CO2硬化酚醛树脂粘结剂的合成研究

CO2硬化碱性酚醛树脂粘结剂是一种环保型铸造用粘结剂，该文以抗压强度为主要考察目标，对CO2硬化碱性酚醛树脂合成过程中的基本影响因素进行了初步分析与探讨，利用正交实验对酚醛树脂的合成配比进行优化，最终确定了合成碱性酚醛树脂原料的最佳配比以及工艺。     

铸造用CO2硬化碱性酚醛树脂粘结剂的研究进展

在现代铸造生产中,粘结剂占有非常重要的地位,它的性能直接影响铸件的质量.酚醛树脂粘结剂在铸造生产中使用较为广泛.对CO2硬化碱性酚醛树脂粘结剂的合成及改性、固化机制、固化过程进行概述并对其发展前景作了展望.     

CO_2硬化酚醛树脂的制备及在缸体砂芯上的应用

CO_2硬化酚醛树脂粘结剂是一种有利于环保的冷芯盒制芯材料。对酚醛树脂本体合成工艺进行了简要的总结,介绍了通过正交试验得到的合成工艺,制备的树脂砂具有吹气硬化,初始强度高的特点。对发气量等工艺性能进行了检测,并重点介绍了该材料在卡车大型柴油发动机缸体砂芯上的应用。生产实践表明,CO_2硬化酚醛树脂粘结剂制芯无毒、无味,浇注铸件内腔表面光洁,砂芯溃散性良好,生产出了合格的缸体铸件。     

铸造用CO2硬化酚醛树脂促硬剂的研究

研究了一种CO2硬化酚醛树脂粘结剂的粉状促硬剂，是由Ca（OH）2、硅酸盐水泥及另外两种金属氧化物复合混制而成，原料便宜易得。使用后可增加酚醛树脂粘结剂CO2气体硬化的敏感性，缩短吹气硬化时间，在吹气硬化后，大幅度地提高了粘结剂的工艺强度，并改善了酚醛树脂粘结剂的抗吸湿性能。介绍了该促硬剂的制备，通过正交试验优化了各组分的添加比例，同时对使用该促硬剂型砂混合料的流动性、可使用时间、吹气硬化时间、吹制的砂芯的存放性、溃散性和发气性等工艺性能进行了对比试验，最后对该促硬剂的增强机理进行了简要的分析。     

铸造用CO2硬化碱性酚醛树脂粘结剂的研究

介绍了一种铸造用CO2硬化碱性酚醛树脂粘结剂的试验研究,选用NaOH作催化剂,以甲醛和苯酚为原料合成了一种碱性酚醛树脂,并优化了合成工艺。通过添加适量的交联剂硼砂和分散剂KOH,硅烷偶联剂以及有机活性助剂等,吹入CO2气体,硬化后,树脂砂芯得到较高初强度和终强度。     

酯硬化酚醛树脂砂的最新进展

详细地叙述了酯硬化酚醛树脂砂采用新型酚醛树脂粘结剂、硬化剂和再生新工艺的最新进展,并对国内酯硬化酚醛树脂砂的研究与应用提出了若干建议。     

一种3D砂型打印用高强度耐高温酚醛树脂的合成及其使用性能研究

合成了一种3D砂型打印用酚醛树脂,探究了其常温强度、耐高温性、可使用时间、稳定性等使用性能。结果表明,该酚醛树脂的常温强度高、粘度低、耐高温性能优异、能够实现快速硬化、体系稳定,是一种性能优异的新型3D砂型打印用酚醛树脂粘结剂。     

多元聚合CO2硬化碱性酚醛树脂合成工艺的优化

介绍了一种新型、绿色环保、经济高效、冷芯盒法用粘结剂的合成工艺优化试验。以氢氧化钠为催化剂,苯二酚或双酚A为改性剂,苯酚和甲醛进行合成试验,并对样品的溃散性、发气性进行测试,确定了CO2硬化碱性酚醛树脂的较佳改性合成工艺。以抗压强度为主要考察指标,通如CO2气体的树脂砂芯硬化后,获得了较高初强度和终强度。     

