The present invention provides a steel sheet or part suitable for enamelling. The steel sheet or part is coated with a coating including polymer in which particles of non-oxide ceramic are homogeneously dispersed. A process for producing an enamelled steel sheet or part which has a reduced firing temperature and reduced time compared with conventional firing temperatures and times is also provided. An enamelled steel sheet or part are also provided.

Method for producing a metal coated steel substrate provided with a coating of a primer composition, comprising applying a layer of the primer composition on the metal coated steel substrate wherein the primer composition comprises basic components selected from the group consisting of CuO, K.sub.20, Li.sub.20, Na.sub.20, Ce0.sub.2 and ZnO; components with intermediate acidity selected from the group consisting of Al.sub.20.sub.3, B.sub.20.sub.3, Cr.sub.20.sub.3, Sn0.sub.2 Sb.sub.20.sub.3 and Fe.sub.20.sub.3; acidic components selected from the group consisting of Mn0.sub.2, Mo0.sub.3, P.sub.20.sub.5, Si0.sub.2, Ti0.sub.2, V.sub.20.sub.5, W0.sub.3 and Zr0.sub.2; wherein all wt. % are drawn on the total primer composition and the total sum of the amounts excluding impurities and after normalization is 100 wt. %, wherein all components are expressed as oxides, wherein the sum of the amounts of Ce0.sub.2+Cr.sub.20.sub.3+CuO+Fe.sub.20.sub.3+Mn0.sub.2+Mo0.sub.3+Sn0.sub.2+Sb.sub.20.sub.3+V.sub.20.sub.5 W0.sub.3 is between about 16.7 and about 48.6 wt. %.

The present invention provides a coated metal member including a metal base and a coat layer made of an amorphous inorganic material formed on the metal base, the coat layer containing pores and carbon particles.

The present invention provides a coated metal member including a metal base and a coat layer made of an amorphous inorganic material formed on the metal base, the coat layer containing pores and carbon particles.

The present invention provides methods for preparing or repairing a chemically-resistant coating such as a porcelain enamel on a metal substrate. One such method involves forming a ground coat on the substrate, cooling the substrate to substantially near ambient temperature, optionally by applying a heat source to cool the substrate slowly, followed by flame-spray depositing a coating material onto the softened ground coat. Then, the substrate is allowed to cool slowly so the chemically-resistant coating can form with less stress. Optionally, an induction coil is used to heat the substrate, both to form the ground coat and to slow the cooling of the substrate. Such methods allow for easier and faster repairs, and even in situ repairs of articles such as chemical reactor vessels, covers, baffles, thermowells, agitators, agitator shafts, pipes, heat exchangers, and storage tanks, as well as white goods such as ovens, stoves, washing machines, driers, in addition to bathtubs, sinks, and shower stalls, in addition to steel girders and steel reinforcing bars. Articles having a chemically-resistant coating also form a part of the invention.

The present invention provides methods for preparing or repairing a chemically-resistant coating such as a porcelain enamel on a metal substrate. One such method involves forming a ground coat on the substrate, cooling the substrate to substantially near ambient temperature, optionally by applying a heat source to cool the substrate slowly, followed by flame-spray depositing a coating material onto the softened ground coat. Then, the substrate is allowed to cool slowly so the chemically-resistant coating can form with less stress. Optionally, an induction coil is used to heat the substrate, both to form the ground coat and to slow the cooling of the substrate. Such methods allow for easier and faster repairs, and even in situ repairs of articles such as chemical reactor vessels, covers, baffles, thermowells, agitators, agitator shafts, pipes, heat exchangers, and storage tanks, as well as white goods such as ovens, stoves, washing machines, driers, in addition to bathtubs, sinks, and shower stalls, in addition to steel girders and steel reinforcing bars. Articles having a chemically-resistant coating also form a part of the invention.

An aluminum member exhibits improved alkali resistance with respect to an anodic oxide coating. The highly alkali-resistant aluminum member includes a material that includes aluminum or an aluminum alloy, an anodic oxide coating that is formed on the surface of the material, and a coating layer that is formed on the anodic oxide coating, and includes a siloxane glass component in a ratio of 90 mass % or more, wherein the coating layer has a thickness of 0.5 to 5.0 m and a coating mass of 0.4 to 5.0 g/m.sup.2.

An aluminum member exhibits improved alkali resistance with respect to an anodic oxide coating. The highly alkali-resistant aluminum member includes a material that includes aluminum or an aluminum alloy, an anodic oxide coating that is formed on the surface of the material, and a coating layer that is formed on the anodic oxide coating, and includes a siloxane glass component in a ratio of 90 mass % or more, wherein the coating layer has a thickness of 0.5 to 5.0 m and a coating mass of 0.4 to 5.0 g/m.sup.2.

Provided are an enamel coating method and apparatus. The enamel coating method includes (a) preprocessing a surface of the metal tube by feeding the metal tube into a preprocessing chamber by an in-feed conveyor; (b) coating the surface of the metal tube with an enamel glaze supplied from an enamel glaze supply nozzle provided inside a coating chamber by feeding the preprocessed metal tube into the coating chamber; and (c) firing the coated metal tube by feeding the coated metal tube into a firing chamber, wherein the (b) coating includes spraying air toward the metal tube by an air spray nozzle provided inside the coating chamber.

Provided are an enamel coating method and apparatus. The enamel coating method includes (a) preprocessing a surface of the metal tube by feeding the metal tube into a preprocessing chamber by an in-feed conveyor; (b) coating the surface of the metal tube with an enamel glaze supplied from an enamel glaze supply nozzle provided inside a coating chamber by feeding the preprocessed metal tube into the coating chamber; and (c) firing the coated metal tube by feeding the coated metal tube into a firing chamber, wherein the (b) coating includes spraying air toward the metal tube by an air spray nozzle provided inside the coating chamber.