Low-temperature sintering behavior and properties of monoclinic-SrAl2Si2O8 ceramics prepared via an aqueous suspension milling process

In this work, by an aqueous suspension milling process, boric acid (H 3 BO 3 ), calcium hydroxide [Ca(OH) 2 ], strontium carbonate (SrCO 3 ) and barium hydroxide octahydrate [Ba (OH) 2 ·8H 2 O] are mixed with strontium carbonate (SrCO 3 ) and kaolin (Al 2 O 3 ·2SiO 2 ·2H 2 O) to prepare SrAl 2 Si 2 O 8 ceramics with a sintering temperature of 950 °C. According to chemical compositions of flux agents B 2 O 3 , CaO·2B 2 O 3 , SrO·2B 2 O 3 and BaO·2B 2 O 3 , raw materials boric acid, calcium hydroxide, strontium carbonate and barium hydroxide octahydrate were introduced to the suspension slurries of strontium carbonate and kaolin to decrease the densification sintering temperature of SrAl 2 Si 2 O 8 ceramics. In addition, the Sr element in SrAl 2 Si 2 O 8 ceramics are partly substituted with Ba and Ca elements, respectively, to investigate the low-temperature sintering behavior of partly substituted SrAl 2 Si 2 O 8 ceramics. The results indicated that the addition of flux agents to SrAl 2 Si 2 O 8 ceramics can availably achieve the densification sintering of SrAl 2 Si 2 O 8 ceramics at 950 °C, whereas the substitution of Sr with Ca or Ba have a great effect on sintering behaviors and dielectric properties of SrAl 2 Si 2 O 8 ceramics. Additionally, main crystal phases of the SrAl 2 Si 2 O 8 ceramics are monoclinic - SrAl 2 Si 2 O 8 and small quartz, but the evolution of crystal phases also depend on flux agents.