Fe~(3+)/Ti~(4+)赋存状态对钛酸铝/莫来石复合材料结构的影响

借助XRD、SEM和能谱分析仪等手段,研究了1 600℃煅烧中低品位矾土制备的钛酸铝/莫来石(Al_2TiO_5ss/3Al_2O_3·2SiO_2ss)复合材料经1 200℃保温12h后结构的稳定性。结果表明:高温煅烧中低品位矾土后,其合成材料的结晶物相组成为3Al_2O_3·2SiO_2ss、Al_2TiO_5ss和少量残存的方石英;Fe~(3+)或Ti~(4+)离子以不同形态赋存于结晶相(3Al_2O_3·2SiO_2ss和Al_2TiO_5ss)和非晶相。含Fe~(3+)/Ti~(4+)离子的3Al_2O_3·2SiO_2ss将Al_2TiO_5ss结晶相分割,使其蜷缩其间,并抑制Al_2TiO_5ss的分解;高温下,二者因组成元素相近而致使晶界融合,进而共同构建了体系牢固的致密骨架结构。由3Al_2O_3·2SiO_2ss和Al_2TiO_5ss等高温物相构成的致密结构将非晶相挤压于空隙结构的3Al_2O_3·2SiO_2ss晶间,避免了低熔点相富集带来的不利影响,进而赋予该Al_2TiO_5ss/3Al_2O_3·2SiO_2ss复合材料良好的结构稳定性。

Influence of existence state of Fe3+/Ti4+ on structure of Al2 TiO5 ss/3Al2 O3·2SiO2 ss composite

The structural stability of Al2 TiO5 ss/3Al2 O3·2SiO2 ss composite based on middle-low grade bauxite calcined at 1600℃ and held subsequently at 1200℃ for 12 h was studied by XRD,SEM and energy dispersive spec-troscope (EDS).The results show that after middle-low grade bauxite being calcined at 1600℃,its crystal phase composition consists of 3Al2 O3·2SiO2 ss,Al2 TiO5 ss and a little cristobalite,in which Fe3+/Ti4+ cations exsit in crystalline phases (3Al2 O3·2SiO2 ss and Al2 TiO5 ss)and amorphous phase (silicate)in different forms.Al2 TiO5 ss is separated and huddled by 3Al2 O3·2SiO2 ss containing Fe3+/Ti4+ cations,restraining its decomposition;in addi-tion,both 3Al2 O3·2SiO2 ss and Al2 TiO5 ss build compact skeleton structure of Al2 TiO5 ss/3Al2 O3·2SiO2 ss synthe-sis system based on middle-low grade bauxite due to their near element composition,which avoids appearance of sili-cate phases with low melting point and further endows good structural stability.