TiCl4-O2体系高温反应制备超细TiO2光催化材料的研究

高温管式气溶胶反应器中,利用ＴｉＣｌ４气相氧化制备超细ＴｉＯ２光催化材料,研究了停留时间和反应温度对粒子形态的影响。结果表明ＴｉＯ２粒度随停留时间延长和反应温度升高而增大;金红石相含量随停留时间延长而增加;当反当温度１３００℃时,粒子中金红石含量出现最大值。以偶氮染料活性艳红Ｘ－３Ｂ为模拟废水,考察粒子光催化活性。光催化活性与粒径和晶型等形态指标有关。等效粒径３６．４ｎｍ,金红石含量１８．９７％Ｔ     

Al-Ti-TiO2体系燃烧合成及其反应过程研究

利用Ａｌ－Ｔｉ－ＴｉＯ_２体系放热反应,采用自蔓延高温合成工艺。原位合成了ＴｉＡｌ基体和Ａｌ_２Ｏ_３颗粒,成功制备出ＴｉＡｌ／Ａｌ_２Ｏ_３复合材料．结合差热分析,通过对不同温度下反应产物相组成分析;对Ａｌ－Ｔｉ－ＴｉＯ_２体系燃烧反应过程进行了初步研究．结果表明,铝热还原反应是一个分步过程,先期发生的Ａｌ－Ｔｉ、Ｔｉ－ＴｉＯ_２反应降低了Ａｌ－ＴｉＯ_２还原反应的起始温度．     

以正钛酸为原料制备纳米TiO2光催化剂

以正钛酸为原料,通过直接水解法制备纳米ＴｉＯ_２;并对样品分别进行了差热分析、Ｘ射线衍射分析和透射电子显微镜分析．结果表明,样品粒子为混晶型纳米ＴｉＯ_２,单分散性良好,粒径分布范围狭窄．当它应用于阴离子表面活性剂十二烷基苯磺酸钠的光催化降解时,与Ｐ－２５光催化剂相比,具有较好的催化活性．同时,我们用Ａｌ_２Ｏ_３陶瓷膜回收纳米ＴｉＯ_２循环再利用;这为纳米ＴｉＯ_２在环保方面的大规模应用创造了条件．     

医用NiTi合金表面溶胶-凝胶法制备TiO2-SiO2薄膜

采用溶胶－凝胶法在ＮｉＴｉ形状记忆合金表面制备了ＴｉＯ_２－ＳｉＯ_２复合薄膜,在提高医用ＮｉＴｉ合金的抗腐蚀性方面,收到了显著的效果．运用电化学方法对不同组成的ＴｉＯ_２－ＳｉＯ_２薄膜在模拟体液中的腐蚀行为进行了研究,结果表明,随薄膜中 Ｔｉ／Ｓｉ比的增加,ＴｉＯ_２－ＳｉＯ_２薄膜的抗腐蚀性增强．划痕试验表明 ＴｉＯ_２－ＳｉＯ_２（Ｔｉ／Ｓｉ＝４：１）膜与ＮｉＴｉ合金基体具有较高的界面结合强度．用原子力显微镜（ＡＦＭ）对ＴｉＯ_２－ＳｉＯ_２薄膜的表面形貌及表面粗糙度进行观察和分析,解释并讨论了ＴｉＯ_２－ＳｉＯ_２薄膜的配方组成与其抗腐蚀性的关系,ＳｉＯ_２含量较少时,薄膜结构致密,膜层均匀平滑,且膜基结合力好,作为医用ＮｉＴｉ合金的表面保护层,可以使其耐腐蚀性有显著提高．     

