Effect of reduced Al2O3 mole ratio on fabrication of cordierite ceramic by solid-state sintering method

Abstract

Cordierite ceramic was fabricated by reducing Al 2 O 3 mole ratio from 2.0 to 1.4 with kaolin, silicon dioxide and magnesium oxide as the raw materials. The effect of reduced Al 2 O 3 mole ratio on the sintering behaviors, phase transition, main properties, and microstructure were characterized in detail. The results show that cordierite phase becomes the main crystallization phase at 1300 o C, and mullite phase can be consumed to produce cordierite phase by reducing Al 2 O 3 mole ratio. But additional quartz phase still exists until 1400 o C. Moreover, the open porosity, pore connectivity and pore size increase as Al 2 O 3 mole ratio reduces from 2.0 to 1.4 while the linear shrinkage percent and bulk density decrease with the reduced Al 2 O 3. It is considered that the sintering activity of the raw materials at low temperature decreases due to the increase of chemically pure magnesium oxide and silica with the decrease of Al 2 O 3 mole ratio, while the crystallization process, pore growth and cordierite phase rather than the liquid phase control the densification process at high temperature.

Formation of anorthite containing cordierite materials through reaction sintering kaolin, MgO and CaO precursors

“…II Phases formed at different temperatures (°C) and their peak positions (cm -1 ). In this work, monolithic cordierite and anorthite containing cordierite materials were developed by solid-state sintering method [47,48]. These ceramic materials might have potential industrial applications.…”

High macroscopic neutron capture cross section ceramics based on bauxite and Gd2O3

“…The two endothermic processes are also observed in the DTA curves, accompanied by a small exothermic peak at 980 °C. This corresponds to the spinel aluminosilicate formation [12,31,32]. This is difficult to observe in the Gd10 mixture.…”

Electrical, Microstructural and Physical Characteristics of Talc-based Cordierite Ceramics

“…The higher rate of the BD increases for both BT3 and BT4 up to 1200ºC (1.90-2.35g/ cm 3 ) is due to development of silicate melts that would vitrify into glassy phase filling the internal pores and glaze the outer surface of the samples (Fig. 8b) [60]. In addition, a possible crystallization of the high-density phases such Above 1200ºC, the BD of BT3 and BT4 samples drop to minimum values (1.80 and 1.89g/cm 3 , respectively, Fig.…”

“…Cordierite is crystallized beginning from 1200ºC at the expense of enstatite, mullite, cristobalite and diopside (Table 3) [21,22,24,55,57]. This is aided by the high contents of TIOs of the batches (2.03-11.44wt.%, Table 2) which accelerates the solid-state formation of orthorhombic cordierite by lowering its crystallization temperature [20,24,27,[58][59][60]. In addition, the TIOs initiate the early formation of silicate-rich melt (68.52-81.39wt.%) at 1355 and 1400ºC, respectively, which is aided by the partial dissolution of mullite, enstatite and cristobalite.…”

“…The dielectric response of these ceramics to application of the electric field is mainly dominated by the phase composition, microstructure, porosity, etc. [24,35,60, 6. Both ε', and tanδ show a decrease with a porosity decrease, displaying a good correlation between the dielectric properties and microstructure of samples.…”