安定化ジルコニアのレーザ溶接 : セラミックスのレーザ溶接(第3報)

概要

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A CO_2 laser has been applied to fusion-welding and surface-melting of sintered zirconia ceramics fully stabilized with CaO, MgO or Y_2O_3,and chemical compositions and preheating temperature required for preventing cracks have been studied. The results obtained are summarized as follows : (1) Although macroscopic crack in the base material is prevented at preheating temperatures higher than 1200℃, intergranular microcrack has been developed in the fusion zone in the zirconia ceramics other than CaO-stabilized zirconia containing 1.7%SiO_2,1%MgO and 0.7%Al_2O_3 as impurities. A low melting point compound of SiO_2-MgO-CaO-Al_2O_3 formed at grain boundary plays an important role to release the shrinkage stress in the fusion zone, producing sound bead. (2) The weld joint strength is decreased by porosities grown at HAZ at lower welding speeds, and at the bead center at higher welding speeds. As the welding speed becomes faster, both porosities are suppressed to grow, increasing weld joint efficiency up to 85-90%. Laser-melted surface layer has shown almost no porosities, providing bending strength and a Weibull modulus which are equal to or somewhat larger than those of the base material.
社団法人溶接学会の論文
1986-05-05