溶胶-凝胶法合成(Na0.5Bi0.5)TiO3微粉

以钛酸四丁酯、硝酸铋、醋酸钠和冰醋酸为原料,利用溶胶-凝胶工艺得到透明凝胶,经干燥后煅烧成(Na0.5Bi0.5)TiO3微粉。通过对溶胶体系水/醇盐的摩尔比、初始pH值及胶凝温度对(Na0.5Bi0.5)TiO3凝胶体系溶胶-凝胶形成过程影响的研究,发现水/醇盐比R在35≤R≤60,pH在2.2~3.5,反应温度在40~60℃时,能够得到透明的溶胶;通过TG-DTA、SEM、X-ray等分析手段对(Na0.5Bi0.5)TiO3粉体进行测试,表明在650℃合成1h可以得到单一钙钛矿(Na0.5Bi0.5)TiO3晶体;采用TEM对(Na0.5Bi0.5)TiO3干凝胶粉体分析其粒径大小约为10nm。     

TiCl4乙醇溶液溶胶--凝胶转变过程的研究

以TiCl4作为前驱体,乙醇作为溶剂制备TiO2溶胶,系统研究了TiO2胶体的溶胶-凝胶转变过程,讨论了不同参数(如温度、浓度等)因素对溶胶体系胶凝时间的影响,并对该过程的活化能进行了计算。研究结果表明,TiCl4在与乙醇混合形成溶液的过程中,即与乙醇及乙醇中的微量水发生醇解和部分水解反应,通过脱氯形成钛醇盐。在随后长时间的成胶化过程中,主要是钛醇盐吸收气氛中的水气发生水解缩聚反应,最终形成无机聚合物凝胶。体系的活化能与TiCl4的初始浓度有关。     

SDS/正丁醇/正庚烷/水微乳液稳定性分析及应用

研究了十二烷基硫酸钠(SDS)/正丁醇/正庚烷/水(或氯化镁与硝酸铝混合水溶液或氢氧化钠溶液)四组分形成稳定微乳液的条件。考察了表面活性剂与助表面活性剂的质量比、温度、pH值、盐浓度对该体系稳定性的影响及水与表面活性剂的摩尔比(ωo)对水核粒径的影响。结果表明,m(SDS)∶m(正丁醇)=4∶6时,反相微乳液最稳定,对温度变化不敏感,pH值为7～13时,具有较好的稳定性,随着镁铝混合盐溶液浓度的增加,反相微乳区域急剧缩小,水核粒径随着ωo增大而增大,在稳定微乳液区域内制备了分布较均匀,尺寸范围30～70 nm的粒状纳米颗粒。     

溶胶-凝胶法制备钛酸铝薄膜的工艺研究

采用溶胶-凝胶法,以钛酸四丁酯(Ti(OC4H9)4)和硝酸铝(Al(NO3)3.9H2O)为前驱体,乙醇为溶剂,利用硝酸铝中所含的结晶水进行水解反应,制备了适于镀膜的钛酸铝溶胶。利用旋转粘度计、光学显微镜和SEM研究了水解抑制剂种类及用量、pH值、前驱体浓度、陈化时间等因素对镀膜效果的影响。在此基础上,采用浸渍-提拉法经过三次镀膜在碳化硅基片上成功制备出均匀、致密的钛酸铝薄膜。     

溶胶凝胶法合成超细钙长石的工艺研究

采用无机盐前驱体原料硝酸铝和硝酸钙取代金属醇盐 ,以溶胶凝胶法制备超细钙长石粉末 ,对影响合成的反应温度、浓度、烧成制度、pH值、工艺路线等进行了系统的研究 ,得到比较好的工艺参数。本制备工艺简单 ,成本较低 ,为钙长石的工业化生产奠定了基础。     

