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41.
Jun Li 《Materials Letters》2007,61(6):1274-1278
The improvement of titanium diboride (TiB2) coatings over the molybdenum substrate was investigated by comparing the electrochemical techniques of continuous current plating (CCP) and periodically interrupted current (PIC). The solvent used was a eutectic Flinak mixture (LiF-NaF-KF, 46.5:11.5:42 molar ratio) with solutes K2TiF6 and KBF4 with the electrochemically-active components in the molar ratio of one to five. The coatings produced by PIC show improvements in morphology and microstructure for the suitable conditions: i = 0.5 A/cm2, frequency = 100 Hz, the time ratio tc/toff (current on/current off) = 4/1. X-ray diffraction (XRD) analyses indicated that the coatings are composed of the relatively pure TiB2 and the preferred orientation is [001] + [110], which is in accordance with the prediction of the two-dimensional crystal nuclei theory. 相似文献
42.
43.
本文研究了用金属有机物热发解法制备PLT8薄膜的工艺过程和基片对薄膜结构的影响,并且给出了铁电性能的测量结果。 相似文献
44.
分析比较了进口锡与国产锡的成分和性能。设计出了新型的引线热浸镀锡合金,它具有较低的工作温度、优良的抗氧化性、流动性和可焊性。 相似文献
45.
粉状阳离子聚丙烯酰胺的研制 总被引:2,自引:0,他引:2
黄祥虎 《高分子材料科学与工程》1992,8(4):120-122
用聚丙烯酰胺胶体,在≥20%浓度的硫酸盐溶液中,进行Mannich反应,经真空干燥后,制取水溶性阳离子型高分子。初步探讨了盐浓度、温度、时间、配比对产物的阳离子度、溶解性的影响。 相似文献
46.
A novel phenacyl anilinium salt, N-phenacyl, N,N-dimethylanilinium hexafluoroantimonate, (PDA), has been synthesized and used as photoinitiator for cationic polymerization of cyclohexene oxide (CHO), butyl vinyl ether (BVE) and N-vinyl carbazol (NVC). Plausible mechanism of the photoinitiation involves the decay of the excited PDA with both heterolytic and homolytic cleavages of carbon-nitrogen bond. Thus, phenacylium cations formed directly or subsequent intermolecular electron transfer, respectively, initiate the polymerization. 相似文献
47.
从氯化铅渣中回收铅铋的研究 总被引:1,自引:0,他引:1
王淼生 《广东有色金属学报》1996,6(1):39-44
本文以柿竹园有色金属矿粗铋火法精炼、气化除铅产出的铅渣为原料,在常压下采用氯化钠水溶液进行浸出处理,有效地分离了铅和铋,并将铅制成了化工产品黄丹及硫酸铅 相似文献
48.
49.
LeAnn Southward Hogan Elizabeth Marschall Carol Folt Roy A. Stein 《Journal of Great Lakes research》2007,33(1):46-61
Lake Erie's food web has been dramatically modified by exotic species. Both exotic dreissenid mussels and the round goby Neogobius melanastomus have shifted the food web from a pelagicbased to a benthic-based one, potentially creating a new pathway for contaminant transfer to top predators. Before the invasion of round gobies, few predators of dreissenids occurred in Lake Erie, allowing contaminants to be confined to these benthic organisms. The invasion of the round goby has produced a new pathway through which these contaminants can enter the food web. To characterize heavy-metal transfer through this new food web and to assess risk to humans, water, surficial sediment, dreissenid, round goby, and smallmouth bass Micropterus dolomieui samples were collected at three sites during summers, 2002 and 2003, and analyzed for total lead (Pb), total mercury (Hg), and methyl mercury (MeHg). In addition, we compared smallmouth bass Pb and Hg concentrations to those measured in 1993/1994, before round gobies were prevalent. Pb biodiminished and MeHg biomagnified through the food web to smallmouth bass; patterns were similar among our three sites. Total Pb concentrations in smallmouth bass were higher before the incorporation of round gobies into their diet. We attributed this decline to changes in food web structure, changes in contaminant burdens in prey, or declines in sediment Pb concentrations in Lake Erie. By comparison, Hg concentrations in smallmouth bass changed little, before and after the round goby invasion, possibly due to a shift in diet that increased growth. Despite a decline in sediment Hg concentrations in Lake Erie, smallmouth bass continued to accumulate Hg at historical rates possibly because of their high consumption rates of benthivorous round gobies. As smallmouth bass continue to consume round gobies during their lives, their Hg concentrations may well continue to increase, potentially increasing the risk of Hg contamination to humans. 相似文献
50.
新型陶瓷与熔融盐复合蓄热材料优化组合的数值模拟 总被引:12,自引:0,他引:12
将高温熔融盐相变蓄热材料和陶瓷固相蓄热材料进行复合 ,成功地研制成了能快速吸热和放热且蓄热密度高、蓄热量大的新型复合蓄热材料。分别以Al2 O3 ,MgO ,SiC为代表的陶瓷材料与 6 0LiF 40NaF ,5 0LiF 5 0KF ,6 0 .1NaCl 39.9MgCl2 ,LiH等为代表的 10余种高温熔融盐材料为复合研究对象 ,对复合蓄热材料的蓄热密度等与温度、复合材料中熔融盐的含量、材料种类间的关系进行了数值模拟研究 ,得到了对复合材料的优化设计具有指导意义的结论 相似文献