Cordierite (Coming EX-66 100/25) catalyst support samples, contaminated by Na2O and CaO, have been studied in the temperature range 800-1200-degrees-C by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results suggest that in CaO-contaminated samples the behaviour is strongly influenced by the Ca2+ ion diffusion rate; additional crystalline phases and microstructures develop at different temperatures. At 1200-degrees-C, anorthite, a tectosilicate, forms in the same way as the crystalline phases carnegieite and nepheline form in the case of Na2O contamination at 800-1000-degrees-C. All these phases have similar composition; their formulae are 2CaO-2Al2O3-4SiO2 and 2Na2O-2Al2O3-4SiO2. For the Na2O-contaminated samples, the formation of a high-temperature liquid phase can explain the presence of the observed glassy phase. In earlier studies of CaO- and Na2O-contaminated samples, mechanical properties were obtained by four-point bending (modulus of rupture); these data can be correlated with the results obtained in the present investigation.
Influence of Calcium-oxide and Sodium-oxide On the Microstructure of Cordierite Catalyst Supports / P., Scardi; N., Sartori; A., Giachello; P. P., Demaestri; Branda, Francesco. - In: CERAMICS INTERNATIONAL. - ISSN 0272-8842. - ELETTRONICO. - 19:(1993), pp. 105-111. [10.1016/0272-8842(93)90082-3]
Influence of Calcium-oxide and Sodium-oxide On the Microstructure of Cordierite Catalyst Supports
BRANDA, FRANCESCO
1993
Abstract
Cordierite (Coming EX-66 100/25) catalyst support samples, contaminated by Na2O and CaO, have been studied in the temperature range 800-1200-degrees-C by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results suggest that in CaO-contaminated samples the behaviour is strongly influenced by the Ca2+ ion diffusion rate; additional crystalline phases and microstructures develop at different temperatures. At 1200-degrees-C, anorthite, a tectosilicate, forms in the same way as the crystalline phases carnegieite and nepheline form in the case of Na2O contamination at 800-1000-degrees-C. All these phases have similar composition; their formulae are 2CaO-2Al2O3-4SiO2 and 2Na2O-2Al2O3-4SiO2. For the Na2O-contaminated samples, the formation of a high-temperature liquid phase can explain the presence of the observed glassy phase. In earlier studies of CaO- and Na2O-contaminated samples, mechanical properties were obtained by four-point bending (modulus of rupture); these data can be correlated with the results obtained in the present investigation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
