Electrochemical behavior of electroplated Zn-P alloy

1　ＩＮＴＲＯＤＵＣＴＩＯＮＥｌｅｃｔｒｏｐｌａｔｅｄＺｎ Ｐｃｏａｔｉｎｇｓｅｘｈｉｂｉｔａｒａｎｇｅｏｆｆａｓｃｉｎａｔｉｎｇｐｒｏｐｅｒｔｉｅｓ ,ｓｕｃｈａｓｈｉｇｈｃｏｒｒｏｓｉｏｎｒｅｓｉｓ ｔａｎｃｅ ,ｅｘｃｅｌｌｅｎｔ ｐａｉｎｔａｂｉｌｉｔｙａｎｄ ｐｈｏｓｐｈｏｒａｔａｂｉｌｉｔｙ ,ｆｉｎｅｗｅｌｄａｂｉｌｉｔｙａｎｄｆｏｒｍａｂｉｌｉｔｙ[1] .Ｔｈｅｒｅｆｏｒｅ ,ｉｎｒｅ ｃｅｎｔｙｅａｒｓ ,ｔｈｅｒｅｈａｖｅｂｅｅｎｓｅｖｅｒａｌｉｎｖｅｓｔｉｇａｔｉｏｎｓｏｎｐｒｅｐａｒｉｎｇ…     

Electrochemical corrosion behavior of bulk ultra-fine grained Fe-Ni-Cr alloy

The corrosion behavior of bulk ultra-fine grained (UFG) Fe-Ni-Cr alloy prepared by equal-channel angular pressing technique was investigated in 0.25 mol/L Na₂SO₄+0.05 mol/L H₂SO₄ solution by electrochemical measurements. As compared to the coarse grained (CG) counterpart, the UFG alloy exhibits an acceleration of the active dissolution and a shrunk passive region with a higher passive current. The Mott-Schottky analysis in conjunction with the point defect model indicates that the donor diffusion coefficient in the passive films of the UFG sample increases greatly to one magnitude order higher and the donor density is slightly lower than that of the CG sample.     

Electrochemical behavior of YAG laser-welded NiTi shape memory alloy

Electrochemical behaviors of laser-welded Ti-50.6%Ni（mole fraction） shape memory alloy and the base metal in 0.9% NaCl solution were investigated by electrochemical techniques as corrosion potential measurement, linear and potentiodynamic polarization. The results indicate that the laser-welded NiTi alloy is less susceptible to pitting and crevice corrosion than the base metal, which is demonstrated by the increase in polarization resistance（Rp） and pitting potential（φpit） and decrease in corrosion current density（Jcorr） and mean difference between φpit and φprot values. It is confirmed by scanning electron microscope micrographs that pits could be observed on the surface of base metal but not on the surface of laser-welded alloy after potentiodynamic tests. An improvement of corrosion resistance of laser-welded NiTi alloy could be attributed to almost complete dissolution of inclusions upon laser welding.     

Electrochemical behavior of Ti-Ni shape memory alloy in fibrinogen solution

Electrochemical behaviors of Ti-Ni shape memory alloy in fibrinogen solution were studied by electrochemical techniques. The results indicate that the addition of the fibrinogen has no obvious effect on the corrosion potential, but decreases the pitting potential markedly and increases the passive current densities. The analysis of energy-dispersive X-ray for samples adsorbing fibrinogen exhibits that the elements of O, C and N exist on the surface of Ti-Ni alloy. Furthermore, the scanning electron microscope micrographs confirm that the configuration of the adsorbing fibrinogen concentrating on surface defects is like cluster and the fibrinogen adsorption concentration is 96.67 mg/m^2 through ultroviolet ray absorption method. Fibrinogen combined with Ti-Ni alloy surface by complex band and its electrochemical transfer accelerated the corrosion of alloy.     

AZ31镁合金在MgSO4溶液中的电化学行为

用线性电位扫描、Tafel极化曲线、恒流放电、交流阻抗、失重法等方法研究AZ31镁合金在MgSO4溶液中的电化学行为，考察其作为电池负极材料的性能，并研究十二烷基苯磺酸钠对AZ31镁合金的缓蚀性能。结果表明：负差效应的存在极大降低AZ31镁合金的电流效率；未经放电时，合金自放电电流密度小，但放电后，自放电增强，存储能力降低。十二烷基苯磺酸钠能对AZ31合金起到缓蚀作用，提高放电电流效率，但会使续放电时出现电位滞后的现象。     

6082铝合金搅拌摩擦焊焊缝的电化学腐蚀行为

通过室温静态挂片试验以及动电位极化曲线测试,在室温0．2mol／LNaHSO3＋0．6mol／L NaCl溶液中,对6082铝合金搅拌摩擦焊（FSW）焊缝以及6082铝合金母材的电化学腐蚀行为进行了研究。结果表明,主轴转速为1200r／min,焊接速度为200mm／min,搅拌头倾角为3°时的焊缝与母材相比,平均腐蚀速率较小,腐蚀电位Ecorr正向移动,腐蚀电流密度J变小。同时使用扫描电子显微镜（SEM）对室温静态挂片试验试样的表面形貌进行了观察,发现焊缝表面上只出现少量较浅的点蚀坑,而母材表面的点蚀现象较为严重。     

