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81.
With the development of ocean engineering, various metallic materials have been applied to the marine environment. It is an urgent requirement to study the galvanic series and alloy composition optimization of metallic materials in the tropical marine environment. In this work, open circuit potentials (OCP) and galvanic series of 36 kinds of metallic materials in Sanya seawater were studied. By considering the response of OCP to tidal changes, the anti-corrosion effects of alloying elements were also ana lyzed. The results show that the OCP of metallic materials in Sanya seawater has a large range. The galvanic series order of metallic materials from high to low in Sanya seawater is: nickel alloy, duplex stainless steel, austenitic stainless steel and pure copper, ferritic stainless steel, martensitic stainless steel, copper alloy, low alloy steel, carbon steel, cast iron, aluminum alloy and aluminum anode. Low-carbon high-alloy content carbon steel and high Cr, Ni contents stainless steel have higher OCP. The potential fluctuations of carbon steel with tidal changes involves two phases: (1) under the dynamics control, the OCP of carbon steel is more negative at high tide; (2) under the diffusion control, the OCP is more positive at high tide. The potential fluctuations of metallic materials reflect the effect of the corrosion product film on the change of ionization balance, and metals with less potential fluctuations have better inhibition on ion diffusion. In Sanya seawater, the carbon steel, which has more alloying content and less carbon content, has less potential fluctuations with the tidal changes and has good oxygen diffusion resistance. The potential fluctuations of austenitic stainless steel with tidal changes are less than that of ferritic stainless steel and martensitic stainless steel. After 2700 h immersion, austenitic stainless steel and martensitic stainless steel, which have a higher content of Mo, have more stable OCP. In other words, the corrosion film gets a better corrosion resistance. The OCP of aluminum anode in Sanya seawater environment increases when the oxygen content is brought up. The OCP of Zn-containing or Ga-containing aluminum anode remains relatively stable. Al bronze and T2 copper have less potential fluctuations with tidal changes, and perform good corrosion resistance in Sanya seawater. 相似文献
82.
在海底故障盾构修复施工中,在盾构切口前方采用双排冻结管和盾构两侧的辅助冻结管进行垂直局部冻结加固土体,使盾构前方形成罩形冻土帷幕,将切口端的漏水通道冻结封闭,为隧道清泥排水和盾构修复提供保障。考虑到海水含盐具有冻土帷幕厚度减小、冻土强度下降等对冻结的不利影响,对冻结方案进行了专门设计与冻结及施工过程的实测研究。通过对冻土温度监测数据的计算和分析,表明罩形冻土帷幕在海底盾构修复中取得了良好效果,验证了该冻结方案在海底盾构隧道修复中的可行性。 相似文献
83.
采用纳米SiO2超细粉末、FeCl3和聚合氯化铝(PAC)强化混凝去除海水中的腐殖酸。结果表明,FeCl3和PAC复配,使铝系絮凝剂良好的分散性与铁系絮凝剂优良的沉降性得到了较好协同效果,浊度和腐殖酸的去除率均好于两者单独使用。两者最适宜配比为:m(Fe)/m(Al2O3)=2,投加超细粉末强化混凝,浊度和腐殖酸的去除率分别可以达到94%和95%,并可以有效地改善絮体的沉降性能,缩短沉淀时间,使絮体和水体分离的更为彻底,水体上部几乎无悬浮物,对进水温度和pH值的适用范围广。 相似文献
84.
壳聚糖在海水混凝处理过程中的助凝作用研究 总被引:2,自引:0,他引:2
将天然高分子絮凝剂壳聚糖(CTS)与无机絮凝剂FeCl3协同使用,混凝处理渤海湾近岸海水,考察了壳聚糖投加量、pH值和沉降时间对浊度和其它污染物去除效果的影响。试验结果表明,CTS对FeCl3助凝效果显著,与单独使用FeCl3相比,其浊度、化学耗氧量(CODMn)和总磷(TP)去除率分别提高了8.3%、9.6%和9.4%。FeCl3与CTS协同使用还可明显改善絮体的沉降性能,缩短沉淀时间。综合考虑各项主要技术指标,其海水混凝适宜条件为m(FeCl3)/m(CTS)=15.0。 相似文献
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Sarah Abduljabbar Yaseen Ghadah Abdaljabar Yiseen Chi Sun Poon Christopher K. Leung Zongjin Li 《Journal of the American Ceramic Society》2023,106(8):4967-4986
The current work scrutinizes the effectuation of seawater on morphological properties, pore structure, and compressive strength during the hydration process of fly ash blended cement at 3, 7, 28, 56, and 90 days to better understand the influence of salinity conditions of seawater on the microstructural modification and strength development of the hydration products as well as the total porosity. The chemical reaction's mechanism of mightily soluble salts, for example, Mg2SO4 and NaCl, with hydrated fly ash and blended cement (calcium-bearing phases) was also confirmed. Fourier-transform infrared spectroscopy has been appointed to observe and characterize the energetics of variation in the formulation of portlandite (CH), calcium silicate hydrate, gypsum (Gy), ettringite (AFt), and calcium chloroaluminate (Friedel's salt [FS]) throughout the hydration process of fly ash blended cement with seawater in comparison with deionized water. X-ray diffraction analysis exposed that the peak intensities of FS, portlandite, and some particular phases of the hydrated fly ash blended cement in seawater are higher and sharper than the comparable peaks in deionized water. Mercury intrusion porosimetry-measurements have been appointed that the total porosity of artificial seawater (ASW) was decreased from 28.9% at 3 days to 19.4% at 56 days. In addition, the average, median, and critical pore diameter were decreased in ASW while compared to deionized water (DIW). The reaction products of this work were also characterized using scanning electron microscopy, EDS, compressive strength, and isothermal calorimeter. 相似文献
89.
以芦蒿叶为原料 ,经过护色、榨汁、离心、调配、均制、杀菌等工艺 ,制成色泽较好、营养丰富、口感良好 ,并具有特殊风味的绿色浑浊蔬菜汁饮料 .同时以Zn2 +、Cu2 +为护色剂 ,对芦蒿汁加工工艺中的护色问题作了初步的研究 ,并对使用单一稳定剂稳定芦蒿汁作了初步的探讨 . 相似文献
90.
利用混凝方法进行海水澄清的预处理工艺,是低温多效蒸馏海水淡化系统采用的传统工艺。在实际运行中,这种传统工艺易使海水淡化换热设备产生污堵现象。通过分析得知,在低温条件下,加入混凝药品是下游海水淡化设备产生污堵的主要原因。为此,进行了各项工艺改进试验。改进工艺后,可全年在设备运行中停止加入混凝药品,也能保证预处理出水满足下级设备的水质要求。采用改进后的海水预处理工艺,提高了海水淡化设备运行的经济效益,为低温多效蒸馏海水淡化的系统设计提供了良好范例。 相似文献