Joule Heating Line and Point AE Sources and the Adhesion of Thin Metal Films

    Published: Jan 1991

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    This paper describes a novel approach for generating line and point sources of ultrasound from a thin metal film attached to an insulating substrate. Both line and point sources are generated by a transient, electrical Joule heating of a long- and a short section of the thin film of narrow width, respectively. It is shown that the line and point sources are of dipolar type. By deconvolving the detected ultrasonic signals it is found that a current pulse of short duration generates a step source with risetime approximately equal to that of an input power pulse while a current pulse of long duration produces a linear ramp source resembling the temporal behavior of the temperature rise in the heated thin film. It is also shown that the failure of the film can be detected in the generated ultrasonic signals as well as in the measured electrical resistance of the film. By suitably processing these signals, information on the adhesion strength of the film to its substrate can be found.


    Quantitative AE, thermoelastic source, thermoelastic generation, point source, line source, Green's functions, thin-film testing, film adhesive strength, metal coatings

    Author Information:

    Kim, KY
    Senior Research Associateprofessor, Cornell University in Ithaca, New York,

    Sachse, W
    Senior Research Associateprofessor, Cornell University in Ithaca, New York,

    Committee/Subcommittee: E07.04

    DOI: 10.1520/STP19084S

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