Process and device for determining the mass fraction of one constituent of a layer, and effecting the quality control of a composite metal sheet

摘要

A process for controlling the weldability of a sheet (1) of the composite metal sheet type having a layer (7) which is interposed between two metal facing sheets (3,5) and comprises a polymer (8) having a filler of conductive particles (9). This process comprises measuring by means of a signal of given frequency f applied to two electrodes (11, 13) disposed in facing relation to each other, each electrode being in contact with a corresponding metal facing sheet (3,5), the voltage/current phaseshift . phi. due to the resistive and capacitive properties of the composite sheet (1). The response of the composite sheet (1) to this signal corresponds to that of an equivalent parallel RC circuit. Thereafter, the mass fraction of the conductive particles (9) is calculated from the value of &phgr;. By comparing the determined mass fraction with prefixed thresholds, the weldability and the vibration- damping capacity of the composite sheet (1) are evaluated.