溶胶-凝胶法Al2O3涂层工程陶瓷抗弯强度的数学解析

应用数学方法分析了Al2O3涂层工程陶瓷抗弯强度的实验结果。叙述了用有限个试样的实验结果估计工程陶瓷总体抗弯强度的原理和方法,对得出的分布特征参数的物理意义进行了探讨,发现置信边值强度μ左可以反映材料总体抗弯强度的大小,而均方差置信区间右边值σ右则可以表征材料性能的分散程度,使用这两个参数可以更可靠地评价工程陶瓷的强度水平,可作为材料强度性能的评价指标。并用该强度指标分析了溶胶一凝胶Al2O3涂层对工程陶瓷表面改性的效果。     

溶胶-凝胶法引入烧结助剂制备SiC-Y3Al5O12复相陶瓷

以碳化硅、六水硝酸钇、九水硝酸铝和六次甲基四胺为主要原料,通过溶胶-凝胶法引入Al2O3和Y2O3复合烧结助剂,液相烧结制备得到SiC-Y3Al5O12(Y3Al5O12简称YAG)复相陶瓷.采用DTA、TEM、XRD等分析测试技术研究了溶胶-凝胶法引入复合烧结助剂过程及复合烧结助剂对SiC-YAG陶瓷的烧结性能、力学性能、物相组成与显微结构的影响.结果表明干凝胶在920℃左右已完全转变成YAG相,最终获得的YAG粒径小,并均匀分散在SiC表面的SiC-YAG复合粉体;复合粉体先干压、再等静压成型后,在1860℃下烧结45 min,所制得复相陶瓷的相对密度达到了96.5%,抗弯强度达到486 MPa,断裂韧性达到5.7 MPa·m1/2.     

溶胶-凝胶法制备α-Al2O3微晶陶瓷的研究

以一水氧化铝(AlOOH)为原料,采用溶胶-凝胶法,经搅拌分散、胶溶、凝胶以及凝胶干燥过程制备了α-Al2O3微晶陶瓷的前驱体,热处理得到α-Al2O3微晶陶瓷.通过TG(DTG)-DTA和XRD等分析测试手段,详细考察了胶溶剂、pH值、固含量等工艺参数对α-Al2O3微晶陶瓷性能的影响,得到了合适的工艺参数.     

溶胶—凝胶法制备超滤Al2O3膜的研究—非担载超滤Al2O3膜的制备

以异丙醇铝为原料通过溶胶-凝胶法制备了非担载超滤Al2O3膜。对主要制备因素即胶溶剂的种类及用量、水解温度和加水量、老化温度及老化时间、焙烧温度等进行了研究。实验表明所制备的非担载超滤Al2O3膜在500℃焙烧所得膜的孔径小于5nm,且孔径分布均匀。     

负载型纳米FeOZrO2/Al2O3催化剂的制备

主要研究制备以大孔A12O3,为基载体的负载型纳米FeOZrO2/Al2O3,复合载体.采用溶胶-凝胶法制备负载型纳米FeOZrO2/Al2O3,复合载体.利用比表面、透射电子显微镜(TEM)等对载体催化剂进行了表征.结果表明:负载型纳米FeOZrOJhl203复合载体的比表面积达到76.53 sq·m/g,FeOZrO2/Al2O3,中的FeO粒子约为40nm,较Fe0/Al2O3中FeO的粒子(100nm)小且分布均匀.     

溶胶凝胶法制备Al2O3超滤膜的研究

氧化铝超滤膜是一种新型的分离膜,性能优异,在生物医学等领域有广阔的应用前景。本文通过采用溶胶凝胶法制备Al_2O_3超滤膜的实验过程,重点研究影响Al_2O_3超滤膜制备的因素。     

溶胶-凝胶法制备Al2O3-ZrO2-SiO2复合薄膜

本文采用溶胶-凝胶法以异丙醇铝、正硅酸乙酯和氧氯化锆为原料，HNO3为催化剂，PVA为成膜助剂，在多孔陶瓷管上制得了Al2O3-ZrO2-SiO2复合薄膜。研究了组分配比对溶胶性质的影响，结果表明Al2O3：ZrO2：SiO2在8：1：2～12：1：2之间时可得到性能符合要求的溶胶。通过扫描电镜可观察到膜的孔径为2～5μm，且膜与基底结合良好。     

