实海暴露黄铜脱锌腐蚀行为及抑制脱锌机理研究

采用金相－扫描电子显微镜和电子探讨Ｘ射线能谱成分分析方法研究了黄铅实海暴露脱锌腐蚀特征及抑制机理。通过对长期实海暴露试样的腐蚀产物和合金基体进行成分分析及形貌观察,研究表明加Ａｓ的Ｈ６８Ａ黄铜晶界优先发生脱锌腐蚀,而加Ｓｎ后,由于-了晶界,　大大提高了单相α黄铜(HSn70-1A)的耐蚀性能.而对双相HSn70-1A黄铜,添加Sn,可在一定程度上抑制脱锌,但并不足以阻止腐蚀沿β相之间的α相晶界的连通.     

用放射性示踪技术研究黄铜应力腐蚀过程的脱锌

用测试~(64)Cu和~(65)Zn同位素γ射线的放射性示踪技术研究了在慢应变速率动态拉伸条件下70/30黄铜在室温1M NaNO_2溶液中,-0.1V(SCE)下的应力腐蚀开裂(SCC)和脱锌行为。结果说明,包含铜在内的局部阳极溶解是该体系SCC的根本原因,而大量的脱锌则加剧了开裂敏感性。在应力达到最高拉伸应力(σ_(UTS))之前的裂纹稳态扩展阶段,脱锌系数最大,此阶段之后由于铜的溶解比例增大,脱锌系数相对较低。在稳态扩展阶段,裂纹尖端导致最大脱锌系数的应变速率估计约为初始应变速率的4倍左右。按择优溶解的体扩散模型算得SCC过程中锌的扩散系数可达10~(-11)cm~2/s数量级以上。文中还讨论了黄铜在亚硝酸盐溶液中SCC过程的脱锌机理。     

黄铜脱锌腐蚀的研究进展

综述了黄铜脱锌腐蚀的优先溶解和溶解-再沉积机制、双空位机制和渗流模型,介绍了抑制黄铜脱锌腐蚀的方法以及微量砷、硼元素对抑制黄铜脱锌腐蚀的作用。重点叙述了微量稀土元素在抑制黄铜脱锌腐蚀中的作用机理和其具有的发展前景。     

砷抑制黄铜脱锌的机理研究

采用浸泡法、电化学和表面分析技术研究了砷对 H62和 H68黄铜脱锌的抑制作用。合金元素砷对两种黄铜有抑制作用.脱锌深厦 D 与含砷量 C 有如下经验关系:D=D/(I BC~n)。电镀砷抑制效果不如合金砷,溶液中砷离子对脱锌无影响。XPS 确定含砷黄铜腐蚀产物膜组成为 CuCl。合金砷的作用可能是改变阴伋反应过电位,有利于黄铜表面生成 CuCl 保护膜。     

氢促进黄铜应力腐蚀及升高脱锌层应力的一致性

黄铜在氨水中腐蚀或应力腐蚀时表面形成脱锌层，它会产生一个会加拉应力，用挠度法和和流和差值法测量了不同氢浓度试样的脱锌层所引起的附加应力，也研究了不同氢浓度试样在氨水中的应力腐蚀敏感性，慢应变速率拉伸表明，黄铜不显示氢脆，但在氨水中显示极高的应力腐蚀敏感性（ISCC），它随试样中氢浓度（C0）升高而升高，脱锌层拉应力σp也随试样中氢浓度的升高而升高，实验表明，应力腐蚀敏感性随氢浓度的变化和脱锌层拉应力随氢浓度的变化相一致。     

热处理工艺对无铅黄铜腐蚀行为的影响

通过向Cu-Zn二元合金中添加高锌当量的铝、镁、硅元素,采用普通铸造法制备了以β相为基体的无铅黄铜,并对其进行670℃×3h固溶,油淬后进行270℃×2h时效,考察了所制备合金在热处理前后的腐蚀行为。结果表明,热处理态的无铅黄铜腐蚀电流密度与脱锌腐蚀速率减小,24h后的脱锌腐蚀层厚度仅为118μm,耐腐蚀性能良好。     

