sealing of Al2O3 capillary using Nd:YAG laser irradiation.•We studied mechanism of void formation inside Al2O3 melted by laser irradiation.•Huge voids attributed to gases emitted from the sealing section.•Outer surface of melted Al2O3 solidified quite quickly during cooling.•Gases emitted cannot reach exterior of melted Al2O3 by solidification quite quickly.