水热法在无机粉体材料制备中的研究进展

综述了水热反应机理、影响水热反应的主要因素及水热法制备无机粉体材料的研究新进展，并对水热法在无机粉体材料制备中的发展前景进行了展望。     

关于水热技术处理垃圾焚烧飞灰的研究探讨

生活垃圾焚烧飞灰含有重金属和有毒有机物,对环境危害十分严重。水热法被认为是一种有效的无害化处理技术,能将飞灰改性,降低飞灰毒性,还可以合成沸石类物质,提高产物的应用价值。本文基于垃圾焚烧飞灰理化特性,对现有的水热处理技术进行了较为全面的总结。根据水热法的机理,系统地介绍了传统水热法、微波水热法、熔融预处理的微波水热法和超声波水热法,并通过对比分析指出各方法在处理效率、处理效果等方面存在的问题。此外,还简要介绍了水热处理后飞灰的主要应用领域。最后结合近几年水热技术的研究现状,提出了新型水热技术在工业化应用上存在的大型化的局限性以及未来发展方向。     

水热法在无机粉体材料制备中的研究进展

综述了水热反应机理、影响水热反应的主要因素及水热法制备无机粉体材料的研究新进展,并对水热法在无机粉体材料制备中的发展前景进行了展望.     

水热法在制备电子陶瓷粉体中的应用

近年来,水热法用于纳米粉体和纳米材料制备,超导材料处理等前沿课题的研究,已引起人们的高度重视,按研究对象和目的的不同,水热法可分为水热晶体生长,水热合成,水热反应,水热处理,水热燃结等,分别用来生长各种单晶,制备超细,无团聚或少团聚,结晶完好的陶瓷粉体,以及在相对较低的温度下完成某些陶瓷材料的合成等,对水热技术的原理和发展,以及该技术在电子陶瓷粉体制备中的应用进行了介绍。     

无机纳米材料的水热合成及其衍生方法

综述了纳米材料水热合成法的研究进展,并总结了水热合成法的优点和缺点,对水热合成法的反应机理作了初步的探讨,对水热反应中水的状态作了简要分析;对由水热法衍生出来的溶剂热和微波水热法也做了分析,介绍了溶剂热反应中经常使用的有机溶剂和微波反应中微波的加热机理;同时论述了目前这几种实验方法的实验进展和应用情况.     

水热法合成YAG粉体的制备工艺

对水热法制备晶体的工艺过程进行了研究。通过实验成功地用水热法制备出了ＹＡＧ单晶粉。用ＸＲＤ方法研究了产物中钇铝石榴石的含量，用ＳＥＭ观察了产物中钇铝石榴石的形貌和晶粒大小。同时对水热工艺中保温温度对产物中钇铝石榴石含量的影响作了探讨。     

单齿络合剂辅助水热合成CdS纳米棒

以单齿络合剂甲胺为辅助通过水热法制备了CdS纳米棒，所得CdS纳米棒分别用TEM、XRD、Raman和PL等技术进行了表征．研究了络合剂甲胺的浓度对CdS纳米晶体形貌的影响．实验发现当络合剂甲胺的浓度为1、5和20wt％时，水热合成CdS纳米晶体的形貌分别为纳米颗粒、短纳米棒和长纳米棒．这也表明络合剂的类型即单齿或双齿络合剂并不是水热合成CdS纳米棒形成的关键因素．基于实验结果，提出了一个可能的水热合成CdS纳米棒的形成机制：络合物结构—控制机理．     

间歇碾磨在钛酸纳米管水热合成中的作用

针对静态水热法合成的钛酸纳米管纯度较低的缺点,在钛酸纳米管的水热合成过程中引入间歇碾磨步骤,显著提高了钛酸纳米管的纯度.通过X射线衍射(XRD)、透射电子显微镜(TEM)/高分辨透射电子显微镜(HRTEM)、比表面积测定等手段对钛酸纳米管的结构和性质进行了表征.结果表明,与静态水热法相比,在钛酸纳米管的水热合成过程中引入间歇碾磨步骤后不仅使所合成的钛酸纳米管的纯度明显提高,而且使纳米管的比表面积和热稳定性明显增加.     