铁基Al2O3陶瓷涂层的研究进展

综述了铁基Al2O3陶瓷涂层的研究现状．重点阐述了Al2O3陶瓷涂层的制备方法和研究热点．展望了Al2O3陶瓷涂层的研究趋势．并提出了今后的主要研究任务。     

缩短溶胶-凝胶法制备Al2O3系膜溶胶时间的探讨

本文以缩短成膜时间为目标,主要对催化剂及水解条件进行了研究。经过对不同的硝酸加入量、水解温度、水解时间的研究,发现以硝酸作催化剂,当H^ ／AL控制在0．08～0．14范围内,水解温度为87℃,水解时间控制在3～4小时时,只需陈化8～10小时,即可得到稳定的澄清溶胶。并且,所制得的复合溶胶涂覆在多孔陶瓷基质上经干燥、热处理后得到性能良好的复合膜。     

凝胶注模法制备多孔莫来石陶瓷的显微结构研究

本文重点研究了凝胶注模法制备多孔莫来石陶瓷的过程中固含量、表面活性剂量、搅拌速度等参数对多孔陶瓷显微结构的影响.结果表明,多孔陶瓷的气孔率、孔径尺寸和连通性可以通过控制制备过程参数来进行调节.当固含量从40wt％增加到70wt％,样品的开孔率和总气孔率分别从88.49％和91.27％降低到76.94％和83.04％,而密度从0.276 g·cm-3增加到0.536 g· cm-3.当表面活性剂浓度由0.25wt％增加到lwt％时,样品开孔率基本保持不变,总气孔率先由84.34％增加到93.26％,再减小到87.63％;密度则由0.413 g·cm-3减小到0.378 g· cm-3,再增加到0.391 g·cm-3.当搅拌速度由1000 r/min增加到1800 r/min时,开孔率由78.12％减小到72.85％,总气孔率则由79.95％先增加至84.18％,再减小到77.09％.     

Microstructure and Mechanical Properties of Mullite Prepared by the Sol-Gel Method

Mullite (3Al₂O₃·2SiO₂) of stoichiometric composition was prepared by mixing boehmite sol and silica dispersion and gelling at a pH of 3. Complete mullitization takes place at or above 1300°C. Ultrafine mullite powder prepared by calcining gel at 1400°C and attrition milling could be sintered to >98% (theoretical density) at 1650°C for 1.5 h. The flexural strength of the sintered body at room temperature was 405 MPa and 350 MPa at 1300°C. Only traces of a secondary phase were observed along the grain boundary.     

Microstructure and Mechanical Properties of Porous Alumina Ceramics Fabricated by the Decomposition of Aluminum Hydroxide

The mechanical properties of Al₂O₃-based porous ceramics fabricated from pure Al₂O₃ powder and the mixtures with Al(OH)₃ were investigated. The fracture strength of the porous Al₂O₃ specimens sintered from the mixture was substantially higher than that of the pure Al₂O₃ sintered specimens because of strong grain bonding that resulted from the fine Al₂O₃ grains produced by the decomposition of Al(OH)₃. However, the elastic modulus of the porous Al₂O₃ specimens did not increase with the incorporation of Al(OH)₃, so that the strain to failure of the porous Al₂O₃ ceramics increased considerably, especially in the specimens with high porosity, because of the unique pore structures related to the large original Al(OH)₃ particles. Fracture toughness also increased with the addition of Al(OH)₃ in the specimens with higher porosity. However, fracture toughness did not improve in the specimens with lower porosity because of the fracture-mode transition from intergranular, at higher porosity, to transgranular, at lower porosity.     

