Papers by Author: Rui Guo

Abstract: Dense multiwall carbon nanotubes (MWNTs) reinforced barium aluminosilicate (BAS)–silicon nitride (Si3N4) composites were fabricated by hot-pressing sintering. The effect of MWNTs on the microstructure, compositional investigations, as well as mechanical characterization of the composites was investigated. The results show that MWNTs were preserved in the composites after sintering and present good adherence to matrix grains. The incorporation of 3% 1-2μm MWNTs effectively improved the fracture toughness of the BAS/Si3N4 composites from 8.02 to 8.6 MPa•m1/2.

Abstract: The barium aluminum silicate-silicon nitride (BAS-Si3N4) matrix-ceramic composite was fabricated using pressureless sintering, at temperatures ranging from 1720°C, which is below the melting point of BAS, to 1850°C. The effect of processing conditions on sinterability, crystalline structure, microstructure and mechanical properties was evaluated. It was demonstrated the BAS glass-ceramic served as an effective liquid-phase-sintering aid, to attain high densities and completed the α-Si3N4–β-Si3N4 phase transformation, and remained as a structural matrix that was reinforced by the rod-like β-Si3N4 grains. Si3N4 grains nucleated and grow in random directions in an almost completely crystallized matrix of hexacelsian BAS. High flexural strength (665±40 MPa) and fracture toughness (7.74 MPa•m1/2) could be obtained from 30wt%BAS-70wt%Si3N4 samples that have been sintered at 1800°C for 120 min with a fine-grained microstructure.