球形粒子在TEOS-DDS溶胶-凝胶过程中的形成

在酸催化正硅酸乙酯(TEOS)溶胶-凝胶过程中,当水量充足时,向体系中加入二甲基二乙氧基硅烷(DDS),可得到一种疏水性球形微粒.利用扫描电镜(SEM)、热重分析(TG)、红外光谱分析(IR)等手段对产物进行了分析测试,并对粒子形成的机理进行了探讨.结果表明,此粒子的形成是在TEOS完全水解的情况下,通过表面的活性硅羟基与DDS水解中间产物的硅羟基之间相互键合形成的.该粒子表面光滑,热稳定性好,具有良好的应用前景.     

铜合金表面巯基官能有机硅溶胶-凝胶涂层中TEOS含量对其防腐性能的影响

以巯基丙基三甲氧基硅烷(MPTMS)为有机前驱体,以正硅酸四乙酯(TEOS)为无机前驱体,盐酸为催化剂,经水解-缩合反应在Cu合金H62表面制备了高固含量的有机-无机杂化溶胶-凝胶涂层。利用红外光谱仪、动态光散射粒度分析仪对涂层的化学成分和溶胶粒子的平均直径进行表征,利用SEM观察涂层的表面和截面形貌,利用拉脱法附着力测试仪和电化学工作站对涂层的附着力和耐蚀性进行表征。结果表明:TEOS的加入有利于提高涂层的热稳定性。随着TEOS含量的增加,溶胶粒子的尺寸呈上升趋势,过量的TEOS会使涂层表面和内部产生孔洞和裂纹等缺陷。当TEOS和MPTMS的摩尔比为0.6时,涂层的交联密度较大且涂层缺陷较少,涂层的耐蚀性最佳。     

DDS含量对有机硅/SiO_2杂化涂层性能的影响

采用溶胶-凝胶法,以正硅酸乙酯(TEOS)为无机相前驱体,甲基三乙氧基硅烷(MTES)和二苯基二甲氧基硅烷(DDS)为有机相前驱体,盐酸和水为催化剂,通过水解-缩聚反应制备了不同DDS含量的有机硅/SiO_2有机-无机杂化溶胶。在100℃下经12 h烘干得到有机硅/SiO_2杂化涂层。涂层性能测试表明:随DDS含量增加,硬度、附着力、耐蚀性(未加DDS耐蚀性较差)有所下降;柔韧性均为1级。低温下涂层耐热性较好。溶胶中n(TEOS):n(MTES):n(DDS)为6:9:2时涂层综合性能最佳。     

TEOS含量对有机硅/SiO_2杂化涂层性能的影响

采用溶胶-凝胶法,以正硅酸乙酯(TEOS)为无机相前驱体,甲基三乙氧基硅烷(MTES)和二苯基二甲氧基硅烷(DDS)为有机相前驱体,盐酸和水为催化剂,通过水解-缩聚反应制备了不同SiO_2含量有机硅/SiO_2有机-无机杂化溶胶.经100℃烘干12 h得到有机硅/SiO_2杂化涂层.红外光谱研究表明不同TEOS含量制备的杂化材料有机、无机两相组成了强相互作用的杂化体系.采用热重分析(TGA)和耐热性试验研究不同TEOS含量有机硅/SiO_2有机-无机杂化涂层的耐热性能;采用电化学阻抗(EIS)、浸泡试验和盐雾试验研究其耐蚀性能,结果表明与未加TEOS的有机硅涂层相比,加入适量TEOS使得杂化涂层的热分解温度提高67℃,并且其耐蚀性能也得到明显提高.     

纳米铁氧体NiFe2O4复合材料制备及电磁屏蔽性能

采用溶胶-凝胶法制备纳米镍铁氧体,在凝胶形成之前加入超细可膨胀石墨,生成的干凝胶粉末在马弗炉中灼热一段时间,在纳米镍铁氧体生成的同时微膨石墨发生膨胀,由此合成出纳米铁氧体复合材料。应用X射线衍射仪、扫描电镜、激光粒度分析仪对产物的晶体结构、微观形貌和粒度分布进行了表征分析,并着重对比研究了不同热处理温度对产物粒径分布的影响。利用小型烟箱试验测出产物在军用红外波段质量消光系数大于0.85m2/g;利用矢量网络分析仪测试其在2~18GHz的电磁参数。结果表明:在纳米铁氧体中添加超细微膨石墨,增加了电磁波的损耗,并在红外波段具有显著的消光特性,兼具红外、微波吸波特性,是一种具有潜在应用前景的隐身材料。     

溶胶内甲基改性法和表面气相处理法制备的SiO_2减反射薄膜疏水性的比较（英文）

基于溶胶-凝胶过程采用2种方法制备具有疏水性能的SiO_2减反射薄膜。在室温下,以六甲基二硅氮烷作为甲基改性剂制备改性SiO_2溶胶,并以此溶胶提拉镀膜。另外,采用对标准TEOS基溶胶-凝胶SiO_2薄膜进行表面气相硅烷化后处理法,获得了疏水性能、激光损伤阈值均高于普通未经后处理薄膜的SiO_2减反射薄膜。比较研究了2种方法获得的减反膜在真空环境下的稳定性,以及抗激光损伤性能。实验发现,表面气相硅烷化后处理更适合制备具有优异光学性能的疏水减反射薄膜。     

染料掺杂Zr-ORMOSILs薄膜的性能

通过在溶胶-凝胶工艺中引入不同的有机改性硅先驱体,将激光染料PM567掺杂于锆-有机改性硅酸盐凝胶玻璃(Zr-ORMOSIL)中.通过旋涂法,将所得的Zr-ORMOSIL溶胶旋涂在载波片上,并测量了薄膜的折射率和厚度.在紫外连续辐照下,以染料荧光强度下降的幅度来表征染料在介质中的光学稳定性.实验结果表明有机改性体的适当加入可提高染料的光稳定性,染料在乙烯基三乙氧基硅烷(VTES)、甲基三乙氧基硅烷(MTES)中,光稳定性较好.当Zr的含量为25%或50%时,激光染料PM567具有较好的光稳定性.随着Zr含量的增加,波导薄膜的折射率增加.综合考虑光稳定性和折射率,可对染料掺杂Zr-ORMOSIL波导薄膜的制备工艺进行优化.以NdYAG激光器作为光源,实现了激光染料掺杂Zr-ORMOSIL薄膜的动态分布反馈(DFB)的连续可调谐激光输出.     

超声辐射溶胶-凝胶法制备活性ZnO及其表征

用溶胶-凝胶法以超声振荡方式制备出粒径为37．0nm左右的六方晶型ZnO微粒。对产物的结构进行了分析；测定了粉体的比表面积并与激光散射测定值进行对照；重点研究了ZnO超细粉的电学性质。     

溶胶-凝胶法制备纳米ZnFe_2O_4复合材料及宽频吸波性能研究

采用溶胶-凝胶法制备纳米锌铁氧体,在凝胶形成之前加入超细可膨胀石墨,生成的干凝胶粉末在马弗炉中灼热一段时间,在纳米锌铁氧体生成的同时微膨石墨发生膨胀,由此合成出纳米铁氧体复合材料.应用X射线衍射仪、扫描电镜对产物的晶体结构和微观形貌进行了表征分析,并着重对比研究了不同热处理温度对产物粒度分布的影响.利用小型烟箱试验测出产物在军用红外波段质量消光系数大于0.9 m~2/g;利用矢量网络分析仪测试其在2～18 GHz的电磁参数.结果表明:在纳米铁氧体中添加超细微膨石墨,增加了电磁波的损耗,并在红外波段具有显著的消光特性..     

溶胶-凝胶法制备高性能防眩膜

采用溶胶-凝胶工艺合成了高性能防眩液,研究了工艺参数对防眩膜性能的影响规律.研究结果表明,当H 2O与TEOS的摩尔比为7～13、HCl与TEOS的体积比为6.0×10-3时,可获得具有较好综合性能的防眩膜,其可见光透过率超过89%,而表面光泽度低于81.3%.     

聚酰亚胺/SiO2杂化材料的溶胶-凝胶法合成、表征及电光性能

采用溶胶-凝胶技术,以4,4'-(六氟异丙基)-苯二酸酐(6FDA)、5,5'-(六氟异丙基)-二-(2-氨基苯酚)(6FHP)、非线性生色分子4-(N-2-羟乙基-N-甲基氨)-4'-[(6-硝基苯并噻唑-2-取代)二氮烯基偶氮苯(HNBDA)、偶联剂γ-氨丙基三乙氧基硅烷(APTES)和正硅酸乙酯(TEOS)水解液合成了系列的聚酰亚胺/SiO2杂化材料,其中TEOS的含量为0～22.5%.采用红外、热分析、扫描电镜、透射电镜和X射线衍射等进行表征.它们的玻璃化转变温度和热分解温度分别为216～366℃和321～438℃,表明具有较好的热稳定性.测定极化后材料832nm处的电光系数γ33为21～35 pm/V,且电光系数保持其初始值的85%以上(100 h),结果表明杂化材料在光器件上具有潜在的应用.     

Evolution of Ti （C, N）-based cermet microstructures

Two series of Ti(C, N)-based cermet materials originating from the same chemical composition but with dif-ferent grain size distribution and sintered to different stages of the sintering cycle have been studied using SEM, TEM,EDX, and XRD. Much of the surrounding structure is formed during solid state sintering. During the solid state sintering, at first, the Mo and W rich (Ti, Mo, W)C inner rim is formed by the interaction among TiC, WC, and Mo2C; then the Mo and W lean (Ti, Mo, W)(C, N)outer rim is formed. During the liquid phase sintering, the outer rim of coarse grains grows rapidly throw a solution-reprecipitation process; aLso coarse grains grow by particle coalescence. The interface between coarse grain outer rim and binder is flat (crystal surface).     

Corrosion protection of pure aluminium and aluminium alloy (AA7075) in salt solution with silane‐based sol–gel coatings

Sol–gel films of tetraethoxysilane (TEOS), phenyltriethoxysilane (PTES) and phenyltrimethoxysilane (PTMS) were prepared on aluminium and aluminium alloy AA7075 and characterised. The corrosion inhibition properties of uncoated and coated specimens were evaluated with potentiodynamic polarisation scan, linear polarisation resistance and open circuit potential measurements. With scanning electron microscopy and optical microscopy effects of the sol–gel coating were shown. Weight loss measurements were performed at different pH‐values. More hydrophobic coatings as PTMS show a considerably better corrosion inhibition capacity as compared to the capacity provided by less hydrophobic ones as TEOS and PTES.     

Al-Si7-Mg消失模振动凝固组织半固态热处理

利用消失模铸造振动凝固技术,得到Al-Si7-Mg合金的近等轴晶组织。在此基础上研究了580℃不同时间保温半固态等温热处理(SSIT)组织中α-Al晶体的形貌与尺寸变化。结果表明:合金580℃保温1h,得到α晶粒的等积圆直径在50~150μm的分布比例达85%,α晶粒圆度均值1.41。通过凝固动力学和热力学分析,得出半固态热处理过程中,低熔点的三元共晶和二元共晶相首先熔化,并随着溶质元素扩散速度的增加,液相不断增多,α晶体形状大小不断改变;当液相率达到平衡之后,α晶粒在界面张力的作用下,不断圆整球化,合并长大。半固态热处理α枝晶演变形式明显不同于等轴晶演变过程。     

组织结构对YT15合金刀具崩刃脆性破损的影响

对不同组织结构的 YT1 5合金刀具进行冲击断续切削的对比实验 ,结果充分证实了 YT1 5合金在适当碳量条件下 WC— Ti C固溶体 ( γ相 )和 WC( α相 )的晶粒大小对YT1 5合金刀具的脆性破损有决定性的影响。鉴于当前我国金属切削技术还处于参差不齐的发展阶段 ,影响 YT1 5合金刀具寿命和消耗主要表现在韧性不够的脆性破损。本文以提高 YT1 5合金韧性为目的 ,根据试验结果提出了 YT1 5合金最佳γ相、α相的晶粒度范围。     

Al2O3/有机硅/SiO2杂化涂层电化学阻抗谱研究

以正硅酸乙酯 (TEOS)、甲基三乙氧基硅烷 (MTES)、二苯基二甲氧基硅烷 (DDS) 和仲丁醇铝 (ASB) 为主要原料,采用溶胶-凝胶法得到Al₂O₃/有机硅/SiO₂杂化溶胶,经100 ℃下固化12 h后得到Al₂O₃/有机硅/SiO₂杂化涂层。红外光谱研究表明,杂化涂层中形成了Al—O—Si键。采用电化学阻抗 (EIS) 研究杂化涂层在3.5%NaCl溶液中浸泡不同时间的阻抗行为,根据阻抗谱特征建立了等效电路图,结合等效电路图和拟合结果分析了杂化涂层在3.5%NaCl溶液中浸泡不同时间的耐蚀性。结果表明,其在3.5%NaCl溶液中具有良好的耐蚀性。     

Effect of dislocation density on the low temperature aging behavior of an ultra low carbon bake hardening steel

Strain aging was studied in an ultra low carbon (ULC) steel with a total carbon content of 20 ppm (wt.%) in order to identify the process stages and mechanism of bake hardening in this type of steel. The effects of dislocation density, varied by means of uniaxial tensile prestraining (1–10%) on the aging kinetics were investigated within an aging temperature range of 50–170°C. The aging was evaluated by means of strength measurements and the determination of interstitial carbon content after aging using a piezoelectric composite oscillator operating at 40 kHz. The interaction between interstitial carbon and dislocations was examined through amplitude dependent internal friction measurements. The influence of dislocation density on the aging behavior have been discussed with reference to the kinetics and mechanism of the aging process.     

Modified aging process for silica aerogel

To increase the porosity and monolithic performance of silica aerogel, two methods were used to age the silica gels derived from tetraethoxysilane (TEOS) by two-step sol–gel process: aging in 100 °C-autoclave with TEOS/ethanol mixed solution and in pure ethanol at room temperature. The structural characteristics and physical properties of the resultant two kinds of aerogels after supercritical CO₂ drying were investigated and compared with the help of infrared spectra (IR), N₂ absorption, differential scanning calorimetry (DSC)/thermogravimetry (TG) and high-resolution ²⁹Si nuclear magnetic resonance (NMR) techniques. Aging in 100 °C-autoclave yields silica aerogel with high pore size and pore volume, twice of that aged in ethanol at room temperature. High aging temperature and pressure can promote the dissolution and reprecipitation process of silica and the esterification process of silanols, which will enhance the backbone strength of silica gel, and hence produce silica aerogel with low bulk density, good monolithic performance and hydrophobic features. While the latter aging method produces silica aerogel with high bulk density and cracking appearance.     

Microstructures of mechanically activated Ti-46at.% Al powders and spark plasma sintered ultrafine TiAl alloy

Powder of Ti-46at.%Al was synthesized through mechanical activation (MA) for different milling times, and the 16 h MAed powder was sintered by using a spark plasma sintering (SPS) process at different sintering temperatures. The XRD profiles showed that the MAed Ti-46at%Al powder for 12,16, and 20 h contained initial α-Ti and Al phases, and that the SPSed TiAl alloys contained the gamma TiAl and α2-Ti3Al phases. The TEM showed two different types of regions in the 16 h MAed Ti-46at.%Al powder. One type consisted of only Al with a grain size about 80 nm, and the other type a mixture of Al and Ti with a grain size of 30 nm. According to the optical micrographs of MA-SPSed samples, the alloys sintered at higher temperatures showed a coarser microstructure. In the case of the 1473 K sintering, typical duplex structures ((α2 + γ) lamella and γ phases) with interlamellar spacings of 50-400 nm and the grain size either less man 100 nm, or 1000 nm were observed.     

高分子纤维增韧SiO_2气凝胶复合材料的制备

以正硅酸乙酯为硅源,乙醇和水为溶剂,芳纶纤维为增强相,通过溶胶凝胶及常压干燥等步骤,实现了芳纶增韧SiO_2气凝胶复合材料的非超临界制备.采用扫描电镜、吸附-脱附等分析手段及热导率测试对所得气凝胶样品进行结构分析和性质表征.结果表明,调节反应体系的各反应参数可以获得具有不同外形、密度及热导率的复合材料;所得气凝胶平均孔径约为10～20 nm,比表面积可达1000 m~2/g,可望在隔热材料等领域得到应用.