Generation and Reduction of Residual Stress in Ceramic/Metal Joints(Mechanics, Strength & Structural Design)

概要

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Methods for crack prevention during ceramic/metal joining are suggested based on the results of a detailed mechanical analysis. The characteristics of the distribution of residual stress produced during solid-state bonding of Si_3N_4 to steel is elucidated based on the results of a thermal elastic-plastic analysis. The principal factor which promotes crack formation is the bending moment which acts on the ceramic substrate ; this is caused by the difference in thermal expansivities of the metal and ceramic substrates. It is suggested that this bending moment should be minimised in order to prevent crack formation in the ceramic substrate. The validity of this approach has been confirmed based on detailed calculations. In addition, the effectiveness of laboratory test specimen designs for measuring the bonded strength of ceramic/metal joints are elucidated, and geometries which facilitate easy specimen manufacture produce lower bending moment and the maximum stress value perpendicular to bonded line than in actual fabricating situations.
大阪大学の論文