实海浸泡条件下聚氨酯涂层的失效行为

目的 在青岛市小麦岛试验站开展实海浸泡试验,探究聚氨酯涂层在实际服役过程中的失效行为。 方法 选用TS55?80聚氨酯涂层/Q235碳钢体系为试验样品,开展实海浸泡试验。从聚氨酯涂层的表面形貌、失光率、色差、涂层附着力、化学结构及涂层热稳定性等角度对聚氨酯涂层的失效行为进行研究。结果 在实海浸泡条件下,聚氨酯涂层表面会出现明显的鼓泡和裂纹等缺陷,在浸泡6个月后的涂层表面可以观察到明显的腐蚀产物。随着浸泡时间的延长,涂层的化学结构发生了明显变化,涂层的热稳定性显著降低。在浸泡12个月后,聚氨酯涂层的失光率为69.9%,属于严重失光;涂层的色差达到3.20,属于轻微变色,涂层的附着力降至0.82 MPa,涂层与金属基体的结合强度大幅下降;聚氨酯涂层的阻抗值降至2.81×10³ Ω.cm²,说明涂层的防护性能基本丧失。结论 在实海浸泡条件下,聚氨酯涂层中颜料颗粒的脱落会造成涂层表面孔隙数量的增加,这会加速海水中水和氧气等腐蚀性介质的渗透过程,使得涂层/金属界面处的电化学反应快速进行,导致涂层的防护性能快速下降。此外,聚氨酯链中氨基甲酸酯键的水解是造成聚氨酯涂层发生降解的主要原因。     

嵊山500吨/日反渗透海水淡化示范工程

本文叙述了嵊山５００吨／日反渗透海水淡化示范工程项目的总体设计,设备的研究和选型,工艺和系统控制过程。     

X70钢的滨海盐渍土-海水宏电池腐蚀

利用电化学阻抗测试技术等,研究了X70钢在滨海盐渍土与海水构成的宏电池中的腐蚀行为。结果表明,构成宏电池之后,海水侧X70钢一直作为宏电池的阳极处于被腐蚀状态,其腐蚀速率为自然腐蚀速率的25.3倍,腐蚀过程主要受阴极反应控制;由于腐蚀产物膜和氯离子的双重作用使宏电池腐蚀速率先有一定程度的降低,然后迅速升高,再有所降低并趋于稳定。试验还发现土壤-海水构成的宏电池的电动势并没有表现出像常规土壤宏电池电动势那样的先升高后降低的趋势,而是先有一定程度的降低,然后迅速升高后趋于稳定,该过程主要受极化电阻的影响。     

5083铝合金与2205不锈钢在天然海水中的电偶腐蚀行为

研究了5083铝合金与2205不锈钢在不同面积比条件下青岛天然海水环境中的电偶腐蚀行为,得到了电偶混合电位和电偶电流。结果表明,2205不锈钢与5083铝合金形成电偶时,由于自腐蚀电位的差值较大,容易造成明显的电偶腐蚀。无论阴阳极面积相等还是在大阴极小阳极的情况下,5083铝合金与2205不锈钢均形成电偶腐蚀,都会加速5083铝合金的腐蚀,2205不锈钢则会受到保护。因此,在海水环境中要避免这两种材料的直接接触,必须采取绝缘防护措施。     

The synergistic effect of seawater's parameters on the corrosion rate of the austenitic stainless steel 304

In this article the corrosion rate of the austenitic stainless steel type 304, under the synergistic effect of environmental factors has been assessed via potentiodynamic polarization scan. Salinity, velocity, pH and temperature are the factors which induce effects on the corrosion rate of the considered metal. Quantitative analysis is applied using the full two-level factorial experimental design method, which results in the contribution value of each parameter in changing the quantity of average corrosion rate in both individual and synergistic cases. Besides this quantitative analysis, qualitative analysis has been used to predict the variation direction. These two analyses show the important role of the synergistic action, which changes the variation direction of corrosion rate and the contribution percentage of each parameter in varying the value of corrosion rate. Applying both these analyses can show the magnitude and quality of each parameter’s effect, which is remarkably valuable in marine applications.     

超级双相不锈铸钢电化学极化表面腐蚀产物的XPS分析

采用X射线光电子能谱(XPS)技术研究了超级双相不锈铸钢在人工海水中经电化学极化后表面腐蚀产物。结果表明：双相不锈钢在人工海水中极化后的钝化膜表层主要以CrO₃、CrOOH、Cr(OH)₃和Fe(OH)₃等氢氧型化合物为主,内层主要以CrO₃、Cr₂O₃、FeO和Ni₂O₃等氧化物为主,同时膜内层存在Fe、Cr、Ni和Mo单质。MoO₄^2-和NH₄⁺吸附在钝化膜表面,对钝化膜起到保护作用。     

