Cermet tool and process for producing the same

Abstract

A cermet tool and process for making the same is disclosed. The cermet tool has a surface coating layer which exhibits a function equivalent to or higher than a hard coating layer of a conventional cermet tool. The tool is economical to produce since no additional step such as a gas phase film forming method is necessary for the formation of the surface coating layer. The surface coating layer has essentially the same hard phase composition as the interior main body part, but the weight content of the binder metallic phase metallic element component is smaller than the average weight content of the binder metallic phase metallic element component through out the cermet (or the weight content in the main body part). This surface coating layer is formed on the surface outermost part of the cermet body. Because the surface coating layer has a content of the binder metallic phase smaller than that in the main body part, it has a hardness higher than the main body part. As a result, the wear resistance of the tool is improved. Furthermore, the surface coating layer is formed by modifying the surface of the cermet itself without employing another step such as a gas phase film forming method.