Properties of silica produced by spark plasma sintering

Using high-purity silica micropowder as the raw material, sintering experiments were performed at different temperatures using spark plasma sintering (SPS) technology. The phase, micromorphology, and internal pores of the sintered samples were characterized by X-ray diffraction, scanning electron microscopy, X-ray computed tomography and other testing methods. These methods explored the phase evolution and the corresponding morphology characteristics of the silica micropowder under the conditions of SPS. Results demonstrate that the solid-phase sintering of silica micropowder starts at 1030 °C, the densification sintering stage begins at 1200 °C, and the densification is completed at 1440 °C. The temperature increase rate was 100 °C/min, and the holding time was 10 min. When the sintering temperature reached 1400 °C the cristobalite phase appeared, and the content of cristobalite was highest at 1500 °C, reaching 13.1 %. As the sintering temperature reaches 1550 °C, the amorphous phase content begins to increase, the porosity and pore size decrease, and a completely transparent quartz glass is obtained at 1600 °C.