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为找出电气元器件在使用一段时间后出现腐蚀现象的原因,研究典型电气元器件在含H_2S环境中的腐蚀行为并提出防护措施。利用便携式多功能气体检测设备对电气元器件所在环境中H_2S、SO_2、NO_2以及NH_3等腐蚀性气体含量进行检测,并采用扫描电子显微镜(SEM)和能谱仪(EDS)手段分析电气元器件的腐蚀微观形貌及锈层中的腐蚀产物成分。电气元器件所处环境中存在腐蚀性气体H_2S,电气元器件在使用环境中发生不同程度的腐蚀反应,出现发黑或失去光泽等现象,表面形的腐蚀产物中均出现S元素。电气元器件在该环境中发生腐蚀现象的主要因素是环境中H_2S气体,建议采取整体净化服役环境中腐蚀性气体的防护措施,可减少或避免发生腐蚀反应。 相似文献
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文章对塔中四油田注水管线结垢腐蚀影响因素进行分析,结果表明:影响结垢的主要因素为回注水中高浓度的钙离子、碳酸氢根离子形成的碳酸钙垢;影响腐蚀的主要因素为回注水质呈弱酸性,氯离子和硫化物含量高,氯离子和硫化氢的协同作用加剧了管道的腐蚀。另外,注水管线中井口流速慢,压力降低,注入水质不配伍等因素都会导致结垢腐蚀。因此,应主要选择针对碳酸钙类型的阻垢剂和防氯腐蚀缓蚀剂以减缓塔中四油田管道结垢腐蚀。 相似文献
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密封材料在全密闭型整机中应用非常普遍,例如:密封条、密封圈、减振密封垫片等。作为整机研制单位,加固型整机是全密闭形整机的主要结构形式,因此,相应地对全密闭型整机使用密封材料的性能提出了更高的环境适应性的要求。作为密封材料的主要物理性能要求是强度、弹性、无挥发性腐蚀气体、外形尺寸等。相应的工艺要求是成型方便。 相似文献
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M. Brinkman K. Fogelman J. Hoeflein T. Lindh M. Pastel W. C. Trench D. A. Aikens 《Environmental management》1980,4(6):511-520
Levels of polychlorinated biphenyls (PCBs) have been determined in the water, in the soils and sediments, and in the biota of a small upstate New York public water supply system, which is near the heavily polluted section of the Hudson River and a disposal site for PCB-containing waste. The impounded water exhibits a significant and relatively uniform level of Aroclor 1016, whereas the ground and surface waters supplying the reservoir do not. Rainfall, which exhibits a high level of Aroclor 1016, constitutes a small but significant source of PCB input. Soil and sediment samples exhibit significant median levels of both Aroclor 1016 and Aroclor 1254, but the local concentrations vary widely. The biota exhibit much higher PCB levels than the water or sediments, and show a strong preference for Aroclor 1254. The PCB levels in the macroinvertebrates are particularly high, suggesting that these organisms may provide a useful indicator for monitoring PCB contamination in aquatic systems. Risk assessment indicates that the lifetime incremental risk of cancer associated with the drinking water is below 10–6. Management of such low levels of PCB contamination is best achieved by reducing the input of PCBs. 相似文献
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二段混凝沉淀-曝气氧化-砂滤处理印刷电路板废水 总被引:5,自引:0,他引:5
探讨印刷电路板废水处理工艺。针对某印刷电路板厂废水水质特点,采用“二段混凝沉淀一曝气氧化一砂滤”工艺对其进行处理。运行结果表明,废水准确分类及预处理、曝气氧化和投加重金属捕捉荆是保证出水达标的重要措施。该工艺处理效果稳定,出水水质低于《污水综合排放标准》(GB8978-1996)中一级标准。本研究为印刷电路板废水的处理提供了一条可行途径。 相似文献
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某云桌面终端在进行中国强制性认证(CCC)时,电磁兼容试验项目电源端传导骚扰、辐射骚扰测试均出现超标现象。将重点从PCB板级电路EMC设计方面剖析其测试不合格原因,并给出相应的整改措施,最后对此案例进行总结,给出类似电子产品在PCB设计时的注意事项,以期能给PCB设计工程师提供一些参考意见。 相似文献
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We conducted a laboratory study to assess the efficiency of nonionic and anionic surfactants in combination with a sparing quantity of ethylenediaminetetraacetate (EDTA) to simultaneously extract heavy metals (HMs) and polychlorinated biphenyl (PCB) compounds from a field-contaminated soil. A soil wash that mobilized both HMs and PCBs was combined with back-extraction with hexane to remove PCBs from the aqueous wash. The aqueous washing suspension was then regenerated by precipitation of the HMs induced by corrosion and hydrolysis of zero-valent Mg to provide a cleaned soil and innocuous extract. Finally, the washing suspension was recycled twice to mobilize more contaminants from the soil particulate fraction. After ultrasonic equilibration, EDTA in admixture with a nonionic surfactant did not appreciably change the efficiency of mobilization of most heavy metals (Al, Cd, Cr, Fe Mn, Ni, and Zn), but did increase the recovery of Cu and Pb. The release of EDTA from HM complexes was efficient for most metals (99%) but was influenced by the chemical characteristics of the surfactant. The EDTA recovery (62-65%) after three cycles of soil washing, hexane back-extraction, and Mg(0) treatment was similar for all reagent combinations. In toto, these studies demonstrate that after treatment with ultrasound, selected heavy metals can be coextracted efficiently from soil with a single washing suspension containing EDTA and a nonionic surfactant. 相似文献
