钛溶胶-凝胶/有机硅树脂复合膜层抗高温氧化性能的研究

探讨了将含有Mo、Cr、Si元素的钛溶胶－凝胶与有机硅树脂以不同比例混合,并在不锈钢表面涂覆成为复合膜层的制备技术。对涂层性能实验表明：钛溶胶－凝胶／有机硅树脂复合涂层较纯溶胶－凝胶涂层具有较好的热稳定性,且复合膜层在800℃的高温下具有优良的抗高温国氧化性能,而且可以避免不锈钢材料在含氯离子的溶液中发生点蚀的现象。     

钛表面制备羟基磷灰石/壳聚糖复合涂层研究

通过原位水热合成和溶胶-凝胶浸提涂敷法在碱处理的钛表面制备了HA/CS复合涂层. 接触角检测表明碱处理使钛表面具有超亲水性.X射线衍射分析表明复合涂层成分为HA和CS, 各组分含量由热重分析确定. 用扫描电镜对复合涂层的形貌进行观察,发现不同HA含量的复合涂层具有不同的形貌. 通过培养成骨细胞考察了复合涂层的细胞相容性.Alamar Blue检测表明HA/CS复合涂层表面细胞粘附及增殖能力较好. ALP检测表明HA/CS复合涂层表面的细胞分化能力较好. 综合研究结果表明, 复合涂层有较好的细胞相容性.     

溶胶-凝胶法制备空心微珠表面钡铁氧体包覆层的研究

铁氧体是微波吸收材料的主要成分之一,应用非常广泛,但由于铁氧体比重较大,制成吸波材料难以满足吸收频带宽、质量轻、厚度薄的要求,因此实际使用的铁氧体吸波涂层往往不是单一的铁氧体涂层,而是通过复合制备成复合铁氧体吸波涂层.以质量轻、化学性能稳定的热电厂粉煤灰空心微珠为基体,以硝酸铁、硝酸钡和柠檬酸为原料,用溶胶-凝胶法在空心微珠表面包覆钡铁氧体涂层,并用差热分析仪(DTA)、X射线衍射仪(XRD)、能谱仪(EDX)和扫描电镜(SEM)对其进行了分析表征,结果表明用溶胶-凝胶法在空心微珠表面能均匀地包覆一层薄的M-型钡铁氧体涂层.     

有机硅溶胶-凝胶防腐蚀涂层研究进展

有机硅溶胶-凝胶涂层是指以烷基烷氧基硅烷为前驱体通过溶胶-凝胶技术制备的涂层。有机硅是分子水平上的有机-无机杂化分子,因此有机硅溶胶-凝胶涂层兼具了有机材料和无机材料的性能,并且能通过合理的调控有机和无机成分来获得所需的性能。其热稳定、耐刮擦性与无机材料的结合性能明显高于普通的有机材料,柔韧性与有机材料的结合性能明显高于一般的无机涂层。近年来,这种新型的、具有特殊性能的涂层被广泛研究用来保护金属材料(如铝、铁、镁、铜基材料)。介绍了有机硅溶胶-凝胶涂层涉及的基本反应、硅烷在金属表面上的成键机理以及在不同金属上的应用等方面的研究进展,并展望了有机硅溶胶-凝胶涂层应用前景及未来的研究方向。     

钛材表面HA生物涂层的溶胶-凝胶法制备

为了获得晶粒细小均匀的羟基磷灰石(HA)涂层,以磷酸三乙酯[(C2H5O)3PO]和四水硝酸钙[Ca(NO3)2·4H2O]为羟基磷灰石前驱体,采用溶胶-凝胶法在钛材表面制备HA生物涂层.采用扫描电镜(SEM)、能谱(EDX)、X射线衍射仪(XRD)研究不同的磷酸三乙酯水解时间、HA溶胶陈化时间和HA涂层热处理温度等对HA涂层表面形貌、成分、物相的影响.结果表明:磷酸三乙酯水解时间对HA涂层形貌影响不大;HA溶胶陈化时间和HA涂层热处理温度对HA涂层的结晶度影响较大,溶胶陈化时间为25 h、热处理温度为600℃时涂层晶粒细小均匀;溶胶陈化时间不够或涂层热处理温度过低,涂层结晶度差;陈化时间过长或涂层热处理温度过高,涂层的晶粒粗大且发生团聚.     

