CHARACTERIZATION OF PURE OR COATED METAL-SURFACES WITH STREAMING POTENTIAL MEASUREMENTS

In the field of corrosion prevention, the characterisation of metal su rfaces is useful to obtain information about the necessary preparation of the surface and about the quality of thin coatings of coupling and protective agents. Electrokinetic measurements can be used to determi ne the properties of modified polymer surfaces, metal sheets, and diff erent surface preparations. However, it was necessary first to create special conditions for measuring the streaming potential, such as elec trical isolation of the sample sheets together with the use of inert s ystems, as shown by the example of aluminium. According to the usual p rocedure the metal was first coated with a thin layer of a coupling ag ent. The effect of this adhesive agent depends on the degree of its ad sorption by the metal surface. The quality of this layer can be charac terised by streaming potential measurements, which can show the degree of coverage, the adhesive strength of the coated layer, and the effec tive chemical properties of the treated surface. These results were co nfirmed by wetting measurements. The production of surfaces which allo w us to couple a coating varnish to the adhesive agent in good quality was demonstrated.