多联内机蚁巢腐蚀机理及预防措施

多联机换热器发生蚁巢腐蚀会导致系统泄漏,使系统无法正常。本文通过介绍蚁巢腐蚀机理及模拟出蚁巢腐蚀现象,针对性提出预防措施。     

挥发性润滑油对铜管蚁巢腐蚀的影响

为了避免铜管蚁巢腐蚀造成制冷空调装置的失效,通过模拟腐蚀试验、扫描电子显微镜、X射线衍射、离子色谱法等对蚁巢腐蚀进行研究。结果表明,挥发性好且含有较少含氧基团的挥发性润滑油更不易引发铜管蚁巢腐蚀。     

制冷空调产品用铜管蚁巢腐蚀研究

为了避免铜管蚁巢腐蚀造成空调制冷装置的失效,通过模拟腐蚀试验、扫描电子显微镜、X射线衍射、离子色谱法等对蚁巢腐蚀进行研究。结果表明,氧气、水分以及油脂物为发生腐蚀的基本条件,腐蚀产物为氧化亚铜。     

空调制冷铜管的蚁巢腐蚀(上)

空调制新华通讯社铜管的一咱特殊腐蚀一蚁巢腐蚀,易造成空调制冷装置的提前失效.本文综述了空调制新华通讯社铜管蚁巢腐蚀的特征、引发腐蚀的物质、影响因素、试验方法、机理和预防措施.     

空调制冷铜管的蚁巢腐蚀(下)

(5) 木材和人造建材[5、9、13] 据1999年报道,在一家酒店的木墙房间中用了2.5年的空调发现蚁巢腐蚀,腐蚀从铜管外表面起始.对房间的空气取样做气相色谱分析,发现了有从木材和人造建材中挥发出的挥发性有机物,如甲醛(在空气中的含量达11～13 μg/m3)、壬醇、甲基丁酮、α-蒎烯、柠檬油精和C14-C26烃类化合物.其中的醛和酮引起铜管蚁巢腐蚀的可能性最大.研究者为此专门用9种醛、6种酮和α-蒎烯、蚁酸和甲酸甲酯等17种挥发性物质的潮湿气氛中做了铜管腐蚀试验,发现蚁酸、甲酸甲酯、甲醛、丙醛等会使铜管产生蚁巢腐蚀,而丙酮和α-蒎烯也产生细小的蚁巢腐蚀.萜烯类物质(3-蒈烯、α-蒎烯)都是从木材中散发出来的挥发性物质,而甲醛则是人造建材的胶粘剂中散发出来的.用17种有机物的1%(V.)水溶液进行铜管3个月暴露试验,3个月后各水溶液的PH值如表6,造成铜管蚁巢腐蚀的深度和形貌特征如表7.     

空调用翅片管式换热器腐蚀及防护研究进展

空调用翅片管式换热器长期使用会受到一定程度的腐蚀,影响换热器的换热性能,导致整个空调系统的能效降低.本文介绍了翅片管式换热器3种主要的腐蚀机理:蚁巢腐蚀、点蚀和间隙腐蚀,从形貌、压降及传热特性3个方面分析了腐蚀对翅片管式换热器性能的影响,结果表明:翅片管式换热器腐蚀后,传热系数和换热量均减小,空气侧压降受影响较小,在5...     

美发店空调蒸发器腐蚀泄漏失效分析

某美发店用空调在安装数月后,其内机蒸发器长U形铜管出现穿孔泄漏现象。对泄漏的铜管进行了宏观检验、金相分析、腐蚀产物成分分析以及复现试验等,分析了其腐蚀泄漏原因。结果表明:该美发店使用的发胶、染发剂、焗油膏等产品使用过程中挥发出的物质,在潮湿环境中聚积在铜管表面水解生成甲酸根、乙酸根等易引起铜管发生蚁巢腐蚀的羧酸根离子以及易引起点腐蚀的氯离子,从而导致铜管发生穿孔泄漏失效。据此建议开发对应更耐腐蚀的空调机型。     

核电站用离心式冷水机组换热器铜管腐蚀泄漏分析

某核电站用离心式冷水机组蒸发器/冷凝器铜管在投运前发生制冷剂泄漏,通过对泄漏点进行微观分析,并从设备制造工艺过程排查产生问题的原因,确认换热器铜管在出厂前内壁残留了少量的空压机润滑油.残留的润滑油在一定潮湿空气中长期暴露而水解酸化形成铜管敏感的羧基酸根介质,进而在铜管表面产生电化学反应形成蚁巢腐蚀,最终造成泄漏.     