介孔/大孔TiO2-SiO2复合氧化物材料的制备与表征

采用正硅酸甲酯和钛酸丁酯作为硅和钛的前驱体,在溶胶一凝胶过程中添加非离子表面活性剂C16EO10.作为结构导向剂合成双孔结构硅钛复合氧化物材料.扫描电镜(SEM)以及N2吸附/脱附法分析表明,材料具有三维连续大孔和骨架介孔的双孔分布结构.通过骨架元素分析(EDS)和X射线衍射分析可知,制备过程中添加的钛可以全部进入凝胶骨架中,且钛在骨架中的分散性较好.采用Hammett指示剂法和吡啶吸附红外光谱法分析了材料表面固体酸性,结果显示,硅钛复合氧化物属于中强酸,酸强度Ho在-5.6～-3.0之间的酸中心数大约为0.30 mmol/g左右.硅钛材料表面含有较丰富的L酸位和相对较少的B酸位.     

金属表面复合保护涂层的制备与性能研究

采用溶胶-凝胶法合成了有机-无机复合溶胶.用提拉法将复合溶胶涂覆在不锈钢基板上,基板上的湿凝胶经热处理后便形成了透明保护涂层.对制备好的涂层进行了附着力和硬度等性能分析,分析结果表明:有机-无机复合溶胶易于成膜,且成膜具有很好的耐磨性、韧性和耐腐蚀性.     

金属表面复合保护涂层的制备与性能研究

采用溶胶-凝胶法合成了有机-无机复合溶胶。用提拉法将复合溶胶涂覆在不锈钢基板上，基板上的湿凝胶经热处理后便形成了透明保护涂层。对制备好的涂层进行了附着力和硬度等性能分析，分析结果表明：有机-无机复合溶胶易于成膜，且成膜具有很好的耐磨性、韧性和耐腐蚀性。     

MWCNT/TiO2复合材料光催化活性研究

以多壁碳纳米管(MWCNT)为基核,以钛酸丁酯为前驱体,分别用溶胶-凝胶法和水热法制备碳纳米管/二氧化钛纳米复合光催化材料.用X射线衍射仪(XRD)、透射电子显微镜(TEM)对样品进行了表征,研究了溶胶-凝胶法和水热法工艺的控制对碳纳米管/二氧化钛复合光催化剂显微组织及性能的影响.以甲基橙为目标降解物,考察了样品的自然光催化活性.结果表明,所得复合粉体中仅有碳纳米管和锐钛型二氧化钛两种物相,其中采用水热法所得样品,其纳米级的球形二氧化钛颗粒可均匀吸附在碳纳米管表面.     

有机硅溶胶复合处理的锌铬膜涂层

为了进一步探索改善锌铬膜涂层性能的途径,扩大锌铬膜涂层的应用范围,采用有机硅溶胶材料对锌铬膜涂层复合处理,并进行性能测试.通过中性盐雾腐蚀、二氧化硫腐蚀、酸性介质腐蚀失重、流水喷淋冲刷前后的盐水浸泡腐蚀失重和附着力以及涂层的硬度测试,对比了锌铬膜涂层采用有机硅溶胶材料复合处理前后的性能变化.结果表明:经过复合处理后的锌铬膜涂层在中性和酸性环境条件下的耐腐蚀性能、耐流水冲刷性都有了大幅度的提高,涂层的硬度进一步增强,使锌铬膜涂层在更为广泛的领域的应用成为可能.     

Titania-assisted dispersion of carboxylated single-walled carbon nanotubes in a ZnO sol for transparent conducting hybrid films

We report a facile chemical route for stabilizing a dispersion of carboxylated single-walled carbon nanotubes (SWCNTs) in a ZnO sol. The dispersion is stabilized via capping of the carboxyl groups on the SWCNT surface by a titania layer, which was confirmed by Fourier transform infrared spectroscopy and transmission electron microscopy. We also demonstrate that the conductivity of the films prepared from the SWCNT/TiO(x)/ZnO sol is dramatically enhanced by thermal treatment and that the thermal stability of the hybridized films with the ZnO sol is notably improved relative to that of a pristine SWCNT film. The structural and chemical changes of the fabricated films were characterized by Raman spectroscopy. As one application, it was presented that thermally treated SWCNT/TiO(x)/ZnO hybrid thin film sensors showed hydrogen sensing characteristics even at room temperature.     

Highly transparent polyimide/nanocrystalline-titania hybrid optical materials for antireflective applications

This study prepared polyimide/titania hybrid thin films of, poly(3,3′,4,4′-Benzophenone tetra carboxylic dianhydride)–(4,4-Diaminodiphenyl Ether)/nanocrystalline titania (BTDA-ODA/TiO₂), with a high refractive index. FTIR analysis confirmed the formation of a polyimide and titania matrix. TGA and DSC analysis gauged the decomposition temperature in the range of 455–532 °C, indicating that the addition of titania could increase the glass transition temperature of hybrid films. XRD results indicate the formation of nanocrystalline titania domains of approximately 8–11 nm in the hybrid films. AFM, SEM, TEM, and XRD results show the formation of well-dispersed nanocrystalline titania. The refractive index was measured by ellipsometry, demonstrating an increase in the refractive index of the prepared hybrid thin films from 1.657 to 1.958, when the titania content was increased from 0 to 90 wt.%. UV–vis analysis gauged the cutoff wavelength in the range of 288–357 nm. The prepared polyimide/titania hybrid thin films were used to develop a three layer antireflective (AR) coating on a glass substrate. The average reflectance of the AR was 0.5% for the PT20/PT90/F-siloxane layer and 0.6% for the PT20/PT90/porous silica. Transparency at 550 nm exceeded 90% for both AR coatings.     

Synthesis and optical absorption property of ordered macroporous titania film doped with Ag nanoparticles

Ordered macroporous anatase titania films doped with Ag nanoparticles (NPs) were synthesized by infiltrating titania sol into the interstitial voids of polystyrene colloidal sphere templates, removing the templates, immersing the films in a silver nitrate solution, and subsequently reducing in hydrogen atmosphere. Ag NPs were distributed uniformly within the macropores of the anatase titania film. Both the macroporous titania films doped with Ag NPs and those without doping have a blue-shift compared with that of the sol–gel derived titania film. Except for the plasma resonance absorption of Ag NPs, the macroporous titania film doped with Ag NPs also has a red-shift compared with the undoped sample. The macroporous titania film doped with Ag NPs have potential applications in the fields of optics, gas sensors, and catalysis.     

Polyimide/silica/titania nanohybrids via a novel non-hydrolytic sol–gel route

Polyimide/silica/titania hybrid films were prepared via a non-hydrolytic sol–gel route. Silicic acid and titanium tetrachloride were used as the precursors of silica and titania, respectively. The absorption band of Si–O–Ti bonds in FTIR spectra of the hybrid films revealed the formation of the hybrid inorganic network between SiO₂ and TiO₂. Scanning electron microscopy results indicated that the nanometer-scaled inorganic domains were homogeneously dispersed in polyimide matrix due to the introduction of silica-stabilized TiO₂ and the interactions between organic and inorganic phases. The studies on the optical properties of the hybrid films indicated the red-shift of the absorption band increased with increasing TiO₂ content, while all the hybrid films maintained their transparencies. The surface resistances of the hybrid samples decreased with increasing TiO₂ content. The thermal decomposition temperature of the ternary hybrid films decreased slightly with increasing TiO₂ content. This kind of hybrid materials may have potential application in the preparation of opto-electronic devices.     

Transparent high refractive index nanocomposite thin films

This work reports the preparation of acetic acid-modified TiO₂ nanoparticles by sol–gel synthesis method. The nanoparticles can be incorporated directly into the polymer matrix to form transparent high refractive index nanocomposite thin films. The result shows that increasing the titania content in the hybrid nanocomposite thin films can significantly increase the refractive index. Hybrid nanocomposite thin film with refractive index value of 2.38 had been prepared. All prepared films also exhibit excellent optical transparency in the visible region.     

Synthesis,properties, and anti-reflective applications of new colorless polyimide-inorganic hybrid optical materials

We report the synthesis, properties and anti-reflective applications of new colorless polyimide-inorganic hybrid thin films prepared from 1,4-bis(3,4-dicarboxyphenoxy)-2,5-di-tert-butylbenzene dianhydride (DDBBDA)/oxydianiline (ODA) with silica or titania precursors. The experimental results suggest that the prepared hybrid films have good thermomechanical properties, excellent transparence, tunable refractive indices of 1.550–1.847, and low optical birefringence. The nanocrystalline titania domain size analyzed form TEM and XRD is in the range of 10–20 nm in the hybrid materials. Three-layer anti-reflective films on glass or polymer substrates processed from the hybrid precursors have a relatively low reflection of less than 0.5% in the visible range. These results indicate that the newly prepared colorless polyimide-inorganic hybrid materials have potential applications for optical devices.     

Synthesis and characteristics of polyimide/titania nano hybrid films

Polyimide/titania (PI/TiO₂) nano hybrid films are synthesized by sol-gel technology. [4,4′-(4,4′-Isopropylidenediphenoxy) bis (phthalic anhydride)] (IDPA), 4,4′-diaminodiphenyl ether (ODA) and 3-aminopropyltrimethoxysilane (APrTMOS) mixed entirely and reacted at room temperature to form the polyamic acid (PAA). Tetraethyl orthotitanate (Ti(OEt)₄) and actylacetone, the latter one is used as chelating agent, are then added to the polyamic acid. After imidization at high temperature, PI/TiO₂ hybrid films with different block chain length, 5000 of PAA and 15000 g mol^− 1, and a cross-linked structure are formed. The resulting hybrid films, containing relatively small amounts of titania, exhibit higher transparency and flexibility. Moreover, as compared with pure PI, the hybrid film formed from APrTMOS has better ability to form a film with a higher titania content. Due to the high and low refractive index (RI) of TiO₂ and APrTMOS, their introduction may lead to the change of the RI of hybrid films. From the transmission electron microscope (TEM) images; the particle size of titania decreases with increasing APrTMOS content. Thermal decomposition temperatures (T_d), with a 5% weight loss, are in the range of 400-540 °C. The dynamic mechanical thermal analysis showed a systematic increase of glass transition temperature, along with a broader and weaker tan δ peak with increasing titania content.     

