不同镍铁合金镀层组合的防腐蚀性

本文根据镍铁合金镀层的性质,论述了镍铁合金镀层的防腐机理,并指出提高镍铁合金镀层抗蚀性能的关键在于控制各镍铁镀层的不同含铁量和镀液的纯度。     

防护—装饰性镍铁合金电镀

苏联莫斯科化学工艺研究所提出一种可以得到含铁20-35％的防护装饰性镍铁合金镀层的电解液。一系列的研究表明,这种硫酸盐—氯化物槽具有整平性能好,镀层光亮的特征。所得防护—装饰性镀层具有较低的内应力,足够高的微观硬度和令人满意的腐蚀特性。     

一种镍铁合金刷镀液的应用

介绍一种镍铁合金刷镀液及其工艺.由这种镀液刷镀取得的镀层含铁量为40～50%,硬度达Hv779,具有较高光泽性.文中还阐述了工艺条件的控制.     

低铁锌铁合金电镀新工艺

研究了在碱性锌酸盐镀液中加入含铁补充剂后,得到镀层含铁量为0.4%～0.8%的锌铁合金电镀新工艺,讨论了影响镀层铁含量的各种因素,测试了镀层及镀液的性能.结果表明,锌铁合金镀层与锌镀层相比,更加光亮、细致,结晶致密,耐蚀性得到进一步提高.     

电流密度对光亮镍-铁合金镀层表面形貌及耐蚀性的影响

通过电沉积方法制备光亮镍-铁舍金镀层,利用扫描电镜测定镀层表面显微形貌(SEM),X射线衍射仪测定合金饺层的相结构(XRD),然后对合金镀层进行浸泡腐蚀实验,观察其腐蚀行为,并测定其庸蚀速率.结果表明:镍-铁合金镀层在质量分数为3.5%的NaCl溶液中的腐蚀速率较在质量分数为5%的H2SO4溶液中的腐蚀速率小,即:在质量分数为3.5%的NaCl溶液中有较好的耐蚀性,最小的腐蚀速率为0.21 mg/(dm2·h),且在电流密度为4～6 A/dm2工艺条件下获得的舍金镀层在两种溶液中都具有较好的耐蚀性能.     

紫铜表面镍-铁合金镀层的织构及性能

向瓦特型镀镍液中添加硫酸亚铁并改变铁、镍离子的质量浓度比,在紫铜表面制备了铁的质量分数不同的镍-铁合金镀层,相应地命名为镍-14.52%铁合金镀层、镍-22.18%铁合金镀层、镍-30.70%铁合金镀层、镍-42.73%铁合金镀层。比较了四种镍-铁合金镀层的织构和性能。结果表明:铁的质量分数是影响镍-铁合金镀层的织构、热膨胀性、显微硬度和抗拉强度的重要因素;镍-30.70%铁合金镀层具有较高的显微硬度和抗拉强度;镍-42.73%铁合金镀层具有较小的平均线膨胀系数。     

单层镍铁合金/铬电镀风扇网罩等的优点及退镀方法

我厂镀件的使用环境比较良好。经过小试,于79年8月将单层全光亮镍铁合金(含铁30％)/铬装饰性     

使用可溶性阳极的镍铁合金刷镀工艺

研究了一种使用可溶性阳极的镍铁合金电刷镀工艺，所得镀层含铁１０％～３０％，硬度为５００～６００ＨＶ，镀液稳定性好，镀层沉积速度快。     

锌铁合金电镀工艺研究

研究了碱性锌酸盐锌铁合金电镀工艺,探讨了各工艺条件对镀层铁含量的影响.通过控制工艺条件,获得了含铁量为9%～12%的光亮锌铁合金镀层.最佳工艺条件为:znO 8～10 g/L,NaOH 110～130 g/L,三乙醇胺20～30 mL/L,FeSO4·7H2O3.3～4.5 g/L,添加剂30～60mL/L,阴极电流密度1～2A/dm2,搅拌速率160～240r/min,温度28～35℃.电化学极化测试和中性盐雾腐蚀试验的结果表明,采用此工艺所得锌铁合金镀层的耐蚀性明显优于纯锌镀层.     

