Sintering behavior and properties of sepiolite-based cordierite compositions with added boron oxide


Abstract: This paper describes the sintering behavior and some properties of sepiolite-based cordierite ceramics with the addition of boron oxide at up to 3% wt. Sepiolite, kaolin, and alumina were used to prepare cordierite compositions in the cordierite phase area in a MgO-Al_2O_3-SiO_2 system with an excess amount of CaO and some Fe_2O_3 that basically came from sepiolite. Sintering of the dry-pressed samples was carried out at 850-1200 °C with a sintering time of 3 h. Sintered samples were characterized by XRD and SEM analysis, density, porosity, thermal expansion coefficient, shrinkage, and flexural strength measurements. The results showed that the addition of boron oxide reduced the cordierite formation temperature by about 100 °C and also reduced the sintering temperatures. The results also showed that the densification increased with increasing sintering temperatures up to 1100 °C, but above that temperature, partial melting began to occur in the samples, especially with larger additions of boron oxide.

Keywords: Sepiolite, sintering, cordierite, natural raw materials

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