枝晶生長的影響
(1. 華中科技大學(xué) 化學(xué)與化工學(xué)院，武漢 430074；2. 華中科技大學(xué) 環(huán)境科學(xué)與工程學(xué)院，武漢 430074；
3. 湖北第二師范學(xué)院 化學(xué)與生命科學(xué)學(xué)院，武漢 430205)
摘 要: 采用動電位掃描和交流阻抗等方法研究Bi摻雜對Sn-3.0Ag-0.5Cu釬料在3.5% NaCl(質(zhì)量分?jǐn)?shù))溶液中電化學(xué)腐蝕性能及枝晶生長的影響；采用SEM和XRD技術(shù)分析其腐蝕形貌及成分。結(jié)果顯示：隨著Bi含量增加，腐蝕電流密度增大，但自腐蝕電位不呈規(guī)律性變化。阻抗譜顯示：摻雜前后阻抗譜特征相同，均可用兩個時間常數(shù)的等效電路模型表示，其擬合誤差＜5%。隨著Bi含量的增加，容抗弧半徑減小，電荷傳遞電阻和腐蝕產(chǎn)物膜電阻均減小，耐蝕性能降低。SEM像顯示，Bi摻雜對釬料在介質(zhì)中電化學(xué)遷移速度有減緩作用，因而對遷移所致的枝晶生長具有抑制作用。XRD譜顯示，枝晶主要成分為Sn和Cu6Sn5，同時伴有少量的Bi和Ag3Sn。
關(guān)鍵字: Sn-3.0Ag-0.5Cu釬料；Bi摻雜；腐蝕行為；枝晶生長；抑制作用
dendrite growth suppression of lead-free Sn-3.0Ag-0.5Cu solder
（1. School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology,
Wuhan 430074, China;
2. School of Environmental Science and Engineering, Huazhong University of Science and Technology,
Wuhan 430074, China;
3. School of Chemistry and Life Science, Hubei University of Education, Wuhan 430205, China）
Abstract:The effects of Bi doping on the electrochemical corrosion characteristics and dendrite growth behavior of lead- free Sn-3.0Ag-0.5Cu solder in 3.5% NaCl solution (mass fraction) were investigated by potentiodynamic polarization and AC impedance measurement. The surface morphologies and elemental compositions of various elements in the solder were determined by analyzing the corrosion product formed on the specimen using SEM and XRD techniques. The results show that the corrosion current density increases with increasing Bi content. However, the corrosion potential does not change regularly. All of impedances of Sn-Ag-Cu solder with and without Bi doping have the same characteristics, the equivalent circuit with two time constants can preferably fit the electrochemical impedance spectroscopy of Sn-Ag-Cu-xBi with error less than 5%, which shows that all electrochemical corrosion characteristics have similar regularities. The impedance arc radius decreases when the Bi content increases, which shows that anti-corrosion capacity decreases with increasing Bi content. The SEM results show that the dendrite growth due to electrochemical migration can be suppressed. XRD results show that the main contents on dendrite are Sn, Cu6Sn5, also tiny Bi and Ag3Sn.
Key words: Sn-3.0Ag-0.5Cu solder; Bi doping; corrosion behavior; dendrite growth; suppression action
