热浸镀锌铝合金的研究

通过热浸镀的方法制得含铝为6.5%（质量分数）的锌铝合金镀层,研究了助镀剂、热镀温度和热镀时间对镀层质量和镀液寿命的影响,中性盐雾试验和二氧化硫加速腐蚀试验结果表明,热浸镀锌铝合金（wAl=6.5%）层的耐蚀性优于镀锌层。     

热浸镀锌技术在电站锅炉产品上的应用

热浸镀锌是电站锅炉钢构件、紧固件等产品上最常用到的一种防止大气腐蚀的方法。本文针对应用在锅炉产品上的热浸镀锌易发生的一些共性问题,如热浸镀锌层的外观、厚度、缺陷修复、表面涂装、紧固件配合等,结合相关标准要求,进行了深入地分析论述。供金属防护以及锅炉制造专业的工程技术人员参考。     

稀土热浸镀锌的研究

1　前言钢结构件采用热浸镀锌层防腐蚀 ,由于使用寿命长 ,得到了广泛应用 ,如高压输电铁架、广播电视发射塔、高速公路护拦、钢结构桥梁、矿井支架、镀锌钢管 (自来水管 )等。由于以上设施都暴露在大气中 ,甚至恶劣的环境中 ,而且大多是永久性设施 ,如何进一步提高热镀锌层的防蚀能力 ,提高使用寿命、显得十分重要。应用稀土热浸镀锌 ,不但可以使热浸镀锌层表面光泽改善 ,而且耐蚀性明显提高 ,寿命延长 ,上锌量反而下降 15%～ 2 5% [1] 。因此 ,深入研究稀土热浸镀锌技术 ,有着十分重要的经济效益和社会效益。2　机理稀土元素在较高的温度下…     

立柱热镀锌层剥落原因分析和改进

某热浸镀锌立柱在冲孔后镀层出现起皱和脱落现象。采用扫描电镜和能谱仪分析立柱不同部位热浸镀锌层的组织结构,发现锌层中脆性ζ相过厚是主要原因,通过适当缩短浸镀时间和在浸镀液中添加0.1%(质量分数)的Al可解决上述问题。     

机械镀锌-镍合金工艺的研究

在机械镀锌、锌-铝工艺的基础上,通过调整活化剂和促进剂的种类及用量,研制开发了机械镀锌-镍合金工艺.利用该工艺在钢基表面上得到了不同配比的锌-镍以及锌-铝-镍合金镀层.对这些镀层进行5%NaCl溶液喷雾加速腐蚀试验以及全浸加速腐蚀试验,并与机械镀锌层进行对比.结果表明,各种配比的锌-镍合金镀层的耐蚀性能皆好于机械镀锌层,并且随着镍含量的增加而提高;锌-铝-镍合金镀层的耐蚀性能比镀锌层提高7倍左右.     

石油运输管道防腐技术研究

采用静态质量损失法考察不同热浸镀铝的温度对石油运输管道在中性盐雾试验的防腐性能影响,利用扫描电镜观察热浸镀铝后石油运输管道在腐蚀前后镀铝层表面的微观形貌。试验结果表明,当热浸镀温度在750～770℃时,浸镀时间5min后,镀层厚度符合要求,镀层厚度符合要求,且镀铝层腐蚀速率在该温度范围内随浸镀温度增加而减小,表明热镀铝法有助于增强石油管道的防腐性能。     

锌(铝)以及有机涂料对钢铁底材的双重防腐保护

介绍了如何区分热浸镀锌层和电镀锌层,强调了表面是否有钝化层的判断及热浸镀锌层和电镀锌层表面的涂料选择;指出了涂装镀锌表面时要去除钝化层;介绍了不同环境下的热喷锌(铝)厚度,强调了热喷铝表面涂敷有机涂层的注意事项,指出了热喷铝表面不能涂敷厚的涂层;介绍了冷涂锌涂料及涂层体系,冷涂锌与热浸镀锌及热喷锌(铝)的比较.     