双层电镀——改善钢板性能的新技术

在钢板的表面首先镀上一层含镍11％的锌—镍合金,然后镀上—层含铁85％的锌—铁合金,可以使钢板的涂漆性能都得到显著改善。     

电沉积Ni-Fe合金工艺及镀层耐蚀性的研究

采用电沉积的方法制备了Ni-Fe合金镀层,对其微观形貌和结构进行了表征,并采用电化学方法研究了所制备的Ni-Fe合金镀层在不同介质中的腐蚀行为。结果表明:在5%硫酸溶液以及3.5%氯化钠溶液中,w(Fe)为19.23%的Ni-Fe合金镀层耐蚀性最好,在5%氢氧化钠溶液中w(Fe)为28.16%的Ni-Fe合金镀层的耐蚀性最佳。     

稀土镧对镍-铁合金镀层铁含量及耐蚀性的影响

研究了在以柠檬酸钠为稳定剂的电镀溶液中加入稀土镧添加剂电镀Ni-Fe合金镀层。通过改变镀液中FeSO_4浓度、控制电流密度及在镀液中加入不同含量的稀土添加剂,可得到铁含量不同的Ni-Fe合金镀层。实验结果表明,在Ni-Fe合金镀液中加入稀土添加剂,可使合金镀层的耐蚀性有所提高。     

Corrosion performance of NiAl intermetallic with Mo,Ga and Fe in neutral and alkaline media

The corrosion resistance of mechanically alloyed NiAl intermetallics with additions of Mo, Ga and Fe, and their combinations, has been studied using potentiodynamic polarization curves and linear polarization resistance tests at room temperature. Solutions included 0.5 m NaCl and 0.5 m NaOH. The Al–42Ni+6Fe and Al–40Ni+6Fe+2Mo alloys exhibited the best corrosion resistance in NaCl whereas the highest corrosion rate was observed on Al–39Ni+6Fe+6Mo alloy, above the NiAl-base alloy. In NaOH, the highest corrosion rate was exhibited by Al–41Ni+6Mo alloy, whereas the best corrosion performance was obtained by alloys with 6Ga, followed by alloys containing 6Fe+2Ga and/or 2Mo+2Ga, and NiAl-base alloy had an intermediate corrosion rate. The alloys with the lowest corrosion rate also had the lowest pitting potential values. So, generally speaking, additions of 6Mo decreased the corrosion resistance of NiAl-base alloys in these environments. The results were supplemented by detailed scanning electronic microscopy studies and chemical microanalysis of the corroded specimens.     

动电位极化曲线法研究铝合金材料在海水中腐蚀现象

用动电位极化曲线法研究不同铝合金材料在海水中的腐蚀情况,探究海水中NaClO和Fe3+含量对铝合金材料的腐蚀影响。结果表明铝合金2024和1100较5052在海水介质中更易发生腐蚀,加入Fe3+会加速铝合金2024腐蚀,加入适量NaClO会减缓其腐蚀。铝合金2024可用作采用5052铝合金作为换热材料的多效蒸馏装置置换海水中重金属离子的预处理材料。     

YD-1添加剂对镍铁合金镀层微观结构的影响

研究了镀液中YD-1对电沉积Ni-Fe合金微观结构的影响.结果表明,YD-1可显著改变电流效率、沉积速率,而对镀层中的铁含量及晶格常数影响较小,YD-1可有效细化晶粒.     

