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101.
102.
Liao Jiefan Hamada Kenji Senna Mamoru 《Journal of Materials Synthesis and Processing》2000,8(5-6):305-311
Mixtures of calcium and magnesium hydroxides and calcium dihydrogenphosphate in various molar ratios were ground in water with a fine grinding machine, which features multiring grinding media. Mechanochemical amorphization of the mixtures occurs quickly by grinding. The mixtures, after grinding for 5, 20, and 60 min, were then subjected to hydrothermal treatment at 573 K for 24 h. The influence of Mg/(Mg + Ca) molar ratio on the thermal behavior of the mechanically activated powders and the structure of the final products has been investigated. The microhomogeneity of Mg, Ca, and P elements on the samples is enhanced by the mechanochemical treatment. A shift in the X-ray diffraction peaks was observed among the final products with different grinding times, presumably due to a partial substitution of calcium by magnesium. 相似文献
103.
Xusheng Du Hong-Yuan Liu Guipeng Cai Yiu-Wing Mai Avinash Baji 《Nanoscale research letters》2012,7(1):111
A facile approach to functionalize carbon nanofibers [CNFs] with nanostructured polyaniline was developed via in situ mechanochemical polymerization of polyaniline in the presence of chemically treated CNFs. The nanostructured polyaniline grafting on the CNF was mainly in a form of branched nanofibers as well as rough nanolayers. The good dispersibility and processability of the hybrid nanocomposite could be attributed to its overall nanostructure which enhanced its accessibility to the electrolyte. The mechanochemical oxidation polymerization was believed to be related to the strong Lewis acid characteristic of FeCl3 and the Lewis base characteristic of aniline. The growth mechanism of the hierarchical structured nanofibers was also discussed. After functionalization with the nanostructured polyaniline, the hybrid polyaniline/CNF composite showed an enhanced specific capacitance, which might be related to its hierarchical nanostructure and the interaction between the aromatic polyaniline molecules and the CNFs. 相似文献
104.
PVC/阻燃抑烟剂体系的力化学改性 总被引:1,自引:0,他引:1
研究了高能振磨作用对PVC/硼酸锌(ZB),PVC/三氧化二锑(Sb2O3)-三氧化钼(MoO3)以及PVC/Sb2O3-MoO3-ZB体系阻燃抑烟性能和力学性能的影响。结果表明,高能振磨可使PVC与ZB、Sb2O3或MoO3分子闯产生化学键合,增强了PVC基体与阻燃抑烟荆ZB,Sb2O3-MoO3,Sb2O3-MoO3-ZB之同的界面相互作用,促进了阻燃抑烟荆(FRs)在PVC中的分散,使PVC/FRs体系的烟密度(Dm)值降低,极限氧指数(LOI)值以及抗冲击强度,拉伸强度,断裂伸长率得到明显提高。 相似文献
105.
ABSTRACTZirconium-boron composite powders with the stoichiometric bulk composition corresponding to ZrB2 were prepared using high-energy milling in a shaker mill starting with elemental boron and zirconium. Milling times up to 3 hours were explored. The characterization of the prepared powders included measuring their particle size distribution, crystal structure, and assessment of particle structure and morphology. Reactions in the prepared powders were characterized using thermal analysis as well as custom ignition and combustion experiments. Composite powders consist of a Zr matrix with B inclusions mostly 100 nm or less in size. The homogeneity of mixing between boron and zirconium improves when the milling time increases from 1 to 2 hours; it is not affected by longer milling times. Boron and zirconium start reacting during milling; the degree of this reaction becomes appreciable when the milling time reaches 2 hours. In air, ignition of both pure zirconium and the prepared powders occurs in the same temperature range of ca. 400–700°C for the heating rates varied from 2000 to 20,000 °C/s. In fuel-rich conditions, ignition of the prepared powders is affected by the reaction between B and Zr, which occurs less readily for powders milled for 2 hours or longer. In air, particles of the prepared composite powders burn faster than either pure boron or zirconium. Flame temperatures for individual composite particles burning in air are reasonably close to those predicted as adiabatic flame temperatures for this composite-air system at stoichiometric and fuel-rich conditions. In combustion products of an air-acetylene flame, the burn rates of the prepared composites are lower than that of zirconium and are comparable to that of boron. Powders prepared by 1-hour milling burn faster than powders prepared using longer milling times. 相似文献
106.
采用机械化学活化方法,在机械活化过程中用K2SO4为活化添加剂,强化锂云母中惰性Li?O配位结构活化转型,通过温和稀酸浸出高效分离锂,考察了活化过程添加剂用量、球磨时间和球料比及浸出条件如酸浓度、液固比、搅拌速度、温度和时间等对锂回收率的影响,确定了最佳工艺条件,讨论了反应过程机理。结果表明,机械化学活化强化破坏云母片层结构中的Si?O?K结构,降低了Si?O配位结构对Li?O配位结构的牵制力,导致Li?O键强减弱,反应活性增加。在最优条件下(精矿与K2SO4质量比5:1,球磨机转速500 r/min,球料质量比20:1,球磨时间3 h,硫酸浓度15vol%、液固比4 L/g、反应温度80℃、浸出搅拌速率200 r/min),锂浸出率可达99.1%。 相似文献
107.
高岭土干粉磨过程的机械力化学变化 总被引:7,自引:1,他引:6
本文较全面系统地介绍了高岭土干粉磨过程中发生的机械力化学变化。采用粒度分析、SEM、XRD、IR、DTA和TG、反气相色谱(IGC)和BET多层吸附等测试方法对干粉磨高岭土进行分析测定。结合高岭石晶体结构特点,从机械力化学角度阐述了在高岭土干粉磨过程中发生的晶格无序化,脱羟基反应、表面性质改变以及团聚作用的机理。 相似文献
108.
应用机械化学原理,研究了在振动磨样机中由磷酸二氢钙(MCPM)和氢氧化钙合成羟基磷灰石(HAP)过程的动力学机制,并建立了相应的动力学模型.结果表明,合成过程为生成中间产物二水磷酸氢钙(DCPD)的两步式反应,其中第二步反应在第一步反应结束后才开始,并且在很短的时间内(<30s)迅速完成,即发生了"爆炸式"反应,反应过程可用类Avrami方程进行表征.探讨了发生"爆炸式"反应的可能机理. 相似文献
109.
Mechanochemistry of Solids: Past, Present, and Prospects 总被引:11,自引:0,他引:11
A historical retrospective is presented beginning from the early observations by alchemists to the establishment of mechanochemistry as a branch of science. The changes in structure and chemical properties of solids under three-axes loading and by combined action of pressure and shift are demonstrated. The peculiarities of the phenomena taking place upon stressing of particle assemblies in various types of energy-intensive grinding mills are discussed. Based on the contemporary concepts, the mechanism of stress field formation and relaxation is analyzed. Among decisive factors influencing the mechanochemical synthesis, the formation and renewal of contact area between reacting compounds, the explosive evolution of heat, and the feedback phenomenon are emphasized. The perspective directions of practical application in the area known as mechanical alloying, as well as in preparation of functional ceramics and catalysts, and in pharmacy are discussed. The main directions for improving research, construction of milling devices, training of specialists, and exchange of knowledge are proposed. 相似文献
110.