Zn—Co合金镀层耐蚀性研究

通过ＮＳＳ试验、ＳＯ２气体腐蚀试验以及ψｔｏｒｒ－ｔ、Ｒｐ－ｔ曲线及循环伏安曲线的测定，对Ｚｎ－Ｃｏ合金镀层耐蚀性进行了研究，并解释了该镀层的耐蚀原因。     

Zn－Co合金镀层耐蚀性研究

通过ＮＳＳ试验、ＳＯ_２气体腐蚀试验以及－ｔ、Ｒｐ－ｔ曲线及循环伏安曲线的测定，对Ｚｎ－Ｃｏ合金镀层耐蚀性进行了研究，并解释了该镀层的耐蚀原因。     

电沉积Fe-Co-Ni三元合金的工艺研究

Fe-Co-Ni合金镀层的硬度、耐蚀性和表面光亮度接近硬铬镀层,一定程度上可代替铬镀层以减少环境污染.用恒电位法电沉积Fe-Co-Ni三元合金,并运用X射线衍射能谱、扫描电镜等方法观察镀层的形貌,同时对镀层的失重率、显微硬度也进行了测定,分析了有机添加剂、温度、pH值和阴极控制电位等工艺因素对电沉积的影响.结果表明:在一定量的有机添加剂下,若镀液温度为50～60℃,pH值为3.0～4.5,阴极电位控制在-1.2 V(vs SCE)时,即能得到光亮、耐腐蚀性好、显微硬度高的Fe-Co-Ni三元合金镀层,其综合性能接近硬铬镀层.     

镍磷合金电镀层耐蚀性的研究

用电化学和电子能谱方法研究了镍磷合金电镀层的耐蚀性。结果表明镍磷合金电镀层耐蚀性较纯镀镍层高５～１０倍。在实验条件下未发现镍的选择性溶解和磷的表面富集。     

锌钴合金镀层结构与耐蚀性研究

通过Ｘ射线衍射和Ｘ光电子能谱对钴的质量分数为０．００６￣０．００８的Ｚｎ－Ｃｏ合金镀层的组成、结构及腐蚀产物进行了分析，并与锌镀层进行比较，指出在Ｚｎ－Ｃｏ合金镀层中，钴使腐蚀产物致密稳定，并在腐蚀过程中形成富钴层，抑制了腐蚀过程。     

二元固溶体型合金凝固过程中固相分数的变化规律

本文首先总结了前人在固相分数计算方面的研究工作。通过对几个主要影响因素的分析,指出了以前所用计算式的适用范围。进而通过对作者最近提出的局部溶质再分配方程修正式的求解,得出了板状技晶和柱状枝晶两种生长形态下适用范围更广的计算式。最后以Al—4.5％Cu合金枝晶生长过程为例,对各式的计算结果进行了对比讨论。并估算了非平衡共晶和θ相的析出量。     

镍钴合金镀层的电沉积及其耐蚀性的研究

研究了Ｎｉ－Ｃｏ合金的电积过程，讨论了电镀工艺条件的改变对合金镀层钴含量的影响。实验结果表明，选择适当的阴极电流密度、电解液温度和镀液ＰＨ值等，可以获得表面光洁、平整和致密的耐蚀性能比镍镀层更好的合金镀层。     

钒对Zn-Fe合金镀层耐蚀性的影响

在电镀液中加入钒盐,在A3钢表面电镀出Zn-Fe合金薄膜.采用稳态法和循环伏安法研究了Zn-Fe合金镀层在30℃下0.5 mol/L H2SO4溶液中的腐蚀行为,采用扫描电镜(SEM)和X射线衍射(XRD)分析了钒对镀层在腐蚀前后微观结构的影响,用交流阻抗法研究了钒对电极等效电路的影响.结果表明,加入钒盐能改变Zn-Fe合金镀层的晶面择优取向和织构系数,当钒盐加入量为0.50～0.75 g/L时,镀层变得均匀、致密,镀层的致钝电流密度Jpp和维钝电流密度Jp明显降低,极化电阻增大,在强酸性溶液中的耐蚀性能明显增强.     

