Zn-Fe合金镀层耐蚀性研究

通过改变工艺条件,可以从碱性溶液中获得含 Fe0.4～0.8%的 Zn-Fe合金镀层。试验表明这种镀层的耐蚀性是普通镀锌层的2倍。含 Fe 量不同的镀层其耐蚀性也不同。含 Fe 在0.4～0.8%的镀层在5%NaCl 溶液中在稳定电位条件下处于钝化区,而且镀层的极化电阻比较大,是镀锌层的2倍以上,而镀锌层在同样溶液中处于活化溶解区,有很大的溶解电流,而且极化电阻较小。腐蚀后形貌观察也表明 Zn-Fe 合金镀层与镀锌层的特征不同,呈花球状形貌。正是由于上述差异决定了 Zn-Fe 合金镀层的耐蚀性是优良的。     

Improving the corrosion behaviour of powder metallurgical 316L alloy by prepassivation in 20% nitric acid

The electrochemical improvement of PM 316L stainless steels by pre-alloyed powder prepassivation in 20% nitric acid in comparison with as-received specimens has been studied in this work. For comparison purposes a simultaneous study was carried out on similar composition wrought AISI 316L steels. Corrosion resistance was studied using evolution of the corrosion potential vs. time, anodic polarisations curves and Zero Resistance Ammeter technique. Reductions of the corrosion rate (i_corr) were observed in prepassivated specimens in neutral chloride media. Crevice resistance was higher for prepassivated specimens and for higher densities and annealing as post-heat treatments.     

Accelerated corrosion tests in the automotive industry: A comparison of the performance towards cosmetic corrosion

Corrosion resistance is an important property requirement for materials used in the manufacturing of automobiles, particularly for vehicles that operate on roads treated with de‐icing salt. This implies to test the corrosion resistance of automotive systems, in order to make a good selection of materials. Field‐tests, including stationary and mobile exposures are normally the most reliable ways of doing this, but they are costly and time consuming, as 2–8 years exposure is generally needed for a full assessment of the corrosion resistance. Since, the use of the standard neutral salt spray test, which is well known to give a poor correlation with field data, a large development in the testing procedures has occurred with the use of cyclic corrosion tests, which alternate between pollution phase and wet/dry periods. Today, there are indeed as many accelerated corrosion tests as automotive manufacturers, which are currently used in order to develop and qualify new products against corrosion, to develop new protective coating systems and select materials. In the present work, steel‐ and zinc‐coated materials in cosmetic and crevice configuration were exposed in a large number of accelerated corrosion tests in the automotive industry. From the study, it was shown that the results and consequently the prediction on the lifetime of the same material were very much dependent on which accelerated corrosion test was used. The results were explained in terms of different salt loads applied in the different tests.     

聚苯胺/石墨烯原位复合水性防腐涂料耐蚀性能的研究

目的研究聚苯胺/石墨烯水性防腐涂料的耐蚀性能。方法采用盐酸为掺杂酸,以聚乙烯基呲咯烷酮(PVP-K30)为空间稳定剂,利用原位聚合法,以苯胺和石墨烯为原料,过硫酸铵为氧化剂,制备聚苯胺/石墨烯复合材料。将聚苯胺/石墨烯、纯聚苯胺、石墨烯分别添加到HG-54C乳液中制备水性防腐涂料,利用动电位极化曲线和盐雾试验对比分析聚苯胺/石墨烯、纯聚苯胺、石墨烯水性涂层的防腐性能,再通过傅里叶红外光谱(FTIR)、扫描电镜(SEM)对比分析其结构和微观形貌。结果聚苯胺均匀地覆盖在石墨烯的片层结构上形成氧化插层结构。当复合材料浸泡在3.5%Na Cl溶液中,腐蚀电流密度为2.3955×10-7A/cm2。盐雾试验表明,聚苯胺/石墨烯的防腐性能优于添加纯聚苯胺和石墨烯的性能。结论聚苯胺/石墨烯涂层具有良好的耐蚀性能,其耐蚀性能优于纯聚苯胺涂层和石墨烯涂层。     

全光亮镍磷合金镀层的耐蚀性

采用个性盐雾实验、浸泡实验和阳极极化曲线测试了全光亮镍磷合金镀层耐蚀性.盐雾实验表明：磷含量为128mass%～153mass％的镀层耐蚀性能最好，磷合量提高到201mass％后，耐蚀性下降；热处理温度在200℃以下时，对镀层耐蚀性影响不大，超过300℃以上，镀层耐蚀性明显下降；浸泡实验表明Ni-P合金镀层与1Cr18Ni9Ti相比，在酸性、碱性和氯离子水溶液中耐蚀性能较好，但不耐硝酸、硝酸盐等强氧化性介质的腐蚀；阳极极化曲线测试表明，磷含量为12.8mass％的镀层在10％HCl、5％NaCl、20%NaOH和3.5％FeCl-3溶液中，均表现出了优异的耐蚀性能.磷合量为20.1mass％高磷镀层在20％NaOH中耐蚀性能优异.      

