Development of dense Sr-substituted CaAl12O19 (CA6) ceramics synthesized by sol-gel combustion method

Abstract

The most alumina-rich compound in the CaO-Al2O3 system is calcium hexaaluminate (CaAl12O19, CA6). CA6 ceramics were synthesized by the sol-gel auto combustion method. CA6 phase formation has been achieved at 1200°C, which is a much lower temperature than the convention process (>1600°C). The influence of Sr2+ 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 CA6. The elongation of the “c” direction of the CA6 crystal structure was found with Sr2+ ion substitution. Surface morphology analysis showed a crystal growth with Sr2+ substitution in CA6 upto x = 0.2 composition. The 1600°C sintered specimen (with x = 0.2 composition) showed the bulk density and open porosity of 3.39 g/cm3 and 4.92%, respectively. Thus, auto combustion synthesis and Sr2+ substitution into CA6 ceramics are feasible and beneficial for the densification of the ceramics.

Keywords

• ca6 ceramics
• sol-gel auto combustion
• sr2+ substitution
• density
• microstructure