High transparent polyimide/titania multi-layer anti-reflective hybrid films

In this study, polyimide-titania hybrid thin films (6FDA-6FpDA-4ABA/TiO₂, PIT) were prepared from soluble fluorine-containing polyimide and titanium butoxide. The soluble polyimide with carboxylic acid terminal groups (6FDA-6FpDA-4ABA-COOH) was synthesized from the precursor s 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 4,4′-(hexafluoroisopropylidene) dianiline (6FpDA), and 4-aminobenzoic acid (4ABA). Such end groups undergo a condensation reaction with titanium butoxide to provide organic-inorganic bonding and thus prevent macrophase separation. The titania content in the hybrid films was varied from 0 to 90 wt.% (PIT0-PIT90). The effects of TiO₂ content on the hybrid film properties and the optimum operating conditions were also investigated. TGA and DSC analysis showed that the decomposition temperature of polyimide was about 468 °C. T_d increased as the titania content in hybrid thin films increased. HRTEMM and XRD results indicated the formation of nanocrystalline-titania domains of around 4-11 nm in the hybrid films. AFM, SEM, TEM, and XRD results indicated the formation of well-dispersed nanocrystalline-titania. FTIR spectra indicated that the amidization was complete and that a cross-linked Ti-O-Ti network had formed. UV-vis and n&k analysis showed that the prepared hybrid films had high refractive index (1.931) and good optical properties. Moreover, the prepared polyimide/titania hybrid thin films were further applied to develop a three layer antireflective (AR) coating on glass and PMMA substrates. The results showed that the average reflectance of the AR coating on the glass and PMMA substrates was 0.5% and 0.8%, respectively. The transparency at 550 nm was greater than 90% for both AR coatings.     

Synthesis of organic-inorganic hybrid sols with nano silica particles and organoalkoxysilanes for transparent and high-thermal-resistance coating films using sol-gel reaction

Organic-inorganic hybrid sols were synthesized from nano silica particles dispersed in water and from organoalkoxysilanes, using the sol-gel reaction. This work focuses on the effects of the three multifunctional organoalkoxysilanes dimethyldimethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), and tetramethoxysilane (TMOS) to form a transparent and high-thermal-resistance coating film. The stability of the hybrid sol was evaluated as a function of the reaction time for 10 d through the variation of the viscosity. The viscosity of the silica/DMDMS and silica/MTMS sol was slightly increased for 10 d. The multifunctional organoalkoxysilanes formed dense silica networks through hydrolysis and condensation reaction, which enhanced the thermal resistance of the coating films. No thermal degradation of the silica/DMDMS sample occurred up to 600 degrees C, and none of the silica/MTMS and silica/TMOS samples occurred either up to 700 degrees C. The organic-inorganic hybrid sols were coated on the glass substrate using a spin-coating procedure. The organic-inorganic hybrid sols formed flat coating films without cracks. The transmittance of the hybrid sol coating films using MTMS and DMDMS was shown to be over 90%. The transmittance of the silica/TMOS sol coating film reacted for 10 d abruptly decreased due to faster gelation. The silica/DMDMS and silica/MTMS hybrid sols formed smooth coating films while the surface roughness of the silica/TMOS coating film markedly increased when the hybrid sol reacted for 10 d. The increase of the surface roughness of the silica/TMOS coating film can be attributed to the degradation of the stability of the hybrid sol and to the loss of transmittance of the coating film. It was confirmed in this study that the use of organic-inorganic hybrid sol can yield transparent and high-thermal-resistance coating films.     

Evaluation of TiO2 coatings obtained using the sol–gel technique on surgical grade type 316L stainless steel in simulated body fluid

Gel titania is the titania which was prepared by hydrolysis of a titanium isopropoxide through a sol–gel process. A film of this titania was coated on surgical grade 316L stainless steel using a sol–gel dipping technique. The densified films at 700 °C in vacuum were characterized by X-ray diffraction and EDXA analysis for its crystallinity and purity. The content of the films were determined by FT–IR spectroscopy. The morphology of the coating was analyzed by SEM. The corrosion behavior of 316L SS samples coated with densified titania films were studied in simulated body fluid Ringer's solution by DC potentiodynamic polarization and AC impedance spectroscopic methods. The corrosion kinetic parameters show a considerable increase in the corrosion resistance for the coated steel samples in comparison to the pristine steel substrates.