纳米TiO2/氟硅烷涂层的自清洁性研究

基于纳米TiO_2/氟硅烷在紫外光照射下由疏水转变为超亲水的特性,制备了纳米TiO_2/氟硅烷涂层,并进行水接触角测试,发现在紫外光照射下其接触角由近150°降低到接近0°,实现从超疏水转变为超亲水,具有良好的自清洁效果。为探究纳米TiO_2含量、紫外光照射时间及不同基材对自清洁性能的影响,进行了正交试验。结果表明:在254 nm紫外光照射下,纳米TiO_2/氟硅烷涂层对自清洁性能的影响程度为紫外光照射时间基材种类纳米TiO_2含量;在365 nm紫外光照射下的影响程度为基材种类紫外光照射时间纳米TiO_2含量。     

建筑卫生陶瓷表面纳米晶氧化钛膜层的涂覆技术研究

本文针对纳米厚度氧化钛涂层均匀性的问题,研究陶瓷釉面上,纳米晶氧化钛溶胶的涂覆方法和相应工艺参数,及其对陶瓷表面亲水特性的影响.所得最佳涂覆工艺为：采用擦涂法,以细毛绒布为擦涂介质,溶胶固体含量为0.5％,擦涂三次后,在400℃的温度下处理30 min.为了强化亲水性,采用365 nm的紫外光照射60 min,可获得接触角小于1°的亲水涂层.     

有机硅烷共缩合制备抗紫外超疏水减反射涂层

具有超疏水自洁功能的减反射涂层对太阳能光热组件在室外长期使用上有重要的意义,可以减少减反射涂层的清洗成本,延长减反射涂层的使用寿命。利用含有甲基和乙基等疏水基团的有机硅氧烷制备具有一定孔隙率的涂层,有望实现减反射和超疏水双重性能。本研究采用四甲氧基硅烷（TMOS）和甲基三乙氧基硅烷（MTES）共缩合,并利用甲氧基三甲基硅烷（MMS）进行羟基封端,制备了可以稳定两个月以上的均一溶胶。通过控制MTES和TMOS的水解工艺条件,采用浸渍提拉法制备了在400～800nm可见光波段平均透光率为97.06%、最高透光率为98.27%、水接触角为165°的超疏水减反射涂层,提出了MTES/TMOS/MMS溶胶的共缩合反应机理。涂层经过紫外耐久测试1080h后,涂层仍具有良好的减反射性能、疏水性和抗刻划强度,表现出良好的紫外耐久性。     

自清洁TiO2薄膜的制备与表征

以钛酸丁酯为钛源,采用溶胶凝胶法制备出降解率可达到83％的Ag—TiO2光催化薄膜。运用红外光谱、热重／差热以及原子力显微镜等分析方法对光催化剂进行了测定和表征。结果表明：光催化薄膜由粒径为10～20nm的AgNO,和TiO2颗粒构成,锐钛晶形结构在500～550℃转变充分。从光催化剂胶体的FTIR谱图看出,制备的具有超亲水性能的SiO2／TiO2薄膜符合结构组成;从水接触图及冲洗图中可以清楚地看出：制备的TiO2／SiO2薄膜水接触角最小约4°,其自清洁效果很好。对Ag—TiO2光催化薄膜和SiO2／TiO2薄膜进行了硅藻吸附能力测试分析。     

自清洁阻燃型可见光催化降解汽车尾气涂层的制备与性能研究

采用水性乳液作为涂层成膜物质,以改性TiO2为可见光催化材料,制备得到可见光催化降解汽车尾气涂层,并通过在涂料组成中引入阻燃剂和自清洁助剂组分,使可见光催化涂层具有一定的阻燃性和自清洁能力.首先对涂层的基本性能进行了系统的测试和研究,利用自主设计的可见光催化降解尾气涂层性能评价装置研究涂层的尾气降解性能;利用热重分析、接触角、防玷污性等手段研究了不同掺量阻燃剂和自清洁助剂涂层的阻燃性和自清洁性能.测试结果表明:该涂层铅笔硬度,拉拔强度,附着力和耐老化性能良好,2 h内对NOx、CO、CO2的催化降解效率依次为67.40％、25.10％、27.64％;涂层厚度1 mm时,耐火极限最终平稳温度为300℃;与水的接触角高达159°,耐沾污性等级≤2.     

