Method for determining the porosity of layers and use of the method to determine adhesive tensile strength

摘要

The method involves generating a pressure wave i.e. shock wave, at a layer surface (4) and/or a substrate surface (3) by a mechanical excitation or laser pulse, where the surfaces are anticipated on a heat-insulating layer (2). A reflected and/or transmitted portion of the pressure wave is detected by a piezoelectric sensor (5). The portion of the shock wave is detected by an interferometer or surface receiver and a streak camera. A spatial and/or temporal detection of a detected pressure wave component is carried out. A pressure wave signal is generated from the component.