电沉积低开裂敏感性黄铜薄膜研究

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	电沉积低开裂敏感性黄铜薄膜研究
	关沂山
学位类型	博士
导师	彭晓
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	腐蚀科学与防护
关键词	黄铜铋非氰化物镀液电沉积开裂生长应力耐蚀堆垛层错 Brass Bi Non-cyanide Bath Electrodeposition Crack Growth Stress Corrosion Resistance Stacking Fault
其他摘要	" 黄铜(Cu-Zn)薄膜因具有与橡胶良好的粘附力和较好的力学性能，应用于轮胎中作为钢帘线和橡胶的过渡层。常用黄铜的制备工艺为“镀铜+镀锌+热扩散退火”的三步工艺。与此相比，如果实现黄铜的一步电沉积，不仅节能降耗，而且能大幅度提高生产效率。利用氰化物镀液可一步电沉积性能优异的黄铜薄膜。但由于氰化物的“毒性”，研究和开发对环境友好的非氰化物镀液引起广泛关注。作为替代氰化物镀液的酒石酸镀液可一步电沉积黄铜薄膜，但薄膜有很高的开裂敏感性。因此，研究黄铜薄膜开裂的原因和探索从酒石酸镀液中制备低开裂敏感性的黄铜薄膜十分必要。本工作利用生长应力原位测量技术研究了酒石酸镀液制备黄铜薄膜开裂的原因。在传统的酒石酸镀液中添加Bi2(SO4)3主盐，从中制备了新型含微量Bi的黄铜薄膜。采用X射线衍射(XRD)、扫描电镜/能谱分析(SEM/EDS)、透射电镜(TEM)、等离子体质谱(ICP)和原子力显微镜(AFM)对含与不含Bi的黄铜薄膜进行表征；并采用动电位极化曲线和电化学阻抗谱(EIS)研究了微量Bi对黄铜耐蚀性能的影响，获得如下主要结论： 1. 沉积工艺参数对薄膜成分影响较大：薄膜中Cu含量随电流密度的增加，沉积温度的降低和镀液中Cu2+浓度的降低而降低。与薄膜中Cu含量随工艺参数的变化规律相似，Bi含量也随电流密度的增加和镀液中Bi3+浓度的降低而降低。 2. 生长应力显著地影响了薄膜中裂纹形态的演化：初始的压应力抑制了薄膜在生长初期开裂。岛接触产生的张应力使裂纹萌生于薄膜表面，且易发生在相邻岛的边界处。持续增加的生长张应力使表面的裂纹随沉积时间延长而向薄膜内部扩展并形成“V”型裂纹。薄膜沉积后期“V”型裂纹向“0”型裂纹的转变是由生长张应力向压应力转变所导致。 3. Bi使黄铜薄膜的生长由张应力转变为压应力，从而抑制了薄膜生长过程中的开裂。Bi改变薄膜的生长应力状态的原因简述如下：首先，大原子半径的Bi固溶黄铜晶格增加了晶格的压应变；其次，Bi的沉积粗化黄铜晶粒可减小生长张应变；最后，Bi的沉积使薄膜以堆垛层错和微孪晶的方式释放生长张应力。 4. Bi不仅有效的减缓了黄铜的脱锌腐蚀，且抑制了黄铜薄膜在腐蚀过程中的开裂，并抑制了电偶腐蚀的发生。含Bi薄膜通过产生堆垛层错的方式降低生长张应变和Bi降低因脱锌腐蚀而产生的张应变被认为是抑制薄膜腐蚀过程中开裂的主要原因。另外，本工作还利用焦磷酸镀液制备了低开裂敏感性的堆垛层错黄铜薄膜。采用XRD、SEM/EDS和TEM对该黄铜薄膜进行表征发现：与酒石酸镀液制备的黄铜薄膜相比，其开裂敏感性显著降低。这可能是与下面两部分原因有关：首先，焦磷酸镀液制备的黄铜薄膜中的晶粒度较大，因而产生较小的生长张应变。其次，焦磷酸镀液中制备的黄铜薄膜可能以产生堆垛层错的方式进一步释放生长张应变。" ; " Brass (Cu-Zn) film has been used as the bridge layer between the steel wire and outer rubber in radial tires because it exhibits excellent adhesion property with rubber and good mechanical property. Conventional deposition process is a three-step method including electrodeposition Cu, electrodeposition Zn and subsequent annealing treatment. Compared with the method, one-step electrodeposition of brass films is a more efficient, time and energy saving method. Such brass films with excellent property have been developed using a cyanide bath. However, because of the toxicity of cyanide, application of the bath is highly limited. Hence, development of an environmentally-friend bath for one-step electrodeposition of brass film is of a great interest. Such a typical one is a tartrate bath. It can deposit brass film but unfortunately the film is highly cracking sensitive. Hence, it is essential to understand the reason why films deposited from tartrate bath has the crack propensity and explore methods to increase the crack-resistance of film. In the present thesis, the cracking mechanism of brass film deposited from tartrate bath has been investigated based on the in situ growth stress measurement. Moreover, Bi2(SO4)3 was added into the tatrate bath for electrodeposition high-quality Bi-containing brass. The films were investigated by X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive analysis (SEM/EDS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and inductively coupled plasma mass spectrometry (ICP). The Bi effect on the corrosion resistance of brass film was investigated by poteniodynamic polarization and electrochemical impendence spectroscopy (EIS). The main results are summarized as follows: 1. The brass film composition is significantly affected by the deposition parameters. Decreasing the applied current density, increasing the deposition temperature and increasing the Cu2+ ion in the bath are favorable to copper deposition. In the mean time, Bi content in the film is also decreased with increasing the current density and decreasing content of Bi3+ ion in the bath. 2. The crack pattern evolution of electrodeposited brass film is significantly affected by the growth stress evolution: The compressive stress inhibited cracks generation in the initial growth stage. Coalescence of crystallites or islands causes the growth stress evolution to the tensile state, which results in cracks nucleating at film surface along island boundaries and extending through thickness. As film further thickens, transforming of cracks from “V”-shaped to “0”-shaped is caused by the post-coalescence compressive stress generation. 3. Bi causes a transition of the growth stress level of brass film from tensile to compressive, preventing the crack generation during film growth. The Bi effect on the transition of the growth stress can be addressed as follows: First, incorporation of Bi with a relative larger atom radius compared to that of Cu and Zn increases the compressive strain in the α-brass lattice; Second, Bi co-deposition coarsens Cu-Zn grains, which favors the decrease of the tensile strain of the film; Third, Bi co-deposition promotes the formation of stacking faults and microtwin into brass film, by which the tensile strain would be released into some extent. 4. Bi decreases the dezincification rate of the brass film and prevents galvanic corrosion between the film and substrate wire, which occurs in the Bi-free brass film coated steel wire primarily due to through-thickness cracking during the corrosion process. A retardation of the accumulation of the film growth tensile stresses through promoting the formation of stacking faults and a decrease in the film dezincification rate are considered as the reasons why Bi prevents cracking during corrosion. In addition, a novel brass film embedded with high density of stacking faults was also co-electrodeposited from a pyrophosphate-based bath. The films were characterized by XRD, SEM/EDS and TEM. The film deposited from pyrophosphate-based bath has improved crack-resistance compared with that from tartrate bath. The main reasons are possibly related to a retardation of the accumulation of the film growth tensile stresses through coarsening the brass grain and generating stacking faults and microtwins in the brass film."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64494
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	关沂山. 电沉积低开裂敏感性黄铜薄膜研究[D]. 北京. 中国科学院金属研究所,2012.