Abstract: A corrosion inhibiting material comprises a water soluble glass of the calcium oxide/phosphorus pentoxide type which, when in contact with water, releases phosphate ions which inhibit corrosion of adjacent metal surfaces. The glass solubility may be controlled by the incorporation of one or more glass modifying oxides. Advantageously the glass is finely ground and then dispersed in a resin carrier to form a primer paint formulation.The preferred glass forming region of a typical calcium oxide/phosphorus pentoxide system is illustrated in the ternary phase/composition diagram of FIG. 1 of the accompanying drawings.

Abstract: Corrosion inhibiting compositions for ferrous and non-ferrous metal surfaces comprise one or more crystalline polyphosphates, e.g. a strontium tripolyphosphate. The compositions have particular application in the preparation of corrosion inhibiting paint compositions. A method of preparation of the polyphosphate materials is described.

Abstract: A corrosion inhibiting paint comprises a resin vehicle containing a water soluble glass which, on dissolution in water, releases corrosion inhibiting materials. The glass itself, or the combination of the glass and the paint, are so constituted that conditions of low acidity, i.e. above pH 4.0, are presented to a metal surface to which the print is applied. The glass may contain phosphorus pentoxide as the glass forming oxide together with one or more Group IIA or IIB metal oxides as the glass modifying oxide or oxides.