METAL SURFACE SCALE CONDITIONING

摘要

Methods and systems are provided for treating oxide scale on the surface of a metal object. In one embodiment, a system temperature control apparatus controls the temperature of metal object's surface to an application temperature below the Leidenfrost temperature point of an alkali metal hydroxide aqueous conditioning solution. An application apparatus wets the metal object's surface at the controlled temperature with a thin layer of the solution that engages the oxide scale, and a heating apparatus heats the wetted surface to a final conditioning temperature above a melting point of the alkali metal hydroxide by an additional value selected to effect conditioning of the oxide scale at a reasonable but not excessive rate by the melting alkali metal hydroxide reacting with the oxide scale. The system terminates additional conditioning to prevent creation of additional oxide scale beyond the conditioned depth.

主权项

1. A method of conditioning the surface of a metal object by treating oxide scale on the surface of the metal object, comprising:
controlling a temperature of a metal object's surface to an application temperature below a Leidenfrost temperature point and below a melting point of 170° C. (338° F.) of an essentially anhydrous alkali metal hydroxide blend within an aqueous conditioning solution, the metal object's surface comprising an oxide scale having an initial depth from the metal object's surface; wetting the metal object's surface at the controlled temperature with a thin layer of the aqueous conditioning solution, the aqueous conditioning solution thin layer engaging the oxide scale; heating the wetted metal object surface in an oxygen-containing atmosphere to a final conditioning temperature that is above the melting point of the essentially anhydrous alkali metal hydroxide blend by an additional value selected from a range of zero to 262° F. (145° C.); in response to the heating the wetted metal object surface in the oxygen-containing atmosphere to the final conditioning temperature, evaporating water in the aqueous conditioning solution and melting the essentially anhydrous alkali metal hydroxide blend on the metal object's surface at the final conditioning temperature; the melted alkali metal hydroxide blend treating the metal object's surface by reacting with the engaged oxide scale and thereby reducing the oxide scale on the metal object's surface that is less than the initial depth; and terminating the treating of the metal object's surface at a conditioned depth from the metal object's surface and preventing treating of the oxide scale beyond the conditioned depth, wherein the conditioned depth is less than the initial depth, by cooling the metal object's surface to a temperature below the final conditioning temperature at an end of a conditioning time period that is no more than thirty seconds after the water is evaporated and the melted alkali metal hydroxide blend reacts with the engaged oxide scale, wherein the conditioning time period is selected as a function of a material parameter and a dimension parameter of the metal object to produce the specified extent of conditioning of the scale on the metal object's surface at the final conditioning temperature; and the terminating of the treating preventing a creation of an additional oxide scale beyond the conditioned depth from the metal object's surface by the melted alkali metal hydroxide reacting with the engaged oxide scale.