WANG Han (1994-), female, Master candidate. E-mail: 17121355@bjtu.edu.cn
The porous mullite-based ceramics were prepared by a particle-stabilized foam method and a subsequent freeze-drying process with α-Al2O3 and SiO2 as raw materials, propyl gallate (PG) as a surface modifier and gelatin as a binder. The effect of aluminum to silicon (Al/Si) molar ratio on the composition, microstructure and properties of the prepared materials was investigated. The results show that the foam stability after foaming at different proportions is >95%. The sintered material is composed of mullite as a main phase and corundum as a second phase, and the mullite phase content decreases from 93.11% (in mass fraction) to 85.11% with increasing the Al/Si molar ratio from 2.0∶1.0 to 3.0∶1.0. The total porosity and bulk density are 85.51%-86.51% and 0.44-0.48 g/cm3, respectively. The open porosity is 84.34%-84.82%. The compressive strength firstly increases and then decreases (i.e., 2.25-2.86 MPa). The vacuum thermal conductivity increases from 0.15 W/(m·K) to 0.22 W/(m·K). It is indicated that the method could be promising to prepare porous mullite-based ceramics with a high porosity, a high strength and a low thermal conductivity.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |