Hydrate formation and its effects on the thermal expansion properties of HfMgW3O12

The thermal expansion curve of HfMgW3O12 correlated with hydration/dehydration accompanying structure and Raman spectral changes.

Sintering Procedure of Calcium Hexaluminate Ceramics

Thermal expansion behavior of ceramic green bodies could be used to determine appropriate sintering procedure for ceramic materials. In this paper, green bodies containing alumina and calcium hydroxide was prepared by slip casting and their thermal expansion behavior was measured. Thermal expansion curve indicated that calcium aluminate (CaO•Al2O3, CA) and calcium dialuminate (CaO•2Al2O3, CA2) are yielded by reaction sintering as intermediate phase compounds in green samples at temperature about 1160°C and 1240°C-1410°C, respectively; and calcium hexaluminate (CaO•6Al2O3, CA6) is yielded as target product at 1450°C-1560°C. Controlled sintering procedure was determined according to thermal expansion curve of green samples. Analysis result to properties of sintered samples indicated that thermal expansion behavior revealed to be a very simple and powerful tool to determine reaction sintering procedure of calcium hexaluminate ceramics.