技术动态

热浸镀锌重防腐蚀技术用于煤矿设备江苏省煤矿研究所、兖州矿业(集团)公司第七十工程处、兖州煤矿设计研究院在室内研究试验的基础上,首次将热浸镀重防腐蚀工艺技术应用于煤矿。在济宁二号煤矿的副井井筒装备中采用了热浸镀锌加环氧玻璃鳞片涂料防护,并且成功地设计出了目前国内最长(12.5m)的燃煤热浸镀锌炉,采用两头砌灶、侧上间接加热的方式,通过鼓风、引风调节控温,基本上达到了锌液温度均匀、锌耗少的要求。此项成果已经通过了技术鉴定。专家们认为:热浸镀锌重防腐蚀涂层是在热浸镀锌涂层表面上涂装有机涂料,使镀(涂)层既具有电化学保护…     

钢铁基体热浸镀锌助镀剂缓蚀性能的研究

以热浸镀锌使用的ＺｎＣｌ２和ＮＨ４Ｃｌ为主要成分，在８０℃时，研究了乌洛托品，ＦＨＸ－１、ＮＰ－１０的添加量和ＰＨ值对钢基体腐蚀速率和缓蚀率的影响，获得了一种稳定，缓蚀的热浸镀锌助镀剂。大大提高了钢基体的前处理质量，确保得到高质量的镀锌层。     

热浸镀锌镀层在酸性盐雾试验中的防腐性能研究

采用2种定制的热浸镀锌试件,经不同周期的酸性盐雾试验后发现热浸镀锌镀层防腐蚀性能存在显著差异性,采用试样照片、镀层厚度损耗曲线、扫描电子显微镜从宏观与微观对照分析,结果表明,镀层在酸性环境中的腐蚀速率明显高于中性环境,影响其防腐蚀性能的主要因素为热浸镀锌的生产工艺以及镀锌水平的高低。     

In625合金和316L不锈钢在NaCl-CaCl2-MgCl2熔盐中的腐蚀机理

为了解Cr元素对含铬合金在三元NaCl-CaCl₂-MgCl₂氯化物熔盐中腐蚀的影响机理，选择两种含铬合金镍基Inconel 625（In625）和铁基奥氏体316L型不锈钢，采用全浸没法分别研究它们在500~700℃下于三元氯化物NaCl-CaCl₂-MgCl₂低共熔盐中的腐蚀行为，以及接触空气程度与温度对腐蚀的影响。绘制了In625合金和316L不锈钢在熔盐中600℃下浸没21 d的腐蚀速率曲线。采用XRD（X射线衍射仪）、SEM（扫描电镜）和EDX（X射线能谱仪）对In625合金和316L不锈钢的腐蚀产物和截面形貌进行分析。结果表明：两种金属的腐蚀程度随着接触空气的量和腐蚀温度的增加而加大；600℃下腐蚀21 d后金属表面和截面的元素及形貌分析表明，Cr具有优先脱溶性；600℃下腐蚀21 d后在合金截面形成了贫Cr区域；致密的腐蚀层可以降低金属的腐蚀速率；在NaCl-CaCl₂-MgCl₂三元氯化物熔盐中镍基合金In625拥有比奥氏体不锈钢更好的耐腐蚀性能。     

镀锌层硅酸盐钝化膜的现状及展望

针对钝化膜的研究现状,从工艺改进、联合添加剂以及无机有机复合钝化三个方面详细介绍了国内外提高镀锌层硅酸盐钝化膜耐蚀性的具体方法,并对镀锌层的腐蚀机理进行了初步探讨。最后指出提高硅酸盐钝化膜耐蚀性仍是今后研究的重点。     

Evaluation of the corrosion behavior of galvannealed steel in chloride aqueous solution and in tropical marine environment