LC4超硬铝合金微弧氧化膜电化学腐蚀特性

用微弧氧化方法在LC4超硬铝合金表面获得较厚的氧化膜,测定了氧化膜的生长曲线及电流密度变化,并用电化学方法测定不同厚度膜的极化曲线,采用零电阻技术测量3.5%NaCl溶液中LC4铝合金-铜电偶对电偶腐蚀情况.用扫描电镜观察合金基体和微弧氧化膜的腐蚀形貌.经过微弧氧化处理后,LC4超硬铝的腐蚀电流密度比基体降低几个数量级,腐蚀电位上升,耐腐蚀性能得到很大提高,但膜超过一定厚度时腐蚀电流密度反而有所升高.较厚的微弧氧化膜大幅度降低了LC4/Cu电偶对的电偶电流,电偶电位正向移动.     

Electrochemical behavior of AMΓ6 alloy in the acetate-phosphate aqueous solutions

It is shown that the effect of potassium phosphate additive on an AMΓ6 type alloy, anodically polarized in potassium acetate solutions, depends on the additive concentration. In small concentrations, potassium phosphate hampers the anodic process, whereas in high concentration, it accelerates the process. The pre-oxidation of AMΓ6-alloy samples in air results in improving their passivation properties during the anodic polarization in the solutions studied.     

Electrochemical behavior of Cu-Zn-Al shape memory alloy after surface modification by electroless plated Ni-P

The electrochemical behavior of Cu-Zn-Al shape memory alloy (SMA) with and without electroless plated Ni-P was investigated by electrochemical methods in artificial Tyrode‘s solution. The results showed that Cu-Zn-Al SMA engendered dezincification corrosion in Tyrode‘s solution. The anodic active current densities as well as electrochemical dissolution sensitivity of the electroless plated Ni-P Cu-Zn-Al SMA increased with NaC1 concentration rising, pH of solution decreasing and environmental temperature uprising. X-ray diffraction analysis indicated that after surface modification by electroless plated Ni-P, an amorphous plated film formed on the surface of Cu-Zn-Al SMA. This film can effectively isolate matrix metal from corrosion media and significantly improve the electrochemical property of Cu-Zn-Al SMA in artificial Tyrode‘s solution.     

Electrochemical behavior of anodized Mg alloy AZ91D in chloride containing aqueous solution

Electrochemical behavior in aerated 3.5 wt.% NaCl solution of Mg alloy AZ91D anodized or not has been investigated by using electrochemical impedance spectroscopy, potentiodynamic polarization and E_corr-t curve. Their microstructures before and after corrosion have been examined under scanning electron microscope. Testing results from E_corr-t and polarization curves indicate that the corrosion behavior of Mg alloy makes significant, characteristic changes due to anodization. Impedance spectra obtained show a regular evolution with exposure time revealing the development of corrosion damage. SEM micrographs confirm that there are pores, defects and microcracks in anodic film which determine the existence of film-vulnerable regions. Electrochemical data are combined with micrographs to explain protection mechanism of anodic film and corrosion mechanism of Mg alloy.     

Electrochemical behavior of the Ti6Al4V alloy implanted by nitrogen PIII

Plasma surface treatments have been used very often to enhance the surface properties of metallic materials. In this work, Ti6Al4V titanium alloy was treated by nitrogen plasma immersion ion implantation (NPIII) in order to obtain improvements in its surface properties, such as corrosion resistance evaluated here. The microstructure and corrosion behavior of the implanted and unimplanted samples were evaluated, using, XRD, GDOES and potentiodynamic polarization and impedance electrochemical spectroscopy tests in 0.6 M NaCl solution. It was verified that the NPIII created resistant layers to corrosive attacks. In corrosion tests by polarization, the implanted samples showed corrosion current density reduction of about 10 times compared to the Ti6Al4V alloy without treatment. Besides that, it was also observed a reduction of the passive current density of one order of the magnitude. In all the studied cases, the polarization curves were shifted to more positive values of potentials, indicating a lower tendency of these PIII treated surfaces to corrosion. The implantation process produced a thin TiN surface layer followed by Ti₂N and then a layer with nitrogen in solid solution, all detected by GDOES combined with X-ray diffraction. These layers promoted an excellent polarization resistance of the Ti6Al4V surfaces on impedance spectroscopy tests also. This better performance in these tests can be correlated with the formation of continuous nitride layer, which could retard chloride ions ingress into the substrate.     

