Aqueous compositions useful as pretreatments prior to painting to reduce the formation of rust in the uncoated condition. The compositions consist essentially of water, a trivalent chromium compound with the formula Cr(H.sub.xPO.sub.4).sub.3, where x can be 1.5 or 2, a silica compound, and optionally hydrogen peroxide. The composition may have a pH between about 1 and about 4. A process for treating a metal surface includes contacting the surface with such aqueous compositions. The compositions and the processes provide benefits in comparison to the zinc phosphate metal pretreatment thought to be the standard in the industry.

The invention relates to a multiple-step method for the corrosion-protective pretreatment of components, said pretreatment being at least partially produced from a metal material predominantly consisting of at least one of the elements iron zinc and/or aluminium, according to which the components are first brought into contact with an acid aqueous composition (A) containing water-soluble compounds of the elements Zr and/or Ti and then with an acid aqueous composition (B) containing phosphate ions and an accelerator. The method is particularly suitable for the pretreatment before an electrocoating.

Provided is a coating material including barium oxide and/or barium hydroxide, and a metal sulfate, wherein a soluble amount of the metal sulfate in 100 g of water is 0.5 g or more at 5 C.

Provided is a coating material including barium oxide and/or barium hydroxide, and a metal sulfate, wherein a soluble amount of the metal sulfate in 100 g of water is 0.5 g or more at 5 C.

An aqueous conversion coating solution comprises a trivalent chromium compound, a zirconate compound, and a dye compound. The trivalent chromium compound can comprise trivalent chromium compounds such as trivalent chromium sulfate. The dye compound can comprise an azo dye, a chromium complex dye, an anthraquinoid dye, and/or a methine dye. The zirconate compound can comprise alkali metal hexafluorozirconate compounds. The conversion coating solution can comprise a phosphorous compound such as an organic amino-phosphonic acid compound. The conversion coating solution can be formed by mixing a dye additive containing the dye with a trivalent chromium conversion coating solution that does not contain a dye. The conversion coating solution can be used to treat metal substrates comprising aluminum, magnesium, and/or zinc.

An aqueous conversion coating solution comprises a trivalent chromium compound, a zirconate compound, and a dye compound. The trivalent chromium compound can comprise trivalent chromium compounds such as trivalent chromium sulfate. The dye compound can comprise an azo dye, a chromium complex dye, an anthraquinoid dye, and/or a methine dye. The zirconate compound can comprise alkali metal hexafluorozirconate compounds. The conversion coating solution can comprise a phosphorous compound such as an organic amino-phosphonic acid compound. The conversion coating solution can be formed by mixing a dye additive containing the dye with a trivalent chromium conversion coating solution that does not contain a dye. The conversion coating solution can be used to treat metal substrates comprising aluminum, magnesium, and/or zinc.

A steel piston for an internal combustion engine includes an amorphous phosphate layer in at least one region thereof. On account of this layer the adhesion of an antifriction coating is improved.

A method of preserving a nuclear fuel includes exposing a surface of a fuel element comprising aluminum to a phosphorus-containing acid and reacting the phosphorus-containing acid with the aluminum to form aluminum phosphate (AlPO.sub.4). A nuclear fuel element includes a nuclear fuel and a shell surrounding the nuclear fuel. The shell comprises aluminum phosphate.

An aqueous conversion coating solution comprises a trivalent chromium compound, a zirconate compound, and a dye compound. The trivalent chromium compound can comprise trivalent chromium compounds such as trivalent chromium sulfate. The dye compound can comprise an azo dye, a chromium complex dye, an anthraquinoid dye, and/or a methine dye. The zirconate compound can comprise alkali metal hexafluorozirconate compounds. The conversion coating solution can comprise a phosphorous compound such as an organic amino-phosphonic acid compound. The conversion coating solution can be formed by mixing a dye additive containing the dye with a trivalent chromium conversion coating solution that does not contain a dye. The conversion coating solution can be used to treat metal substrates comprising aluminum, magnesium, and/or zinc.

An aqueous conversion coating solution comprises a trivalent chromium compound, a zirconate compound, and a dye compound. The trivalent chromium compound can comprise trivalent chromium compounds such as trivalent chromium sulfate. The dye compound can comprise an azo dye, a chromium complex dye, an anthraquinoid dye, and/or a methine dye. The zirconate compound can comprise alkali metal hexafluorozirconate compounds. The conversion coating solution can comprise a phosphorous compound such as an organic amino-phosphonic acid compound. The conversion coating solution can be formed by mixing a dye additive containing the dye with a trivalent chromium conversion coating solution that does not contain a dye. The conversion coating solution can be used to treat metal substrates comprising aluminum, magnesium, and/or zinc.