共沉淀法制备钛酸钡微粉的研究

对以ＴｉＣｌ_４和ＢａＣｌ_２为原料,以ＮＨ_４ＨＣＯ^３＋ＮＨ_３·Ｈ_２Ｏ作沉淀剂,制备钛酸钡粉末的过程进行了详细的热力学分析,找出了合成钛酸钡的条件和范围,详细地讨论了反应方式和前躯体洗涤条件．实验研究了反应物钡钛比,终点ｐＨ值,煅烧温度,以及分散剂对产物理化性能的影响．结果表明：在ＮＨ_４ＨＣＯ_３／ＢａＣｌ_２＝１．２,ＴｉＣｌ_４／ＢａＣｌ_２＝１－１．０１,充分搅拌反应１ｈ,煅烧温度９２０℃,煅烧时间２ｈ条件下,可以制得较理想的产物．在反应体系中加入适量分散剂可以明显降低产物的粒径．     

La2O3在MgO-Al2O3-SiO2-TiO2微晶玻璃中的作用

在ＭｇＯ－Ａｌ_２Ｏ_３－ＳｉＯ_２－ＴｉＯ_２玻璃中添加不同数量的氧化镧,采用差热分析、Ｘ射线衍射及电子显微镜等技术研究了氧化镧对玻璃析晶过程与力学性能的影响．氧化镧的加入使玻璃中析出α－堇青石相的温度降低;同时避免了高膨胀方石英相的析出．随着氧化镧加入量的增加,玻璃整体析晶能力下降,微晶玻璃中晶相含量减少,晶粒尺寸增大,微晶玻璃的弹性模量与硬度减小,断裂韧性增加,体现出大尺寸长柱状金红石晶粒的增韧作用．     

硬盘基板用微晶玻璃的析晶过程研究

利用差热分析、热膨胀曲线与Ｘ射线衍射等方法研究了含ＴｉＯ_２和ＺｒＯ_２的 ＭｇＯ－Ａｌ_２Ｏ_３－ＳｉＯ_２玻璃的析晶过程．７８０℃时玻璃中析出的镁铝钛酸盐促使玻璃在８００℃析出Ｍｇ－透辉石,随后在 ９３０℃Ｍｇ－透辉石和镁铝钛酸盐开始向假蓝宝石、金红石和Ｚｒ／Ｔｉ固溶体转变;１０３０℃假蓝宝石开始转变为β－石英固溶体,而在１１２５℃以上温度,β－石英固溶体转化为α－堇青石、方石英和顽火辉石,同时金红石和Ｚｒ／Ｔｉ固溶体向锆英石和钛酸镁转变．依据玻璃析晶序列,选择在９３０～１０５０℃间温度下对玻璃进行热处理,制得以假蓝宝石为主晶相的微晶玻璃．此微晶玻璃具有细小均匀的晶粒结构,具有高的弹性模量（１２０ＧＰａ）和良好的表面性能,是适宜的硬盘基板材料．     

熔化过程中PbO-PbBr2-PbF2-P2O5系统玻璃成分的变化

了研究ＰｂＯ－ＰｂＢｒ_２－ＰｂＦ_２－Ｐ_２Ｏ_５系统玻璃在熔化过程中成分的变化,本文应用定 量化学分析法测出了玻璃在熔化后的成分．结果表明,ＰｂＯ－ＰｂＢｒ_２－ＰｂＦ_２－Ｐ_２Ｏ_５系统玻璃熔化 时氟和磷的损失较大,铅的损失相对较小;溴的损失随配料中各元素含量的多少而变化．氧含 量的变化受Ｐ_２Ｏ_５的挥发以及氧、水分与玻璃熔体中卤化物的反应程度两个因素影响．相关化 学反应的热力学计算与分析结果相吻合．     

原位氮化法制备纳米TiN-Al2O3复合粉体

以化学共沉淀法制备的纳米ＴｉＯ_２－Ａｌ_２Ｏ_３复合粉体为原料,采用原位选择性氮化的方法制备了纳米ＴｉＮ－Ａｌ_２Ｏ_３复合粉体．应用化学热力学原理分析、计算了氮化反应的条件和机理,研究了氮化条件对氮化反应的影响．实验结果表明,氮化反应在７００℃时开始进行,在９００℃保温５ｈ,氮化反应进行完全,ＴＥＭ照片显示纳米ＴｉＮ 颗粒均匀分布于Ａｌ_２Ｏ₃基体中,粒径为５０～７０ｕｍ．     