Alloys cathodically modified with noble metals

The truly remarkable corrosion resistance of alloys containing small amounts of noble metals relies on the principle that the high exchange-current density for the reduction of hydrogen can shift the corrosion potential of the alloy to a value in the passive region, causing it to passivate spontaneously. Research indicates that additions of 0.1 to 0.4% PGMs to chromium in sulphuric acid cause the alloy to self-passivate easily and also increased the corrosion resistance by several orders of magnitude. The effectiveness of the PGMs in promoting corrosion resistance was found to decrease in the order Pt>Pd>Ir>Ru>Os. An enrichment of PGMs at the surface of the alloys occurred during the period of active dissolution. The effect of cathodic additions in ferritic stainless steels became more enhanced with an increase in the chromium content of an alloy. Furthermore, if molybdenum and a PGM occur together in an alloy, a synergistic beneficial effect is exerted on the corrosion resistance. The effect of the cathodic modification of austenitic stainless steels is not as dramatic as for ferritic stainless steels. Little is known about the effect of PGMs on the corrosion behaviour of duplex stainless steels. Work on titanium-palladium alloys led to the development of a commercial titanium-palladium alloy containing 0.2% palladium, which is especially suited to reducing conditions. By contrast with the chromium and stainless-stell alloys, the addition of PGMs to titanium was found not to be detrimental to its corrosion resistance in highly oxidizing media. The surface alloying of materials with PGMs by various methods could prove to be a more cost-effective method than bulk alloying.     

Synthesis of carbon nanotubes by catalytic conversion of methane: Competition between active components of catalyst

Catalytic growth of carbon nanotubes from methane was studied as competitive catalytic process in situ of both oxidative (partial oxidation) and non-oxidative (pyrolysis) conversion. Ni and Fe may act as either competing or cooperative catalyst components in the process of carbon nanotubes growth. The competition between Ni and Fe in the process of carbon nanotube growth on Ni-Fe based stainless steel alloy during partial oxidation of methane results in suppression of Ni catalytic activity in favor of Fe. The discrimination is so strong that iron is segregated from Ni-Fe based stainless steel alloy leaving characteristic Ni-enriched corrosion caverns. Interaction between Ni and Fe during non-oxidative conversion, in contrast to the oxidative conversion, leads to cooperative effect; the activity of bimetallic catalyst increases as compared with monometallic one. Depending on particular catalyst bed composition, the nanotubes of various morphologies may occur. In particular, the use of perovskite-type catalyst for partial oxidation of methane leads to formation of “olive-branch”-like peculiar carbon nanostructures.     

Influence of rare earth Y on the corrosion behavior of as-cast AZ91 alloy

The influence of different contents of rare earth Y on the corrosion resistance of AZ91 alloy was investigated by the salt spray test and electrochemical measurements. It was found that the proper amount of Y was effective on improving the corrosion resistance of AZ91 alloy. The optimal modification effect was obtained when the Y content in the alloys was 0.3 wt.%. However, with the increase of rare earth Y, the corrosion rate became bigger slightly, and further addition of Y content over 0.3 wt.% resulted in the increment of the corrosion rate. It is suggested that the excessive rare earth Y can reduce the corrosion resistance of AZ91 alloy.     

Influence of composition on corrosion behavior of as-cast Cu-Zr alloys in HCl solution

The corrosion behavior of the as-cast Cu-Zr alloys, with 15%, 30%, and 66% Zr (in at.%) were investigated in 0.1 mol/l HCl solution. Results revealed that the Cu-15 Zr alloy has the lowest corrosion rate in the potential region of selective dissolution of Zr as the result of the low Zr content. The corrosion rate was remarkably increased when Zr increased from 15% to 30%. The corrosion rate of the Cu-66Zr alloy is close to that of the Cu-30Zr alloy. This illustrates that the Zr content has little effect on the selective dissolution rate of Zr when Zr arrives at a certain degree in Cu-Zr alloys. In the potential region of simultaneous dissolution of Cu and Zr, the corrosion rate at the higher anodic potential depends on the content of both Cu and Zr, and the Cu-30Zr alloy has the worst corrosion resistance.     

一步电沉积制备高活性高稳定镍铁合金析氧电催化剂

以镍网为基底,通过一步电沉积方法成功制备出用于碱性水电解的多孔镍铁合金析氧反应(Oxygen Evolution Reaction,OER)电极.镍铁的沉积伴随强烈的析氢,此条件下构筑出的多级孔结构成为电极用于OER反应时液相中传质与气泡释放的适宜传递通道.在析氧反应中,电流密度为10 mA·cm-2时的过电位仅为21...