浅析南京市公园白蚁综合防治方法

针对南京市国防园、清凉山公园、玄武湖公园内树木白蚁为害现状，分别采取人工挖蚁巢、挂黑光灯诱杀有翅生殖蚁、化学药剂防治、埋设诱杀包诱杀等多种方法进行防治。经过综合治理后，三家公园内白蚁危害率显著下降，取得很好的防效。     

线性极化技术及其在评定金属耐蚀性能方面的应用(二)

三、线性极化技术评定金属耐局部腐蚀性能的研究——“局部腐蚀指数δ”的初步探讨金属和合金在各种介质中表现的腐蚀状态有均匀腐蚀和局部腐蚀之分。严格说来,任何腐蚀都是不均匀腐蚀。所谓均匀腐蚀是指腐蚀状况的分布大体上是各处均匀的。对于很多腐蚀体系,常常会发生所谓局部腐蚀的现象,如点腐蚀,溃疡腐蚀,隙缝腐蚀,晶间腐蚀,水线腐蚀,选择性腐蚀,应力腐蚀,微生物腐蚀等。发生局部腐蚀时,腐蚀的总量往往是不大的,但危害极大。例如     

微量元素的添加对空调制冷用铜管耐蚀性的影响

分析空调与制冷系统中铜管发生蚁穴腐蚀的机制和原因,研究在典型蚁穴腐蚀易发生的甲酸氛围中微量元素的添加对空调制冷用铜管耐蚀性的影响。结果表明：在纯铜中添加微量元素可以提高制冷铜管耐蚁穴腐蚀的能力,Mn氧化物膜层对提高制冷用铜管的耐蚁穴腐蚀性能发挥了积极的作用。     

Failure analysis of a copper tube in a finned heat exchanger

This paper reports on the failure analysis of a finned heat exchanger which leaked in the pressure test during commissioning. The heat exchanger was composed of panels made of thin-walled copper tubes and aluminum fins, and the structure was typical of equipment used in the heating, ventilation and air-conditioning industry. The tube material was phosphorus deoxidized copper Cu–DHP. In the pressure test, one of the tubes was found to have three leakage points. The investigation showed that the failure was a consequence of ant-nest corrosion, as all the experimental findings, together with the copper grade and the tube dimensions, were typical of this corrosion mechanism. Corrosion had initiated from the outer surface of the tube. The paper presents the morphology of the failure using optical and scanning electron microscope (SEM) micrographs. The presence of a contaminating organic substance on the outer tube surface and inside the corrosion crack was verified by SEM/EDS analyses. The corrosion mechanism and the relevant chemical reactions given in the literature are summarized, and the conditions in which the failure may occur are presented. Ant-nest corrosion is a special form of local corrosion, and associated most often with deoxidized copper tubes used in heat transfer applications as in this study.     

Electrochemical Corrosion Behavior of Nanocrystalline Materials—a Review

Nanocrystallization significantly influences the electrochemical corrosion behaviors of metals/alloys in liquid system. In active dissolution, nanocrystallization accelerates the corrosion reactions. If the corrosion products are dissoluble, the corrosion rate is increased by nanocrystallization; if the corrosion products are insoluble, the corrosion rate is decreased on the contrary because the corrosion products act as a block layer to delay the dissolution. In passivation, nanocrystallization changes the composition of the passive film, and results into different morphology and growth process of the passive film, both of which improves the formation of compact film and influences the semiconductor property. It influences the passivation depending on fast element diffusion and special adsorbed ability. The small grain size improves the element diffusion, which leads to the different composition of passive film (passive elements enrichment such as Cr, Ti). The small grain size also changes the surface condition, which influences the ions adsorption. All increase the corrosion resistance of materials. In local corrosion, nanocrystallization increases the unstable points on the surface of the materials, which increases the possibility of local corrosion. However, the excellent ability of element diffusion helps heal the local corrosion points, which inhibits the growth of the local corrosion.     