纳米磨料制备花岗石抛光磨具的研究

以纳米三氧化二铝和纳米二氧化锡等作为复合纳米磨料，以酚醛树脂为粘结剂在160℃和8MPa的条件下预压，然后在硬化炉里硬化制备花岗石抛光磨具。磨削对比试验表明：纳米磨料花岗石抛光磨具的磨削性能、耐磨性能、耐水性能均优于普通磨料花岗石抛光磨具，前者的抛光光洁度达98度。     

铸造用CO2硬化酚醛树脂粘结剂固化机理的研究

通过核磁共振、红外光谱等手段,对铸造用CO2硬化酚醛树脂粘结剂的结构以及固化机理进行了研究,认为CO2硬化的酚醛树脂粘结剂的固化机理是,在吹入CO2后使粘结剂体系的pH值降低,在弱碱性的条件下,硼酸盐的负离子与甲阶酚醛树脂的酚羟基进行了配位交联.研究中发现:羟甲基与硼砂的反应活性比酚羟基与硼砂的反应活性要大得多,在粘结剂的配制过程中,树脂中羟甲基已经参与了与硼砂的反应;在吹入CO2气体硬化后,有大量硼酯键的生成.由于大部分的羟甲基已经发生了反应,在这一阶段发生B-O配位反应的是酚羟基;吹气硬化过程的体系放热反应的热作用对硬化也起到了很大的促进作用.     

熔盐体系中电沉积制备TiB2镀层的研究现状

介绍了熔盐体系中电沉积制备TiB2镀层技术中熔盐的选择、电镀工艺和参数的选择，概述了不同熔盐体系中B离子、Ti离子在阴极沉积的电化学机珲以及TiB2的合成机理，论述了TiB2惰性阴极在铝电解工业中的研究现状，最后分析了熔盐体系中石墨电极上制备TiB2镀层的可行性。     

Chemical modification of the surface of highly dispersed metal salt crystals

Approaches to chemical modification of surfaces of metal salt crystals, which until recently are not considered objects for surface modification, are collected and analyzed. Possibilities of postsynthetic modification and modification in situ during synthesis of metal salt nanoparticles are discussed. Data for structures of the surface complexes forming upon the interaction of modifiers (organic molecules) and ions on a particle surface and the stability and properties of such complexes are given. Areas of and prospects for practical application of different surface-modified metal salts are shown.     

温和条件下碲化铅纳米颗粒的制备

以Pb(CH_3COO)_2·3H_2O和TeO_2为原料,硼氢化钾为还原剂,在常压下,室温至70 ℃碱性水溶液中成功地制得了PbTe纳米粉末.粉末X射线衍射分析表明制备的粉末为NaCl结构,透射电子显微镜观察表明颗粒粒径随反应温度升高而增大,从8 nm (室温) 增加至40 nm (70 ℃).能谱(EDS)分析表明产物的组成元素为Pb和Te.还对PbTe纳米颗粒的形成机理做了探讨.     

Low temperature molten salt preparation of molybdenum nanoparticles

Pure molybdenum (Mo) nanoparticles (NPs) were synthesized by a novel molten salt technique using Na₂MoO₄ and Al as starting materials and NaCl, KCl and NaF to form a reaction medium. The effects of salt type, reaction temperature and salt to reactant ratio on the synthesis of Mo NPs were investigated in detail. Phase pure Mo NPs with a crystalline size of about 46 nm were synthesized at as low as 650 °C which was much lower than that required by other conventional reduction methods. Among the salts tested, the NaClKClNaF ternary salt showed the best accelerating effect on the low temperature Mo NPs formation, and the optimal weight ratio of salt to reactant was 1.0:1.0. The “dissolution-precipitation mechanism” played a dominant role in the molten salt synthesis of Mo NPs.     

The synthesis of new electron-deficient naphthoquinones

The syntheses and electrochemical properties of two novel electron-deficient naphthoquinones are described. Quinone (4) readily forms a charge transfer salt with tetrathiofulvalene (TTF). The key step in the synthesis of the quinones is an active nickel powder-assisted cycloaddition of a substituted o-xylylene to fumaronitrile.     

