The electrochemical behavior of brass in 0.1 M HCl solution

Abstract

Estudou-se a eletrodissolução de um latão comercial (60,9Pb) e do cobre em HCl 0,1 M usando a técnica de voltametria cíclica e eletrodo rotatório de disco e anel. O mecanismo de dissolução deste latão e do cobre apresentam diferentes parâmetros cinéticos. O mecanismo de dissolução do componente Cu da liga é análogo ao do cobre puro.The electrodissolution of com mer cial brass (60.8Cu-36.3Zn-2.9Pb) and pure cop per in 0.1 M HCl were com par a tively stud ied us ing cy clic voltammetry and a ro tat ing ring-disk electrode. The dis so lu tion mech a nism of both spec i mens pres ents dis tinct ki netic pa ram e ter s. How ever, the dis so lu tion mech a nism of the Cu com po nent of brass is the same as that ob serv ed for pure cop per. Key words: cop per dis so lu tion, ( α+β)-brass, ro tat ing ring-disk elec trode, voltammetry In tro duc tionThe an odic dis so lu tion of bi nary al loys in dif fer ent aque ous en vi ron ments has been in ves ti gated un der a wide range of ex per i men tal con di tions 1-6 mainly fol low ing a dispute be tween se lec tive and si mul ta neous dis so lu tion processes of the com po nents. In this work, the dis so lu tion of com mer cial brass (60.8Cu-36.3Zn-2.9Pb) in 0.1 M HCl was in ves ti gated. An un der stand ing of the al loy dis so lu tion mech a nism re quires knowl edge of such a pro cess for pure cop per. De spite the num ber of pub li ca tions on this subject 5-8 , the dis so lu tion of Cu-Zn al loys con tain ing Pb has not re ceived much at ten tion. The aim of this pa per is to obtain in for ma tion on the electrodissolution mech a nism of com mer cial brass in 0.1 M HCl, us ing cy clic voltammetry and a ro tat ing ring-disk elec trode. Ex per i men tal MethodA con ven tional three elec trode cell has been used. The elec tro chem i cal mea sure ments were made us ing a Cu disk (99.99% pure), and one of com mer cial brass (60.8Cu-36.3Zn-2.9Pb) with a 0.2 cm 2 ap par ent area as a work ing elec trode. Each elec trode was pol ished with emery pa per up to grade 600, and rinsed with al co hol and distilled wa ter. To de tect the for ma tion of sol u ble spe cies, dur ing the voltammetric sweep of the work ing elec trodes (Cu and brass) a ro tat ing ring-disk elec trode (RRDE) with a gold ring was used. The col lec tion ef fi ciency of the RRDE is N = 0.50 9 . For the de tec tion of the cuprous spe cies the ring po ten tial was fixed at 0.45 V vs. SCE, in which ox i dation to Cu(II) takes place. To de tect the Cu(II) spe cies, the ring po ten tial was set at -0.1 V vs. SCE. A sat u rated cal omel elec trode (SCE) was used as the ref er ence, and all poten tials were re ferred to this elec trode. A large area Pt wire, prop erly shielded, was used as the coun ter elec trode. The elec tro lyte so lu tions con sisted of 0.1 M HCl pre pared from an a lyt i cal grade re agents and twice dis tilled wa ter. Ex per iments were car ried out un der Ar gas sat u ra tion at 298 K. A bipotentiostat (EG&C, model 366) and a ro ta tor (EG&C, model 636) were em ployed for the mea sure ments. ...

Dissolution Behavior of Brass Polarized by Alternating Current in Sodium Phosphate Aqueous Solution

“…Corrosive [16][17] and electrochemical [18][19][20][21] properties of brass in aqueous solutions have been studied in a number of works. The electrochemical dissolution of brass was investigated by potentiodynamic polarization and cyclic voltammetry methods with and without the presence of Clions in NaHSO 3 solution.…”

“…The electrochemical properties and passivation of Cu-30Zn alloy in the alkaline medium have been considered, increasing the NaOH concentration on the potentiodynamic curves basis has led to an increase in corrosion current density [19]. In the following study, the electrodisolution brass (60.8Cu-36.3Zn-2.9Pb) and pure copper were comparatively studied in 0.1 M HCl using cyclic voltammetry and a rotating ring-disc electrode and similarity of dissolution mechanism of copper and pure copper in the brass composition was discovered [20]. The electrochemical properties of α, β ' -brass (CuZn 40 Pb 2 ) were investigated at different pH values in basic nitrate solutions.…”