非晶态Cr-C合金镀层与晶态Cr镀层的耐蚀性比较

用电化学方法对同积法制备的非晶态Ｃｒ镀层在几种常见腐蚀介质中的耐蚀性进行了测定。结果表明,非晶态Ｃｒ－Ｃ合金镀层的耐蚀性均明显优于晶态Ｃｒ镀层,文化馆速率约为晶态Ｃｒ镀层的０．５％～２．５％,通过对镀层孔隙率和表面形貌的研究表明,非晶态Ｃｒ－Ｃ合金镀层表面细致、均匀、无微裂纹,抑制了腐蚀微电池的形成,耐蚀性明显提高。     

Electron field emission properties of electro-deposited diamond-like carbon coatings

Field emission studies were carried out on diamond-like carbon films deposited by an electro-deposition technique onto SnO₂-coated glass substrates. A mixture of acetic acid and water was the electrolyte. The films are compact with surface roughness 10 nm. Work function (φ) values obtained from the Fowler–Nordheim model varied between 15 and 214 meV, while the field factor (β) varied between 4 and 700. The critical field was found to vary between 2 and 28 V/μm.     

Corrosion behaviour of hot dip zinc and zinc-aluminium coatings on steel in seawater

A comparative investigation of hot dip Zn-25Al alloy, Zn-55Al-Si and Zn coatings on steel was performed with attention to their corrosion performance in seawater. The results of 2-year exposure testing of these at Zhoushan test site are reported here. In tidal and immersion environments, Zn-25Al alloy coating is several times more durable than zinc coating of double thickness. At long exposure times, corrosion rate for the Zn-25Al alloy coating remains indistinguishable from that for the Zn-55Al-Si coating of similar thickness in tidal zone, and is two to three times lower than the latter in immersion zone. The decrease in tensile strength suggested that galvanized and Zn-55Al-Si coated steel suffer intense pitting corrosion in immersion zone. The electrochemical tests showed that all these coatings provide cathodic protection to the substrate metal; the galvanic potentials are equal to −1,050, −1,025 and −880 mV (SCE) for zinc, Zn-25Al alloy and Zn-55Al-Si coating, respectively, which are adequate to keep the steel inside the immunity region. It is believed that the superior performance of the Zn-25Al alloy coating is due to its optimal combination of the uniform corrosion resistance and pitting corrosion resistance. The inferior corrosion performance by comparison of the Zn coating mainly results from its larger dissolution rate, while the failure of the Zn-55Al-Si coating is probably related to its higher susceptibility to pitting corrosion in seawater.     

WC-10Co-4Cr涂层在不同温度酸与NaCl溶液中的耐腐蚀性能

为提高1Cr18Ni9Ti不锈钢在NaCl和酸溶液环境中的耐磨损性能,利用等离子喷涂制备两种晶粒WC-10Co-4Cr涂层,研究其在3.5%(质量分数,下同)NaCl溶液与酸溶液(pH=5.0)中的耐腐蚀性能。结果表明:涂层中含有WC,W_2C,W以及η相(Co_xW_xC)。两种涂层在3.5%NaCl溶液中的腐蚀电位均高于1Cr18Ni9Ti基体的腐蚀电位。在不同温度酸溶液(pH=5.0)中,纳米WC-10Co-4Cr涂层的电位差随温度的变化最小。涂层在NaCl和酸溶液中腐蚀机制分别为:WC-10Co-4Cr涂层表面吸附氧粒子与涂层中的Co和WC在3.5%NaCl溶液中形成电偶;在酸溶液中(pH=5.0),涂层中的Co溶解形成Co²⁺离子,和WC相直接形成电偶腐蚀,导致涂层表面出现孤立的WC颗粒。     

