Synthesis of functional ceramics using highly polymerized hydroxoaluminum complexes

用Al金属溶解法制备的聚羟基铝（PHA）溶液在干燥时形成凝胶，由大体积的平面Al物种组成，用不同[OH/Al]比（2.00 ~ 2.53）的PHA溶液制备透明凝胶，并研究了PHA溶液对陶瓷材料性能的影响。这些凝胶在500-900℃和1000℃下分别转化为活性氧化铝和α-氧化铝。由此获得的活性氧化铝显示出两种类型的孔，即，3-4 nm的较小孔和4-30 nm直径的较大孔。为了获得具有均匀孔的活性氧化铝，将四甲基氯化铵（TM）加入到PHA溶液中，然后干燥以形成PHA-TM复合凝胶。由TM含量[大于或等于]30%的复合凝胶获得的γ-氧化铝显示出在3至4 nm范围内的尖锐且精确控制的单峰孔径分布，这取决于加热温度。γ-氧化铝的孔容最大，为0.25 cm^3 关于我们 由<-1>PHA溶液和可膨胀合成氟云母制备了氧化铝柱撑氟云母。将氧化铝柱撑云母粉末压坯在500-700℃下烧成，得到具有可切削性的氧化铝柱撑云母烧结体，同时保留了氧化铝柱撑结构。柱撑结构的耐热性取决于氧化铝柱撑氟云母的粒度，特别是主体云母晶体的c^* 尺寸;由粗颗粒获得的烧结体的耐热性高于由细颗粒获得的烧结体的耐热性。为了获得具有高耐热性的微孔固体，在聚乙烯醇（PVA）存在下进行了氧化铝柱撑氟云母的合成。所得产物在500℃时具有2.7 nm的大面间距，在600℃时具有403 m^2g^-1的最大表面积<-1>。以<-1>氧化铝柱撑氟云母/γ-氧化铝复合材料为原料，制备了含PHA的凝胶或煅烧凝胶，并将其与氧化铝柱撑氟云母/γ-氧化铝复合材料烧结体进行了比较，结果表明，煅烧凝胶制备的复合材料烧结体具有良好的微孔性能。氧化铝柱撑云母的前体，即，PHA插层氟云母，可用作低温烧结复合材料的粘结剂。少

Fabrication of ceramic materials has been undertaken by using polyhydroxoaluminum (PHA) solutions, which lead gels on drying and consist of bulky and planar Al species, obtained by Al metal dissolving method.Transparent gels were obtained from PHA solutions having different [OH/Al] ratios of 2.00-2.53. These gels were transformed into activated alumina and α-alumina by heating at 500-900℃ and 1000℃, respectively. Activated alumina thus obtained exhibited two kinds of pores, i.e., smaller pores of 3-4 nm and larger pores of 4-30 nm in diameter. To obtain activated alumina having uniform pores, tetramethylammonium chloride (TM) were added to the PHA solutions followed by drying to form PHA-TM composite gels. The γ-alumina obtained from the composite gels having【greater than or equal】30% TM content showed a sharp and precisely controlled monomodal pore size distribution in the range of 3 to 4 nm, depending on the heating temperature. The γ-alumina gave the highest pore volume of 0.25 cm^3 … More g^<-1> at 400℃.Alumina-pillared fluorine micas were obtained from PHA solutions and expandable synthetic fluorine micas. Sintered bodies of the alumina-pillared micas having machinability were obtained by firing the powder compacts of the alumina-pillared micas at 500-700℃ with retaining their pillared structure. Thermal durability of the pillared structure depends on the particle size of alumina-pillared fluorine micas, especially on the c^*-dimension of the host mica crystals ; thermal durability of the sintered bodies obtained from coarse particles is higher than that from fine particles.In order to obtain microporous solids having high thermal durability, synthesis of alumina pillared fluorine micas has been undertaken under the presence of poly (vinyl alcohol)(PVA). The products thus obtained gave the large basal spacing of 2.7 nm at 500℃ and the maximum surface area of 403 m^2g^<-1> at 600℃. The surface area of the product was above 300 m^2g^<-1> even after heating at 800℃, showing high thermal durability.Sintered bodies of alumina-pillared fluorine mica/γ-alumina composites were obtained from the alumina-pillared micas and the gels or calcined gels containing PHA.The sintered composite bodies prepared by using the calcined gels retained microporous properties. The precursors of alumina-pillared micas, i.e., PHA intercalated fluorine micas, can be used as binders for sintering composites at low temperatures. Less