Mg对Zn-6%Al镀层凝固组织的影响及耐腐蚀性的研究

研究了Mg含量对Zn-6%Al合金镀层凝固组织及其耐腐蚀性能的影响。结果表明,Mg对合金镀层凝固组织和耐腐蚀性的影响明显,当Mg含量在3%以内时,随着Mg含量的增加,镀层凝固组织中出现了耐腐蚀相MgZn2,晶粒不断细化,形成了Zn/Al/MgZn2三元共晶,并且随着Mg含量升高更加均匀致密,镀层的耐腐蚀性不断增强;当Mg含量达到3%时,镀层的耐腐蚀性能最好;Mg添加量超过4%后,镀层耐蚀性有所下降,进一步添加Mg镀层会出现漏镀等质量缺陷。XRD分析表明,含Mg镀层表面经过盐雾腐蚀后主要形成具有优良耐腐蚀性的腐蚀产物Zn5(OH)8Cl2.H2O,Mg促进了腐蚀产物Zn(OH)2向Zn5(OH)8Cl2.H2O的转变,有利于镀层耐腐蚀性的提高。     

铜含量对近共晶Al-11.6Si合金组织与性能的影响

在近共晶Al-11.6Si合金中,添加不同含量的铜,通过对比合金的组织、流动性、耐腐蚀性、力学性能等参数,研究铜含量对近共晶Al-11.6Si合金组织与性能的影响,确定合金中铜的最佳添加量。研究表明,随着铜含量的增加,合金中Al₂Cu相体积分数不断增加,尺寸不断增大;合金流动性呈现递增的趋势;腐蚀电流密度和腐蚀速率不断增大,耐腐蚀性能逐渐下降;合金抗拉强度呈现先增大后减小的趋势,当铜含量为3%时,合金铸态和T6热处理后的抗拉强度达到最大值,分别为257 MPa、330 MPa,伸长率则不断减小。     

Ru元素对镍基高温合金在热环境中腐蚀行为的影响及计算机辅助分析

研究了不同Ru含量镍基高温合金的腐蚀行为。结果表明,随着Ru含量的增加,镍基合金外腐蚀层的脱落逐渐减轻,表明合金抗腐蚀性能不断提高。尤其是在Ru含量达到3%以后,合金的耐腐蚀性能大大提高。     

微量元素Fe对高铝铜合金腐蚀行为的影响

利用合金化、电子探针、扫描电镜及静态浸泡腐蚀实验等方法和实验手段研究了Fe对新型铝青铜Cu-14Al-xFe合金腐蚀性能的影响.结果表明,增加Fe含量,合金中形成弥散分布的K相(以AlFe,AlFe3等为主),细化了合金组织,提高了合金耐腐蚀性能.当w(Fe)=5%时合金的耐腐蚀性最好,当w(Fe)>5%时,合金的耐腐蚀性下降.     

Ca含量对Mg-Al-Zn合金组织及腐蚀性能的影响

采用重力铸造法制备了Ca含量分别为0、0.3%、0.6%、0.9%、1.2%和1.5%的Mg-Al-Zn-x Ca合金。通过金相显微镜和扫描电子显微镜观察了样品的微观组织,并利用电化学分析和静态失重法研究了合金的耐腐蚀性能。结果表明,合金的主要腐蚀机理是α-Mg和第二相之间形成的电偶腐蚀。合金的耐腐蚀性随Ca含量的提高先增强后下降,在Ca含量为0.9%时耐腐蚀性最优。这种现象与不同Ca含量合金中第二相形貌的变化有关。     

Ca对ZA104镁合金耐腐蚀性能的影响

采用金相显微镜、静态失重腐蚀试验和电化学工作站,研究了不同Ca含量对ZA104合金在3.5%的NaCl溶液中耐腐蚀性的影响。结果表明,随着Ca含量增加,ZA104镁合金在NaCl溶液中的静态失重腐蚀速率先减小后增加;添加Ca后,ZA104合金的自腐蚀电位均增大,当Ca含量为0.3%时,合金的极化曲线表明其自腐蚀电流密度值最低,耐蚀性最好。Ca的添加有利于细化合金组织,提高合金的耐腐蚀性能。     

K金首饰中镍含量与镍释放量关系研究

我国的K金首饰包括9K、14K、18K、22K几类,通常K金首饰是在主体为黄金的基础上按照一定比例含量掺入部分杂质元素,若其中的镍含量过高发生镍释放,可能导致佩戴人过敏。采用XRF荧光光谱仪检测饰品中的含镍量,研究K金饰品含镍量值与镍释放量间的关系。设定定性方法测试K金首饰中镍含量5%为镍释放量的阴性值的阀值,筛选K金首饰的镍释放量是否符合要求,再确定进行镍释放量定量检测。结果表明,对于饰品镍含量5%的产品,可以不进行镍释放量的检测;对于饰品镍含量5%~10%的产品,可以选择部分产品进行镍释放量检测;对于饰品镍含量10%的产品,都需要定量检测镍释放量。     