亲水膜表面处理对空气冷却器运行能耗的影响

采用溶胶-凝胶技术在铝箔表面涂覆有机涂层,并制备了有机亲水涂层空气冷却器,介绍了在低温化工领域有机涂层对空气冷却器换热效率的影响。并采用实验方法测试了采用亲水涂层和未采用亲水涂层的空气冷却器在四个除霜周期中的运行能耗并进行了对比分析。实验结果表明:有机亲水涂层空气冷却器表面有较好的润湿性能,可以提高空气冷却器的换热效率。在经过多个除霜周期后,有机亲水涂层依旧保持良好的亲水性。     

超疏水SiO2@OTES自清洁涂层的制备及性能

以纳米二氧化硅颗粒、正辛基三乙氧基硅烷(OTES)和硅烷偶联剂KH560为前驱体,采用溶胶凝胶法制备了超疏水SiO₂@OTES自清洁涂层。在酸性催化剂及有机溶剂中,OTES、KH560将纳米颗粒表面由亲水改性为疏水。探究了纳米SiO₂、OTES、KH560三种原材料含量对超疏水涂层润湿性能的影响。结果表明,当掺杂3.5 g纳米SiO₂,8%的OTES与2%的KH560时,涂层达到最佳疏水效果,其接触角为(154±1)°,滚动角为(3.3±0.5)°。采用SEM、FTIR红外光谱仪、X射线光电子能谱(XPS)对超疏水SiO₂@OTES材料的表面形貌与化学成分进行了表征。实验表明制备出的超疏水SiO₂@OTES自清洁涂层具有良好的自清洁防污、耐低温与耐磨性能,且将涂层回收重新制得的表面仍具有超疏水性。     

TiO2溶胶的制备以及在建筑陶瓷中的应用

以钛酸丁酯[Ti(OB)4],无水乙醇,乙酰丙酮(AcAc)等为原料,采用溶胶-凝胶和喷涂方法制备自清洁瓷砖。以油酸为有机污染模拟物,研究了TiO2薄膜厚度及热处理制度等工艺因素对自清洁性能的影响。结果表明当热处理温度450℃、保温40~60min、膜厚在60~70nm,可以获得光催化性能优良的自清洁瓷砖。采用XRD等测试手段对薄膜的物相组成等进行了表征,揭示了瓷砖自清洁性能与薄膜结构之间的关系。     

面向陶瓷表面自清洁和防覆冰应用的耐候性石墨烯超疏水涂层制备

超疏水涂层应用广泛，尤其在解决陶瓷表面自清洁、防覆冰等方面具有重要的应用价值。本文采用石墨烯与甲基硅树脂为主要原料制备超疏水涂料，结合喷涂和热处理技术在陶瓷基体表面制备了石墨烯超疏水涂层。实验对该涂层的显微结构和基团组成进行测试分析，探究了石墨烯超疏水涂层的自清洁性能和防覆冰功能，并通过长期户外实验，考察涂层的耐候性。结果表明：当甲基硅树脂溶液添加量为150μL、热处理温度为200℃时，制备的石墨烯涂层具备最佳的超疏水性能。采用该超疏水涂层修饰的陶瓷表面，具备优异的自清洁和防覆冰功能，以及长期户外耐候性。     

纳米三氧化二铁改性聚酰亚胺的研究

采用化学合成法及溶胶凝胶工艺制备了聚酰亚胺(PI)/纳米Fe2O3复合材料,采用古埃法、傅立叶变换红外光谱分析、吸水性能测试、拉伸性能测试等表征了材料的结构及特有的超顺磁性.结果表明,PL/纳米Fe2O3复合材料与纯PI相比具有超顺磁性,且其拉伸强度大幅提高,吸水率下降.     

浸渍工艺及烧成温度对SiO2纳滤膜微观结构的影响

以平均粒径为10 nm和80 nm的硅溶胶为主要原料,采用浸渍提拉法在50 nm超滤支撑体上制备了SiO2纳滤膜.研究了烧成温度对膜层密度和气孔率、物相组成、热膨胀及显微结构的影响,探讨了溶胶浓度与膜厚度的关系,确定了合适的烧结温度和镀膜工艺.结果表明:随烧结温度升高至800℃以上时,SiO2纳滤膜的密度显著提高,在850℃以上会析出方石英相,导致其在200℃左右因方石英相变而出现膨胀突变;600℃和700℃分别是10 nm和80 nm硅溶胶制备的SiO2纳滤膜的合适烧结温度;以浓度为16.9wt％的10 nm硅溶胶镀膜在600℃烧成后可以形成微结构均匀、厚度约1μm的SiO2纳滤膜.     