Ti35合金在含氟离子硝酸中电化学腐蚀行为

Ti35合金具有优良的耐腐蚀性能,可在沸腾状态下高浓度的氧化性酸介质中进行长期工作,是商业后处理较为理想的候选材料。本文采用电化学测试系统测试了Ti35合金在含有不同氟离子浓度的6M硝酸溶液中的开路电位(OCP)、极化曲线、电化学阻抗谱(EIS),探讨了氟离子对Ti35合金耐蚀性能的影响。结果表明：随着氟离子浓度的增加,合金耐蚀性下降,但总体而言合金仍具有良好的耐蚀性。影响合金耐蚀性转变的氟离子浓度临界值约为50ppm,进一步应用混合电位理论,解释合金耐蚀性转变的原因。     

Electrochemical and corrosion behavior of a 304 stainless-steel-based metal alloy wasteform in dilute aqueous environments

The electrochemical and corrosion behavior of a stainless-steel-based alloy made as a prototype metallic nuclear wasteform to immobilize ⁹⁹Tc, has been studied in a number of reference solutions ranging in pH from 4 to 10. The results showed the 47SS(304)-9Zr–23Mo prototype alloy contained at least five distinct phases with the majority of the Re, used as a Tc surrogate, contained within a Fe₂Mo intermetallic phase. Polarization studies showed this alloy exhibited generally passive behavior in a range of dilute aqueous environments. Impedance measurements indicated passivity breakdown events can occur and lead to localized corrosion, especially in slightly alkaline conditions.     

Electrochemical synthesis and corrosion behavior of poly(N-ethyl aniline) coatings on Al-2024 alloy

Poly(N-ethyl aniline) coating was electrodeposited onto Al-2024 by using cyclic voltammetry. The coating was characterized by infrared spectroscopy, cyclic voltammetry and UV-Vis spectroscopy. The corrosion resistance of the film was evaluated by dc polarization studies. These coatings were formed in aqueous solution of oxalic acid. The concentration of monomer and oxalic acid were kept constant at 0.1 and 0.3 M, respectively. The formation of the polymer coating was monitored by cyclic voltammetry and infrared spectroscopy. Preliminary dc polarization results show that poly(N-ethyl aniline) has a corrosion rate of about 0.004 mmpy, which is significantly lower (about one order of magnitude) than that for the non-coated Al-2024.     

Electrochemical corrosion behavior of Al–Si alloy composites reinforced with in situ TiB2 particulate

Understanding the corrosion behavior of TiB_2p‐reinforced aluminum matrix composites is crucial for their development as effective composites. In this work, corrosion characteristics of in situ TiB₂ particulate reinforced Al–Si alloy (A356) composite after T6 treatment are investigated by electrochemical techniques. The electrochemical impedance spectroscopy (EIS) reveals that the protection of nature film for the composites is worse than that for A356 alloy. Polarization experiments testify that the composites are susceptible to corrosion compared with their matrix alloys. Moreover, the corrosion resistance of the composites markedly decreases with increase in the TiB₂ content. The observations of the corrosion morphologies after polarization test show that the corrosion primarily occurs at the interdendritic sites with a large amount of TiB₂ particulates. Corrosion progress continues into the composite inner along the regions of α‐Al dendrite. The poor corrosion resistant properties of the composites are considered primarily due to the galvanic corrosion between noble TiB₂ reinforcements and more active aluminum matrix, as well as the weak protection of the defective nature film on the composite.     

Cu-Ni-Si-Mg合金的时效特性

通过电导率、硬度、XRD、动力学4个方面研究Cu-2.4Ni-0.57Si-0.1Mg合金4种工艺下最佳的电导率与硬度配合.结果表明,试验合金经过热轧后在450℃时效4h的硬度和电导率的配合最佳,综合性能达到最高点;通过时效处理从过饱和固溶体中析出Ni2Si相,使合金导电性上升,同时硬度也可大幅度提高.随着温度和时间的增加,发生了过时效现象,析出相长大,失去共格特征,Ni2Si又逐渐溶解到基体中,缺陷也逐渐减少,导致硬度显著下降.     

在二甲亚砜中La—Ni—Co合金模膜的电化学制备

研究了二甲亚砜（ＤＭＳＯ）中Ｌａ＾３和Ｎｉ＾２＋在Ｐｔ,Ｃｕ和Ｎｉ电极上的电化学行为,结果表明,Ｎｉ＾２＋在Ｐｔ电极上一步不可逆还原为Ｎｉ（０）,Ｌａ＾３＋在Ｐｔ电极上表现为准可逆电极过程。在２９８Ｋ时,利用循环伏安法测定０．０１ｍｏｌ．Ｌ＾－１ＮｉＣｌ２－０．１ｍｏｌ．Ｌ＾－１ＬａＣｌ３－０．１ｍｏｌ．Ｌ＾－１ＬｉＣｌ－ＤＭＳＯ溶液中Ｌａ＾３＋的扩散系数为３．１＊１０＾－６。在铜电极上于－２．２     

Magnetically soft amorphous-crystalline alloys for magnetic head cores

A magnetically soft iron-base alloy in the form of ribbon with an amorphous-crystalline structure was developed and studied. The magnetic properties of this alloy are superior to those of purely amorphous alloys designated for the same use, which, moreover, contain 80% of the expensive metal cobalt. Magnetic heads were fabricated using the amorphous-crystalline alloy with which it was possible to increase the informational capacity, speed, and service life of external memory devices for electronic computers.Scientific Research Center for Electronic Calculator Technology, I. P. Bardin Central Scientific Research Institute for Ferrous Metallurgy (TsNIIChERMET). Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 32–35, March, 1994.