镁合金表面铈盐掺杂硅烷膜的腐蚀电化学行为

目的为进一步提升镁合金表面常规硅烷膜的耐蚀性能。方法在γ-氨丙基三乙氧基硅烷溶液中掺杂0.50 g/L硝酸铈,采用简单化学浸渍处理,在AZ91D镁合金基体表面制备了铈盐掺杂硅烷膜。借助扫描电子显微镜(SEM)观察了铈盐掺杂前后硅烷膜的表面微观形貌,通过开路电位-时间曲线、电化学交流阻抗谱(EIS)和中性盐雾试验(NSS)研究了铈盐掺杂对5%Na Cl溶液中硅烷膜耐蚀性能的影响。结果铈盐掺杂硅烷膜比普通硅烷膜更厚且平整,其致密性、均匀一致性较好,完全覆盖了镁合金基体,已看不到磨痕。铈盐掺杂硅烷膜的稳定电位约为-1.31 V,且需要的稳定时间最长。铈盐掺杂硅烷膜具有更大的低频阻抗数值,有效遏制了侵蚀性粒子向镁合金基体的迁移和扩散,避免了镁合金基体发生阳极溶解反应。结论采用向硅烷溶液中添加硝酸铈的方法,能够在AZ91D镁合金表面制备出铈盐掺杂硅烷膜。由于铈离子在某种程度上修复了硅烷膜层中的微裂纹和缺陷,显著提升了硅烷膜的耐蚀能力。     

TZM合金在酸、碱腐蚀介质中的腐蚀行为研究

对TZM、掺杂La-TZM合金进行酸性和碱性介质腐蚀试验,设计腐蚀周期分别为10、30、50、70 d 4个阶段。通过对2种TZM和掺杂La-TZM合金在2种腐蚀介质中不同腐蚀周期的质量损失、失重速度、平均腐蚀率以及腐蚀形貌的研究与比较,分析TZM合金在2种介质中的腐蚀机理,以及掺杂La对于TZM合金的耐酸、碱腐蚀性能的影响。研究表明TZM合金在酸性介质中主要发生电池反应,阳极金属溶解,阴极析氢;腐蚀在金属表面缺陷、杂质富集、晶界处以及位错处优先进行,并且表面存在划痕处的小于0.00254 mm的窄缝处发生缝隙腐蚀。TZM合金在碱性介质中几乎不发生腐蚀;掺杂稀土元素镧可以略微提升TZM合金的耐蚀性,但提升效果不显著。     

铝合金阳极氧化方法及成膜机理的研究进展

对铝合金阳极氧化的发展现状及趋势进行了总结和展望。首先,介绍了阳极氧化工艺的类型,并着重阐述了最常用的酸性阳极氧化以及碱性阳极氧化的特点。随后,概括了阳极氧化膜生长机理的研究进展,包括氧化膜的生长过程及提出的相关理论。此外,对碱性阳极氧化的研究现状进行了归纳,并简要介绍了其与酸性阳极氧化在氧化膜结构特点及生长机理方面的异同。最后,针对当前阳极氧化技术存在的问题和面临的挑战,对其未来的发展趋势做了展望,并指出了阳极氧化技术的发展方向。     

镀锌板在不同加速腐蚀环境下的腐蚀行为研究

目的研究中性盐雾环境、中性盐雾加周浸环境和中性盐雾加湿热环境下镀锌板的腐蚀行为,明确不同加速腐蚀试验环境对镀锌板腐蚀行为的影响。方法对镀锌板进行中性盐雾、中性盐雾加周浸、中性盐雾加湿热等不同类型的加速腐蚀试验,通过失重法、SEM、XRD以及极化曲线等方法,对比不同加速腐蚀试验类型对镀锌板腐蚀行为的影响。结果在三种加速腐蚀试验环境下,镀锌板的腐蚀过程基本相同:镀锌层及白色锌锈腐蚀、锌层破裂、锌层完全脱落、基体碳钢腐蚀。腐蚀产物都以Zn(OH)_2、γ-FeOOH、ZnO、Fe_2O_3等为主。三种环境下镀锌板的腐蚀都不均匀,不同位置的腐蚀情况存在一定差异。其中,中性盐雾环境下材料腐蚀情况最为严重,中性盐雾加周浸环境次之,中性盐雾加湿热环境下最轻。结论三种加速环境都是主要通过Cl~-在锌表面的沉降和溶解作用增强介质的导电性能,加剧锌层的腐蚀。在中性盐雾环境中,Cl~-浓度最高,试样腐蚀最严重。在中性盐雾加周浸环境中,SO_4~(2-)与Cl~-协同作用,腐蚀也较严重。而中性盐雾加湿热环境中,Cl~-被稀释,腐蚀情况最轻微。     

