METHOD FOR ACTIVATING SURFACE OF METAL MEMBER

A method for activating the surface of a metal member, that is, activating a passivated coating film present in the surface of a high alloy steel member, which makes it difficult to effect a diffusion penetration treatment such as a gas nitriding method or a gas carburizing method for forming a nitrided layer, a carburized layer or a carburized and nitrided layer on the surface of a metal member, which method comprises using a gas generally used in a gas heat treatment, forming an HCN gas in a furnace through the utilization of a catalytic action of the surface of a metal to be treated and/or a material of the furnace, to thereby activate the passivated surface of the high alloy steel member. The above method is free from disadvantages such as the formation of deposits in a furnace, the wear of the wall surface in a furnace, and the necessity of the treatment for converting an exhaust gas to a harmless material, which have been problems in the case of a conventional activation treatment using a halogen compound, and thus can be advantageously used as a method for activating the surface of a metal member which is useful as a pretreatment for a diffusion penetration treatment.