平板α-Al2O3陶瓷微滤膜的制备与表征

采用固态粒子烧结法和浸拉提渍工艺研制出α-Al2O3平板式陶瓷微滤膜,探讨涂膜液中固含量对膜孔径及纯水通量的影响,并研究涂层工艺及烧成制度对膜形成的作用。同时对微滤膜的孔径大小及分布,膜孔隙率、纯水通量及抗弯强度等性能进行表征。实验结果表明,制备出平均孔径为0.7μm的平板陶瓷膜,其具有表面性质连续完整、孔径分布窄以及机械强度大的特点。     

甲醛在水泥基涂层中的吸附扩散研究

以白水泥为胶凝材料,添加重钙、滑石粉等填料、助剂,制备了不同厚度的水泥基涂层,使用双仓法研究了甲醛在涂层中的吸附、扩散行为.同时,利用X射线衍射仪(XRD)、扫描电镜(SEM)、压汞仪(MIP)、氮气吸附仪表征了涂层材料的物相、结构等性质,并对吸附、扩散机理进行了探讨.结果表明,甲醛在水泥基涂层中具有扩散能力,扩散量随厚度呈现线性减小趋势,扩散的临界厚度为3 mm.涂层对甲醛具有吸附能力,吸附量随时间、厚度呈现一阶指数增长变化规律.表征测试显示涂层微观呈多孔性,总孔隙率为36.5％,孔径范围为3.6 nm～212.7μm,具有大孔、中孔结构.涂层的多孔结构是其具有吸附、扩散能力的结构基础,而矿物表面吸附与过渡扩散共同作用是影响吸附、扩散的主要机制.     

溶胶-凝胶法制备二氧化硅无机膜的实验研究

以正硅酸乙酯为先驱体,用溶胶-凝胶法在A l2O3基体上制备了SiO2无机膜。重点考察了涂膜温度、溶胶浓度及添加剂对膜性能的影响。结果表明:在较高的温度下涂膜可以提高膜的性能;采用浓溶胶和稀溶胶结合的方式涂膜不但可以提高制膜效率,还可以提高膜的性能。添加剂DMF能够均化膜孔径,提高膜的性能。     

Preparation of alumina membranes for micro- and ultrafiltration applications

Abstract

A very thin disc type ceramic membrane (0·3-0·8 mm thickness, 25-30 mm diameter) made of pure alumina and suitable for microfiltration applications has been prepared by a tape casting process. A sol coating was applied to the disc to form an ultrafiltration membrane. T he pore size of the membrane could be varied in the range 0·1-0·7 μ m and porosity in the range 25-55% by optimising the ex perimental parameters. The most important factor for determining the pore size of the membrane was found to be the initial particle size distribution of the ceramic powder. Firing temperature and soaking time are other crucial parameters affecting volumetric porosity. Water permeability through the membrane under suction and under positive pressure is comparable with that of ceramic membranes prepared by conventional methods. In addition, a typical membrane shows a very narrow pore size distribution in the range 0·1-0·4 μm, with a median pore size of 0·28 μm. A very sharp drop in the pore size distribution pattern around 0·4 μm indicates that no pores larger than this exist. This implies that all particles with radius > 0·4 μm are trapped in the membrane, providing excellent separation efficiency. Results of microbial separation tests confirmed the possibility of micro-organism separation through these membranes.     

Production of meso- and giga-porous zirconia particles — An improved multi-step particle aggregation process

Macro- and giga-porous zirconia supports were prepared from a 20% colloidal sol of zirconia (ZrO₂) by a combination of a polymer-induced colloid aggregation (PICA) process and the oil emulsion (OE) method. The effect of the pH of the initial sol on the size of the PICA particles, and subsequently on the final product, made by oil-emulsion assisted aggregation of the PICA particles was thoroughly investigated. Both the PICA and the OE methods were further optimized for performance. Particle morphology and porosity of the resultant particles were characterized by scanning electron microscopy, mercury intrusion-extrusion porosimetry, and nitrogen adsorption-desorption sorptometry. The supports were comprised of stable aggregates of 50-250 μm in size. The pore and throat size distributions showed narrow bi-modal distributions over two distinct size scales: 10-100 nm and 600-3000 nm. In addition, different combinations of aggregation techniques and porous supports prepared in previous steps for use in a subsequent aggregation were evaluated. Optimal amounts of zirconia sol and 10-100 micron porous spherical particles produced by the OE method in an earlier step were combined in an additional OE process to yield stable giga-porous supports. Porous zirconia particles obtained after calcination and sintering had particle sizes of 0.15-3.5 mm and multimodal pore and throat distributions over a range of 50 nm-8 μm.     