输电塔塔腿镀锌层电化学腐蚀性能研究

目的利用冷镀锌层进行输电塔塔腿防护和损伤修复。方法采用电化学腐蚀试验,并结合扫描电子显微镜等试验手段,研究输电塔塔腿镀锌层的耐腐蚀性能。结果在Na Cl和NaHSO_3溶液中进行电化学腐蚀时,镀锌层的腐蚀速率随着溶液pH的增大而下降,腐蚀电流密度减小,耐腐蚀性能逐渐变好。在pH为4的酸性溶液中,锌层表面凹凸不平,腐蚀产物主要是ZnSO_4。在中性和碱性溶液中,锌层溶解减弱,腐蚀后锌层表面较为平整,腐蚀产物呈针状或片状,腐蚀产物为ZnSO_4和Zn_5(OH)_8C_(12)·H_2O。结论在NaCl和NaHSO_3酸性溶液中,镀锌层腐蚀电位较低,腐蚀速度较快,镀锌层发生晶界腐蚀而使表面凹凸不平。随着pH值的增大,镀锌层腐蚀速度快速降低,在pH值为10的碱性溶液中,镀锌层腐蚀速度显著降低,耐腐蚀性能增强。     

2A12 铝合金硬质阳 极氧化及膜层性能研究

目的对混合酸电解液体系中2A12铝合金硬质阳极氧化膜层的制备及性能进行研究。方法采用以硫酸为主的混合酸电解液体系,对2A12铝合金进行硬质阳极氧化,研究混合酸电解液主要成分对2A12硬质阳极氧化膜层性能的作用和影响。结果在硫酸的溶解、有机酸吸附以及添加剂的耦合作用下,混和酸电解液避免了2A12铝合金硬质阳极氧化膜制备过程中存在的烧蚀现象,膜层平均硬度达到400HV0.05以上。WX添加剂能够明显改善2A12铝合金硬氧化膜层的耐蚀性能,经过168 h的中性盐雾试验,仅出现了5%的白霜,但与相同厚度的7A04铝合金硬质阳极氧化膜层相比,耐蚀性较差。结论建议制备有耐蚀性要求的硬质阳极氧化膜层时选用铜含量较低的铝合金材料。     

LY11铝合金及H62黄铜的土壤腐蚀行为

用埋设试件的方法,在酸性,中性及碱性土壤中,研究了ＬＹ１１铝合金及Ｈ６２黄铜 经过１、３、５年３个试周期后的腐蚀特性。结果表明,ＬＹ１１铝合金在土壤中腐蚀主要表现为局部 腐蚀,Ｈ６２黄铜主要表现为脱锌腐旬,腐蚀程度主要取决于土壤类型及质地,在质地明显不均匀的碱 性土壤中腐蚀严重,而在质地较均匀的中性粘土及酸性粘土中腐蚀轻微。     

镁合金阳极氧化膜在NaCl溶液中的腐蚀行为

利用盐水浸泡实验研究了AZ91D镁合金阳极氧化膜层在3．5％NaCl溶液中的腐蚀行为。结果表明：AZ91D镁合金阳极氧化膜层不论封闭与否,在中性NaCl溶液中浸泡出现第一个腐蚀点后,膜层表面均很少再出现新的腐蚀点,而是原有的腐蚀点向纵、横两个方向扩展形成腐蚀坑,表面呈“树枝”状腐蚀形貌;浸泡溶液的pH值对阳极氧化膜层的耐蚀性影响很大,酸性溶液中的腐蚀速率明显大于中、碱性溶液的;随浸泡溶液温度的升高阳极氧化膜层的腐蚀速率加快。据此,提出了AZ91D镁合金阳极氧化膜层在NaCl溶液中腐蚀过程的模型。     

Electrochemical properties and structure of vanadium-based conversion coatings on electro-galvanised steel

The corrosion resistance of vanadium-based conversion coatings on electro-galvanised steel (EG) was examined in terms of the different valence species V⁵⁺ and V⁴⁺ as the raw material in the treatment solution. The effects of mixing phosphoric acid with the vanadium-based conversion coating have also been investigated. Corrosion performance was tested by neutral salt spray test and the mechanism of corrosion resistance was analysed by electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. It was found that conversion coatings formed from V⁵⁺ or V⁴⁺ did not clearly show different corrosion behaviour, but that the addition of phosphoric acid to the solution including V⁵⁺ improved corrosion protection. These results indicate that mixing phosphoric acid lowers the pH of the solution and improves corrosion resistance. The role of phosphoric acid is also explained by the formation of hydrogen bonds at the interface between the vanadium species and EG substrate.     