CVD制备纳米TiN合金镀层工艺研究

为了提高汽车行星齿轮轴的耐磨性和耐腐蚀性,设计了CVD沉积纳米Ti N合金镀层工艺,并在轴表面制备了纳米Ti N合金镀层;通过试验分别研究了镀层硬度与纳米Ti N含量间的关系,以及镀层的耐磨性耐腐蚀性能。结果表明:镀层硬度随Ti N质量的增加而增大,耐磨性和耐腐蚀性均有成倍提高。     

微量元素Co对高铝铜合金腐蚀行为的影响

利用合金化、电子探针、扫描电镜、及静态浸泡腐蚀试验等方法和试验手段研究了Co元素对新型铝青铜Cu-14Al-X合金腐蚀性能的影响。结果表明,增加Co含量合金中形成弥散分布的[Co,Fe]K相组织,可细化合金组织,提高合金耐腐蚀性能。当Co含量为5．5％时,合金耐腐蚀性能最好,当Co含量超过5．5％时,合金的耐腐蚀性下降。     

挤压态Mg-Sn-Ca合金的显微组织、力学及生物腐蚀性能（英文）

制备了用于骨科的挤压态Mg-Sn-Ca合金,并应用金相显微镜、扫描电子显微镜、X射线衍射仪、拉伸测试、浸泡测试和电化学测试等仪器和方法对其进行研究。结果表明:当锡添加量为1%,钙含量从0.2%增加到0.5%时,挤压态Mg-Sn-Ca合金的显微组织变得均匀,力学性能增加,耐腐蚀性提高。钙含量进一步增加到1.5%时,合金的强度增加,但伸长率和耐腐蚀性降低。在钙含量为0.5%的合金中,锡的含量从1%增加到3%时,合金的最大抗拉强度增加,耐腐蚀性降低。当锡含量为2%时,合金呈现最低的屈服强度和伸长率。挤压态Mg-Sn-Ca合金的这些行为受到Sn/Ca比率的控制。分析表明挤压态Mg-1Sn-0.5Ca合金有潜力作为可降解骨科植入体。     

Einfluß von Eisen auf die Korrosionsbeständigkeit von Nickelbasislegierungen als mögliche Werkstoffe für SCWO-Reaktoren

Effect of iron on the corrosion behaviour of nickel based alloys for SCWO plants An experimental set up to study corrosion at high temperatures and high pressures and able to simulate the conditions of supercritical water oxidation is described. On the basis of the alloys AC 66, 45 TM, G-3 and 601 H the influence of iron on the corrosion behaviour of nickel base alloys in aqueous solution under high pressures containing oxygen and chloride is shown and discussed. The corrosion resistance of the nickel base alloys is decreased with increasing iron concentration in the whole temperature range (100 °C–420 °C). The corrosion started at lower temperatures and the weight loss increased rapidly with increasing iron content. The corrosion morphology changed from uniform corrosion for alloys with less iron content to deep pits for alloys with high iron concentrations.     

Characterization of Electroless Ni-P Deposits on Surface of AZ91D Magnesium Alloy

Characterization of electroless nickel deposits on magnesium alloys was investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and electrochemical potentiodynamic polarization analysis.The result of XRD showed that the electroless nickel deposits on magnesium alloys were composed mostly of amorphous Ni-P and partially of microcrystalline nickel.The phosphorus content in the Ni-P deposits was 10.8%by the calculation of EDS.SEM micrographs showed that morphology of electroless nickel deposits on magnesium alloys was a typical cellular structure,and the growth of cellular structure was influenced by surface condition of substrate.Zinc layer between substrate and electroless nickel deposits was not found by the results of SEM and EDS,which indicated that the zinc layer on the surface of magnesium alloy was very thin,and the zinc would dissolved while being immersed in electroless nickel plating solution.The thin zinc layer was almost dissolved completely before Ni-P plating.The result of electrochemical potentiodynamic polarization analysis showed that the corrosion potential Ecorr of electroless nickel deposits in 3.5%NaCl solution was about-0.53 V,which was 1 V higher than that of magnesium alloys substrate.And corrosion current density of Ni-P deposits in 3.5%NaCl solution was much smaller than that of magnesium alloys substrate at the same potential value,which indicated that corrosion resistance of electroless Ni-P deposits was excellent.Discoloration time of concentrated nitric acid test for electroless nickel deposits on magnesium alloys was 445 s,which also indicated excellent corrosion resistance.     

