Diffusion bonding (DB)

as a solid state welding

has been increasingly applied in aeronautical and space industries. The defects induced in thick DB plate are much more difficult to be found out by conventional ultrasonic techniques because of their characteristics of kiss-bonding

small-size and distribution and high ultrasonic attenuation. A new ultrasonic imaging technique

which is based on non-linear ultrasonic (NLU) components of the received signals resulted from diffusion bonding interface

is developed into nondestructive evaluation (NDE) of thick diffusion bonded plate. The experimental results show the powerful ability to the NDE of thick plate diffusion bonds by using the NLU visual method. The maximum thickness of diffusion bonding is up to 70mm.