TiCI4高温气相氧化合成纳米二氧化钛颗粒的研究Ⅱ.颗粒晶型结构控制

在高温气相反应器中,利用ＴｉＣＩ４氧化反应制备纳米ＴｉＯ２颗粒,分析了ＴｉＯ２颗粒化学组成,研究了操作参数对ＴｉＯ２晶型结构的影响。结果表明,ＴｉＯ２颗粒中金红石相含量随反应温度变化出现最大值,并随停留时间延长而增大;加入ＡＩＣＩ３能增加ＴｉＯ２表面的氧空位,促使锐钛相向金红石相转化,使金红石相含量较未掺铝时大幅度提高,当反应温度１１００℃、进料中ＡＩＣＩ３和ＴｉＣＩ４摩尔比为０．２５、停留时间１．７３ｓ,可得到纯金红石相纳米ＴｉＯ２颗粒。     

TiCI4高温气相氧化合成纳米二氧化钛颗粒的研究Ⅰ.颗粒粒度控制

在高温气相反应器中,利用ＴｉＣＩ４氧化反应制备纳米ＴｉＯ２颗粒,研究了操作参数对颗粒粒度的影响。结果表明提高氧气预热温度,有利于促进成核,制备的ＴｉＯ２粒径小、分布窄;ＴｉＯ２粒度随着反应温度提高、停留时间延长或ＴｉＣＩ４起始浓度增加而增大;加入ＡＩＣＩ３对ＴｉＯ２颗粒形态有较大影响,ＴｉＯ２平均晶粒尺寸随着掺铝量增加而减小。     

Heat treatment on TiO2 nanoparticles prepared by vapor-phase hydrolysis

TiO₂ nanoparticles are prepared by vapor-phase hydrolysis of TiCl₄ below 550°C and are characterized by TEM, XRD and XPS before and after heat treatment at various temperatures. It shows that anatase/amorphous particles start to transform to rutile at certain temperature. Such transformation temperature tends to decrease with the decrease of particle size. When the rutile phase starts to be formed, the particles grow rapidly, while they grow slowly before the appearance of rutile titania. The Ti2p_3/2 binding energies tend to increase as particle sizes decrease, especially for particles below 50 nm in size.     

四氯化钛水解法制备纳米氧化钛超细粉体

研究了改变溶液的酸碱度来控制ＴｉＣｌ４水解,制备锐钛上超细ＴｉＯ２纳米粉体的过程,采用ＸＲＤ,ＴＥＭ、ＳＡＥＤ和ＴＧ－ＤＴＡ等方法对所得粉体进行了表征,发现水解后的沉淀经真空干燥后,不用任何热处理,室温下即有锐钛矿相存在,其原始粒径约为３．８ｎｍ,粉体于４００℃煅烧２ｈ,可得到平均粒径为７ｎｍ的纯钛矿相纳米氧化钛粉体。     

爆温对气相爆轰合成纳米TiO2结构和性能的影响

采用气相爆轰法制备纳米TiO₂粉末, 并研究爆温对样品的结构和性能的影响。使用XRD、TEM及甲基橙溶液降解来表征样品的结构与性能。结果表明: 爆温对样品中金红石相含量有一定影响,在爆温为2524 K时, 金红石相含量达到最大值92.2%; 爆温对样品的平均粒径有重大影响, 爆温与样品的平均粒径呈线性关系, 爆温越高, 样品的平均粒径越大,当爆温由2399 K提高到3114 K时,平均粒径由87.2 nm提高到172.9 nm; 爆温对样品的光催化性有着间接影响, 爆温越高, 样品的平均粒径越大, 光催化效能降低。当爆温为2399 K时, 制备样品的平均粒径为87.24 nm, 锐钛矿比例为31.7%, 光催化活性最高, 在紫外光下40 min甲基橙溶液降解率为90.82%, 反应速率常数k为0.062。     

Preparation of cobalt nanoparticles by hydrogen reduction of cobalt chloride in the gas phase

Cobalt nanoparticles were produced by the hydrogen reduction of cobalt chloride vapor in a multistage tubular aerosol flow reactor. Reaction zone temperature, preheating temperature, mole fractions of CoCl₂ and H₂, and residence time were considered as key process variables for the control of particle size and size distribution. Ranging from 50 to 78 nm in average diameter, cobalt nanoparticles with narrow size distributions were synthesized throughout our experiments. All of the considered process variables affected the particle size and size distribution in the synthesis of cobalt nanoparticles. As the reaction zone temperature and the CoCl₂ mole fraction increased, the average particle diameter increased. But the average particle diameter decreased as the residence time of reactants increased.     

