无机铝溶胶可纺性的研究

无机铝溶胶可纺性的研究薛明俊，周世，王淙，邱天，赵艳华，冯俊军（华东理工大学２００２３７）ＩｎｖｅｓｔｉｇａｔｉｏｎｏｆｔｈｅＳｐｉｎｎａｂｉｌｉｔｙｏｆＩｎｏｒｇａｎｉｃＡｌｕｍｉｎａＳｏｌｕｔｉｏｎ￥ＸｕｅＭｉｎｇｊｕｎ；ＺｈｏｕＳｈｉｇｕｉ；Ｗ...     

Sol-Gel技术制备锆溶胶的研究

以廉价无机盐氧氯化锆（ZrOCl·28H2O）为起始原料,采用溶胶-凝胶（Sol-Gel）技术合成出锆溶胶,并探讨了制备过程中各种因素对锆溶胶性质的影响。     

溶胶-凝胶法制备钇掺杂的纳米氧化锆粉体

以廉价的无机盐氯氧化锆、硝酸钇、草酸为原料，在不同的溶剂体系条件下，采用溶胶—凝胶法进行钇掺杂的ZrO2（YSZ）纳米粉体的制备研究，并通过扫描电子显微镜（SEM）、热重—差热（TG／DTA）分析、X射线粉末衍射（XRD）等手段对该粉体进行表征。结果表明：两种溶剂体系下制得的干凝胶在650℃，3h热处理，都得到了Y完全固溶、球形、立方相、分散性好的纳米YSZ粉体。     

溶胶-凝胶法制备超细氧化镁陶瓷纤维

以碱式碳酸镁和柠檬酸为原料,采用溶胶- 凝胶法成功制得超细氧化镁陶瓷纤维,并应用红外光 谱仪(FTIR)分析了胶体的形成;应用DSC分析了凝 胶前驱体的热处理过程;通过XRD、SEM分析和观察 了凝胶前驱体纤维及其于450℃热处理后所得到的 超细氧化镁陶瓷纤维的形貌和结构。结果表明:凝胶 的可纺性主要受合成反应溶液中柠檬酸与镁离子物 质的量比、溶液的pH值及搅拌时间的影响,在柠檬 酸与镁离子的物质的量比为2,溶液的pH值在4.0 ～5.0,搅拌时间为16～18h的条件下,制得的凝胶 具有较好的可纺性;凝胶的热分解经历脱水、分解及 氧化镁的形成3个阶段,前驱体凝胶纤维经450℃保 温0.5h处理后,可得到直径均匀,表面光滑、致密的 超细氧化镁陶瓷纤维,其直径可在1μm以下。     

溶胶纺丝法制备氧化锆纤维研究进展

溶胶凝胶法制备可纺性锆溶胶的常见体系以及几种纺丝方法,并对其进行了对比;对凝胶纤维的热处理进行了阐述,强调了气氛预烧结的重要性。     

溶胶凝胶法制备锆-钴高温防氧化粉体

在调节剂柠檬酸铵的作用下,采用溶胶凝胶法制备了Y稳定的Zr-Co粉体,经高温烧结制得致密陶瓷薄膜。利用场发射扫描电镜（SEM）表征了Zr-Co粉体的形貌特征和烧结后的陶瓷薄膜结构,热重（TG／DTA）分析了Zr-Co粉体烧结过程的失重和相转变吸放热过程,X射线衍射（XRD）分析跟踪了不同温度段烧结体系的组成变化趋势,在此基础上对粉体烧结后陶瓷薄膜的防氧化效果进行了分析,结果表明：温度对粉体的颗粒形貌和晶相结构有较大的影响,高温烧结的粉体性质稳定,经过1200℃烧结后的陶瓷膜层具有很好的致密性,具有很好的防氧化效果。     

Enhanced corrosion resistance of magnesia-chrome refractories impregnated with zirconia sol

