CO₂ Laser Welding of Ceramics (Report 2)

Weld Joint Strength of Mullite Ceramics

Abstract

Mechanical strength of laser-welded mullite ceramics with 48wt% and 59wt% Al₂O₃ has been estimated by a three-point bending test. Resistances to thermal shock and thermal cycle have also been discussed. Results obtained are summerized as follows:
(1) In 48 wt% Al₂O₃, strength of weld joint decreases with increasing number of blowhole which tends to appear adjacent to the fusion boundary due to high viscosity of the molten material. Alumina filler, which decreases the viscosity of the molten material, can enhance the joint efficiency up to 100%.
(2) In 59 wt% Al₂O₃, 100% of joint efficiency is obtainable in root bend test. However, the joint efficiency in face bending is not as high as 50% due to the weld defect in the bead surface. Filler material increases the joint efficiency by forming reinforcement.
(3) Resistances to thermal shock and thermal cycle of weld joint are as high as those of the base materials.