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对国内某气田集气管线带有焊缝的失效弯头进行了分析,利用Fluent软件模拟了焊缝与90°弯头处流体流型流态,分析了集气管线在该处的冲刷腐蚀机理。结果表明:焊缝和弯头外弧侧内壁处具有较高的漩涡强度,使该处腐蚀产物从金属表面剥离;受近壁面较高湍流强度的流体影响,剥离的腐蚀产物快速向主流体运移,裸露的金属基体继续被腐蚀,最终使焊缝和弯头外弧侧内壁发生严重的冲刷腐蚀。两端具有焊缝的天然气集输管线弯头,在焊缝、外弧侧内壁的冲刷腐蚀速率较高,在无内防护的服役过程中易发生腐蚀穿孔。 相似文献
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采用动电位极化扫描、电化学阻抗谱等方法研究在地下咸水不同电导率、p H值和流速条件下,B30铜镍合金和316L不锈钢的腐蚀行为。结果表明:随着地下咸水电导率的增加,B30铜镍合金自腐蚀电流密度迅速增加,点蚀敏感性增大,而316L不锈钢自腐蚀电流密度的增加较缓慢,耐蚀性明显优于B30铜镍合金。在酸性溶液中,B30铜镍合金发生均匀腐蚀。随着p H值的增大,B30铜镍合金点蚀倾向增大,316L不锈钢点蚀倾向减小。流速为1 m/s的冲刷腐蚀条件可以破坏B30铜镍合金钝化膜的形成,而不影响316L不锈钢钝化膜的稳定性。这为热泵系统如何选择金属材料提供了参考。 相似文献
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铜镍合金在我国实海海域的局部腐蚀 总被引:3,自引:0,他引:3
研究了B10、B30铜镍合金板材和管材在我国青岛、舟山、厦门和榆林4个海水腐蚀实验站分别暴露1、2、4、8、16 a的局部腐蚀规律.结果表明:全浸区榆林海域、舟山海域和青岛海域均有一定程度的局部腐蚀,其中榆林海域因温度高和海生物附着的共同作用导致铜镍合金的局部腐蚀最严重;而厦门海域对铜镍合金的局部腐蚀有一定的减缓作用,使铜镍合金板材没有局部腐蚀发生;各海域对铜镍合金的腐蚀作用基本均以沿晶腐蚀为主,但程度不同;暴露16 a,在厦门海域B30合金的Ni、Mn和Fe含量比青岛海域和榆林海域B30合金的Ni、Mn和Fe含量高;提高B30合金的耐蚀性,是厦门海域的铜镍合金板材基本不发生局部腐蚀的内在原因. 相似文献
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采用宏观形貌观察、化学成分分析、电化学性能测试、腐蚀产物分析等,对某天然气井口"Z"型管管异径接头环焊缝的泄漏原因进行分析,结合3D建模和腐蚀模拟试验对法兰面均匀腐蚀和焊缝局部腐蚀进行了综合分析。结果表明:法兰、异径接头、管体材质化学成分与组织正常,焊条选择与母材相匹配,未发生未焊透和未熔合缺陷;法兰装配后在两法兰端面间产生装配间隙,这是天然气中的腐蚀介质进入该间隙导致法兰面发生均匀腐蚀的原因;法兰与异径接头对焊错边量较大,异径接头与管体内焊缝余高明显,进而导致管件内错边和内焊缝余高处产生湍流和流体回流现象,在流体冲刷和腐蚀的作用下加剧了焊缝金属的损失,从而在焊缝内形成凹槽,导致焊缝壁厚快速减薄,最终在焊缝上发生穿孔泄漏。 相似文献
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铝土矿酸介质中铁的行为 总被引:4,自引:1,他引:4
研究了高温高压条件下铝土矿中铁在硫酸介质中的溶解行为,结果表明:在一定的温度条件下,铝土矿的赤褐铁矿能较好地溶于硫酸溶液中,而铝土矿中含铝矿物的性质不发生变化,从而为铝土矿的进一步加工利用提供了条件。详细讨论了反应温度、反应时间、硫酸浓度、液固比等因素对铁的溶解行为的影响,得出了在最佳工艺条件,即在反应温度160℃、反应时间3h、硫酸浓度0.7mo1/L和液固比6:1时除铁效率最高。 相似文献
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Progress in application of rare metals in superalloys 总被引:1,自引:0,他引:1
Rare metals play an important role in development of superalloys. Over the last two decades, the application of the rare metals in superalloys has achieved progress significantly. They present multi-beneficial effects for strengthening the matrix and the c0phase, increasing the lattice misfit, cleaning the grain boundary, improving the carbides and eutectics, refining the grain, stabilizing the oxidation film, etc., so that the elevated temperature rupture life and elevated temperature oxidation resistance are improved significantly, leading to a broad application in the superalloys. In order to meet the higher demand for better superalloys in the future, more intensive research is necessary on the effects of the rare metals on the superalloy, and especially on the combination effect of various rare metals and mutual influence among them. Utilization of the computational materials science and combinatorial high throughput experiment will be of importance in application of rare metals in superalloys. 相似文献
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none 《腐蚀工程科学与技术》2013,48(1):53-56