LY12铝合金NaOH介质电解着色膜耐蚀性的电化学评价

在弱碱性介质中阳极氧化制备LY12铝合金着色膜,用动电位扫描法极化曲线和极化电阻电化学测试技术方法研究了着色膜在中性和酸性介质中的耐蚀性能以及时效腐蚀行为。结果表明,着色膜在中性和酸性介质中均具有良好的钝化性能,耐孔蚀性能也显著提高。结合X射线衍射、表面形貌和电子能谱探讨橄榄绿色膜层的成分和结构对其耐蚀性能的影响。研究表明,着色膜的厚度约为4μm,主要由刚玉结构的α-Al_2O_3构成,膜内富集氧和其它耐蚀元素有利于耐蚀性的提高。     

循环阳极极化曲线评价LY12A1合金表面稀土转化膜耐腐蚀性能的研究

提出利用循环阳极极化曲线研究转化膜耐腐蚀性能 的方法.介绍了LY12 Al合金表面稀土转化膜的工艺.将稀土转化膜与其它转化膜的耐腐蚀性 能进行比较.利用循环阳极极化曲线的“相对环面积”研究转化膜耐腐蚀性能可得出转化膜 耐腐蚀规律性.     

Plasma electrolytic oxidation of AZ91D magnesium alloy with different additives and its corrosion behavior

Plasma electrolytic oxidation (PEO) of Mg‐based AZ91D alloys was investigated using 50 Hz AC anodizing technique in an alkaline borate solution, which contained a new kind of organic additive and without F, P, and Cr. The anodizing technological parameters have been optimized and a kind of ivory‐white smooth anodic film with high corrosion resistance was obtained. It was found that the formation of the anodic films was always coupled with sparking and oxygen evolution, whose intensity changed with the additive and anodizing voltage. All EIS plots have two capacitive loops and one low frequency inductive component. Two capacitive arcs present the barrier and porous layer of the PEO film and the inductive component in the low frequency domain is a complex behavior due to the porous structure connected to the electrolyte. EIS plots and fitting results show that a self‐sealing process of the PEO firm with different additives takes place in the beginning of immersion time, then corrosion attack becomes a preponderant process to promote the degradation of the film. Tafel results show that PEO treatment decreases the corrosion current density by four, even five orders of magnitude, while additives content does not affect strongly the electrochemical corrosion behavior. Salt spray test shows that the PEO film formed with NaAlO₂ and Na₂SiO₃ presents good corrosion resistance, over 600 h without any sealing treatment. The difference of corrosion resistance arose by additives examined by electrochemical techniques and salt spray test does not show strict corresponding relationship.     

烧结钕铁硼电镀锌铁合金工艺与耐蚀性能

采用弱酸性氯化物镀液在钕铁硼基体上制备了高耐蚀性的锌铁合金镀层,讨论主要工艺参数对镀层铁含量的影响,优化工艺条件。采用盐雾试验(NSS)、SEM和电化学方法研究镀层的耐蚀性能和耐蚀机理。结果表明,优化工艺条件后合金镀层含铁质量分数为0.92%,钝化后在质量分数3.5%的Na Cl溶液中出白锈时间达到196 h。合金镀层对钕铁硼基体起到阳极保护的作用,镀层结晶致密,填补了钕铁硼基体的固有缺陷,同时又为获得致密的钝化膜创造了条件,减少了镀层表面的缺陷,使镀层整体具有极高的电阻,提高了其耐蚀性能。     

Wet corrosion of nitride PVD films in supercritical solutions

Nitride TiN, TiAlN and CrN films exhibit a high performance with respect to steel corrosion protection in supercritical water. However, for practical applications their corrosion resistance in water solutions is more important. Wet corrosion of nitride PVD films in neutral, acid and alkaline supercritical solutions was studied. The highest stability of the films was revealed in neutral sodium chloride and alkaline CH₃NH₂ solutions. In the latter case regular cubic spinel crystals were formed on the surface of TiAlN films. Acidic solutions destroy nitride films due to growth of corrosion products beneath the coating layer.     

化学处理液中的La及BTA 对铜合金表面性能的影响

为了提高铜及其合金的耐蚀性能,研究了稀土La盐与BTA对铜合金缓蚀的协同作用,化学处理后的铜合金表面耐蚀性能得到改善。利用扫描电镜及XRD,对铜合金处理后的表面形貌及结构进行了分析;通过阳极极化、交流阻抗等电化学测试方法分析了La盐与BTA对铜合金表面性能的影响。结果表明:稀土La盐与BTA的加入使铜合金表面形成了均匀、致密的转化膜,从而提高了铜合金表面的耐蚀性能。