Abstract: 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.

Abstract: 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 softened ground coat on the substrate by heating to or maintaining an elevated temperature, 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 softened 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. Articles having a chemically-resistant coating also form a part of the invention.

Abstract: A process for preparing a chemically resistant coating in which a substrate is sequentially contacted with a ground coat, fired, contacted with an intermediate coat, fired, and contacted with a cover coat and fired. The intermediate coat is comprised of a minor amount of inorganic fiber which has a softening point in excess of 950 degrees Centigrade, an average length of from about 100 to about 750 microns, an average diameter of from about 515 microns, and an average aspect ratio of from about 10:1 to about 75:1.

Abstract: A process for preparing a chemically resistant coating in which a substrate is sequentially contacted with a ground coat, fired, contacted with an intermediate coat, fired, and contacted with a cover coat and fired. The intermediate coat is comprised of a minor amount of inorganic fiber which has a softening point in excess of 950 degrees Centigrade, an average length of from about 100 to about 750 microns, an average diameter of from about .?.515.!. .Iadd.5-15 .Iaddend.microns, and an average aspect ratio of from about 10:1 to about 75:1.