An approach to a surface composition analysis of magnetic coatings

The uppermost pigment particles of a magnetic coating are covered by a thin layer of organic material. Compared to the bulk of the binder formulation, this layer is highly inhomogeneous. At the phase boundaries to air and pigments, concentration gradients are observed which influence the mechanical behavior of the coating, especially when changes take place that are effected by time and climatic conditions. By applying ESCA and SIMS techniques, important information on this surface layer could be obtained concerning: (1) the thickness of this layer, its distribution, and its differences between magnetic and nonmagnetic particles; (2) the incompatibilities and varying distribution of the components of a given formulation; and (3) the mobility of low molecular additives (alteration during changes of climatic conditions or transfer of substances onto contacting bodies)