水热电泳沉积功能陶瓷涂层技术的研究进展

水热电泳沉积技术结合了水热法和电泳沉积法的优点,是近几年发展起来的制备功能涂层的重要工艺技术,有着良好的应用前景.详细介绍了水热电泳沉积技术的原理、影响沉积工艺的因素,概述了水热电泳沉积动力学并总结了该技术在制备功能陶瓷涂层上的应用.指出水热电泳沉积技术是很有发展前景的涂层制备工艺;在进行水热电泳沉积应用研究的同时,应进一步开展其理论研究,探索水热电泳沉积技术的原理,建立合理的具有指导意义的理论及数学模型.     

KOH碱性环境中TiO_2纳米管的水热制备及机理探讨

以锐钛矿型纳米TiO2粉体为前驱体,KOH溶液为水热介质,采用水热法成功地制备出TiO2纳米管.研究了水热条件及后处理过程对TiO2纳米管形貌、晶型结构的影响,并对TiO2纳米管的形成机理进行了初步探讨.结果表明,经140℃水处理24h、酸洗干燥、400℃恒温煅烧2h后,可得到多层中空、两端开口的锐钛矿型TiO2纳米管.     

Australian Coral as a Biomaterial: Characteristics

In order to produce effective implants, the materials used must be biocompatible. Hydroxyapatite (HAp) is a bioactive material similar to the mineral component of teeth and bone which is often used for orbital implants and bone graft applications. HAp can be manufactured from corals via hydrothermal conversion. Coral is particularly useful as a starting material for hydroxyapatite production because of its porous nature. When a porous structure is used tissue ingrowth can occur readily and hence an excellent mechanical bond can be achieved. A large pore size and a high degree of pore interconnections are desirable implant properties. In the present paper a comparison of the properties of four different species of Australian coral has been made to determine the most favourable species to use as a starting material for hydrothermal conversion.     

Synthesis and characterization of super-microporous material with enhanced hydrothermal stability

Super-microporouos silicon material with high hydrothermal stability denoted as MCM-41-T has been prepared from mesoporous MCM-41 by high temperature treatment. The structural and chemical property of MCM-41-T has been characterized by X-ray diffraction, transmission electron microscopy, N₂ adsorption-desorption, infrared spectroscopy and ²⁹Si MAS NMR. The characteristic results show that Si-OH groups are forced to condense by high temperature treatment, and the pore size of MCM-41-T is around 1.5 nm in the super-microporous range. Compared with the original material MCM-41, the hydrothermal stability of MCM-41-T has been significantly enhanced.     

笼型有序二氧化硅介孔材料的制备

通过锻烧法除去结构导向剂制备笼型有序介孔二氧化硅,采用SEM、TEM／HRTEM等表征手段对各种材料进行了表征,说明水热晶化温度对材料的介观形貌影响起决定性作用,而水热晶化温度在150℃时所得介孔材料Si-150结构规则排列的笼型介孔孔道是一种理想的纳米反应环境。用透射电镜的表征手段证明了该种材料为三维笼型结构。     

Solidification of coal fly ash using hydrothermal processing method

Solidification of Coal Fly-ash (CFA) has been carried out using a hydrothermal processing method. In the hydrothermal processing, the CFA was first compacted in a mold at 20 - 50 MPa, and then hydrothermally cured in an autoclave. The hydrothermal curing was performed at 150 – 250°C for 15 – 60 h. The experimental results showed that NaOH solution, Ca(OH)₂ content, compaction pressure, autoclave curing temperature and time significantly affected the strength of solidified bodies. The most important strength-producing constituent in the solidified bodies produced with CFA was tobermorite, or tobermorite-like calcium silicate hydrate. When the CaO/SiO₂ ratio of the starting material was close to 0.83, tobermorite readily formed and the formed tobermorite enhanced the strength of solidified bodies. The tensile strength determined by the Brazilian test reached more than 10 MPa under the hydrothermal processing. As such, the hydrothermal processing method may provide a high potential for recycling CFA on a large scale.     

