Abstract: A chemically and thermally stable chromate free aqueous liquid treatment for metals, especially aluminum, that imparts corrosion resistance as good as that from conventional chromate containing treatments, contains water and:(A) a component selected from the group consisting of H.sub.2 TiF.sub.6, H.sub.2 ZrF.sub.6, H.sub.2 HfF.sub.6, H.sub.2 SiF.sub.6, H.sub.2 GeF.sub.6, H.sub.2 SnF.sub.6, HBF.sub.

Abstract: Heating an aqueous mixture of a fluoroacid such as H.sub.2 TiF.sub.6 and an oxide, hydroxide, and/or carbonate such as silica produces a clear mixture with long term stability against settling of any solid phase, even when the oxide, hydroxide, or carbonate phase before heating was a dispersed solid with sufficiently large particles to scatter light and make the mixture before heating cloudy. The clear mixture produced by heating can either be mixed with water soluble and/or water dispersible polymers, for example with dispersed polymers of the diglycidyl ether of bisphenol-A or an acrylic acid polymer, or with soluble hexavalent and/or trivalent chromium, to produce a composition that improves the corrosion resistance of metals treated with the composition, especially after subsequent painting.

Abstract: Heating an aqueous mixture of a fluoroacid such as H.sub.2 TiF.sub.6 and an oxide, hydroxide, and/or carbonate such as silica produces a clear mixture with long term stability against settling of any solid phase, even when the oxide, hydroxide, or carbonate phase before heating was a dispersed solid with sufficiently large particles to scatter light and make the mixture before heating cloudy. The clear mixture produced by heating can either be mixed e with water soluble and/or water dispersible polymers that are polyhydroxyalkylamino- substituted polymers and/or copolymers of p-vinyl phenol, or with soluble hexavalent and/or trivalent chromium, to produce a composition that improves the corrosion resistance of metals treated with the composition, especially after subsequent painting.

Abstract: An exceptionally effective chromium free corrosion protective surface treatment composition for aluminum and its alloys is an aqueous acidic liquid comprising water and: (A) from about 0.8 to about 1.2 w/o of H.sub.2 ZrF.sub.6 ; (B) from about 0.08 to about 0.12 w/o of dispersed silica; (C) from about 0.08 to about 0.12 w/o of a water soluble or dispersible polymer of 3-(N-methyl-N-2-hydroxyethylaminomethyl)-4-hydroxystyrene; and (D) from 0.10 - 0.15 w/o of 1-propoxy-2-propanol. The surface to be treated is contacted with the composition and then dried without rinsing. A conventional organic coating may advantageously be applied over the surface produced by this treatment.

Abstract: An aqueous acidic treating solution and process for forming a chromium-containing passivate coating on the surface of zinc or zinc-aluminum alloys to enhance bare corrosion resistance and inhibit discoloration thereof upon exposure to ambient environments. The treating solution contains as its essential constituents, chromium ions, nitrate ions, phosphate ions.

Abstract: An aqueous acidic composition provides improved corrosion resistance to a metal, e.g., ferrous, zinc or aluminum surface upon contact. The composition contains dissolved hafnium and/or zirconium, fluoride, preferably a vegetable tannin compound, and optionally phosphate ions.

Abstract: Disclosed is a process for cleaning and treating an aluminum surface to improve the corrosion resistance and paint receptivity of the surface. The treating composition is an aqueous vegetable tannin composition, and the cleaning composition is an aqueous acidic fluoride containing cleaner.

Abstract: Disclosed are a composition and process useful for the treatment of an aluminum surface comprising contacting the surface with an aqueous solution containing at least 0.000025 weight percent of a vegetable tannin, which solution exhibits a pH of at least 3. Best results can be obtained via a two-stage tanin treatment in which the treating solution of the first stage also contains titanium and fluoride in dissolved form.