Electrochemical behavior of copper-nickel alloys in acidic chloride solutions

The electrochemical behavior of Cu-Ni alloys in acidic chloride medium was investigated. Commercial Cu-Ni alloys were investigated using potentiodynamic techniques, complemented by electrochemical impedance spectroscopy. The influence of alloy composition, chloride ion concentration and immersion time on the electrochemical response of the alloys was analyzed. Results of present investigations with pure metals (Cu and Ni) are also considered in this paper for the sake of comparison. Potentiodynamic measurements reveal that the increase in nickel content decreases the corrosion rate of the alloy and when the nickel content exceeds 30%, an increase in the corrosion rate was recorded. Also, the corrosion current density increases with increasing the concentration of chloride ions up to 0.6 M.The experimental impedance data were fitted to an equivalent circuit model representing the electrode/electrolyte interface. The relevance of the proposed model to the corrosion/passivation phenomena occurring at the electrode/solution interface was discussed.     

Influence of nickel additions on the corrosion behaviour of low nitrogen 22% Cr series duplex stainless steels

Four 22% Cr duplex stainless steel alloys containing varying nickel contents of approximately 5%, 7%, 9% and 13% were melted in a vacuum induction furnace, hot rolled, solution annealed and water quenched. Their corrosion behaviour was investigated in sulphuric acid and sodium chloride solutions using potentiodynamic polarization and chronoamperometric techniques. Increasing nickel contents have an appreciable influence on the observed corrosion behaviour. Polarization curves show similarities in the uniform corrosion behaviour of the alloys in the various solutions, but significant differences in their pitting resistance in chloride environments. Alloy 2209 (22% Cr - 9% Ni) generally exhibited the highest resistance to uniform corrosion, while alloy 2213 (22% Cr - 13% Ni) displayed the best pitting corrosion resistance. X-ray diffraction analysis of the surfaces of the alloys after corrosion in the different media revealed different corrosion products. Scanning electron micrographs revealed that the alloys were differently attacked by chloride ions, with different pit depths and morphologies. The corrosion behaviour exhibited by the alloys was attributed to the influence of nickel on phase modification, microstructural refinement, and the types of films formed in different environments. Uniform corrosion behaviour of the alloys was concluded to be predominantly controlled by phase composition and ratio, while pitting resistance was chiefly controlled by an alloy’s nickel contents.     

Corrosion behavior of Fe-Cr and Fe-Ni-base commercial alloys in flowing Ar-42.6%O2-14.7%Br2 gas mixture at 700 °C

The corrosion behavior of Fe-Cr and Fe-Ni-Base commercial alloys has been investigated in an argon-42.6% oxygen-14.7% bromine gas mixture at 700 °C which was one of the environments encountered in the UT-3 thermochemical water decomposition reaction process to produce hydrogen. The test alloys were type 304 and 310 stainless steels, Incoloy 800, and Incoloy 825. Two-dimensional thermodynamic phase stability diagrams were constructed for iron, chromium, nickel, and titanium to predict the condensed corrosion products that are stable with respect to the representative alloying elements when the alloy is exposed to the argon-42.6% oxygen-14.7% bromine gas mixture at 700 °C. The oxides were thermodynamically stable phases with respect to the corresponding metals. Post-reaction treatment of test alloys included discontinuous mass-change measurements, scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) for morphological and compositional investigation of the corrosion products, and the X-ray diffraction (XRD) for phase identification. XRD identified oxides and spinels as corrosion products but low-melting metal bromides were detected for all alloys with deleterious effects on high-temperature properties of these alloys during exposure to the environment. The poor corrosion resistance of the test alloys was mainly caused by the cracking and spalling of iron and chromium-rich oxides and further growth of various metal bromides beneath the oxide scale following prolonged exposure. The high iron content of the test alloys had deleterious effects on the performance of these alloys in the environment.     

Effect of surface preparation on corrosion properties and nickel release of a NiTi alloy

Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys.The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied.Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system.Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed.Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film.     

Morphological characterisation and spectroscopic studies of the corrosion behaviour of tungsten heavy alloys

Tungsten-based alloys have been used in a wide variety of industrial and military applications. These alloys are composed mainly of tungsten (88-95%) with various combinations of nickel, cobalt, iron and copper usually making up the remaining fraction.The corrosion behaviours of five munitions grade tungsten alloys of interest have been examined using immersion tests and wet-dry cycle tests to determine the mechanisms involved in the release of the metallic components. Analyses carried out using SEM, EDS and grazing incidence XRD techniques, show the release of tungsten as well as alloying elements due to galvanic corrosion resulting from the difference in electrode potential between the tungsten phase and the binder phase in all cases studied. The extent of corrosion was directly related with the dissolution of tungsten in the binder phase during the sintering stage of manufacture. In W-Ni-Co-Fe alloys binder phase corrosion was observed while the relatively noble tungsten phase was less affected. The reverse was observed for a W-Cu alloy.     