An investigation was made into the corrosion behavior of commercial galvannealed steel in 10⁻² mol dm⁻³ NaCl aqueous solutions and in a tropical marine environment, using scanning electron microscopy (SEM), galvanostatic electrochemical stripping (GES), potentiodynamic linear polarization (PLP), and electrochemical impedance spectroscopy (EIS) techniques and open circuit measurements (E _oc). For purposes of comparison, a commercial galvanized steel was also subjected to similar corrosion tests. GES and SEM techniques allowed for the identification of ζ, δ and Γ intermetallic phases and revealed cracks in the galvannealed steel. The PLP, EIS and E _oc results indicated that the galvannealed coating was more corrosion resistant than galvanized coating in an aqueous medium, but that their corrosion behaviors were similar in the marine environment. The corrosion behavior of the galvannealed steel was affected by the evolution of the cracking process in the Zn–Fe layer due to the dissolution of zinc-rich phases, while the galvanized steel displayed generalized corrosion in the aqueous medium and localized corrosion in the marine environment.     

气固相硫协同作用下水冷壁的高温腐蚀特性

利用高温管式炉对电站锅炉水冷壁受热面常用的两种管材（12Cr1MoVG和15CrMoG）开展高温腐蚀实验研究,采用腐蚀增重法,得出气相硫、气固相硫作用下试片的腐蚀动力学曲线,并利用SEM和EDS对腐蚀试片表面及断面的微观形貌和元素成分进行分析。结果表明：两种材料的腐蚀动力学曲线都满足双对数曲线规律,气固相硫协同作用对金属的腐蚀性强于单因素气相硫的影响,15CrMoG的抗腐蚀性能优于12Cr1MoVG;腐蚀层大致可以分为3层,依次为剥离叶片层、过渡层和腐蚀渗透层,气相硫腐蚀下腐蚀层较厚并且质地紧密,气相硫与固相硫协同腐蚀下腐蚀层较薄并且质地疏松,极易剥落;此外腐蚀层中存在硫元素富集现象,腐蚀渗透层中的硫元素质量分数高达6.65%,并且氧元素含量从金属基体表面到腐蚀层表面呈现递增规律。     

PTA装置不锈钢材料腐蚀磨损的探讨

采用自制的实验装置,模拟PTA生产装置中回转式干燥机蒸汽列管工作条件,对奥氏体不锈钢0Cr18Ni9(304)、00Cr17Nd4Mo2(316 L)、00Cr19Ni13M03(317 L)和双相不锈钢00Cr22Ni5Mo3N(2205)在含有溴离子和对苯二甲酸颗粒的醋酸介质中,进行腐蚀磨损性能研究。结果表明,4种不锈钢的腐蚀磨损速率随着腐蚀介质温度的升高而增加;在低温时,腐蚀磨损速率差别不大;当温度超过80℃以后,腐蚀磨损性能的差异变大,其中2205的耐腐蚀磨损性能最好,其次为317 L,316 L,而304则最差。相同条件下,腐蚀磨损速率大于均匀腐蚀速率。建议用2205代替316 L制作PTA同转蒸汽管干燥机的加热列管。     

Epoxysilane as adhesion promoter in duplex system

Coatings are one of the most used protection methods for metals. Metallic coatings, such as zinc and its alloys, are used to protect steel in mild corrosive environments. In aggressive environments, on the other hand, organic coatings must be employed in the so-called duplex systems. However, the galvanized steel/organic coating adhesion is a problem and many attempts had been done to solve it with the incorporation of a chromate-based or phosphate-based interlayer. Nowadays, the use of these compounds is questioned due to their environmental impact and new adhesion promoters, like silanes, are being investigated. The aim of this paper was to study the adhesion and the anticorrosive behavior of a duplex system with a layer of glycidoxypropyltrimethoxysilane (γ-GPS) between the zinc and the coating. Polarization tests and corrosion potential measurements were done on the γ-GPS/galvanized steel to select the better anticorrosive pretreatment conditions for the application of an organic traditional paint. Dried and wet adhesion of the coating to the pretreated substrate was studied by the standard tape test. Salt spray test and electrochemical noise technique were employed to study the corrosion behavior of the duplex systems. Results showed that the films of γ-GPS formed on galvanized steel diminished the corrosion current of the metal, but they do not protect the substrate by a barrier effect. The incorporation of the pretreatment in the duplex system increased the adhesion of the paint, especially when the pretreated substrate was cured 1?h at 200?°C.     