溶胶凝胶法制备SiO2气凝胶/石英纤维增强石英复合材料及其性能表征

以正硅酸乙酯、无水乙醇、去离子水为原料制备胶液后,真空浸渍石英纤维复合材料,经固化、超临界干燥成型、表面改性等工艺使其内部填充纳米级的SiO2.利用阿基米德法测试了材料的吸水率和显气孔率,利用BET法和短路波导法对气凝胶的比表面积和孔径以及材料的介电性能进行了表征,并分析了憎水机理.结果表明,填充前后复合材料的吸湿率由最初的17.36%降至1.21%,降幅高达93%,辅以防潮涂层后吸湿率更可低至为0.052%;介电常数基本没有变化,损耗角正切有所降低,降幅最高达51.2%.     

Preparation and characterization of mesoporous γ-Al2O3 membranes

以粒径为0.3～0.4 μm的α-Al₂O₃为原料,通过悬浮液真空抽吸法,制备出平均孔径约为70 nm的完整无缺陷的片状α-Al₂O₃支撑体;以仲丁醇铝为前驱体,采用颗粒溶胶路线制备出稳定的Boehmite溶胶,以此溶胶采用浸浆法,在制备的α-Al₂O₃支撑体上制备出完整无缺陷的γ-Al₂O₃中孔膜,并考察了烧成温度对γ-Al₂O₃中孔膜性能的影响。结果表明,本文制备出的γ-Al₂ O₃膜的孔径约为3 nm,对PEG的截留分子量为2800～5300,纯水渗透通量为11.5～25.9 L.m^-2.h^-1［7.6×10⁵ Pa,（14±1）℃］。说明在孔径为70 nm左右的载体上直接制备孔径为3 nm的完整的中孔膜是可行的。     

超声场对锆溶胶的影响研究

研究了超声场分布、超声时间和超声功率对锆溶胶粒径分布的影响,还表征了超声场分散溶胶所制的非担载膜的性能。实验结果表明:扩散场处理的溶胶粒径分布比驻波场处理的溶胶粒径分布略窄;提高超声功率有助于减小溶胶粒径,超声时间的增加,溶胶粒径逐渐减小,且超声处理过的溶胶稳定性得到提高;超声处理的溶胶和未超声处理的溶胶所制得的非担载膜最可几孔径均为4 nm,但前者的比表面积和孔体积略有下降。     

Assembly of 8YSZ nanoparticles into gas-tight 1-2 μm thick 8YSZ electrolyte layers using wet coating methods

The application of a thin film electrolyte layer with a thickness in the micrometer range could greatly improve current solid oxide fuel cells (SOFCs) in terms of operating temperature and power output. Since the achievable minimal layer thickness with conventional powder coating methods is limited to ∼5 μm, a variety of thin film methods have been studied, but results on regular large-scale anode substrates are still lacking in the literature. In this paper, a wet coating process is presented for fabricating gas-tight 1-2 μm thick 8YSZ electrolyte layers on a regular NiO/8YSZ substrate, with a rough surface, a high porosity and a large pore size. These layers were deposited in a similar way as conventional suspension based layers, but the essential difference includes the use of coating liquids (nano-dispersion, sol) with a considerably smaller particle size (85 nm, 60 nm, 35 nm, 6 nm). Successful deposition of such layers was accomplished by means of an innovative coating process, which involves the preparation of a hybrid polyvinyl alcohol/8YSZ membrane by dip-coating or spin-coating and subsequently burning out the polymer part at 500 °C. Results from He leak tests confirmed that the sintered layers posses a very low number of defects and with values in the range 10⁻⁴-10⁻⁶ (hPa dm³)/(s cm²) the gas-tightness of the thin film layers is satisfactory for fuel cell operation. Moreover, preliminary results have also indicated a potential reduction of the sintering temperature from 1400 °C to the range 1200-1300 °C, using the presented coating process.