In order to enhance the corrosion resistance to molten vanadates and silicates of middle and upper checker bricks in glass furnace regenerator with petroleum coke as fuel, the present research improved the microstructure, compactness and corrosion resistance of magnesia-chrome refractories by vacuum impregnation with zirconia sol. The results show that the vacuum impregnation of zirconia sol and the increased impregnation times led to the significant increase in the bulk density and decrease in the apparent porosity of refractories, and the impregnated zirconia particles enhanced the corrosion and penetration resistance. The penetrated zirconia particles in the pores decreased the porosity and pore size of refractories, resulting in the inhibited penetration of vanadate and silicate liquid phases during the corrosion process. In addition, the zirconia particles around periclase particles also prevented the reaction between molten corrosion reagent and periclase, thus enhancing the corrosion resistance of refractories. The present study provides an effective method for improving the corrosion resistance of magnesia-chrome checker bricks in regenerator of glass furnace with petroleum coke as fuel.     

正交实验法研究SiO_2溶胶稳定性

以正硅酸四乙酯(TEOS)、乙醇(EtOH)、H2O为原料,HCl为催化剂,N,N-二甲基甲酰胺(DMF)为添加剂,采用溶胶-凝胶法制备了Si O2溶胶。利用正交实验考察温度、EtOH、H2O、DMF、pH值对Si O2溶胶稳定性的影响。结果表明,对溶胶稳定性影响的强弱程度为EtOHH2O温度DMFpH值。n(EtOH)对溶胶稳定性影响最大,随着n(EtOH)增加,溶胶稳定性升高。其次是n(H2O)与温度的影响,溶胶稳定性随着n(H2O)增加而升高,随温度升高溶而降低。随n(DMF)增加,溶胶稳定性升高。在酸性条件下,溶胶稳定性随pH值增大而升高。     

Effect of sol size on nanofiltration performance of a sol-gel derived microporous zirconia membrane

This paper reports the effect of sol size on nanofiltration performances of sol–gel derived microporous zirconia membranes. Microstructure, pure water flux, molecular weight cut-off (MWCO) and salt retention of zirconia membranes derived from zirconia sols with different sizes were characterized. Thermal evolution, phase compo-sition, microstructure and chemical stability of unsupported zirconia membranes (powder) were determined by thermogravimetric and differential thermal analysis, X-ray diffraction, nitrogen adsorption–desorption and static solubility measurements. Results show that nanofiltration performance of zirconia membranes is highly depen-dent on sol size. The sol with an average size of 3.8 nm, which is smaller than the pore size of theγ-Al2O3 support (pore size:5–6 nm), forms a discontinuous zirconia separation layer because of excessive penetration of sol into the support. This zirconia membrane displays a MWCO value towards polyethylene glycol higher than 4000 Da. A smooth and defect-free zirconia membrane with a MWCO value of 1195 Da (pore size:1.75 nm) and relative high retention rates towards MgCl2 (76%) and CaCl2 (64%) was successfully fabricated by dip-coating the sol with an appropriate size of 8.6 nm. Zirconia sol with an average size of 12 nm exhibits colloidal nature and forms a zirconia membrane with a MWCO value of 2332 Da (pore size:2.47 nm). This promising microporous zirconia membrane presents sufficiently high chemical stability in a wide pH range of 1–12.     

溶胶-凝胶法制备可纺莫来石溶胶的特性研究

以水作为分散剂,以异丙醇铝、氯化铝和正硅酸乙酯为原料,盐酸和醋酸做复合催化剂,聚乙烯醇为纺丝助剂,采用溶胶-凝胶法合成了可纺莫来石溶胶,并分析了获得适宜拉丝性的原料的较佳配比、不同水解时间对后续热处理的影响及溶胶粘度与温度的关系,为制取连续莫来石纤维提供必要借鉴.采用DTA-TG,IR,XRD及旋转粘度计分析测试了胶体各方面的性能.     