某核电厂循环水泵叶轮失效原因分析及防护措施

目的提高核电厂海水循环水泵(以下简称"循泵")叶轮的耐磨性能。方法采用表面工程技术,在叶轮表面涂刷熔融环氧粉末涂层、WC涂层和耐磨陶瓷涂层,以提高叶轮的耐磨性。通过对比材料本身的硬度和断裂韧性,分别评价两种新材料在海水中的耐磨性能,并通过实践验证对三种涂层的耐磨可行性进行了详细分析。结果分析结果表明,该双相不锈钢叶轮的损坏为典型的磨损腐蚀,同时伴随着微弱的电化学腐蚀。经过实践验证,厚度为0.8~1 mm的熔融环氧粉末涂层由于与金属基材间的结合力较差,使用一周期后存在大面积的脱落现象,起不到保护叶轮的作用。厚度为0.5 mm的WC涂层在运行后检查发现涂层存在一定程度的减薄,部分区域仍存在微弱的冲蚀现象,而且其价格较昂贵,使用效果与经济性不成比例。耐磨陶瓷涂层整体达到了牺牲涂层从而保护母材的目的。结论实践表明仅靠选材无法彻底根除磨损腐蚀,结合表面工程技术,综合使用效果和经济性,最终确定耐磨陶瓷涂层为循泵叶轮表面防护的最佳涂层。     

羧甲基壳聚糖对海水中X70管线钢的缓蚀效果

采用电化学试验、扫描电子显微镜、XRD和FTIR等技术研究了羧甲基壳聚糖及其复配缓蚀剂对海水中碳钢的缓蚀效果。结果表明:羧甲基壳聚糖的缓蚀率随着其质量浓度的升高而升高,当质量浓度为5g/L时缓蚀率达到43.4%,质量浓度继续升高,缓蚀率增大不显著;添加钨酸钠后的复配缓蚀剂使腐蚀速率进一步降低,缓蚀率达57.4%;FTIR、SEM和XRD测试表明羧甲基壳聚糖可吸附在金属表面,形成致密的保护膜。     

天然海水微生物对5083铝合金初期腐蚀行为的影响

利用荧光电子显微镜,扫描电镜及能谱表面分析技术和开路电位,电化学阻抗谱,动电位极化电化学技术研究了在天然海水中浸泡初期,天然海水微生物对5083铝合金腐蚀行为的影响.结果表明,在天然海水中,铝合金表面形成良好的生物膜.电化学结果表明,在天然海水中铝合金腐蚀电位负移,点蚀电位正移,电荷转移电阻增大,说明短期浸泡时,天然海水生物膜的形成可以抑制其腐蚀,尤其对点蚀具有明显的抑制作用.在无菌海水中,随时间的增长,铝合金的腐蚀也受到一定程度的抑制,原因是锈蚀产物的形成对铝合金具有一定的保护作用.     

Economics of small solar-assisted multiple-effect stack distillation plants

The objective of this paper is to compare the economics of using solar energy to operate small, multiple-effect seawater distillation systems in remote areas with the conventional method of using fossil fuels. The particular multiple-effect system used is an advanced horizontal-tube, falling-film system called “multiple-effect stack” (MES) in which the pumping energy requirement is relatively low compared with the horizontal in-line system. Three system configurations were investigated: (1) a conventional system using a steam generator to provide steam for the MES evaporator and a diesel generator to provide pumping power, (2) a solar-assisted system which uses solar thermal collectors to provide hot water (instead of steam) for the evaporator and a diesel generator for pumping power, and (3) a solar stand-alone system which uses solar thermal collectors for the evaporator heat requirement and a solar PV array to provide electrical energy for pumping. At the present time, solar energy cannot compete favorably with fossil energy, particularly under the present international market prices of crude oil. However, in many remote sunny areas of the world where the real cost of fossil energy can be very high, the use of solar energy can be an attractive alternative. Two important cost parameters affect the relative economics of solar energy vis-à-vis conventional (fossil) energy: the collector cost in dollars per square meter and the cost of diesel oil in dollars per giga Joule. Solar energy becomes more competitive as the local cost of procuring conventional fuel increases and as the collector cost decreases. The water cost from a solar thermal-diesel-MES system (configuration #2) can be seen to approach the water cost from a steam generator-diesel-MES system (configuration #1) when the collector cost drops to $200/m² and diesel oil cost at the remote site reaches $50/GJ. Using a 100% solar system (configuration #3) with solar thermal and solar PV collectors, the economics was seen to improve in favor of the solar system. Even when diesel fuel can be procured at $10/GJ at the remote site, the cost of water from the solar system can be seen to approach that from a conventional plant when thermal collectors costing $200/m² are used. The cost of water from the solar system was shown to be always less than that from a conventional system which uses diesel oil procured at the high price of $50/GJ, but always higher than water produced from a conventional system using diesel oil at the low price of $10/GJ.