Effect of AlN as sintering aid on hot-pressed ZrB2–SiC ceramic composite

Mechanical properties and thermal shock behavior of hot-pressed ZrB2–SiC–AlN composites

“…1) showed a uniform distribution of reinforcing particles in the ZrB 2 -matrix. Analysis by EDS (not shown here) indicated that the gray matrix was ZrB 2 and the dark gray particles were a SiC-AlN, which was in reasonable agreement with results reported in the literature [6]. The formation of a solid solution was consistent with the SiC-AlN phase diagram [8].…”

“…On the other hand, due to the high melting point of the constituents and the presence of oxide impurities on the particle surfaces, the sintering of ZrB 2 powders to full density is rather difficult. The introduction of AlN can promote the densification through a marked reduction in porosity by filling of inter-particle voids as a result of formation of a glassy phase causing liquid phase sintering [5,6]. The research work of Han et al [6] on the ZrB 2 -SiC-AlN ceramics has shown that the addition of AlN improved the sinterability, flexural strength and fracture toughness * Corresponding author.…”

“…The introduction of AlN can promote the densification through a marked reduction in porosity by filling of inter-particle voids as a result of formation of a glassy phase causing liquid phase sintering [5,6]. The research work of Han et al [6] on the ZrB 2 -SiC-AlN ceramics has shown that the addition of AlN improved the sinterability, flexural strength and fracture toughness * Corresponding author. of ZrB 2 -based ceramics due to the improvement in densification and inhibition of grain growth.…”

Effect of graphite flake orientation on microstructure and mechanical properties of ZrB2–SiC–graphite composite

“…Among its properties, ZrB 2 has an ultrahigh melting point (>3000 • C), high Young's modulus, high hardness, low electrical resistivity (∼10 −5 cm), high thermal conductivity (>60 W/m K), and good resistance to chemical attack [1][2][3][4][5][6][7]. The combination of these characteristics makes ZrB 2 ceramics useful for high temperature structural applications, such as cutting tools, thermal protection for hypersonic vehicles, molten metal crucibles, high temperature electrodes, and thermowell tubes for steel refining [1][2][3][4][5][6][7][8]. Historic studies implied that phase pure diborides could not be pressurelessly sintered to full density due to strong covalent bond and low self-diffusion as well as the hexagonal crystal structure that allowed for anisotropic grain growth and entrapped porosity (i.e., coarsening is more favorable than densification) [4,7].…”

Effect of graphite flake on microstructure as well as mechanical properties and thermal shock resistance of ZrB2–SiC matrix ultrahigh temperature ceramics

“…Zirconium diboride (ZrB 2 ) based ultrahigh temperature ceramic matrix composites are a leading candidate as potential materials for a variety of high temperature structural applications [1][2][3][4][5][6][7], such as furnace elements, plasma arc electrodes, hypersonic aircraft, reusable launch vehicles, or rocket engines and thermal protection structures for leading edge parts on hypersonic reentry space vehicles at over 1800 • C [1,2]. It is primarily because ZrB 2 has an excellent combination of mechanical, physical, chemical and oxidation resistance properties [1,2,8,9].…”