自结合多孔六铝酸钙合成方法研究

Research on synthesis method of self-bonding porous calcium hexaluminate

以活性α-氧化铝和自制的活性石灰(煅烧温度为750℃)为主要原料,按照原料特点及六铝酸钙的理论组成进行配料,试验采取共磨粉外加55%(质量分数)蒸馏水制成泥料,振动成型,常温养护12 h及110℃干燥24 h后,于1 450℃经6 h烧成。并利用XRD和SEM分析烧后试样的相组成和显微结构。试验结果表明,以活性α-氧化铝和活性石灰为原料经1 450℃焙烧6 h可以形成六铝酸钙。活性石灰的水化膨胀所形成的多孔结构使氧化铝与氧化钙反应生成的六铝酸钙晶体自由生长,形成"珊瑚状"结构。片状结构六铝酸钙晶体在三维空间交叉生长加强了结构的稳定性,在整个结构中出现大量分布均匀的微小间隙。

Main raw materials of active α-Al2O3 and selfmade active lime（calcining temperature of 750 ℃） were mixed according to the characteristics of the raw materials and the theoretic composition of calcium hexaluminate.Clay material,constituted by co-milling with the extra addition of 55%（mass fraction） water,was casted in the vibration mode.Specimens were cured at ordinary temperature for 12 h,dried at 110 ℃ for 24 h,and then sintered at 1 450 ℃ for 6 h.Composition and micro-structure of the prepared specimens were investigated by XRD and SEM.Results indicated that calcium hexaluminate can be synthesized with active α-Al2O3 and active lime as raw materials while sintering at 1 450 ℃ for 6 h.Calcium hexaluminate crystals produced by the reaction of α-Al2O3 and lime grew freely owning to the porous structure expanded by active lime hydration and the coral-like structure was finally formed.Cross growth of flaky calcium hexaluminate crystals in 3D space reinforced structure stability and uniform distribution of lots of tiny gaps in the whole structure was formed.