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Contaminated sediments dredged from navigable waterways often are placed in confined disposal facilities to prevent further spread of the pollutants. Reducing contaminants to acceptable levels would allow for disposal of the sediments and further dredging activity. A greenhouse study was conducted to evaluate plant treatments and the addition of an organic amendment to decrease the concentration of PCB congeners found in Arochlor 1260. Sediment treated with the amendment and either low transpiring plants or no plants had the greatest removal of the PCB congeners. High-transpiring plants apparently prevented the highly reducing conditions required for reductive dechlorination of highly chlorinated PCBs. Most likely, the amendment provided labile carbon that initiated the reducing conditions needed for dechlorination. The sediment moisture content and moisture-related plant parameters were significant predictors of the PCB loss. Carex aquatalis and Spartina pectinata are predicted to be the most effective plant treatments for phytoremediation of PCBs. 相似文献
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Organochlorine compounds are known to be atmospherically transported to long distances from their original sources. To understand the influence of California's Sierra Nevada range on the air transport and subsequent distribution pattern of some of these residues within the range, we have chosen salmonid fish as an indicator species. Fish were collected from 10 locations throughout the northern and central Sierra Nevada and polychlorinated biphenyl (PCB), toxaphene, chlordane, and DDT [1,1,1-trichloro, 2,2'-bis (p-chlorophenyl) ethane] residues in muscle tissue were analyzed. Rainbow trout (Oncorhynchus mykiss) were found in all sampling locations, and therefore analyses mainly focused on this species. When similar-sized rainbow trout samples from several similar oligotrophic, high-altitude lakes and streams were compared, it became apparent that altitude is one of the factors affecting the residual levels of PCB (r(2) = 0.882), but not for total DDT, toxaphene, or chlordane in trout. Analysis of correlations among these four organochlorine compound residue groups indicated that there are modest correlations in patterns of distribution between chlordane vs. toxaphene (r(2) = 0.345), and chlordane vs. total DDT (r(2) = 0.239), but toxaphene residues are not correlated with PCB or total DDT. In view of significant correlation to the altitude it is concluded that PCB residue in rainbow trout is a good monitoring tool for studying the effect of high-altitude mountain ranges on the long-range transport and distribution of those persistent pollutants. 相似文献
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Spatial and temporal distribution of polychlorinated biphenyl (PCB) concentrations in soils of an industrialized city in Turkey 总被引:2,自引:0,他引:2
Surface soil (0-5 cm) samples from 43 sampling sites covering the entire urban territory of Bursa, an industrialized city in Turkey, were collected in each season and analyzed for 83 polychlorinated biphenyls (PCBs). The mean concentration of total PCBs (Σ83 PCBs) among all sites over the four seasons was 2121.51 pg/g dry weight (dw), with a range of 207.61-5461.95 pg/g dw. Total PCB concentrations in the soil samples collected near an industrial region were the highest in all seasons. In general, PCB patterns were dominated by low-chlorinated homologue groups (≤ 5 Cl groups at a 79% level). The predominant homologue group found in Bursa city soils was the penta-CBs (29.1%) followed by the tetra-CBs (25.5%) and tri-CBs (17.6%). A total of seven dioxin-like PCB congeners (CB-77, 81, 105, 114, 118, 123, and 126) were found in every sampling location and their mean total concentration for all locations and seasons was 259.27 pg/g dw, with a range of 7.02-1581.13 pg/g dw. A significant relationship (r = 0.77, p < 0.01) was found between the concentrations of dioxin-like PCBs and the seasonal average sum of PCB concentrations. A correlation between light congeners (相似文献
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大多数天然气藏CO2含量为10%~98%,CO2在不同的温度、压力条件下腐蚀极其严重。文章主要针对高含CO2天然气运输管道腐蚀的问题,开展缓蚀剂的筛选,重点开展CO2腐蚀规律研究与实验,评价环境温度、CO2分压、流动速度对腐蚀规律的影响,明确缓蚀剂的影响因素,结合管材的材质,优选评价不同类型的缓蚀剂,缓蚀效率分别为90.53%和92.64%,在管道凝液介质的气相及液相中都有较高的缓蚀效率。通过设计现场加药工艺及制度,监测评价缓蚀剂缓释效果和腐蚀情况,可防止管道运输过程中CO2腐蚀的侵害,长输管线内腐蚀控制良好。 相似文献