缓蚀剂对镁合金化学镀镍的影响

目的寻找有效抑制镁合金腐蚀的缓蚀剂,提高镀层质量。方法研究缓蚀剂的种类和用量对缓解镁合金腐蚀的影响,研究不同缓蚀剂对化学镀镍层的影响。采用全浸失重实验对缓蚀剂的性能进行评价,并通过扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)和电化学测试对不同缓蚀剂下所得镀镍层的性能进行表征。结果经过初步筛选,六次甲基四胺(Hexamethylenetetramine)、氟化胺(NH_4F)、氟化氢铵(NH_4HF_2)缓蚀剂的效果较明显。AZ9l D镁合金在腐蚀溶液中,随着添加六次甲基四胺浓度的增加,腐蚀速率先减小后增加。随着添加氟化铵、氟化氢铵浓度的增加,腐蚀速率逐渐减小。添加缓蚀剂的体系中较不加缓蚀剂的体系中测得的电化学曲线好。六次甲基四胺、氟化铵、氟化氢铵效果最好时,质量分数分别为1%、1.5%、2%。不同种类缓蚀剂均可以有效抑制镁合金的腐蚀,减小腐蚀电流。加入缓蚀剂的化学镀镍配方沉积和镀覆效果明显,镀层电化学性能也有很大的提升。结论六次甲基四胺(Hexamethylenetetramine)、氟化胺(NH_4F)、氟化氢铵(NH_4HF_2)缓蚀剂的使用可以有效抑制镁合金的腐蚀,提高化学镀镍层的质量。     

Corrosion behavior of Ni-Cr-base commercial alloys in flowing Ar-42.6%O2-14.7%Br2 gas mixture at 700°C

Corrosion behavior of Ni-Cr-Base commercial alloys has been investigated in an argon-42.6% oxygen-14.7% bromine gas mixture at 700°C which was one of the environments encountered in the UT -3 thermochemical water decomposition reaction process to produce hydrogen. The test alloys were Inconel 600, Hastelloy C-276, Inconel 625, and Nimonic 80A. Two-dimensional thermodynamic phase stability diagrams were constructed for nickel, chromium, iron, tungsten, cobalt, titanium, and aluminium to predict the condensed corrosion products that are stable with respect to the representative alloying elements when the alloy is exposed to the argon-42.6% oxygen-14.7% bromine gas mixture at 700°C. The oxides were thermodynamically stable phases with respect to the corresponding metals. Post-reaction treatment of test alloys included discontinuous mass-change measurements, scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) for morphological and compositional investigation of the corrosion products, and the X-ray diffraction (XRD) for phase identification. XRD identified oxides and spinels as corrosion products but low-melting metal bromides were also detected for all alloys with deleterious effects on high-temperature properties of these alloys during exposure to the environment. The poor corrosion resistance of Inconel 600 and Hastelloy C-276 was mainly caused by the cracking and spalling of iron and nickel-rich oxides and further growth of various metal bromides beneath the oxide scale following prolonged exposure. Inconel 625 and Nimonic 80A alloys performed better than Inconel 600 and Hastelloy C-276, mainly because of their aluminium alloying element and lower iron content.     

Surface treatment of NiTi shape memory alloy and its influence on corrosion behavior

Influence of various surface treatments of a NiTi alloy on its surface chemistry and corrosion resistance was studied. NiTi (50.9 at.% Ni) alloy was subjected to mechanical polishing (MP), chemical etching (CHE) in an acidic bath, combination of mechanical polishing and oxidation at 530 °C/10 min in air (MPO) and combination of chemical etching and oxidation at 530 °C/10 min in air (CHEO). Scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectrometry were used for the surface examination. Corrosion behavior was determined by measuring potentiodynamic curves and nickel release into a model physiological solution with pH = 2. It was shown that oxidation at 530 °C has a slightly retarding effect on the nickel release in the case of MP material. However, in the case of CHE material, oxidation negatively influences corrosion, i.e. it strongly accelerates the nickel release, despite that it produces a relatively thick Ni-depleted oxide layer. Chemical etching was evidenced to produce the best corrosion performance in terms of nickel release. By comparing the MP and MPO sample, it was evidenced that oxidation significantly enhances susceptibility to the pitting corrosion. The findings obtained in our work were discussed in relation to variations in the surface chemistry and structure after different treatments.