黄铜脱锌体扩散机制研究

应用电化学和表面分析技术研究了砷对H_(62)与H_(68)黄铜脱锌效应研究。脱锌深度(D)与含砷量(C)服从下列关系式:D=D_0/ (1_B·C~n)。用正电子湮没技术测得了τ_2值且与双空位(τ_(2))值相符。脱锌后τ_2的相对强度变化量△I_2与平均寿命变化量△τ_m包含着脱锌深度D的信息。这就为锌在优先溶解过程中双空位体扩散机制提供了直接证据。     

铋含量对黄铜脱锌腐蚀性能的影响

采用显微组织分析和脱锌腐蚀实验方法,研究了不同铋含量对黄铜的微观组织以及黄铜脱锌腐蚀性能的影响.结果表明,铋在铸态黄铜中为单质相,不固溶于基体中,主要以薄膜状存在于晶界上.在黄铜中加入铋可以明显改善黄铜的脱锌腐蚀性能,并且随着Bi含量的增加,黄铜的耐脱锌腐蚀性能增加.     

黄铜静态腐蚀脱Zn层引起拉应力的研究

研究了黄铜在静态腐蚀表面疏松层的应力状态,通过测量自由端挠度的变化及用ＳＥＭ技术测量脱Ｚｎ层的厚度,计算了在脱Ｚｎ层和基体界面处生产的拉应力,其稳定值约等于黄铜屈服强度的１／５,在ＳＣＣ过程中这个附加的拉应力将协助外应力促进位错发射和运动,从而ＳＣＣ裂纹形核。     

α黄铜选择性溶解的研究

采用恒电流E-t曲线与旋转盘环电极方法研究了α黄铜(Cu32Zn)在酸性Na2SO4和HNO3稀溶液中的阳极溶解行为,得到的典型E-t曲线上存在几个特征区,证明在较低电流密度条件下的初始阶段只存在Zn的选择性溶解。用恒电位法研究了Cu32Zn选择性溶解过程,得到了按抛物线衰减的暂态扩散曲线,由i-t-1/2直线关系求得了不同介质中Cu32Zn中Zn的固相扩散系数D在10-16～10-13cm2·s-1数量级,发现中性介质中测出的D值比酸性介质中要大两个数量级。     

Study of dezincification corrosion behavior of brass exposed to seawater and its inhibition mechanism

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Hydrogen-increased dezincification layer-induced stress and susceptibility to stress corrosion cracking of brass

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氢对黄铜脱锌层引起拉应力的影响

黄铜表面在氨水中腐蚀或应力腐蚀时形成脱锌层 ,由此产生一个附加拉应力。实验结果表明 ,脱锌层拉应力σp 随黄铜试样中氢含量w(H)的升高而线性升高 ,即σp/MPa =13.2 5 .2× 10 -6w(H)。黄铜中的氢含量达到 3× 10 -6时 ,可使黄铜在氨水中的应力腐蚀敏感性升高 10 %。氢促进黄铜应力腐蚀的原因是氢含量的增大会引起脱锌层拉应力的增大。     

The stress-assisted dezincification of 70/30 brass in ammonia

Zinc and copper losses from 70/30 brass specimens tensile loaded to various stress levels and exposed to 10 N NH₄OH were estimated at different time intervals by atomic absorption spectroscopic analysis of the corrodent. Dissolution of each element was found to be accelerated with increasing tensile stresses. The preferential dissolution of Zn was also found to increase with stress and a maximum in the dezincification occurred at about 105 MPa. Corrosion of the brass as a whole, however, increased monotonically with stress. Applied stresses altered the open circuit potential of the brass by a maximum of ±10⁻¹ mV MPa-1, and its potentiostatic polarization curve was shifted to higher current densities. The depth of dezincification for short intervals calculated from the present results showed that dezincification could be a viable mechanism for transgranular stress corrosion cracking of brasses.     

