Production of metal powder compact with controlled porosity by spark plasma sintering process

Spark plasma sintering (SPS) is a new process for sintering of various kinds of materials. The SPS method was tested in the fabrication of porous materials having high strength and porosity. 316L stainless steel powders classified (44-63 μm and 63-75 μm) were used as raw materials. After inserting and tapping of powder in a cylindrical graphite mold with inner diameter of 15 mm, SPS was performed in the temperature range of 600-1000°C for 1 min with heating rate of 100°C/min in vacuum atmosphere and applied pressure of 15 MPa. The apparent porosity of specimens decreased from about 55% to 31% with increase of sintering temperature from 600 to 1000°C. Deep dimple traces of ductile fracture were observed on fracture surfaces of sintered bodies with high sintering temperature (900-1000°C) due to the strong neck formation and growth. Using alumina supporter and through control of punch length, porosity could be controlled from about 53% to 40% at a sintering temperature of 900°C, and the hardness value was increased