Synthesis of functional ceramics using highly polymerized hydroxoaluminum complexes

陶瓷材料的制备是用聚羟基铝（PHA）溶液进行的，该溶液干燥后呈凝胶状，由大块的平面Al组成，由Al金属溶解法获得。从[OH/Al]比值为2.00-2.53的PHA溶液中获得透明凝胶。分别在500 ~ 900℃和1000℃加热后转化为活性氧化铝和α-氧化铝。得到的活性氧化铝具有2种孔径，即孔径较小的3 ~ 4 nm和孔径较大的4 ~ 30 nm。为了获得具有均匀孔隙的活性氧化铝，在PHA溶液中加入四甲基氯化铵（TM），然后干燥形成PHA-TM复合凝胶。在TM含量大于或等于30%的复合凝胶中得到的γ-氧化铝，随着加热温度的变化，其孔径分布在3 ~ 4 nm范围内，呈精确控制的单模态分布。在400℃时，γ-氧化铝的孔隙体积最大，为0.25 cm^3 . More g^<-1>。从PHA溶液和可膨胀合成氟云母中制备了氧化铝柱状氟云母。将铝柱云母粉末压块在500 ~ 700℃下烧制，得到了具有可切削性的烧结体，并保留了铝柱云母的柱状结构。柱状结构的热耐久性取决于氧化铝柱状氟云母的粒径，尤其是母体云母晶体的c^*维；粗颗粒烧结体的热耐久性高于细颗粒烧结体。为了获得具有高热耐久性的微孔固体，在聚乙烯醇（PVA）存在下进行了氧化铝柱状氟云母的合成。所得产物在500℃时基间距为2.7 nm，在600℃时最大表面积为403 m^2g^<-1>。即使在800℃加热后，产品的表面积仍大于300 m^2g^<-1>，具有较高的热耐久性。以铝柱云母和含PHA的凝胶或煅烧凝胶为原料制备了氧化铝柱氟云母/γ-氧化铝复合材料的烧结体。使用煅烧凝胶制备的烧结复合体保留了微孔性能。氧化铝柱云母的前驱体，即PHA插层氟云母，可作为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