Morphology and structure of LiNb0.6Ti0.5O3 particles by molten salt synthesis

M-phase LiNb_0.6Ti_0.5O₃ (LNT) plate-like particles with large anisometric shape were firstly fabricated by molten salt synthesis (MSS) method in LiCl flux. Effects of reaction temperature, holding time and the weight ratio of LiCl salt to the original powders on the phase structure and morphology of the synthesized particles were investigated. The LiNb_0.6Ti_0.5O₃ powders generally showed a multi-layer structure, exhibiting irregular hexagonal or triangle morphology. The reaction temperature showed a strong influence on the particle growth process, and pure LNT particles are obtained at 950 °C. Further increasing the reaction temperature and holding time could increase the average size of the particles. It revealed that the thickness of the plat-like particles was increased as the contents of the chloride salts increased. The synthesis process, the relation between crystal structure and morphology of particles were also discussed.     

碳热还原结合熔盐法制备碳化钛粉末与表征

以NaCl为熔盐介质,采用锐钛矿型钛白粉和炭黑为原料,探索一种碳热还原结合熔盐法合成高纯碳化钛(TiC)的方法。借助XRD研究了反应温度和原料配比对合成碳化钛的影响,采用SEM、TEM、EDS、粒度分析仪、热力学分析等检测分析手段对合成产物的特性和过程进行分析。结果表明:相比传统的碳热还原合成碳化钛的方法,NaCl熔盐介质的引入可以有效地降低碳化钛的合成温度(从1700℃到1550℃)以及合成高纯碳化钛的时间(从10 h到3 h)。结合研究成果,提出了熔盐介质中溶解-沉淀的合成机理。     

Synthesis and electrical properties of two new conducting materials containing unsymmetrical tetraselenafulvalenes

We report the synthesis and characteristics of two new unsymmetrical π donors in the TSF family, dimethyl-4,5 and trimethylene-4,5 tetraselenafulvalenes (UDMTSF and TTSF). The temperature dependences of the electrical conductivity are also reported for the charge transfer complex TTFS-TCNQ and for the radical cation salt (UDMTSF)₂ClO₄.     

拓扑微晶转换法合成片状KNbO3粉体

以K2CO3,Nb2O5为原料,KCl为熔盐,采用熔盐法合成片状K4Nb6O17粉体,系统研究了熔盐含量、合成温度和保温时间对K4Nb6O17粉体形貌的影响。当熔盐含量与反应物的质量比为5:5,合成温度为1050℃,保温3h的条件下,能够制备出长5~100μm,宽5~10μm,厚1~3μm,边缘整齐且具有钙钛矿结构的片状K4Nb6O17粉体。以获得的片状K4Nb6O17粉体为前驱体,采用拓扑微晶转化法,在950℃下保温8h,成功制备出了片状KNbO3粉体,可作为制备织构化铌酸钾钠无铅压电陶瓷的模板剂。     

Molten salt synthesis of La0.8Sr0.2MnO3 powders for SOFC cathode electrode

For La_0.8Sr_0.2MnO₃ (LSM) perovskite, used as the cathode material for solid oxide fuel cells (SOFC), it is known that the formation of a triple-phase-boundary is restrained due to the formation of a second phase at the YSZ/electrode interface at high temperature. To decrease the 2^nd phase, lowering the sintering temperature has been used. LSM powder was synthesized by molten salt synthesis method to control its particle size, shape, and agglomeration. We have characterized the phase formation, particle size, shape, and sintering behavior of LSM in the synthesis using the variation of KCl, LiCl, KF and its mixed salts as raw materials. In the case of KCl and KCl-KF salts, the particle size and shape of the LSM was well controlled and synthesized. However, in the case of LiCl and KCl-LiCl salts, LiMnO_x as 2^nd phase and LSM were synthesized simultaneously. In the case of the mixed salt of KCl-KF, the growth mechanism of the LSM particle was changed from ‘diffusion-controlled’ to ‘reaction-controlled’ according to the amount of mixed salt. The sintering temperature can be decreased below 1000 °C by using the synthesized LSM powder.