Ceramics bonded to metal joints may develop flaws due to residual stresses that develop during the cooling process. Scanning acoustic microscopy is a well-recognized tool for charactering elastic properties and can be applied to materials with elastic discontinuities such as debonding at the ceramic/metal interface. Acoustic information is obtained using the V (z) curve method, which measures the output voltage signal of a transducer as a function of the distance between the transducer and a specimen. The velocity of the surface acoustic waves, V_saw, can be calculated from the V (z) curve. In this work, a simulation of the V (z) curve was updated. The pupil-function splitting method was combined with the angular-spectrum approach of V (z) theory in order to obtain the V (z) curve for interfaces between different materials. The V_saw values at the interface were calculated from the simulated V (z) curve. A series of experiments were performed to measure the V_saw values at the interface of a Si₃N₄/Cu joint using the scanning acoustic microscope. By comparing the measured values with the calculated values, the reliability of this simulation was verified. The simulation can be used to test the boundary conditions of bimaterial samples.

Date Published: 1 April 2015
PDF: 14 pages
Proc. SPIE 9437, Structural Health Monitoring and Inspection of Advanced Materials, Aerospace, and Civil Infrastructure 2015, 943703 (1 April 2015); doi: 10.1117/12.2084485

Published in SPIE Proceedings Vol. 9437:
Structural Health Monitoring and Inspection of Advanced Materials, Aerospace, and Civil Infrastructure 2015
Peter J. Shull, Editor(s)