新型Cu-Cr-Ni系耐海水腐蚀钢耐蚀性能及机理EI北大核心

针对海洋环境腐蚀特点,通过添加合金元素Cu,Cr和Ni开发一种新型船体用耐蚀钢(B-NS)。利用电化学实验、全浸实验和周浸实验对B-NS的耐蚀性能进行评估,同时通过扫描电镜和能谱对锈层截面形貌和成分进行分析。结果表明:合金元素的添加可有效降低B-NS钢的饱和电流密度和全浸以及周浸条件下的腐蚀速率,同时促进周浸条件下更加稳定、致密保护性锈层的生成。合金元素赋予B-NS钢优异耐腐蚀性能,主要表现在提高B-NS钢热力学稳定性,促进锈层生成以阻挡侵蚀性介质腐蚀基底和赋予锈层阳离子选择性,阻止Cl-渗透进锈层。     

Corrosion resistance of MA5 magnesium alloy with electric-arc coatings

We study the possibilities of increasing the corrosion resistance of MA5 magnesium alloy by applying aluminum electric-arc coatings from D16 and AMg6 solid wires, a mixture of wires of different kinds (D16 + AMg6), and a powder wire in an aluminum sheath with B₄ C + Ni Cr B Si mixture. The electrochemical characteristics of these coatings are studied in a 3% NaCl aqueous solution. It is shown that aluminum electric-arc coatings strongly increase the corrosion resistance of the alloy. The best characteristics are exhibited by the AMg6 coatings.     

Corrosion behavior of plasma sprayed ceramic and metallic coatings on carbon steel in simulated seawater

Al₂O₃, ZrO₂ and Ni60 coatings were produced on carbon steels by plasma spray. Ni60 was used as the bond coat in all the cases. The microstructure of these coatings was analyzed by scanning electron microscopy (SEM). The corrosion behavior of the plasma spray coated samples as well as uncoated samples was evaluated by open circuit potential (OCP) measurements, potentiodynamic polarization tests, and electrochemical impedance spectroscopy (EIS) in simulated seawater. The results showed that Ni60 coating protected carbon steels against the corrosion and plasma spraying ceramic powders on metallic coating improved the corrosion resistance of the coatings further. The corrosion resistance of the Al₂O₃ coating was superior to that of the ZrO₂ coating due to the relatively few defects in Al₂O₃ coating.     

Corrosion resistance of molybdenum coatings obtained by a contact melting method

The corrosion resistance and fatigue strength of molybdenum coatings obtained by a contact melting method on 1Cr18Ni9Ti steel and on EI 437B alloy were investigated. It was shown that the use of such a coating on EI 437B alloy quadruples its fatigue strength in liquid Pb-Bi eutectic.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 5, No. 6, pp. 704–708, November–December, 1969.     

Corrosion resistance of biodegradable polymeric layer-by-layer coatings on magnesium alloy AZ31

Biocompatible polyelectrolyte multilayers (PEMs) and polysiloxane hybrid coatings were prepared to improve the corrosion resistance of biodegradable Mg alloy AZ31. The PEMs, which contained alternating poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH), were first self-assembled on the surface of the AZ31 alloy substrate via electrostatic interactions, designated as (PAH/PSS)₅/AZ31. Then, the (PAH/PSS)₅/AZ31 samples were dipped into a methyltrimethoxysilane (MTMS) solution to fabricate the PMTMS films, designated as PMTMS/(PAH/PSS)₅/AZ31. The surface morphologies, microstructures and chemical compositions of the films were investigated by FE-SEM, FTIR, XRD and XPS. Potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution measurements demonstrated that the PMTMS/(PAH/PSS)₅/AZ31 composite film significantly enhanced the corrosion resistance of the AZ31 alloy in Hank’s balanced salt solution (HBSS). The PAH and PSS films effectively improved the deposition of Ca-P compounds including Ca₃(PO₄)₂ and hydroxyapatite (HA). Moreover, the corrosion mechanism of the composite coating was discussed. These coatings could be an alternative candidate coating for biodegradable Mg alloys.