Measurement of interface strength by the modified laser spallation technique. II. Applications to metal/ceramic interfaces

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Abstract
Part II of this series presents applications of the modified laser spallation technique to several interface systems. For metal/pyrolytic graphite (PG) interfaces, the tensile strength of interfaces between 3‐μm‐thick coatings of Sn, Sb, Cu, Nb, Al, and Cr on a PG substrate were measured in units of MPa to be 18.53, 5.99, 15.46, 41.16, 16.53, and 15.47, respectively. It was found that the interface fracture mechanisms depend on the elastic‐plastic properties of the coatings, but are independent of the interface strength. Interface strength between diamond, SnO2, and Nb coatings on polycrystalline alumina substrates were measured to be ≳140, 320, and 280 MPa, respectively. It is shown that the brittle fracture takes place at the interface upon spalling even if the plastic deformation exists within the coatings.