Papers by Keyword: Mullite Composite

Abstract: In order to aviod much high energy and CO₂ generation. Microwave sintering (MS) is always carried out to prepare refractory. In this work，MS was proposed to sinter mullite composite. An insulation structure based on hybrid heating mode was well designed with the wall of high-aluminum refractory and the aided heaters of SiC. The sintered samples under different sintering processing were characterized by appearent porosity detection and volume density. Phase composition was investigated by X-ray Diffraction (XRD) analysis. Surface and fracture Flied Emission Scanning Electron Microscopy (FESEM) was applied to observe pore distribution and grain growth. Sintering profile was provided in this work. It was found that mullite composite could be prepared within 1h at relative lower temperature around 1300°C. Compared with samples prepared by convitional sintering (CS), MS samples presented better densification and more uniform grain growth. Microwave plasma phenomena was explored inside MS samples, however, not found in CS ones.

Abstract: Unidirectional pore structured porous mullite composite has been fabricated using a TBA-based freeze-gelcasting of coal fly ash/alumina slurries. After sintering at 1300-1500o C, the shrinkage, apparent porosity and compressive strength of the resulting porous composites were investigated. After sintering at 1500o C, the composite showed the maximum compressive strength of ~51 MPa and the minimum apparent porosity of ~64%.

Abstract: A novel technique to synthesize mullite by the oxidation of Al-Si alloy powder was used for the manufacture of mullite via pressure molding. The mixed powder was consisted of powders of Al-Si alloy, Al2O3 and SiO2 and additives or powders of Al-Si alloy, Al2O3, SiO2 and ZrO2 and additives. Those mixed powders were milled in nonaqueous slurry in order to prevent the oxidation of Al-Si alloy. Then the green bodies were pressureless sintered in air at ≥1380 °C. The Oxidation caused an internal volume expansion, resulting in reducing shrinkage stresses during reaction- bonding of composites, which minimized the sensitivity to crack formation. Comparing with non zirconia reinforced mullite composites, the effect of the microstructure and mechanical properties of mullite composites were studied.

Abstract: Porous mullite with a porosity of about 78% was fabricated using Al(OH)3, SiO2 and AlF3 powders to develop non-asbestos friction materials for brake pads. A mullite composite was fabricated by infiltrating liquid phenolic resins to the porous mullite. The effects of the processing parameters (infiltration frequency, immersion duration and resin temperature) on the properties of the mullite composite obtained by the liquid infiltration technique were studied. SEM analysis reveals that the parameters affected the degree of infiltration and hardness of the mullite composite by changing the infiltration frequency and immersion duration. With increasing immersion duration and infiltration frequency, the resultant porosity had lower values. In the case of hardness, the measured values showed an opposite tendency.