Study of the influence of the trisodium nitrilotriacetic as a complexing agent on the copper, tin and zinc co-deposition, morphology, chemical composition and structure of electrodeposits

• Cu–Sn–Zn ternary alloy deposition from various composition of NTA bath was studied.
• Voltammetric studies show four cathodic processes independent of bath composition.
• EDS shows Cu–Sn–Zn co-deposition at electrodeposition potential − 1.60 V.
• SEM shows electrodeposits with irregular crystallites.
• XRD results show Cu–Sn–Zn ternary alloys were formed by mixing of different phases.

The electrodeposition of Cu–Sn–Zn ternary alloys on to AISI 1010 steel from an acid bath, pH 4.99, containing trisodium nitrilotriacetic (NTA) was investigated, with different proportions of the metal ions in the baths. The Cu–Sn–Zn voltammetric profile showed four cathodic regions, irrespective of bath composition. The first three regions were associated with the reduction of the Cu-NTA and Sn-NTA complexes, and in the last region with Cu-NTA, Sn-NTA and Zn-NTA complexes reduction, attributed through of the analysis of the voltammetric curves together with the energy-dispersive X-ray spectroscopy (EDS) results. EDS analysis showed that only in cathodic region c4 occurred the transition from Cu–Sn binary alloy to Cu–Sn–Zn ternary alloy, regardless of bath composition. In addition, Cu–Sn–Zn co-deposition, at Ed − 1.60 V (cathodic region c4), was normal regardless of bath composition. Analysis of the photomicrographs of Cu–Sn–Zn electrodeposits obtained at electrodeposition potential (Ed) –1.60 V, with electrodeposition charge density (qd) of 3.0Ccm− 2, from 0.20Cu2 +/0.050Sn2 +/0.050Zn2 + bath presented the highest grain size (0.77 μm) and from 0.15Cu2 +/0.075Sn2 +/0.075Zn2 + bath presented smaller grain size (0.27 μm), all formed by irregular crystallites. Adhesion test showed that the Cu–Sn–Zn electrodeposit obtained at Ed − 1.60 V, with qd 3.0Ccm− 2, from 0.10Cu2 +/0.10Sn2 +/0.10Zn2 + bath presented a good adherence to the 1010 steel substrate, being classified as Gr2. Laser scanning confocal microscopy (LSCM) showed that roughness increased from 1.48 μm to 2.98 μm when Cu2 + ions concentration in the electrodeposition baths decreased. X-ray diffraction pattern indicated that the Cu–Sn–Zn electrodeposits produced at Ed − 1.60 V with qd 3.0Ccm− 2, depending on bath composition, presented structure crystalline with a mixture of Sn, SnO, CuZn, Cu5Zn8, η-Cu6Sn5 and Cu20Sn6 phases, indicating the formation of Cu–Sn–Zn ternary alloy.