Papers by Author: Ji Ping Guo

Abstract: The mixture of amorphous silica extracted from coal fly ash and fused silica was used to prepare density silica ceramic through slip-casting method. The XRD results showed that a large amount of cristobalite was formed at 1300°C which can weaken mechanical properties. The SEM results showed that glassy phase present from fused silica promoted ceramic densification. According to the experiment results, it was found that the bending strength was highest when mixing 65wt% fused silica and sintering at 1200°C for 4 hours.

Abstract: Porous mullite was prepared from a reactive mixture of Al metal powder and the fly ash produced by power plant. The sintering ceramics was characterized for the pore structure and phase identification studies. It was found that the sintered specimen expands at first (1300-1400°C) and then shrinks which was correspondence to the changing of open porosity. The expansion was attributed to the fact that the alumina produced from the oxidation reaction of Al powder made the volume larger than the starting mixtures. At 1550°C, it was inferred that the alkaline element in the fly ash made the mullite decomposed then destroyed the mullite structure. The SEM photographs suggested us that the pore diameter of the sintered ceramics might be adjusted by adding Al powder with different grain sizes. Moreover, because of the rod-like mullite produced in the pores, Mg metal addition could develop the further modification of the pore structure with similar porosity (47% at 1400°C/4h) compared with that (53%) with 0wt % Mg metal powders.

Abstract: Porous SiO2 ceramics had been successfully prepared by gelcasting. The open porosity of obtained samples was between 0.40 and 0.46, which reached its maximum at 1100°C. The change of line shrinkage rate was opposite to the open porosity. The microstructure was investigated though X-ray diffraction (XRD) and scanning electronic microscope (SEM).