Effects of Y2O3 on microstructure and mechanical properties of ZrB2–SiC ceramics

Toward Oxidation-Resistant ZrB2-SiC Ultra High Temperature Ceramics

“…Hot Pressing Hot pressing is the conventional method for fabricating UHTCs and has been used extensively, [8][9][10]12,16,17,20,22,27,33,35,39,47,48,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] with typical temperatures of~2173 K (1900°C) and applied pressures between 30 and 50 MPa. It allows full densification without the use of sintering aids, although most research employs modest amounts of sintering aids such as silicides, borides, metals (e.g., Ni), or C to reduce processing times and temperatures, thus reducing the costs associated with the production technique.…”

“…Zhang et al [35] found that adding 3 vol pct improved sinterability of the powders and suppressed grain growth by reacting with oxides on the starting powder surfaces. Grain size refinement improved the fracture toughness and flexural strength of the material.…”

Pressureless sintering of (ZrB2–SiC–B4C) composites with (Y2O3+Al2O3) additions

“…During liquid phase sintering under free flow of argon, loss of gaseous species is possible. In the presence of many phases (such as ZrB 2 , SiC, and B 4 C), additives (Y 2 O 3 , Al 2 O 3 ) and surface oxides (SiO 2 , ZrO 2 , B 2 O 3 ) the reaction among them during sintering and cooling is unknown and the densification mechanisms may be controlled by dissolution-precipitation or evaporation-condensation [27]. A sintering temperature of 1600°C is considered as a critical temperature to form molten YAG and to achieve a full density of YAG/ZrB 2 composite by liquid phase sintering [30].…”

“…The addition of rare earth oxide yttria (Y 2 O 3 ) has been shown to react with oxide impurities (ZrO 2 , B 2 O 3 , SiO 2 ) in ZrB 2 -SiC composites and improve densification and mechanical properties [27]. Similarly Al 2 O 3 + Y 2 O 3 have been used to reduce the sintering temperature and to increase densification rate of ZrB 2 -SiC composites [28].…”

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].…”