以冰为模板制备氧化铝多孔陶瓷及其结构特征

以水玻璃溶液为粘结剂,以冰为造孔模板制备氧化铝多孔陶瓷。采用扫描电镜观测多孔陶瓷的显微结构。结果表明,冰是一种理想的造孔模板,浆体特性对多孔陶瓷结构影响较大,当浆体中相对固相含量增大,多孔陶瓷的孔隙会减小;当浆体粘度降低,易得到片层状与微孔复合结构的多孔陶瓷。     

Carbon Oxidation Reaction over Pt/Spherical Alumina Beads Catalysts Prepared by Sputtering Method

Pt catalysts supported on Al₂O₃ beads prepared by a sputter deposition method showed the higher surface concentration of Pt than impregnated Pt catalysts. The catalytic activities of the oxidation of acetylene carbon black over the sputtered Pt catalysts were higher than those over the impregnated Pt catalysts with the same Pt content.     

Controlling Mechanical Properties of Porous Mullite/Alumina Mixtures Via Precursor-Derived Alumina

This study focuses broadly on synthesis and characterization of porous mullite/alumina mixtures for use as matrices in oxide fiber composites. Specifically, an assessment is made of the utility of a precursor-derived alumina (PDA) in controlling both the modulus and the toughness of mullite-rich particle mixtures. Property changes are probed through models of the mechanical behavior of bonded particle aggregates. Consideration of the conditions needed to cause crack deflection at a fiber–matrix interface yields an upper allowable limit on the concentration of PDA to ensure damage tolerance in a fiber composite. The predicted critical concentration lies in the range of about 7–9%, depending on the mullite/alumina ratio in the particle slurry and the subsequent aging treatment. Values slightly below this limit should yield composites that exhibit a desirable balance between fiber- and matrix-dominated properties.     

过滤器用氧化铝多孔陶瓷

以氧化铝为原料 ,用碳化硅和活化剂混合物作粘合剂 ,用碳酸氢铵作发泡剂制得了过滤器用氧化铝多孔陶瓷 ,并研究了添加剂量和烧成温度对陶瓷气孔率和强度的影响     

Properties of Modified Anodic-Spark-Deposited Alumina Porous Ceramic Films as Humidity Sensors

α-Alumina films formed by anodic spark deposition in the melt of NaHSO₄-KHSO₄ mixture (200°C) exhibited a porous structure. It has been found that the porosity and amount of α-phase varied with anodic current density. By electrical measurements, films were found to exhibit a continuous open-pore structure, causing failure of humidity sensors. This problem can be overcome by reanodization of the anodicspark-deposited alumina films in either borax aqueous solution or sulfuric acid solution for a short time to form an effective barrier layer at the pore base. The modified anodic-spark-deposited alumina films showed highly sensitive response to water vapor change in the range of −76° to +20°C dew point with much improved long-term stability. The humidity characteristics of the α-alumina films were qualitatively explained in terms of the BET theory and condensation theory.     

Porous Titania Ceramic Prepared by Mimicking Silicified Wood

A porous titania ceramic with a woodlike microstructure that was analogous to silicified wood was prepared. The production of "titanified wood" was performed using the following process: (i) introduction of titanium tetraisopropoxide into wood materials via vacuum infiltration, (ii) hydrolysis of the titanium tetraisopropoxide in the cell structure to form a titania gel, and (iii) firing at a temperature of 600°–1400°C in air. The resulting titania ceramic had the same external and internal forms of the original wood.     

造孔剂法制备多孔生物玻璃陶瓷的工艺研究

通过造孔剂法,以溶胶-凝胶法制备的生物玻璃58S和熔融法制备的生物玻璃45S5为原料,以NH4 HCO3与淀粉的混合物为造孔剂制备生物玻璃陶瓷.利用XRD和SEM等材料分析测试手段研究了烧成温度、造孔剂添加量、成型压力及45S5的用量对多孔材料显微结构、表面形貌、抗折强度的影响.结果表明:在成型压力20 MPa,造孔剂含量60％,烧成温度800℃及45S5的加入量10％的工艺参数下,制备出抗折强度达到4.5 MPa,孔隙率达到68.74％的珊瑚状结构的多孔生物玻璃陶瓷材料.