【摘要】：金屬銅具有良好的導(dǎo)電性、導(dǎo)熱性和延展性,是防止?jié)B氮、滲碳的優(yōu)良鍍層,在電鍍中常作為金、銀、鎳等金屬的打底層或中間層。氰化物電鍍銅可以直接在鋼鐵、鋅合金表面進(jìn)行電鍍而不生成置換層,且得到的鍍層光亮、致密,但由于氰化物有劇毒,急需開(kāi)發(fā)出一種可以替代氰化物鍍銅的體系。本文通過(guò)對(duì)比不同的輔助配位劑,確定了以焦磷酸鉀為輔助配位劑,以DMH為主配位劑的復(fù)合配位無(wú)氰電鍍銅工藝。通過(guò)單因素實(shí)驗(yàn),研究了鍍液組分和工藝條件對(duì)鍍液穩(wěn)定性、陰極電流效率以及鍍層外觀、微觀形貌等的影響,確定了優(yōu)化的乙內(nèi)酰脲體系無(wú)氰電鍍銅工藝。實(shí)驗(yàn)結(jié)果表明,硫酸銅濃度、焦磷酸鉀濃度、溫度、攪拌強(qiáng)度等條件對(duì)鍍層的外觀及鍍液的陰極電流效率、工作電流密度上限的影響較大。優(yōu)化后的鍍液組成及工藝條件分別為:硫酸銅25g·L~(-1),DMH 100 g·L~(-1),焦磷酸鉀60 g·L~(-1),碳酸鉀30~90 g·L~(-1):p H 9~10,溫度50℃,攪拌速度600 rpm,陰極電流密度為1.5~4.0 A·dm-2。在此條件下,可以得到外觀平整、光亮、致密的銅鍍層。通過(guò)Hull槽實(shí)驗(yàn)篩選出了可用于本體系的添加劑,發(fā)現(xiàn)加入添加劑后鍍層的外觀得到改善,光亮電流密度范圍明顯變寬,但鍍液的陰極電流效率有所降低。實(shí)驗(yàn)證明,鍍液的穩(wěn)定性、分散能力、覆蓋能力優(yōu)異,陰極電流效率達(dá)到80%,電沉積速度達(dá)到32μm·h~(-1);鍍層與鋼鐵基體結(jié)合牢固,孔隙率較少。用SEM觀察發(fā)現(xiàn),鍍層晶粒細(xì)小,細(xì)致均勻。循環(huán)伏安曲線、陰極極化曲線等電化學(xué)研究表明,DMH與焦磷酸鉀復(fù)配體系中Cu~(2+)的電沉積過(guò)程為擴(kuò)散控制的不可逆過(guò)程,Cu~(2+)的陰極傳遞系數(shù)α為0.8548,在含有25 g·L~(-1)的Cu~(2+)的鍍液體系中,Cu~(2+)的擴(kuò)散系數(shù)為3.79×10-9 cm2·s~(-1)。焦磷酸鉀的加入增大了陰極極化,抑制了析氫反應(yīng)的發(fā)生,提高了陰極電流效率;但添加劑的加入使鍍液的陰極極化減小,這不符合電沉積的實(shí)際需求,需要再進(jìn)行深入探索。
[Abstract]:Metal copper has good electrical conductivity, thermal conductivity and ductility. It is an excellent coating to prevent nitriding and carburization. It is often used as the bottom layer or intermediate layer of gold, silver, nickel and other metals in electroplating. Copper electroplating with cyanide can be carried out directly on the surface of iron and steel and zinc alloy without the formation of replacement layer, and the coating is bright and dense. However, because cyanide is highly toxic, it is urgent to develop a system that can replace cyanide copper plating. In this paper, by comparing different auxiliary coordination agents, the process of complex coordination without cyanide electroplating with potassium pyrophosphate as auxiliary coordination agent and DMH as coordination agent was determined. The effects of bath composition and process conditions on bath stability, cathodic current efficiency, coating appearance and micromorphology were studied by single factor experiments. The optimized cyanide free copper plating process was determined. The results show that the influence of copper sulfate concentration, potassium pyrophosphate concentration, temperature and stirring intensity on the appearance of the coating, cathodic current efficiency and working current density upper limit of the plating solution are significant. The optimized bath composition and process conditions are as follows: copper sulfate 25g L ~ (-1), DMH 100g L ~ (-1), potassium pyrophosphate 60g L ~ (-1), potassium carbonate 3090 g L ~ (-1): p H 910, temperature 50 鈩，

本文編號(hào)：2311382