水热法制备尖晶石LiMn2O4正极材料的研究进展

介绍了近年来国内外有关水热法合成锂离子电池正极材料尖晶石LiMn2O4的研究工作,从锰源的选取对尖晶石锂锰氧化物的水热制备方法中存在的优缺点进行了比较和评述。对今后LiMn2O4水热合成研究以及发展方向等方面做了阐述。     

Hydrothermal ageing of CSM-laminate during water immersion — an acousto-ultrasonic study

Acousto-ultrasonics represents a very attractive and promising technique for detecting flaws and studying degradation of composite material. Studies of damage under hydrothermal ageing incurred by random fibre-reinforced laminates have been carried out with this technique. It is shown that the “stress wave factor” is a sensitive indicator of random fibre composite strength reduction due to a hydrothermal effect. The same study can be used for the estimation of strength from the data generated under accelerated conditions.     

Low temperature hydrothermal synthesis of Ba(Mg1/3Ta2/3)O3 sol-derived powders

Powders of the microwave dielectric material barium magnesium tantalate Ba(Mg1/3Ta2/3)O3 have been produced by hydrothermal synthesis at moderately low temperatures (160 to 350°C). It was found that while it is relatively straightforward to produce the material in the desired perovskite phase at or below 200°C, the powder particles tend to be highly irregular in morphology with extremely small dimensions (of the order of 10 nm) and deficient in magnesium (with some precipitation of the excess magnesium as the hydroxide). The effects of both higher synthesis temperatures and different feedstock preparation were thus investigated with the aim of improving the precipitation of magnesium under hydrothermal conditions in order to produce a more homogeneous, stoichiometric powder and significant progress was made. It was found that when near-stoichiometric particles are formed, they adopt rounded morphologies and exhibit larger particle sizes (around 30–50 nm). These results show that the hydrothermal feedstock and the synthesis temperature used have a profound effect on particle stoichiometry, which in turn affects the growth morphology of the particles.     

Fe3O4/PVDF复合材料的介电性质研究

采用水热法合成纳米Fe3O4颗粒,并以其作为导电颗粒,与聚偏氟乙烯按不同比例混合,用精密阻抗分析仪（Agilent4294A）测试复合材料的介电性能,结果表明,随着复合材料中Fe3O4含量的变化,复合材料发生渗流效应,适当调节Fe3O4的含量,就能得到具有较好介电性能的复合材料。     

多相氢氧化铝向薄水铝石相转变过程的微观结构研究

以铝直接水解法所得氢氧化铝粉为原料,经水热处理获得了纯相的薄水铝石粉体。研究了水热反应温度对产物γ-AlOOH晶体结构及微观形貌的影响,并利用XRD、SEM、TEM、HRTEM、粒度分布和TG-DSC对样品的物相、微观形貌及晶相转变过程进行分析表征。结果表明,水热温度对于制备纯相薄水铝石发挥重要作用,且有利于优化合成条件。随着水热温度的升高,物质结构转变动力也随之增强,可实现由多相氢氧化铝向纯薄水铝石相转变。利用CASTEP软件分别对薄水铝石、拜耳石及诺耳石体系进行几何优化,计算各体系的总能量。证实在同一计算精度下,薄水铝石的总能量最低,说明该体系最稳定。     

Hydrothermal processing of materials: past,present and future

The hydrothermal technique provides an excellent possibility for processing of advanced materials whether it is bulk single crystals, or fine particles, or nanoparticles. The advantages of hydrothermal technology have been discussed in comparison with the conventional methods of materials processing. The current trends in hydrothermal materials processing has been described in relation to the concept of soft solution processing, as a single-step low energy consuming fabrication technique. Also some recent developments in multi-energy processing of materials such as microwave-hydrothermal, mechanochemical-hydrothermal, electrochemical-hydrothermal, sonar-hydrothermal, etc. have been discussed. An overview of the past, present and future perspective of hydrothermal technology as a tool to fabricate advanced materials has been given with appropriate examples.