(1. 中南大學(xué) 有色金屬材料科學(xué)與工程教育部重點實驗室，長沙 410083；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 利用循環(huán)伏安和計時安培研究Sn-Cu合金體系在玻碳電極上的電沉積行為，通過陰極極化曲線、SEM觀察及EDS分析討論檸檬酸和硫脲對Sn-Cu共沉積的影響。結(jié)果表明，Sn-Cu共沉積過程為擴散控制的不可逆過程；在沉積電位−600~−750 mV的范圍內(nèi)Sn-Cu共沉積初期結(jié)晶行為滿足三維Scharifker-Hills瞬時成核模型，隨著過電位的增大，形核活性點增多，形核弛豫時間縮短；當(dāng)沉積過電位大于−700 mV時，Sn2+的擴散系數(shù)約為 6.435×10−6cm2/s；檸檬酸和硫脲的加入細化了鍍層晶粒，使鍍層表面更加平整和致密。此外，硫脲的加入降低了鍍層中銅的含量，使合金鍍層中銅的含量維持在0.5%~2.0%(質(zhì)量分?jǐn)?shù))。
關(guān)鍵字: Sn-Cu合金；形核；循環(huán)伏安；電沉積；
additives on deposition process
（1. Educational Key Laboratory of Non-ferrous Metal Materials Science and Engineering,
Central South University, Changsha 410083, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The electrodeposition of Sn-Cu alloy system on the glass carbon electrode was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The effect of citric acid and thiourea additives on Sn-Cu alloy codeposition was discussed by cathodic polarization curve, SEM observation and EDS analysis. The results indicate that the electrodeposition process of Sn-Cu is an irreversible process controlled by diffusion, and the codeposition of Sn-Cu alloy system in the initial stage follows Scharifker-Hills (SH) instantaneous nucleation/growth mechanism in the potential range of −600− −750 mV. With increasing the overpotential, the activity-point for nucleation increases, and the nucleation relaxation time reduces. When the deposition overpotential is higher than −700 mV, the diffusion coefficient of Sn2 + is 6.435×10−6cm2/s. The addition of citric acid and thiourea refines grains in coating and the surface of coating becomes more even and compact. The presence of thiourea reduces clearly the copper content in coating and makes the copper content remain in the range of 0.5%−2.0%(mass fraction).
Key words: Sn-Cu alloy; nucleation; cyclic voltammetry; electrodeposition
