Characterization of Bronze Corrosion Products on Exposition to Sulphur Dioxide

Abstract

In the main frame of the research aimed to model the corrosion growth on bronze surface, the objective of the work here reported has been to characterize the corrosion products formed on laboratory samples of bronze alloy (Cu Sn12), during the early stage of exposure to moist air with sulfur dioxide. A cycling corrosion cabinet was used to control 200 ppm gas concentration, relative humidity (RH) and temperature, according to the DIN 50018 (Kesternich test).The method is designed to evaluate how well the surface resists to sulfur dioxide corrosion; the test cycle consists of 8 hours exposure to sulfur dioxide at 40°C temperature and 100% relative humidity, followed by 12 hours drying at room condition. Weight variation, Spectrophotometer, Scanning Electron Microscopy with X-ray microanalysis (SEM-EDS), X-ray Diffraction (XRD) analysis were carried out for the tarnish products characterization. Some of the compound identified were brochantite (Cu4(OH)6SO4), chalcanthite (CuSO4•5H2O) cuprite (Cu2O), cassiterite (SnO2) and ottemannite (Sn2O3).

A Mathematical model of copper corrosion

“…Otherwise, the chalcanthite formation was detected during the early stage of the corrosion processes and the intensity of its characteristic peaks decreases as a function of time. The same consideration can be made for the ottemannite formation, detected with SEM-EDS in localized micro-crack areas, which are rapidly covered by basic copper sulfates [7,8]. 4.2.…”

“…The calibration of the model has been made with reference to a precise experimental campaign, which is described in [7], where the main characteristics of the experimental setting are reported. Experiments were carried out in a cyclic corrosion cabinet (Erchisen Mod.…”

“…It is based on fluid dynamical and chemical relations and it is characterized by a double free boundary: one between copper and cuprite, the other between cuprite and brochantite. Its calibration has been elaborated according to the experimental results in [7]. The paper is organized as follows: in the Section 2.1 we analyze the main chemical corrosion phenomena and in Section 2.2 we review the main mathematical models already proposed in literature.…”

Research on the Regularity and Mechanism of Copper Corrosion in Air Containing Sulfur Dioxide

“…Verdigris generates with the SO 2 decomposition in adsorbed liquid film on metal surface. Some substances generated in the decomposition process can combine with copper ions(generated by chemolysis of copper oxide and corrosion cell ), a large amount of chemical reaction are involved in the process above [1,2].SO 2 can be absorbed in aerosol particles and oxidized into SO 4 2even if copper is just exposed to atmosphere in a short time, for the reason that sulfur dioxide dissolves in water. In a similar vein, SO 2 can interact well with hydroxyl to produce H 2 SO 4 , which can dissolve in water in a soon.…”