压力设备腐蚀失效案例统计分析

收集整理近年来有关压力容器管道的腐蚀失效案例,并对其进行了归纳与分析.从整体的腐蚀情况来看,应力腐蚀及其它应力作用下的腐蚀失效形式是压力容器管道比较突出的腐蚀失效问题,同时奥氏体不锈钢、碳钢及低合金钢三种材料的腐蚀失效较严重.     

舰载机的腐蚀失效及其预防

介绍了舰载机点蚀、丝状腐蚀、晶间腐蚀、应力腐蚀和氢脆5种常见的腐蚀失效模式及其形成机理、失效现象与特征、影响因素等,列举了与设计、制造工艺、材料等因素相关的导致飞机构件腐蚀失效的典型案例,并根据案例的失效原因提出舰载机腐蚀失效的预防与改进措施,以及在设计、制造工艺和选材方面的一些建议。结果表明,飞机的腐蚀控制是一项系统工程,设计中需要充分考虑对导致腐蚀的因素进行有效控制,并注意细节防腐设计;飞机构件在进行合理的防腐设计的同时,材料的工艺状态和材料的选择与环境之间,及材料与工艺之间,应在防腐方面有科学严谨的匹配。     

酸沉降对混凝土耐久性的影响及研究进展

总结了近年来关于酸沉降对混凝土耐久性的影响及研究进展.从混凝土在酸性介质中发生腐蚀的热力学条件以及碳化作用、硫酸盐的腐蚀、酸腐蚀、H 和SO42-共同腐蚀方面阐述了酸沉降对混凝土的腐蚀机理;并通过一些典型试验,从模拟试验装置,室内外暴露试验、室内加速腐蚀试验、不同水泥基材料的抗腐蚀试验以及各种腐蚀程度预测公式方面阐述了主要的试验研究方法及重要的试验研究成果;总结了在评价混凝土酸蚀程度时使用的各种评价指标.酸沉降对混凝土耐久性影响的研究虽然取得了一些进展,但在室内加速腐蚀试验与自然腐蚀之间的相关性研究方面还比较欠缺,应加强这方面的研究.     

MHB4新型合金抗蚀性能研究

用中频感应炉熔炼了新型超低碳高合金奥氏体不锈钢ＭＨＢ４和３１６Ｌ不锈钢,研究了它们在不同介质中的抗腐蚀性能。结果表明,由于ＭＨＢ４增加了Ｃｒ、Ｎｉ、Ｍｏ的含量,并加入Ｗ,极大地提高了抵抗Ｃｌ＾－离子引起的点蚀能力,因此ＭＨＢ４的耐点蚀、耐缝隙腐蚀以及在合成海水中的抗蚀性均优于３１６Ｌ不锈钢。     

An investigation of blade failures in combustion turbines

An examination of several cracked and uncracked second row blades of 50MW class combustion turbines has been conducted to identify the cause of failure. Results show that these failures have been caused by environment-assisted creep in a manner similar to stress corrosion. A window of grain boundary spikes, indicative of the corresponding stress variation was observed locally at the region of failure. A superimposition of the stress window and the corrosion window seems to create the conditions under which creep and grain boundary corrosion can occur concurrently in a synergistic fashion. Results show that when the machines are operated at different ratings, the types of corrosion found in the blades remain unchanged, but the magnitude and the location at which the different corrosion features are observed are changed systematically. The specific changes that occur with decreased operational rating are: (1) An increase in the distance above the platform at which the layer type corrosion transitions into non-layer type hot corrosion. (2) An increase in the distance at which the window of grain boundary spiking activity is observed. (3) A decrease in the density and depth of oxide spikes, with a corresponding increase in the density and depth of sulfide spikes. The observations regarding these changes are significant in as much as they provide a potential tool for estimating the temperature and stress profiles and the propensity for cracking at the trailing edge of the second row blades, based on corrosion observations alone.