Assessing quality of diffusion bonded joints with interlayer using ultrasonic/ultrasound

The aim of the present study is to establish an inspection procedure for assessing the quality of diffusion bonded joints made with an interlayer, non-destructively using ultrasonic method. In order to establish the procedure, bonding between copper and copper is made, with nickel as interlayer, though the bonding does not require any interlayer and no practical applications either. Since Copper and Nickel form isomorphs system and are easily available, this combination was chosen. Moreover, this combination represents many actual combinations which require interlayer and hence the inspection procedure and findings developed based on this system will be Very useful for correlating the quality of bonds made between materials which have practical applications and needs to be bonded with interlayer. The reflection of echo from interface, area fraction bonded and 'C' scan image obtained from ultrasonic 'C' scan show an estimate of the bond quality. The observed parameters were correlated with the destructive test to calibrate the ultrasonic parameters. The mechanism of bonding is determined by the grain growth equation. The bond interface and bonded samples were analysed using optical and scanning electron microscopy (SEM). The chemical composition of the fractured and bonded area is determined using the Energy Dispersive Spectrometry (EDS). It is established that the ultrasonic 'C' scan can be employed for regular inspection of diffusion bonding joints, made with interlayer. (C) 2016 Elsevier B.V. All rights reserved.