Fabrication, microstructure and corrosive behavior of different metallographic tin-leaded bronze alloys part II: Chemical corrosive behavior and patina of tin-leaded bronze alloys
2015; Elsevier BV; Volume: 169; Linguagem: Inglês
10.1016/j.matchemphys.2015.11.044
ISSN1879-3312
AutoresKhalida Kareem, Shahid Sultan, Lingfeng He,
Tópico(s)Corrosion Behavior and Inhibition
ResumoThis paper presents the chemical corrosion behavior and surface morphologies including cracks, pits and corrosive-depth of “patina” in the different metallographic Cu–Sn–Pb bronze alloys by the trace amounts of S2−, SO42−, NO3−, Cl− and CO32− aggressive environments. Typical patinas have been formed as brochantite patina (Cu4SO4·(OH)6) by SO42− solution with 46–144 μm corrosion depth, atacamite patina (Cu2(OH)3Cl) by Cl− solution through many subsequent “dissolution-ion pairing-precipitation” steps with 15–70 μm corrosion depth, gerhardite patina (Cu(NO3) (OH)3) by NO3- solution with 0.3 μm corroded layer, gerhardite or lead nitrate (Pb(NO3)2) or malachite (Cu2(OH)2CO3) patina by CO32−/NO3- solution as 390 μm depth of corrosive layer, atacamite Cu2Cl(OH)3 along with cuprite (Cu2O) and cessiterite (SnO2) patina with 11–390 μm multilayered corrosive crust by CO32−/Cl− solution, and a mixed black patina of brochantite, brendtite (SnS2), roxbyite (Cu7S4) by S2− solution with 34–256 μm corrosive depth. Among all environments, the deterioration rate is evaluated as order of S2− > CO32−/Cl− > Cl− > CO32−/NO3- > SO42− > NO3−. The minor bronze disease is observed in highly tin-contained alloys (>19%), while the amount of lead in alloy exhibits no specific role in corrosion. Based on these results, the phenomenological models of corrosion behavior due to an internal oxidation, ionic migration and de-alloying of “a protective barrier” are proposed.
Referência(s)