GB586132A - Protecting metal surfaces against corrosion and corrosion fatigue by means of inorganic coatings - Google Patents

Abstract

Protecting metallic surfaces against corrosion by applying thereto one or more coatings, free from ammonium chloride, the ingredients of which first interact to form zinc chloride, and then with zinc oxide present as an ingredient, form a zinc oxychloride cement on the said surfaces. The zinc chloride may be formed by reacting zinc and zinc oxide with certain chloride solutions (e.g., the chlorides of lead, magnesium, manganese, barium, strontium and calcium). Inhibitors of corrosion, such as zinc dust, and lead powder may be added, as may also compounds of copper, mercury, arsenic or other poisonous elements or complex organic compounds to discourage the growth of living organisms. Pigments such as iron oxides, china clay, red lead and ferri-cyanides may be present and also oxidizing agents such as red lead, lead chromate and ferric oxide. If rust is present on the surface to be coated a wash of tartar emetic or other antimony salt is applied first, while if oil or grease is present, wetting agents of the sulphated alcohol type may be added to the coating. A typical single coating consists of zinc dust (containing zinc oxide), lead chloride, china clay and iron oxide, and a typical two-coat composition consists of a first coat of lead chromate, barium chloride and water, followed by zinc dust (containing zinc oxide), china clay, potassium chromate and water. Numerous other examples of such coatings are given. Specification 149,365, [Class 95], is referred to.