Development of dense Sr-substituted CaA12O19 (CA6) ceramics synthesized by sol-gel combustion method

The most alumina-rich compound in the CaO-Al2O3 system is calcium hexaaluminate (CaAl12O19, CA(6)). CA(6) ceramics were synthesized by the sol-gel auto combustion method. CA(6) phase formation has been achieved at 1200 degrees C, which is a much lower temperature than the convention process (>1600 degrees C). The influence of Sr-2(+) substitution on the densification of Ca1-xSrxAl12O19 (x = 0, 0.1, 0.2, and 0.3) ceramics was investigated. The X-ray diffraction analysis and structural refinement indicated the substitution of Sr2+ ions into the lattice of CA(6). The elongation of the c direction of the CA(6) crystal structure was found with Sr2+ ion substitution. Surface morphology analysis showed a crystal growth with Sr2+ substitution in CA(6) upto x = 0.2 composition. The 1600 degrees C sintered specimen (with x = 0.2 composition) showed the bulk density and open porosity of 3.39 g/cm(3) and 4.92%, respectively. Thus, auto combustion synthesis and Sr2+ substitution into CA(6) ceramics are feasible and beneficial for the densification of the ceramics.

Automated summary

By synthesizing CA(6) ceramics through the sol-gel auto combustion method, the study successfully achieved CA(6) phase formation at a lower temperature of 1200 degrees C compared to conventional processes. The substitution of Sr2+ ions into the lattice of CA(6) was found to improve densification and bring structural changes to the ceramics. The incorporation of Sr2+ up to a composition of x = 0.2 resulted in crystal growth and enhanced bulk density in the sintered specimens.