铝溶胶的制备条件对其凝胶成球性能的影响

以硝酸和拟薄水铝石为原料制备了铝溶胶,考察了x(H+/Al摩尔比)和φ(六亚甲基四胺溶液与硝酸溶液的体积比)值对铝溶胶在油中凝胶成球性能的影响。使用氧化铝颗粒的Zingg指数对铝溶胶制备条件进行了评价。结果表明:铝溶胶和半透明铝溶胶的制备条件是x分别大于0.05和0.07;增大x和φ值均利于铝溶胶的凝胶化,但过大的x和φ值不利于溶胶收缩成球;Zingg曲线在1附近的平稳区间对应的x和φ值是合适的铝溶胶制备条件。     

醇盐水解法制备高纯镁铝尖晶石粉体

以金属Mg、AL与正丁醇为原料,采用溶胶凝胶法合成平均粒径在25～35 μm之间的高纯镁铝尖晶石超微粉体.将金属Mg、Al同时加入正丁醇中反应,得到高纯度镁铝双金属醇盐,并通过红外光谱分析研究醇盐的结构.经过对醇盐水解反应的正交实验研究,确定了最优的水解条件.干凝胶在700℃煅烧开始出现镁铝尖晶石相,并于1 200℃形成晶相完全的镁铝尖晶石粉体.     

异丙醇钛控制水解的小角X射线散射

由金属醇盐水解制备溶胶的方法已广泛应用于溶胶-凝胶法制备纳米孔无机膜,但对金属醇盐水解机理的认识十分有限。通过控制异丙醇钛[Ti(i-OC_3H_7)4]在异丙醇(i-C_3H_7OH)中水解制备TiO_2溶胶,利用小角X射线散射(SAXS)方法研究了由不同H_2O/Ti(i-OC_3H_7)4的反应混合物[Ti(i-OC_3H_7)4:H_2O:i-C_3H_7OH=1:m:30(摩尔比)]形成TiO_2溶胶的过程,探讨了控制Ti(i-OC_3H_7)4水解的过程中胶粒形成与长大的规律。研究结果表明,所合成的TiO_2溶胶的胶粒粒径小于10 nm,胶粒的形成和长大与H_2O/Ti(i-OC_3H_7)4摩尔比密切相关。H_2O/Ti(i-OC_3H_7)4(摩尔比)≥2.0时,随着H_2O/Ti(i-OC_3H_7)4增加,溶胶的稳定性下降。     

异丙醇镧铝水解工艺参数对胶体性质的影响

影响醇盐水解过程的各种因素对胶体颗粒的形成与性质起着重要作用.工艺参数对镧铝醇盐水解过程、胶体颗粒的形成和胶体的性质的有很大影响.本文对pH值、油酸等影响因素对镧铝醇盐水解、缩聚和凝胶过程,进行了较详细的探讨,并对其形成机理做了初步研究,并得到相应结果.     

溶胶-相转移法制备改性有机铝溶胶包膜长余辉发光粉

以异丙醇铝为原料，硝酸作为胶溶剂制备了铝的水溶胶，而后通过相转移法得到了氧化铝的有机溶胶，将发光粉放入有机溶胶内进行包膜，得到具有耐水性发光材料。制备水溶胶时，体系要保持pH值在4～5之间，n（H2O）：n（Al^3＋）为150：1，表面活性剂的浓度为3．0×10^-2mol／L；经过包膜后耐水性、光学性能的测试确定了最佳包膜量为10％。但初始亮度降低较大，为原粉亮度的92％。     

大颗粒超高纯度硅溶胶的制备及其表征(英文)

采用新工艺路线制备四乙氧基硅烷（tetraethoxysilane,TEOS）,以TEOS为原料制备超纯度大颗粒硅溶胶。TEOS是烷氧基硅烷法制备甲硅烷的副产物,经过精馏提纯以后,加入盐酸或氨水催化剂,采用溶胶-凝胶法制备硅溶胶。结果表明：TEOS和硅溶胶金属杂质离子总含量都低于0.3mg/L。用盐酸催化TEOS水解制备溶胶,胶粒直径达到129nm;用氨水催化,胶粒直径达272nm。当物质的量比n（C2H5OH）/n（TEOS）=6,n（H2O）/n（TEOS）=5,搅拌速度为250 r/min,制备的硅溶胶胶粒均匀度最好。加水不搅拌,胶粒很容易发生团聚,但是,当搅拌速率高于500 r/min时,胶粒出现团聚现象。     

