常压干燥法制备CNTs掺杂TiO2气凝胶

以钛酸丁酯为原料,乙酸为有机配体,甲酰胺为干燥控制化学添加剂(DCCA),采用溶胶凝胶法制备碳纳米管(CNTs)掺杂TiO2复合醇凝胶,并结合常压干燥等后续工艺,制备了CNTs掺杂TiO2块体气凝胶。采用XRD、BET、TEM、SEM、EDS、DSC及FT-IR等对样品进行表征。结果表明:制备态CNTs掺杂TiO2气凝胶晶型为无定型,比表面积为601.7 m2/g;在氮气保护下,经950℃热处理后,比表面积为136.8 m2/g,TiO2以锐钛矿相存在,且均匀密集包覆在CNTs表面,对甲基橙光降解具有较高光催化活性。     

疏水SiO_2气凝胶的常压制备

以乙烯基三乙氧基硅烷(VTES)为先驱体,无水乙醇(EtOH)作溶剂,采用Sol-Gel酸碱两步法常压制备疏水SiO2气凝胶材料。使用X射线衍射仪、傅立叶红外光谱仪对SiO2气凝胶的结构进行表征,并通过视频光学接触角测定仪测出气凝胶对水的接触角范围为115°～150°,呈现好的疏水性能。同时研究表明,不同EtOH/VTES摩尔比以及不同酸、碱催化剂浓度对气凝胶的体积收缩率、体密度有较大影响。试验所获得的样品体密度大致分布在0.13～0.43g/cm3范围,体积收缩率分布在20%～70%之间。     

镀锌钢板纳米SiO2有机膜的电化学行为

通过往水溶性丙烯酸树脂(AC)中加入不同含量的纳米SiO2,在热镀锌钢板上获得一系列有机/无机复合涂膜,应用电化学测试手段对纳米SiO2改性丙烯酸树脂涂膜在5%NaCl水溶液中的电化学行为进行了研究。结果表明:当有机膜中SiO2含量为8%～12%时其阳极极化曲线呈现出类似钝化的特征,增大了镀锌层的阳极极化作用,更好地阻滞了电极反应的发生。其原因可能是由于涂膜中的SiO2与Zn表面发生化学反应生成性能稳定的ZnSiO3化合物,也可能是膜中胶态SiO2的溶解-再沉积所致。     

亚微米球形镍粉的两步法可控制备与表征

以H_2C_2O_4·2H_2O为沉淀剂,NiSO_4·6H_2O为镍源,第1步通过共沉淀法制得NiC2O4前驱体粉末;然后在H_2气氛、中温条件下(250~500℃)煅烧还原,第2步制得高规则度的亚微米球形镍粉。采用扫描电子显微镜、X射线衍射、激光粒度分析等检测手段对所制备的样品形貌、显微结构进行表征。结果表明:亚微米球形镍粉纯度高,二次颗粒粒径约为40μm,由大量大小均匀、分散性好的粒径0.5μm左右的一次颗粒团聚而成,这种结构保证了镍粉具有良好的成形性和烧结活性。随煅烧温度的升高,结晶度逐渐升高;亚微米球形镍粉的最佳制备工艺参数为:镍离子浓度0.7mol·L~(-1),反应温度40℃和煅烧温度500℃。镍粉的晶粒长大活化能为26.9kJ·mol~(-1),其晶粒长大机制为界面扩散控制机制。     

酸碱复合催化溶胶-凝胶法制备 SiO2减反膜及膜性能研究

采用酸催化法、碱催化法和酸碱复合催化法制备了SiO2溶胶,进而制得SiO2减反膜。表征了薄膜的表面形貌,测定了薄膜的透射率和硬度。结果表明,不同催化溶胶制得的膜层在表面形貌、减反效果和薄膜硬度等方面存在明显差异:酸催化得到的薄膜,孔隙率和透过率最低,但硬度和抗划伤性最好;碱催化得到的薄膜,孔隙率和透过率最高,但硬度和抗划伤性最差;酸碱复合催化得到的薄膜,孔隙率、透过率、硬度和抗划伤性能介于以上二者之间,性能与酸碱复合催化溶胶的制备工艺密切相关。     

金刚石工具加工SiO2f/SiO2复合材料的可行性研究

针对石英纤维增强陶瓷基复合材料(SiO_2f/SiO₂)制造的薄壁壳体零件加工过程中存在加工效率低、切削力较大易导致零件破裂和加工表面粗糙度不易达到要求等问题,为寻求零件可行的加工刀具和工艺参数,在阐述微刃切削原理基础上,用其研制的整体多刃PCD刀具和电镀金刚石磨头,开展金刚石工具加工SiO_2f/SiO₂复合材料的可行性研究。结果表明：采用基于微刃切削原理设计的整体多刃PCD刀具加工SiO_2f/SiO₂,因刀具锋利和多刃特点可以实现较大的切深并获得较大的切削效率,但是切削力相对较大;相比于整体多刃PCD刀具,电镀金刚石磨头加工SiO_2f/SiO₂时切削力较小,加工后工件表面质量较好,且其表面粗糙度较低;     

常压化学气相沉积SiO2涂层的制备及其性能研究

    以正硅酸乙酯(TEOS)为源物质,空气为载气和稀释气,采用常压化学气相沉积法(APCVD)在HP40钢表面制备了SiO₂涂层.采用光学显微镜、扫描电子显微镜、能量色散能谱仪、D＼MAX-C型X射线衍射仪、显微硬度仪等,研究了SiO₂涂层的组织结构、表面形貌、物相组成和显微硬度;并用热震实验法和剥离实验法研究了涂层与HP40基体的结合强度.结果表明,所制备的SiO₂涂层厚度约为1 μm,由细小颗粒组成,颗粒比较均匀、大部分颗粒的粒径均在1 μm以下;涂层无明显孔隙,与基体的结合强度较高;其显微硬度明显高于HP40基体.     

纳米LiInO2光催化剂的溶胶-凝胶法制备与表征

本文利用溶胶-凝胶法制备了LiInO₂纳米材料,采用X-射线衍射(XRD)、扫描电镜(SEM)和紫外-可见吸收光谱等测试手段,研究了制备条件对LiInO₂微观结构的影响因素,并以亚甲基蓝为目标降解物研究了LiInO₂的光催化性能。研究结果表明：制备的LiInO₂纳米粒子具有LiFeO₂的晶型,颗粒尺寸约50-100纳米,制备样品的焙烧温度对其结构和性能产生了明显地影响,在氙灯(300W)照射90 min条件下,纳米LiInO₂对亚甲基蓝的光催化降解率达92%,活性位点捕获实验表明光生空穴在降解亚甲基蓝的机制中占主导作用。     

SiO2气凝胶及纤维复合SiO2气凝胶隔热材料表征方法

SiO₂气凝胶及纤维复合SiO₂气凝胶材料因轻质、高效、导热系数低等优点在保温隔热领域备受关注,应用前景广阔。其隔热性能、力学性能与微观结构、化学组成密切相关。本文对现阶段常见的微观结构、隔热性能、力学性能的表征方法做了介绍,常见的有密度、疏水角、晶态结构、微观形貌、比表面积及孔径分布、导热系数、化学组成、热稳定性、抗弯抗压等。综述了以上各种表征方法存在的优缺点及表征参数变化说明的问题。各种表征方法得到的表征参数之间存在紧密联系,需要从多角度理解和分析。     

在两步CeO2修饰的多孔YSZ-Al2O3管上制备高渗透性和热稳定性Pd膜(英文)

采用化学镀技术在经过不同修饰方式后的多孔YSZ-Al₂O₃管上沉积Pd膜。采用SEM、AFM、XRD和气体渗透测试方法研究不同修饰方式对多孔YSZ-Al₂O₃管表面质量及Pd复合膜渗透性能的影响。结果表明,经两步CeO₂修饰后,多孔YSZ-Al₂O₃管表面具有更小的孔径分布和粗糙度。经两步CeO₂修饰后的多孔管上沉积的Pd膜在500℃、700 kPa压差下具有更高的氢渗透流量(0.549mol·m^-2·s^-1)和H₂/N₂选择性(14241)。不同热循环测试和1000 h持久渗透测试结果表明,在经两步CeO₂修饰后的多孔管上沉积的Pd膜具有较高的渗透稳定性。     

Br掺杂纳米多孔TiO2的制备及其吸附性能

以钛酸四丁酯为钛源,NH4Br为溴源,应用水热技术制备Br掺杂纳米多孔TiO2材料(Br/TiO2)。利用X射线衍射仪和场发射扫描电镜表征材料的结构和形貌,并从热力学和动力学角度研究Br/TiO2对阳离子蓝X-GRL的吸附行为。结果表明:Br掺杂有利于形成棒状交联的多孔结构,增强TiO2对阳离子蓝X-GRL的吸附性能,吸附效率为92.2%,是空白样品的1.56倍。动力学研究表明:该吸附行为符合准二级动力学模型,测得其表观活化能为14.551 kJ/mol,说明该吸附属于物理吸附。热力学研究表明:Br/TiO2对阳离子蓝X-GRL吸附自由能变为8.343-5.600 kJ/mol,吸附熵变为137.10 J/(K.mol),吸附焓变为33.773 kJ/mol,该吸附过程是一个自发的吸热过程。     

