The Development of an Electroconductive SiC-ZrB 2 Ceramic Heater through Spark Plasma Sintering

The SiC-ZrB₂ composites were fabricated by combining 30, 35, 40 and 45vol.% of Zirconium Diboride (hereafter, ZrB₂) powders with Silicon Carbide (hereafter, SiC) matrix. The SiCZrB₂ composites, the sintered compacts, were produced through Spark Plasma Sintering (hereafter, SPS), 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 Diffractometer (hereafter, XRD) analysis. The relative density of the SiC+30vol.%ZrB₂, SiC+35vol.%ZrB₂, SiC+40vol.%ZrB₂, and SiC+45vol.%ZrB₂ composites were 88.64%, 76.80%, 79.09% and 88.12%, respectively. The XRD phase analysis of the sintered compacts demonstrated high phase of SiC and ZrB₂ but low phase of ZrO₂. Among the SiC-ZrB₂ composites, the SiC+35vol.%ZrB₂ composite had the lowest flexural strength, 148.49㎫, and the SiC+40vol.%ZrB₂ composite had the highest flexural strength, 204.85㎫, at room temperature. The electrical resistivities of the SiC+30vol.%ZrB₂, SiC+35vol.%ZrB₂, SiC+40vol.%ZrB₂ and SiC+45vol.%ZrB₂ composites were 6.74×10?⁴, 4.56×10?³, 1.92×10?³, and 4.95×10?³Ωㆍ㎝ at room temperature, respectively. The electrical resistivities of the SiC+30vol.%ZrB₂, SiC+35vol.%ZrB₂ SiC+40vol.%ZrB₂ and SiC+45[vol.%]ZrB₂ composites had Positive Temperature Coefficient Resistance (hereafter, PTCR) in the temperature range from 25℃ to 500℃. The V-I characteristics of the SiC+40vol.%ZrB₂ composite had a linear shape. Therefore, it is considered that the SiC+40vol.%ZrB₂ composite containing the most outstanding mechanical properties, high resistance temperature coefficient and PTCR characteristics among the sintered compacts can be used as an energy friendly ceramic heater or electrode material through SPS.