二氧化硅溶胶的制备及性能影响研究

以正硅酸乙酯、水、乙醇和酸性催化剂为原料，制备了SiO2溶胶。研究了催化剂的种类、反应温度、反应时间、添加剂等因素对SiO2溶胶性能的影响。实验结果表明：在[H^＋]相同的条件下，酸催化剂对溶胶粘度的影响为：HF〉HCI〉HN03〉H2S04〉HAC，对凝胶时间的影响为：HAC〉H2S04〉HC1〉HN03〉HF，几种溶胶固含量的大小为：H2S04〉HN03〉HCl〉HAC，制备二氧化硅膜用硅溶胶较适合采用盐酸或硝酸作为催化剂；随着反应温度的升高，溶胶的粘度、固含量和粒径均逐步增大，凝胶时间则缩短；随着反应时间的延长，溶胶的粘度、固含量以及粒径逐步增大，凝胶时间则变短；向在溶胶中加入DMF后，溶胶粘度、固含量变小，凝胶时间延长，SiO2粒子的粒径增大。     

Effect of strontia on the densification and mechanical properties of sol–gel alumina

Boehmite sol was prepared by hot water hydrolysis of aluminum iso-propoxide using nitric acid as the catalyst. Hydrolysis was carried out at 80 °C for 80 min. Calcium nitrate was added and the peptization was complete at 80 °C for 1 h. The sol was precipitated in ammonia, the precipitate was aged for 24 h, dried at 120 °C and calcined at 500 °C for 3 h. The calcined powder was milled at 230 rpm for 6 h. The amount of calcium oxide was varied from 1 to 20 vol.%. The particle size and particle size distribution of the calcined powders were studied. The average particle size was found to increase with calcia content. The powder was compacted into cylindrical pellets using uni-axial press at 180 MPa and sintered at 1600 °C for 6 h. Mechanical properties such as hardness, fracture toughness, diametrical tensile strength and flexural strength for compacts containing various concentrations of strontium oxide was studied. There was a slight decrease in the density with increase in strontia content. Increase in the mechanical properties such as hardness, fracture toughness and diametrical tensile strength was observed with increase in strontia content.     

Kinetic Investigation of Reaction Between Metallic Silver and Nitric Acid Solutions

In this study, the reaction kinetics between metallic silver and nitric acid solutions was investigated by taking into consideration the parameters of temperature, solid‐to‐liquid ratio, stirring speed, nitric acid concentration, particle size and addition of sodium nitrite. It was determined that the dissolution rate of the process increased with decreasing particle size and solid‐to‐liquid ratio, and increasing nitric acid concentration, reaction temperature and the amount of the sodium nitrite in the solution. In addition, it was observed that the stirring speed had more effect on the dissolution rate at low stirring speeds than at high stirring speeds. In the present study, the examination of shrinking core models of fluid‐solid systems showed that the dissolution of metallic silver in the nitric acid solutions was controlled by the reaction on the surface. A semiempirical model, which represented well the process, was developed by statistical methods. The activation energy of the process was found to be 57.66 kJ mol^–1.     

硝酸对溶胶-凝胶法制备AlOOH胶粒粒度的影响

为获得孔径可控的氧化铝滤膜,以异丙醇铝为原料,硝酸为胶溶剂,使用溶胶-凝胶法制备了AlOOH溶胶,并通过纳米粒度仪、Zeta电位等表征手段,研究了硝酸用量对AlOOH胶粒粒度及粒度分布的影响。结果表明,硝酸与异丙醇铝摩尔比R(n(HNO₃):n(Al(C₃H₇O₃)₃))为0.2~0.7时,随着R增大,AlOOH胶粒的平均粒径从66.69 nm(R=0.2)增大到138.80 nm(R=0.7),其粒度分布曲线的半高宽(FWHM)由144.62 nm增加到267.74 nm。AlOOH溶胶的粒度增大不是由颗粒团聚引起的,而是硝酸加入增大了异丙醇铝水解反应常数,使单位体积内能发生缩聚的中间产物增加,从而促进了AlOOH胶粒的生长。     