Application of Ni-free high nitrogen stainless steel for bipolar plates of proton exchange membrane fuel cells

Ni-free 23Cr-1N stainless steel was examined as bipolar plates for proton exchange membrane fuel cells. Corrosion resistance of the 23Cr-1N stainless steel was better relative to 22Cr stainless steel in the simulated cathodic environments. As confirmed by X-ray photoelectron spectroscopy, the polarized 22Cr and 23Cr-1N stainless steels at pH 2.3 presented predominantly chromium oxide in the outer passive layers. At pH 4.3, the passive layer of the polarized 22Cr stainless steel changed to iron oxides dominant. Interestingly, on the other hand, the polarized 23Cr-1N stainless steel preserved chromium oxide rich outer passive layer, which provides good corrosion resistance. As a result, although the initial cell voltage was slightly lower (∼40 mV), the 23Cr-1N stainless steel bipolar plates employing cell showed better cell voltage stability up to 1000 h, compared with the 22Cr stainless steel employing cell. The operation voltage became further higher through a surface modification of the 23Cr-1N stainless steel with TiN nanoparticles. It seems that the corrosion resistive Ni-free 23Cr-1N is possible to apply for bipolar plates of proton exchange membrane fuel cells.     

A comparative study between Cr(VI)-containing and Cr-free films for coil coating systems

In this work, the protection conferred by Cr(VI)-containing and Cr-free pre-treatments and primers used in hot dip galvanized steel (HDG) coated systems were studied. The EIS results showed a differentiated behaviour for the specimens with Cr(VI) compared to the chromium-free ones. The samples with Cr(VI), both in the pre-treatment and in the primer, presented a better corrosion performance when compared to the Cr-free ones.

Moreover, it can be said that the pre-treated and primed samples without Cr(VI) presented lower resistive properties and higher delamination fractions throughout the immersion time. The amount of Cr in the primer also influenced the coating resistance for shorter periods of immersion, but for long periods the passivating effect of Cr seems to be determinant.

When topcoat was applied, i.e. for a complete system, the Cr-free specimens performed better than the Cr(VI)-containing ones, perhaps due to a better adhesion of the topcoat to the primer in the former case. This leads to the conclusion that there is a risk in assessing the behaviour of a paint scheme on the basis of the individual behaviour of each layer.     

1Cr11Ni2W2MoV 模锻件耐蚀性改进工艺

针对航空用1Cr11Ni2W2MoV马氏体不锈钢毛坯模锻件表面存在贫化层而导致耐蚀性明显下降的问题,提出采用硫酸?磷酸?铬酸混合液对其进行电化学抛光。耐蚀性、晶间腐蚀、氢含量等指标的检测结果均表明该方法可行。     

Adhesion characteristics and corrosion stability of epoxy coatings electrodeposited on phosphated hot-dip galvanized steel

The influence of hot-dip galvanized steel (HDG) surface pretreatment with phosphate coatings on the corrosion stability and adhesion characteristics of epoxy coatings electrodeposited on HDG steel was investigated. Phosphate coatings were deposited on hot-dip galvanized steel from baths with different concentrations of NaF (0.1, 0.5 and 1.0 g dm⁻³) and at different temperatures (50, 65 and 80 °C). The influence of fluoride ion concentration in the phosphating bath, as well as the deposition temperature of the bath, on the adhesion characteristics and corrosion stability of epoxy coatings on phosphated HDG steel was investigated. The dry and wet adhesions were measured by a direct pull-off standardized procedure, as well as indirectly by NMP test, while corrosion stability was investigated by electrochemical impedance spectroscopy (EIS).