Hydrothermal synthesis of monoclinic zirconia sol

In this study, we demonstrate a synthetic method of zirconia sol using ZrO(NO₃)₂·xH₂O as Zr⁴⁺ precursor, tetramethylammonium hydroxide as mineralizer, and oxalic acid as a complexing agent. X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and UV–vis adsorption spectroscopy were used to characterize the nanocrystals. The effect of oxalic acid content on the growth of zirconia nanocrystals was investigated. Zirconia sol cannot be synthesized without oxalic acid. The oxalic acid content has no obvious effect on the phase formation of monoclinic zirconia. The transparent and monoclinic zirconia sol with particle size <10 nm was synthesized. This provides a new hydrothermal system for the synthesis of zirconia sol.     

Effect of mixed-shaped silica sol abrasives on surface roughness and material removal rate of zirconia ceramic cover

Zirconia ceramic, as mobile phone body-materials, will become increasingly important with the coming of 5G communication technology. Surface quality and material removal rate of zirconia ceramic cover are vital factors to determine its wide application. Therefore, mixed-shaped silica sol abrasives were prepared by ion connecting-inducting method and applied to achieve a good surface quality and a high material removal rate on zirconia ceramic cover by using chemical mechanical polishing (CMP). Mixed-shaped silica sol abrasives contained spherical and beaded shapes were measured by scanning electron microscopy (SEM). Si–O–Al bonds were formed in the mixed-shaped silica sol abrasives and were proved by X-ray photoelectron spectroscopy (XPS). Results of CMP tests showed that zirconia ceramic cover obtained a low surface roughness of 1.824 nm and an efficient material removal rate of 0.33 μm/h. Compared with traditional spherical silica sol abrasives, the polishing rate of mixed-shaped silica sol abrasives increased by 242%. Additionally, solid-phase chemical reactions happened to formed ZrSiO₄, ZrAl₂Si₂O₉ in the CMP process. Moreover, friction coefficient was tested and polishing mechanism had been explored by a contact-friction model in this work.     

Preparation of zirconia powders by sol-gel route of sodium glycozirconate complex

Zirconia powders were prepared by a sol-gel method, using sodium glycozirconate complex as precursor synthesized via the Oxide One Pot Synthesis (OOPS) process. Gelation of this precursor was achieved through the variation of the hydrolysis ratio without the use of the dopants. The gel samples were also calcined at different temperatures. The resulting zirconia was characterized using X-ray diffraction (XRD), SEM and nitrogen adsorption/desorption. The solid materials obtained after heat treatment at 500 °C by varying the hydrolysis ratio have large surface areas of 154-220 m² g⁻¹ and a narrow pore size distribution in the mesopore region. By variation of the heat treatment, the zirconia xerogels existed in either an amorphous, tetragonal, or monoclinic form at room temperature. Based on XRD data the first identifiable crystalline structure developed from the amorphous phase was the tetragonal polymorph, which was formed between 500 and 800 °C. When the temperature was raised to 1000 °C, zirconia powder with a monoclinic structure was obtained. Surface areas about 280 m² g⁻¹ was obtained after calcination at 400 °C, which drop to ca. 70 m² g⁻¹ following treatment at 1000 °C.     

锆质溶胶的制备与性能表征

采用工业ZrOCl2.8H2O,结合非均匀沉淀法及水热法制备了锆溶胶。系统分析了不同浓度的前躯体溶液、pH值以及缓冲溶液等因素对制备的锆溶胶粒径、稳定性的影响。通过非均匀沉淀法,在室温条件下,缓慢将氨水与氧氯化锆溶液滴加至缓冲溶液中,制得前驱体沉淀,经抽滤洗涤后用硝酸重新分散滤饼,于75℃水浴加热5~12 h,制得澄清透明状纳米级锆质溶胶。结果表明,溶胶中粒子呈伞状、柱状,且分散均匀。溶胶粒子大小为12~15 nm。在pH值为0.8~1.4条件下,溶胶能长期稳定存在。干燥后的锆质凝胶以非晶态形式存在,且非晶态凝胶在450℃左右转变为四方相ZrO2。经1100℃热处理,保温1 h转变为单斜相ZrO2。     

锐钛矿型F-TiO2溶胶光催化剂的制备及表征

引言 二氧化钛溶胶光催化剂由于具有粒子颗粒度小、催化活性高、容易固载到基质材料上等优点而受到了广泛的关注.