Preparation and characterization of nano TiO2/micron Cr2O3 composite particles

Nano-TiO₂/micro-size Cr₂O₃ composite particles were first prepared by hydrolysis of Ti(OBu)₄ in an abundant acidic aqueous solution without calcinations at room temperature. XPS analysis shows that the element C, O, Ti and Sn existed on the surfaces of the composite particles. Observation by field emission scanning electronic microscope shows TiO₂ particles of 10-15 nm covers on Cr₂O₃ powder surfaces to form nanometer/micron composite particles. UV-vis spectra show a red shift of the absorption edge and a significant increase of absorption intensity in the visible region. These results confirm that TiO₂ of anatase type can be synthesized on the surface of Cr₂O₃.     

等离子喷涂Al2O3/TiO2复合粉末的Sol-Gel法制备

传统热喷涂粉末由小颗粒粉体混合团聚制得,流动性差、致密度低,制得的涂层均匀性差、性能不稳定。以有机金属盐为原料,采用溶胶-凝胶法及喷雾干燥法制备出氧化钛质量分数为13%的氧化铝-氧化钛(AT-13)复合前驱体粉末。采用TG-DSC、XRD、FESEM、霍尔流量计研究了粉体反应机理、物相组成、微观结构及流动性能,同时利用维氏硬度计、FESEM-EDS对制得的涂层性能进行了分析比较。结果表明,凝胶经喷雾干燥工艺后可获得球形Ti(OH)4/Al OOH复合粉体,直径约为40μm;与传统团聚粉体相比,前驱体粉末流动性更为优异,为43 s/50 g;由该粉末制得的涂层表面光滑、元素分布均匀、力学性能稳定、耐磨损性能优良,平均显微硬度达873.8 HV0.3,磨损量较团聚粉末涂层减少三分之一。     

孔道Al2O3/SiO2对NaAlH4-Tm2O3体系储氢性能的影响

以机械球磨法制备具有可逆吸放氢性能的NaAlH4-Tm2O3储氢材料体系。利用相同制备方法进一步研究两种不同孔道材料(大孔Al2O3与介孔SiO2)对NaAlH4-Tm2O3体系储氢性能的影响,测试样品的循环吸放氢性能,并对样品吸放氢前后的结构进行表征。结果表明:大孔Al2O3材料的添加并不能明显改善NaAlH4-Tm2O3体系的放氢速率和放氢量,而介孔SiO2的加入使NaAlH4-Tm2O3体系在150℃条件下5 h内的首次放氢量(质量分数)达到4.61%,高于NaAlH4-Tm2O3体系的4.27%,增加了约8.0%。此外,添加介孔SiO2的NaAlH4-Tm2O3体系放氢速率也有所提高。     

镍钛合金的溶胶-凝胶法多孔TiO2薄膜表面改性（英文）

在经过 NaOH-HCl 预处理的镍钛合金基体上,采用溶胶-凝胶法制备纳米多孔 TiO2薄膜;当涂覆一层致密内膜和一层多孔外膜时,可得到无裂纹的薄膜(试样 TC1+1)。X 射线衍射表明,TiO2薄膜由锐钛矿组成,在热处理的基体中还检测到少量的 Ni4Ti3相。X 射线光电子谱分析表明,试样 TC1+1 的 TiO2薄膜完全覆盖了镍钛合金基体。试样 TC1+1 的表面亲水,接触角约为 20°,紫外光照处理 15 min 后接触角降低到(9.2±3.2)°。在 0.9% NaCl溶液中的动电位极化实验表明,试样 TC1+1 的耐蚀性高于抛光的镍钛合金试样的。     

High transmittance and superhydrophilicity of porous TiO2/SiO2 bi-layer films without UV irradiation

In order to obtain the TiO₂ films with high transmittance and superhydrophilicity without UV irradiation, porous TiO₂/SiO₂ bi-layer films were prepared by spin coated SiO₂ sol and TiO₂ sol including polyethylene glycol 2000 (PEG 2000) onto glass and subsequent calcination at 550 °C. Meanwhile, factors that affect the TiO₂/SiO₂ bi-layer films transmittance and superhydrophilicity were investigated in details by observing their surface morphologies and measuring their water contact angles (WCAs), spreading time and transmittances. The results indicated that the as-prepared TiO₂/SiO₂ bi-layer film showed superhydrophilicity without UV irradiation when 0.5 wt.% PEG 2000 was added in TiO₂ sol. At the same time, its maximum transmittance was as high as 92.3%. The spreading time was only about 0.16 s. More importantly, the resultant film had an excellent stability of the superhydrophilic property.     

