【作者】 张华；

【导师】 许茜；

【作者基本信息】 东北大学 ， 化学工艺， 2014， 硕士

【摘要】 电镀铬在电镀工业中有着非常重要的地位。镀液中的铬酐以及铁铜离子含量直接影响到镀层的品质,因此快速、准确、简单、低成本的分析出镀铬液铬酐及铁铜离子的含量,对于镀铬工艺的发展有着十分重要意义。现存的分析方法有选择性差、灵敏度低、费用昂贵和离线取样等缺点,本文针对以上缺点,使用电化学方法研究普通镀铬液铬酐以及铁、铜离子浓度。利用线性扫描伏安法对普通镀铬液中铬酐含量进行了分析,通过电化学方法分别对高低浓度铁、铜含量进行了研究；同时研究了阳离子交换膜对Cu2+、Fe3+选择透过性,为同步分析Cr2O72与Fe3+和Cu2+提供相关技术支撑。本文主要研究结果如下：(1)通过对Cr03的标准镀液进行线性伏安扫描,确定Cr2O72-/7Cr3+氧化还原电对的还原峰电位在0.5V附近,且氧化还原过程为不可逆过程。在Cr03含量为2.5g·L-1-20g·L-1的范围内,Cr2O72-/Cr3+还原峰电流ip与Cr03浓度呈很好的线性关系。使用此种方法,分析某工厂镀铬液,所得结果与标准进行比较,误差在5%以内,能够满足工艺的要求。从而能够在含有高浓度铬酐低浓度铁铜离子的镀铬液中,快速、准确的分析铬酐含量,为实现在线监测提供了有效的方法。(2)分别对CuSO4和Fe2(SO4)3标准溶液进行线性伏安扫描及循环伏安测试,得出了：Cu2+/Cu电对还原峰电位在-O.1V附近,Fe3+/Fe2+电对的还原峰电位在0.33V附近,且氧化还原过程均为不可逆过程。通过线性伏安扫描,得出了：0.156-0.625g·L-1CuSO4的含量范围内,Cu2+/Cu还原峰电流ip与CuSO4浓度呈很好的线性关系；0.625-10.Og·L-1Fe2(SO4)3的含量范围内,Fe3+/Fe2+还原峰电流ip与Fe2(SO4)3浓度呈很好的线性关系。通过电位分析法,得到了：0.625-5.00g·L-1CuSO4的含量范围内,开路电压E与lg[Cu2+]呈很好的线性关系。并通过方波伏安分别测试2.5μM-12.5μM的范围内低浓度Cu2+离子浓度和2.0μM-10.0μM的范围内低浓度Fe3+离子浓度,同样得出了ip与Cu2+浓度以及ip与Fe3+浓度呈很好的线性关系。以上研究为测量CuSO4溶液和Fe2(SO4)3溶液中Cu2+含量和Fe3+含量提供了理论和实验依据。(3)对离子交换3h后的阳离子交换膜截面进行SEM测试,得出阳离子交换膜对Cu2+有选择性透过。CuSO4溶液和H2SO4补偿溶液进行离子交换,对H2SO4补偿溶液进行方波伏安扫描,随着离子交换时间的增加,CuSO4溶液浓度的增加,Cu2+/Cu电对的还原峰电流增大。得到Cu2+/Cu电对还原峰电流ip与CuSO4浓度以及离子交换时间的对应关系。同样,Fe2(SO4)3溶液和H2S04补偿溶液进行离子交换,对H2SO4补偿溶液进行方波伏安扫描,随着离子交换时间的增加,Fe2(SO4)3浓度的增加,Fe3+/Fe2+电对的还原峰电流增大。得到了Fe3+/Fe2+电对还原峰电流ip与Fe2(SO4)3浓度以及离子交换时间的对应关系。实验得出阳离子交换膜对于Cu2+和Fe3+均有一定的选择透过性,作为在线分析选择离子交换时间为lh。为Cr2O72-与Fe3+和Cu2+分离,消除Cr2072-对铜铁电化学信号的影响,实现在线测量镀铬液中Fe3+和Cu2+提供了理论基础和技术支撑。更多还原

【Abstract】 Chromium plating has a very important position in the electroplating industry. The concentration of chromic anhydride, iron and copper directly affects the quality of the coating. It is very important in development of the chrome plating process in order to analyse the concentration of chromic anhydride, iron and copper with a quick, accuract, easy and lowcost method. The existing analysis methods have the disadvantages of bad selectivity, low sensitivity and high cost. To solve these problems, this paper uses electrochemical methods. The concentration of chromic anhydride, iron and copper was studied by electrochemical methods. The analysis and research were based on the concentration of chromic anhydride in common chrome plating solution by linear sweep voltammetry, and studied the high and low concentrations of ion and copper. In addition, the permselectivity of cation-exchange membrane to Cu2+and Fe3+was studied. It provides technology supports for simultaneous analysing of chromic anhydride, iron and copper. The main results are summarized as follows;The linear sweep voltammetry method was chosen to study the chrome plating solution. We can find that the reducing peak potential is about0.5V. And the redox system is irreversible. The reductive peak currents were linear with concentrations of chromic anhydride in the range of2.5to20g·L-1. Analyzing a factory chrome plating solution, the error is within5%. The results meet the technical requirements. So we can quickly and exactly analyze the concentration of chromic anhydride from the chrome plating solution within high chromic anhydride and low ion and copper. This study provides an effective method for on-line monitoring.Linear sweep voltammetry and cyclic voltammetry were chosen to study the CuSO4and Fe2(SO4)3solution. We can find that the reducing peak potentials of Cu2+and Fe3+are about-0.1V and0.33V. The redox systems both Cu2+and Fe3+are irreversible. The reductive peak currents of Cu2+were linear with concentrations of CuSO4in the range of0.156to0.625g·L-1. In addition, the reductive peak currents of Fe3+were linear with concentrations of Fe(SO4)3in the range of0.625to5.00g·L-1. Potentiometric analysis is chosen to study the CuSO4solution. Open circuit voltage E and lg[Cu2+] had a good linear relationship. Square wave voltammetry is chosen to study the CuSO4and Fe2(SO4)3solution. The reductive peak currents of Cu2+were linear with concentrations of Cu2+in the range of2.5to12.5μM. And the reductive peak currents of Fe3+were linear with concentrations of Fe3+in the range of2.0to10.0μM. The research provides some references for the determination of Cu2+and Fe3+in the unknown concentration of CuSO4and Fe2(SO4)3solution.Through SEM of ion exchange cation membrane section after exchange3h, we find Cation exchange membrane has certain permeability to Cu2+. CuSO4solution and H2SO4compensation solution for ion exchange. Square wave voltammetry was chosen to study the H2SO4compensation solution. With the increase of ion exchange time and concentration of CuSO4solution, the reductive peak currents of Cu2+increase. The reductive peak current, concentration of CuSO4and ion exchange time have a corresponding relation. Similarly, Fe2(SO4)3solution and H2SO4compensation solution for ion exchange. With the increase of ion exchange time and concentration of Fe2(SO4)3solution, the reductive peak currents of Fe3+increased. The reductive peak current, concentration of Fe2(SO4)3and ion exchange time have a corresponding relation. The experiment concluded that the cation exchange membrane has a certain permselectivity for Cu2+and Fe3+. Selecting ion exchange time for1h as on-line analysis. This study provides a theoretical basis for analyzing Fe3+and Cu2+in the chrome plating solution by online monitoring.更多还原