The inhibitive action of some azoles towards the corrosion and dezincification of 70Cu---30Zn brass in ammonia solution

An attempt has been made to study the effect of some azoles on the corrosion and dezincification of 70Cu---30Zn brass in ammoniacal solution using weight loss, solution analysis and potentiostatic polarization techniques. The inhibition efficiency of azoles for the corrosion and the dezincification of 70Cu---30Zn brass has been found to decrease in the order benzimidazole > 2-mercaptobenzothiazole > benzotriazole. Benzimidazole has been found to give almost complete protection against corrosion as well as dezincification of 70Cu---30Zn brass in ammoniacal solution. Potentiostatic polarization studies have shown that all the compounds inhibit both cathodic as well as anodic reactions, indicating a mixed type of inhibition.     

Diffusion mechanism of dezincification in double-phase brass exposed to seawater

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冷变形及退火温度对无铅铋黄铜耐蚀性能的影响

采用脱锌腐蚀深度测量方法,光学显微镜分析和SEM等分析方法,研究了不同的冷变形量和退火温度对无铅易切削铋黄铜的耐脱锌腐蚀性能的影响.结果表明,该铋黄铜经过冷变形以后(15%～36%),由于β相沿着冷加工方向分布,同时位错密度和残余应力的增加,导致了其耐脱锌深度增加,并且冷变形程度越大,其脱锌腐蚀性能越差.退火处理可以改善冷拉铋黄铜的腐蚀性能,在250℃退火后,其具有较好的耐脱锌腐蚀性能.     

Investigation of corrosion behavior of silver coated brass in acidic solutions

The corrosion behavior of uncoated brass and electrolytically silver coated brass in cyanide solutions such as 0.1 M HCl, 0.1 M H₂SO₄ and 0.1 M H₃PO₄ was investigated by Tafel polarization curves and cyclic voltammetry curves at 1., 24., 48., 72., 96. and 168. hours. The coating efficiency was calculated by current density of corrosion determined from Tafel polarization curves. Surface analysis of coated brass immersed into acidic solution by 168 hours was done. It is concluded that silver coating is very effective to protect the corrosion of brass for a long time.     

海军黄铜HSn62-1的长期大气腐蚀行为

通过在3种典型大气环境中进行为期20年的现场暴露试验,研究海军黄铜HSn62-1的腐蚀质量损失和力学性能损失,采用扫描电子显微镜和XRD观察和分析腐蚀外貌、横截面和腐蚀产物。结果表明:HSn62-1的长期大气腐蚀质量损失随暴露时间的关系遵循C=KT n,腐蚀质量损失在工业酸雨大气环境中最大,在海洋大气环境中最小;腐蚀速率在工业酸雨和海洋大气环境中随时间逐渐降低,而在半乡村大气中逐渐升高;暴露20年后,HSn62-1的力学性能损失在工业酸雨大气环境中最大,在半乡村环境中最小;HSn62-1在3种典型大气环境中均发生脱锌腐蚀,腐蚀产物主要为Cu2O和ZnO。     

稀土铝黄铜在NaCl溶液中腐蚀行为的研究

设计了一种无砷的HAl77-2-Re耐腐蚀铝黄铜.利用失重法、电化学测试、X射线衍射分析、扫描电镜与能谱分析等手段研究了这种稀土铝黄铜在NaCl(3.5%)溶液中的耐腐蚀性能及其腐蚀行为.结果表明:在稀土铝黄铜的腐蚀过程中,稀土参与了表面腐蚀产物膜的形成,增大了极化电阻,抑制了腐蚀的进行,提高了合金的耐腐蚀性能;与含砷铝黄铜相比,表现出了较好的耐腐蚀性能.