| abstract |
A method and apparatus are provided for treating the surface of a metal body through phase transformation, ion implantation, and/or diffusion and to form new phases of metallic materials. The method and apparatus have been shown to be particularly useful to improve the hardness and corrosion resistance of ferrous and non-ferrous metals. Generally, the method comprises irradiating a portion of the metal body ( 18 ) with a laser ( 12 ), and directing a stream of gas ( 22 ) onto the same portion of the metal body simultaneously with and preferably for a duration after the laser is turned off. Preferably, the laser ( 12 ) is a carbon dioxide laser operated in a pulsed mode to control heating of the metal ( 18 ). The gas ( 22 ) is preferably carbon dioxide to quickly cool the metal when the laser is off, and to provide carbon atoms for deposition onto the body. The entire process may be carried out in an environment at atmospheric pressure, obviating the need for a vacuum chamber or pressure controlled furnace or similar apparatus. After treatment, the hardness and corrosion resistance of at least a ferrous body are dramatically increased. Advantageously, both sides of a thin metal body, such as a metal tube, may be simultaneously treated. Further, a new, highly oxygenated, hard and extremely corrosion resistant metal phase may be created. |