邻苯二甲醛合成新工艺研究

邻苯二甲醇在乙酸水溶液中通过硝酸氧化得到目的产物邻苯二甲醛。在单因素实验基础上进行了正交实验,考察醇/酸摩尔比、反应温度、反应时间、醋酸用量等对产品收率的影响。结果表明,优化工艺条件为邻苯二甲醇与硝酸的摩尔比1∶2.5,反应温度80℃,反应时间1 h,收率可达76.0%,含量99.5%。     

Optimized synthesis and properties of surfactant-free water-reducible acrylate-alkyd resin emulsion

In this work, a modified alkyd resin (basic alkyd resin) was synthesized using maleic anhydride (MAH) to replace part of phthalic anhydride (PA) to achieve the target product acrylate-grafted-alkyd hybrid resin. The resin was then dispersed in water to form water-reducible emulsion. The properties were examined, including the extent of neutralization of final emulsion, ratio of MAH/PA in basic alkyd resin, mole ratio of basic alkyd resin to modified vinyl monomers, mole ratio of vinyl monomers (MMA/St/AA) on water dispersion stability of emulsion, particle size, drying time and mechanical properties. The optimal synthesis conditions produced a final emulsion particle size of 81.1 nm with good storage stability, hydrolytic stability and shorter drying time. The optimized synthesis conditions were identified as 80% neutralization, 1:0.8 mole ratio of basic alkyd resin to modified monomers, 4:3:2 modified monomers MMA/St/AA and 0.18 mole ratio of MAH/PA.     

硫酸氢钠催化合成十六烷二酸二乙酯的研究

以十六烷二元酸与乙醇为原料,采用硫酸氢钠做催化剂合成十六烷二元酸二乙酯。考察了原料的摩尔比、反应时间、催化剂量和带水剂对酯化收率的影响。通过分析实验结果,得出反应的最佳条件:醇酸摩尔比7∶1,催化剂量为二元酸质量的5%,带水剂环己烷为酸醇总质量的15%,回流反应时间5h,酯化的最高收率可达94.5%。硫酸氢钠重复使用4次后酯化收率为80.7%。     

聚硅酸/聚丙烯酰胺复合絮凝剂的研究

以硅酸钠为前驱体,制备得到硅溶胶,然后采用原位聚合法一步合成了聚硅酸/聚丙烯酰胺复合絮凝剂,通过红外光谱对合成产物的结构进行了表征。采用透光率、化学需氧量去除率对絮凝剂的絮凝效果进行了表征,并探讨了聚硅酸pH值、老化时间、聚合反应温度和时间等合成条件对絮凝效果的影响。结果表明,当硅酸钠浓度为0.5 mol/L、聚硅酸pH=5、老化时间为24 h、丙烯酰胺为5 g、引发剂用量为0.3 g,聚合反应温度为70 ℃、时间为90 min时,得到的聚硅酸/聚丙烯酰胺絮凝剂的絮凝效果最佳。     

Sol–Gel Synthesis and Characterization of Alumina–Calcium Hexaaluminate Composites

Boehmite sol was prepared by hot water hydrolysis of aluminum iso-propoxide using nitric acid as the catalyst. Calcium nitrate to yield 0–20 vol% calcia was added to the boehmite sol. The boehmite with additives was calcined at 600°C for 3 h. The calcined powder was milled at 230 rpm for 6 h and particle size was measured using Laser particle size analyzer. The powder samples were calcined at 1600°C for 3 h and the formation of calcium hexaaluminate was discussed using phase diagram, transmission electron microscope, energy dispersive spectra, and X-ray diffraction spectra. The powder samples calcined at 600°C for 3 h were compacted into cylindrical pellets and sintered at temperatures ranging from 1400° to 1600°C for 6 h and the formation of hexaaluminate (platelike) grains were confirmed using Scanning electron microscope and optical microscopy.