热处理对二氧化钛表面二氧化硅包膜的影响

通过单流匀速滴定法在二氧化钛颗粒表面均匀包覆一层二氧化硅,系统地研究热处理温度对这层硅包覆层的形貌和相组成的影响;采用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、透射电子显微镜(TEM)和傅立叶红外光谱仪(FTIR)等手段对包硅二氧化钛颗粒进行表征。结果表明:150℃热处理形成连续致密的硅二氧化硅覆层;500℃热处理3 h后形成岛状二氧化硅膜;700℃热处理后形成不连续的硅二氧化硅覆层,并有脱落的倾向;当温度升到1 000℃时,硅二氧化硅覆层会脱落,二氧化钛的粒径增大,大约在1 000℃,二氧化硅包覆层结晶化。     

The crystalline phase stability of titania particles prepared at room temperature by the sol-gel method

Titania particles having anatase, brookite and rutile phase were prepared at various H⁺/TTIP (Titaniumtetraisopropoxide) mole ratios and room temperature by the sol-gel method. The crystalline phases according to the variation of the post heat treatment temperature were observed. The crystalline phase and the phase transformation, morphology, and crystallite size were identified by using XRD, TG/DTA, Raman spectroscopy and TEM. The brookite phase of titania particles prepared at the H⁺/TTIP mole ratio of 0.02 and room temperature was not transformed into anatase or rutile even with the heat treatment at 750°C, and also the anatase phase was stable at the temperature as high as 850°C. However, the titania particles prepared at the H⁺/TTIP mole ratio of 0.67, which contained the mixed phases of anatase, brookite, and rutile at room temperature, showed only rutile phase at temperature of 750°C. It was thus shown that the initial crystalline phase of the primary particles prepared at room temperature had an important effect on the phase transformation behavior upon post heating. Phase transformation from brookite to anatase and subsequently to rutile occurred with heating.     

Role of particle size of alumina on the formation of aluminium titanate as well as on sintering and microstructure development in sol–gel alumina–aluminium titanate composites

With a view to develop low temperature fine grained alumina–aluminium titanate composite, influence of alumina particle size on the temperature of formation of the aluminium titanate, sintering behaviour and microstructure development of alumina–aluminium titanate composite prepared through a sol–gel core shell approach is reported. The alumina matrix composite containing 20 wt% aluminium titanate has been prepared from alumina powders having different average particle size in the range 300–600 nm. The alumina particle size appears to have no significant influence on the formation temperature of in situ formed aluminium titanate. However, the microstructural analysis of the dense ceramic showed that the average grain size of the alumina–aluminium titanate composite increases with increase in the alumina particle size. XRD analysis indicated the absence of rutile titania in the sintered composite ensuring complete formation of aluminium titanate. Smaller starting alumina particle size led to finer grain size composites. The present study therefore shows that although the starting particle size of alumina has no significant role on the lowering of formation temperature of aluminium titanate, it does influence the microstructure of the composite.     

气相燃烧合成二氧化钛纳米颗粒

建立了CO气相燃烧合成纳米颗粒材料技术 ,利用TiCl4 气相氧化合成粒度小于 10 0nm纯金红石或锐钛和金红石混合相的TiO2 颗粒。混合温度升高、TiCl4 进料量减小、停留时间缩短时 ,二氧化钛颗粒粒度减小。随混合温度升高、TiCl4 进料增大以及停留时间延长 ,TiO2 颗粒中金红石含量增大。在反应物中加入AlCl3 作为晶型调节剂时 ,金红石含量增大。