The Development of an Electroconductive SiC-ZrB2 Composite through Spark Plasma Sintering under Argon Atmosphere

Abstract

The SiC-ZrB2 composites were fabricated by combining 30, 35, 40, 45 and 50 vol. % of zirconium diboride (ZrB2) powders with silicon carbide (SiC) matrix. The SiC-ZrB2 composites and the sintered compacts were produced through spark plasma sintering (SPS) under argon atmosphere, and its physical, electrical, and mechanical properties were examined. Also, the thermal image analysis of the SiC-ZrB2 composites was examined. Reactions between β-SiC and ZrB2 were not observed via x-ray diffraction (XRD) analysis. The apparent porosity of the SiC+30vol.%ZrB2, SiC+35vol.%ZrB2, SiC+40vol%ZrB 2, SiC+45vol.%ZrB2 and SiC+50vol.%ZrB2 composites were 7.2546, 0.8920, 0.6038, 1.0981, and 10.0108%, respectively. The XRD phase analysis of the sintered compacts demonstrated a high phase of SiC and ZrB2. Among the SiC+ZrB2 composites, the SiC+50vol. %ZrB2 composite had the lowest flexural strength, 290.54MPa, the other composites had more than 980MPa flexural strength except the SiC+30vol.%ZrB2 composite; the SiC+40vol.%ZrB2 composite had the highest flexural strength, 1011.34MPa, at room temperature. The electrical properties of the SiC-ZrB2 composites had positive temperature coefficient resistance (PTCR). The V-I characteristics of the SiC-ZrB2 composites had a linear shape in the temperature range from room to 500°C. The electrical resistivities of the SiC+30vol.%ZrB 2, SiC+35vol.%ZrB2, SiC+40vol.%ZrB2 SiC+45vol.%ZrB2 and SiC+50vol.%ZrB2 composites were 4.573×10-3 , 1.554×10-3 , 9.365×10 -4, 6.999×10-4, and 6.069×10-4.cm, respectively, at room temperature, and their resistance temperature coefficients were 1.896×10-3, 3.064×10-3, 3.169×10-3, 3.097×10-3, and 3.418×10-3/°C in the temperature range from room to 500°C:, respectively. Therefore, it is considered that among the sintered compacts the SiC+35vol.%ZrB2, SiC+40vol.%ZrB2 and SiC+45vol.%ZrB2 composites containing the most outstanding mechanical properties as well as PTCR and V-I characteristics can be used as an energy friendly ceramic heater or ohmic-contact electrode material through SPS.