AbstractThe effect of sulphides on the corrosion of zinc in artificial sea water has been studied over the pH range 6·5 to 8·6. A comparison of the weight loss and potential values of specimens in aerated and deaerated sea water, with or without the addition of sulphide, has shown that at pH values > 7·2 the presence of sulphides increases the corrosion, while at lower pH values it is partially inhibited. This is related to changes in the concentration of S2- ions in the solution. The corrosion products formed in the more corrosive solutions were shown to consist mainly of ZnS, which is believed to cause loss of adhesion of the corrosion products on the zinc surface, and thus to accelerate the corrosion. 相似文献
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The effect of anomalies detected in x-ray diffraction and metallographic examination of welded joints on the properties of resistance butt welded joints in 1201 aluminium alloy is determined and recommendations are given for the standards for permissible defects. 相似文献
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Ag—Cu—Ti钎料中Ti元素在金刚石界面的特征 总被引:18,自引:2,他引:16
研究了金刚石钎焊接头中碳化物形成元素Ti与金刚石(或石墨)之间的相互作用行为。通过对接头界面处的成分分布和断口形貌观察,分析了Ti的作用机理、新生儿合物TiC的断口形及生长规律,结果表明:在一定的条件下,Ti元素与组成金刚石(或石墨)的碳元素发生反应形成TiC层;碳化物层使钎料与金刚石之间产生冶金结合;TiC与金刚石之间存在有明显的界面,TiC断口的微观表面形态呈韧窝状;在金刚石表面初始形成的TiC的生长方向与金刚石的晶向指数有关。 相似文献
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S. J. Drew M. A. Mannan K. L. Ong B. J. Stone 《International Journal of Machine Tools and Manufacture》2001,41(4)
Most investigations of chatter have made the assumption that torsional vibration is not a significant factor. Some recent work has shown that chatter in grinding is affected by a change in the torsional stiffness of the workpiece drive. Also, a theoretical model of grinding chatter has been developed that confirmed the significance of torsional effects. However, the model for the grinding force was assumed to be a dynamic equivalent of a published steady-state model. This paper describes tests conducted to measure the variation in force caused by an oscillation in workpiece speed. The oscillating test results indicate that the torsional vibration of the workpiece may well be a significant effect on chatter in grinding. Moreover, as the grinding force changes with workpiece speed, it may be possible to use variation of workpiece speed at high frequency to reduce chatter. 相似文献
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目的: 评价湖南省人民医院院区2016年利奈唑胺临床应用的合理性及有效安全性,为其临床应用提供参考。方法: 采用回顾性研究,利用医院信息管理系统调取2016年使用利奈唑胺患者病例资料,设计调查表,统计用药合理率,分析不合理原因;计算临床治愈率,病原菌清除率及综合治愈率;监测用药前后红细胞、血红蛋白、血小板下降程度。结果: 利奈唑胺临床应用合理率为48.1%,不合理原因主要是适应症把握不准确及疗程不合理;临床有效率为40.4%,病原菌清除率为42.3%,综合治愈率为56.4%;骨髓抑制发生率为21.2%,发生的平均年龄为(81.4±8.7)岁,平均用药时间为(13.6±5.6) d。结论: 我院区利奈唑胺临床应用合理性有待提高,正确把握适应症和疗程将很大程度提高合理率;综合疗效尚可,老年患者需特别注意骨髓抑制的发生。 相似文献
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Abstract Flash welding, through conferring a number of important advantages, such as high productivity, good-quality welds, and suitability for welding of components with large cross-sections, is extensively used for shop welding of rails, plating of hot coils, welding of wheel rims, etc.1–3 More compact welding facilities are also being sought through further exploitation of mechanical control technology for practical applications in job-site welding of rails, H-steel sections, etc.4 相似文献
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