To provide a boronization method for performing impregnation and diffusion of boron (B) into a surface of a metal product by a relatively simple method in a short period of time, and by a method for easily adjusting the hardness depth.

An ejection powder containing boron components, for example, boron carbide (B4C) is ejected at the ejection speed of ≥80 m/sec., or with the ejection pressure of ≥0.2 MPa to the surface of a metal product to be treated and collides with the surface of the metal product. The speed of the collided ejected powder is changed before and after the collision, and boron carbide (B4C) is heated by the surface of the metal product with the energy. Thus, boron (B) as a component of boron carbide (B4C) is subjected to the activated adsorption to the surface of the metal product and subjected to impregnation and diffusion to deposit a layer of boride such as FeB, Fe2B, Co2B and TiB2.

COPYRIGHT: (C)2008,JPO&INPIT