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Porous YSZ ceramics were prepared by a gel-casting method using tert-butyl alcohol (TBA) as solvent and Al2O3 fiber as reinforcement. Effects of sintering temperature, soaking time and Al2O3 fiber content on porosity, microstructure, compressive strength, and fracture toughness of the porous ceramics were studied. Compressive strength of porous YSZ ceramics was improved while the porosity decreased with the increase of sintering temperature and soaking time. Addition of Al2O3 fibers significantly strengthened and toughened porous YSZ ceramics; however, the laws of strengthening and toughening were different. The strength of the porous YSZ ceramics reached maximum at the addition of 10vol% Al2O3 fibers, and the corresponding compressive strength and flexural strength were 100.2±25.4MPa and 61.5±11.3MPa, respectively. Fracture toughness of the porous YSZ ceramics monotonically increased with increasing of Al2O3 fibers, and could be improved from 0.5MPam1/2 to 1.2MPam1/2 (improved by 140%). The strengthening and toughening mechanisms of Al2O3 fibers were discussed. [ABSTRACT FROM AUTHOR]

Abstract: Porous yttria-stabilized zirconia (YSZ) ceramics were fabricated by tert-butyl alcohol (TBA)-based gel-casting method for potential applications in heat-insulation materials. The effect of sintering temperature on compressive strength of porous YSZ ceramics was investigated on the basis of measurements linear shrinkage, porosity and pore size. As the sintering temperature increased from 1350 to 1550°C, a decrease of porosity from 77 to 65%, a decrease of average pore size from and an increase of linear shrinkage from 15.4 to 31.8% were observed. The compressive strength increased remarkably from 3 to 27MPa with increasing sintering temperature from 1350 to 1550°C, which was related to the corresponding change of linear shrinkage, porosity, pore size and microstructure. A remarkable decrease of compressive strength with increasing porosity was observed. The compressive strength decreased also with increasing pore size. [Copyright &y& Elsevier]

Boron carbide submicron powder was synthesized with boron oxide and graphene as starting materials by gas-solid reaction method using two different apparatuses. The effects of calcination temperature and holding time, apparatus type and B 2 O 3 /C ratio of the starting materials on the phase composition and morphology of the synthesized powders were evaluated. A newly formed residual carbon morphology distinct from original graphene were present in samples synthesized at a higher B 2 O 3 /C ratio or temperature. The synthesis temperature of ∼1500 °C was found to be more suitable to obtain boron carbide powder without the existence of residual carbon. The new type of apparatus enabled the synthesis of boron carbide phase at a relatively lower temperature, due to its more efficient use of B 2 O 3 vapor. [ABSTRACT FROM AUTHOR]