2019 年 33 巻 p. 54-57
Coal ash generated in thermal power plants is kneaded, extruded through a pipe by a screw, and formed into a pellet shape in extruder machines. As the screw rubs with high-hardness ash at high pressure, the edge becomes most susceptible to wear. By welding a wear-resistant material to the edge of the screw, it is possible to increase the continuous use time of such machines. Therefore, a weldable functionally graded material (FGMs), cemented carbide, was developed using the spark plasma sintering (SPS) method. This FGMs consists of three layers: wear-resistant, intermediate, and weldable layers. As these three layers have different sintering temperatures, sintering is carried out via the SPS method using an appropriate mold. The application of this material to the screw surface of an extruder results in a lifetime of approximately 3000 h, which is about three times longer than that of a conventional product coated by thermal spraying.
