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91.
Model compound studies were carried out to elucidate the reaction mechanisms taking place during the liquefaction of coal with the hydrogen produced from the reaction of zinc and water. In compounds of the type Ph-(CH2)n-Ph the splitting of the aliphatic bridge was easier with higher n values. Ether type compounds such as diphenylether were unreactive although the C-O bond in dibenzylether was easily cleaved. Condensed ring aromatic compounds gave low conversion with hydrogenation being facilitated by an increase in ring number. Phenolic compounds such as phenol did not react well, but the reactivity increased with increase in aromatic ring size. The cleavage of the aliphatic bridge was accelerated by the OH group, for example, in the case of 4-hydroxydiphenylmethane bond scission was about 15 times higher than that of diphenylmethane. Heterocyclic compounds were unreactive. 相似文献
92.
We review our X-ray absorption spectroscopy studies of adsorbate geometries on the O-terminated (000
) and Zn-terminated (0001) basel faces, as well as the non-polar (10
0) prism face of ZnO. Studies employing near-edge X-ray absorption fine-structure (NEXAFS) and surface X-ray absorption fine-structure (SEXAFS) are included. 相似文献
93.
Zinc vaporization of Mn-Zn ferrites was quantitatively characterized in terms of oxygen partial pressure P O2 , temperature, grain size and sample geometry. The amount of zinc loss was measured as a function of time at various temperatures by a thermogravimetric method. The weight loss due to irreversible zinc vaporization showed a linear behavior with time and increased exponentially with temperature. The observed weight loss due to zinc evaporation at 1100°C was small, whereas a significant weight change was detected at 1200°C. The weight loss was even greater in a reducing atmosphere ( P O2 = 5 × 10−5 ). Below 1300°C, the diffusion of elemental zinc was sufficiently fast to compensate the zinc loss at the interface region, resulting in a linear dependence on time. At temperatures ≥1400°C, the weight change no longer followed the linear dependence and showed a rather parabolic behavior with a concave upward slope. The core shape and the gas flow around ferrite cores were important factors that affected the rate of zinc vaporization, but not the grain size. 相似文献
94.
95.
以自制的环氧树脂乳状液为漆基、磷酸锌作为活性防锈颜料合成了水性环氧防腐涂料。研究了涂料中颜基比、固化剂与环氧树脂的当量比等对涂膜性能的影响。结果表明,颜基比小于1,固化剂CEN-537与环氧树脂E-44的当量比为1或稍大于1时,所得涂膜的各项性能指标可达到较好的平衡;涂料的防绣性能与以硅铬酸铅为防绣颜料的传统涂料相当。新研制的水性环氧防腐涂料性能达到了国外同类产品的水平。 相似文献
96.
97.
Zinc diffusion and extractability as affected by zinc carrier and soil chemical properties 总被引:1,自引:0,他引:1
A. S. Modaihsh 《Nutrient Cycling in Agroecosystems》1990,25(2):85-91
This work was carried out to evaluate the effect of soil chemical properties, Zn carrier and time elapsed after fertilizer application on the diffusion and extractability of Zn. A soil block technique was used to study zinc diffusion and DTPA extractability from ZnEDTA and ZnSO4 fertilizers in three soils that varied in texture, CaCO3 content, organic matter content, and pH using Zn65 tracer. ZnEDTA diffused readily in all soils, moving 20–25 mm from the fertilizer layer after three days. The rate of Zn diffusion and the extractability of Zn, however, varied among the soils and were lowest in Baha soil with the highest clay content, organic matter, and CEC despite its lower pH. The high pH and CaCO3 content in Dirab soil did not restrict the diffusion or reduce the extractability of ZnEDTA in this soil. On the other hand, the diffusion of Zn from ZnSO4 fertilizer was largely restricted in all soils and was confined to 5 mm from the fertilizer layer after 13 d. The extractability of ZnSO4 fertilizer was largely affected by soil pH and CaCO3 content and was lowest in Dirab calcareous soil. Organic matter amendment at 5% (as alfalfa) considerably reduced the diffusion and the extractability of ZnSO4 in both Dirab calcareous and Bakyria noncalcareous soils. The application of 1% (w/w) elemental S reduced soil pH and increased Zn diffusion from ZnSO4 fertilizer in Bakyria soil but had slight effect on Dirab calcareous soil. 相似文献
98.
POE和T-ZnOw协同改性聚丙烯的研究 总被引:3,自引:1,他引:3
以聚丙烯(PP)、热塑性弹性体(POE)、四针状氧化锌晶须(T-ZnOw)为原料,制备了PP/POE/T-ZnOw复合材料;研究了复合材料的结晶结构和力学性能。结果表明:T-ZnOw能诱导β晶型的生成,在快速冷却的条件下POE也能诱导生成β晶型。随着T-ZnOw含量的增加,PP/POE/T-ZnOw复合材料的冲击性能不断提高。T-ZnOw含量为20%时,PP/POE/T-ZnOw的冲击强度比纯PP提高了82.5%;拉伸强度和断裂伸长率先增加后降低。T-ZnOw的加入还能很好地改善复合材料的熔体流动性能。 相似文献
99.
采用乳化液膜法制备出草酸锌微细颗粒,乳化液膜体系以煤油为油相,以含量高于95%的二-(2-乙基己基)磷酸酯为载体,选取丁二酰亚胺类表面活性剂T155为膜相稳定剂,内、外水相分别为草酸和硝酸锌溶液,外水相Zn2 透过膜相与内水相草酸结合生成草酸锌微细颗粒。反应在40min时基本平衡,Zn2 萃取率达到90%。实验考察了反应条件对产物粒径的影响,研究表明,粒径随表面活性剂用量的增加、油水比(O/A)的增大而减小,外水相Zn2 浓度的降低可以有效地减小颗粒的粒径。TG、SEM和XRD分析证明合成产物是含两个结晶水的均匀草酸锌颗粒。将制得样品在500℃下煅烧2 h得到粒径均匀的六方纤锌矿晶系ZnO颗粒。 相似文献
100.
K. G. Vasantha Kumari P. Divya Vasu Viswanathan Kumar Thangavelu Asokan 《Journal of the American Ceramic Society》2002,85(3):703-705
Formation of spinel phases in ZnO–Sb2 O3 and ZnO–Sb2 O3 –Bi2 O3 systems is studied by the use of X-ray diffraction. The formation of nonstoichiometric Zn2.33 Sb0.67 O4 phase is observed in both the systems at ∼900°C. However, in these systems, at higher temperatures ( T ≥ 1100°C), formation of the inverse spinel phase Zn7 Sb2 O12 is observed. The study has been extended to understand the effect of CrO3 doping on the stability of the different spinel phases in the previously mentioned systems. Interestingly, in both the systems, samples doped with CrO3 , displayed the presence of Zn2.33 Sb0.67 O4 phase <1200°C, indicating the stabilization of the spinel phase by CrO3 . 相似文献