Preparation of ZrB2-SiC composites by arc melting and their properties

Abstract

ZrB 2 -SiC composites were prepared by arc melting using ZrB 2 and b-SiC powders as raw materials and their Vickers microhardness, electrical conductivity and thermal conductivity were investigated. The eutectic composition of the ZrB 2 -SiC system was ZrB 2 -58.5 molSiC with a labyrinthine microstructure 100 nm in width and several mm in length. The hardness of the ZrB 2 -SiC composites increased with increasing SiC content and showed the highest value of 24 GPa at an indenter load of 4.9 N around the eutectic composition. The ZrB 2 -SiC eutectic composite had the highest fracture hardness of 6 MPa m 1/2 . The electrical conductivity of ZrB 2 -SiC composites ranged from 3.2×10 4 to 5.0×10 6 S m -1 at room temperature and decreased with increasing temperature. Their thermal conductivity at room temperature was 70 to 95 W m -1 K -1 and decreased with increasing temperature. The eutectic composite had the lowest thermal conductivity.

Microscopic, mechanical and thermal properties of spark plasma sintered ZrB2 based composite containing polycarbosilane derived SiC

“…relative densities of the spark plasma sintered ZrB 2 -SiC p composites vary from 91.91% for 1900°C, 91.95% for 2000°C and 93.04% for 2100°C sintered composites. This result is also in covenant with the works of Tu et al who stated less density of the composite by SPS to a favoured evaporation of ZrB 2 at high temperature which is much lower than both the melting point of ZrB 2 and decomposition temperatures of SiC [23]. It appears that mechanical interlocking between ZrB 2 and SiC grains is an important phenomenon for effective mass transfer among the ZrB 2 grains and also elimination of closed pores to a final densification of the composite and it is more prominent in high temperature sintering process.…”

Microstructure and densification of ZrB2–SiC composites prepared by spark plasma sintering

“…The ZrB 2 -SiC system is known as a eutectic system. 3 Although the eutectic temperature has not been precisely determined, it should be independent of composition. Since the electrical conductivity of ZrB 2 is higher than that of SiC, the temperature inside ZrB 2 -40 mass% SiC should be higher than that of ZrB 2 -80 mass% SiC.…”

“…[1][2][3] ZrB 2 -SiC composites are known to have higher strength, fracture toughness and oxidation resistance than monolithic ZrB 2 , and the addition of SiC particles has been found to improve the oxidation resistance and fracture toughness of ZrB 2 . 3,4 ZrB 2 -SiC composites have been commonly prepared by using conventional pressureless sintering, 4,5 hotpressing, [6][7][8][9][10][11][12][13] and reactive hot pressing.…”

“…14 However, fully dense composites have been hardly obtained because of high melting temperature and strong covalent bonding of ZrB 2 and SiC. [1][2][3] Spark plasma sintering (SPS) makes it possible to densify ZrB 2 -SiC composites at a lower temperature and in a shorter time compared with conventional techniques. 1,[15][16][17][18] In the SPS technique, a pulsed direct current passes through graphite punch rods and dies simultaneously with a uniaxial pressure.…”

Preparation of B4C-ZrB2-SiC eutectic ceramics by arc melting method

“…ZrB 2 -SiC ceramics [10,11], as ultra-high temperature ceramics, have been widely investigated in the world. Two eutectic compositions, ZrB 2 -77.4mol.%SiC and ZrB 2 -58.5mol.%SiC [12], have been reported. However, the property of eutectic composites has not been presented.…”