PREPARATION METHOD OF TUNGSTEN CARBIDE SINTERED BODY FOR FRICTION STIR WELDING TOOL

摘要

The present invention relates to a preparation method of a tungsten carbide sintered body for a friction stir welding tool used in a friction stir welding tool of a high melting point material such as steel, titanium and the like or a dissimilar material such as aluminum, magnesium-steel, titanium and the like using pulsed current activation through a discharge plasma sintering apparatus. The preparation method comprises the following steps: filling a tungsten carbide (WC) powder in a mold made of a graphite material; mounting the mold filled with tungsten carbide powder in a chamber of a discharge plasma sintering apparatus; making a vacuum inside of the chamber; molding the tungsten carbide powder while maintaining a constant pressure inside the mold and increasing the temperature according to a set heat increase pattern until the temperature reaches a final target temperature; and cooling the inside of the chamber while maintaining the pressure pressurized in the mold after the molding step. According to the preparation method of a tungsten carbide sintered body for a friction stir welding tool, it is possible to obtain a high relative density of 99.5% or higher, and to prepare a uniform sintered body having a homogeneous tissue with little particle growth, high toughness, high abrasion resistance and high strength within a short time by a single process when preparing a tungsten carbide sintered body appropriate for a friction stir welding tool by using pulsed current activation through a discharge plasma sintering apparatus. In addition, since a sintered body is prepared with only a tungsten carbide single material, excluding a sintering additive such as cobalt, a preparation method is simplified, preparation costs are reduced, and toughness, abrasion resistance and strength are superior compared with a sintered body containing cobalt, a sintering additive.