Polythiophene/SiO2 nanocomposites prepared in the presence of surfactants and their application to glucose biosensing

Conducting polythiophene/SiO₂ (PT/SiO₂) nanocomposites were prepared in the presence of three different surfactants (anionic, cationic and non-ionic) via chemical oxidative polymerization in an anhydrous medium to create an enzyme-immobilized polymeric amperometric biosensor. An anionic surfactant, sodium dodecylbenzenesulfonate (DBSNa), a cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), and a non-ionic surfactant, poly(ethylene oxide) (20) sorbitan monolaurate (Tween 20), were used as additives. The properties of the nanocomposites were investigated, as a function of surfactant type and the amount of PT contained, by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM results reveal that all PT/SiO₂ samples form nanometer-dimensioned globular structures. The highest conductivity obtained was 2.7 × 10⁻² S cm⁻¹ for a PT/SiO₂-Tween 20 nanocomposite. Thermogravimetric analysis (TGA) shows that the residue decreases with increasing amount of PT. Glucose oxidase (GOX) was immobilized by crosslinking to the conducting PT/SiO₂ composites and was used for amperometric detection of glucose.     

SiO2-TiO2-ZrO2干凝胶制备工艺和性能

采用正硅酸乙酯(TEOS)、氧氯化锆(ZrOCl2·8H2O)和钛酸丁酯(TBT)为前躯体,以无水乙醇(EtOH)为溶剂通过溶胶-凝胶法制备以SiO2作为干凝胶主组分的SiO2-TiO2-ZrO2干凝胶.研究了多元干凝胶的溶胶-凝胶法制备技术、干凝胶改性技术以及各种制备工艺参数的影响规律.当原料比m(氧氯化锆)∶m(钛酸丁酯)∶m(氨水)∶m(TEOS)∶m(EtOH)=1∶2.7∶5.0∶16.7∶106.7时,经过水解、老化及溶剂替换后,制得气孔率约85％,比表面积190 ～210 m2/g,孔径6～ 30 nm,粒子直径小于20 nm,导热系数可达到0.0857 W·m-1 ·K-1的SiO2-TiO2-ZrO2干凝胶.     

Electrochemical decomposition of SiO2 pellets to form silicon in molten salts

Direct electrochemical reduction of porous SiO₂ pellets in molten CaCl₂ salt and CaCl₂-NaCl salt mixture was investigated by applying 2.8 V potential. The study focused on the effects of temperature, particle size of SiO₂ powder starting material and the behavior of cathode contacting materials during electrochemical reduction process. The starting materials and the electrolysis products were characterized by X-ray diffraction analysis and scanning electron microscopy mainly. The studies showed that smaller particle sizes and higher temperatures had slightly positive effects in increasing the reduction rate within the ranges covered in this study. The results were interpreted from variations of current and accumulative electrical charge that passed through the cell as a function of duration of electrochemical reduction under different conditions. Microstructures and compositions of the reduced pellets were used to infer that electrochemical reduction of SiO₂ in molten salts may become a method to produce silicon that could be used in solar energy utilization. Furthermore, X-ray diffraction analysis results indicated that the silicon produced at the cathode reacts with contacting materials; nickel, and iron in stainless steel to form Ni-Si and Fe-Si compounds due to very reactive nature of silicon especially at high temperatures.     

TiO2/ SiO2一维光子晶体的制备及其光子带隙特性

以普通载玻片为基体,采用溶胶-凝胶法制备了TiO2/SiO2一维光子晶体,对该结构的截面形貌、各层厚度及结晶形态、反射谱特性进行了分析。结果表明:TiO2和SiO2膜的平均厚度分别为69 nm和83 nm,结晶形态分别为锐钛矿和无定形态;该结构在波长544 nm处的反射率达到了94%,且其FWHM=194 nm(486~680 nm)。运用传输矩阵法对该结构进行仿真计算,得到的计算结果与测试结果趋于一致。最后讨论了入射角对一维光子晶体反射谱的影响。