Atmospheric Corrosion Of Zn Research Articles

Corrosion Behavior of Zinc Covered with Native Oxides Under Thin Solution Films

This study clarified the influence of native oxides on the atmospheric corrosion of Zn. The electrochemical impedance spectroscopy (EIS) values of native-oxide-covered Zn were measured under thin solution films of 10 μm to 500 μm in thickness. The native oxides were formed by exposing pure Zn plates to humidified air at two different temperatures, 25°C and 60°C, for the duration of one week. EIS was applied to the native-oxide-covered Zn for measurement under thin solution films; the results were analyzed using a transmission line equivalent circuit to determine the charge-transfer resistance (Rct). The native oxide formed at 25°C strongly suppressed the corrosion rate (1/Rct) of Zn, which was independent of the solution film thickness (Xf). However, the 1/Rct was not reduced by the native oxides formed at 60°C, as it was dependent on Xf. This paper discusses the different behaviors of the native oxides in the context of corrosion protection.

Effects of NaCl, SO2, NH3, O3, and ultraviolet light on atmospheric corrosion of Zn

AbstractThe atmospheric corrosion behavior of Zn was studied in laboratory environments containing constituents that have not previously received much attention, in particular, humidity, SO2, NH 3, and O 3, along with ultraviolet (UV) light irradiation and a preloading of NaCl. After exposure, corrosion rates were measured using mass loss, and corrosion products were identified by X‐ray diffraction, Fourier transform‐infrared spectroscopy, and energy dispersive spectroscopy. In this study, UV light and O 3 did not significantly affect the Zn corrosion rate in the absence of Cl −. However, when NaCl was present, UV light inhibited the Zn corrosion rate below 90% relative humidity (RH) and accelerated the Zn corrosion rate at 99% RH. The presence of UV light also increased the formation of zinc hydroxyl sulfate and gordaite when exposed to 120 parts per billion (ppb) SO 2 and NaCl. The combination of SO 2 and O 3 with the preloading of NaCl increased the corrosion rate of Zn compared with NaCl alone. NH 3 at a concentration of 550 ppb did not have a significant effect on the Zn corrosion rate.

Formation of Galvanic Cells and Localized Corrosion of Zinc and Zinc Alloys Under Atmospheric Conditions

Atmospheric corrosion of Zn and Zn alloys with local NaCl contaminations was studied in situ by scanning Kelvin probe. The corrosion process was accompanied by the formation of clearly separated an...

Effect of carbon dioxide on the atmospheric corrosion of Zn–Mg–Al coated steel

The atmospheric corrosion of line hot dip ZnMgAl coating was investigated at low and ambient concentration of CO2 as a function surface chloride concentration and temperature and compared to conventional hot dip galvanised (GI) and Galfan coatings. The corrosion of zinc coatings was enhanced in low CO2 conditions and ZnMgAl material was more affected than GI, and in the range of the Galfan coating. An obvious pH effect was underlined in low CO2 conditions. Layered double hydroxide (LDH) and simonkolleite were mainly formed on ZnMgAl coating in the absence of CO2 while hydroxycarbonate and simonkolleite were dominating in ambient air.

Corrosion of Zn under acidified marine droplets

Atmospheric corrosion of Zn under a variety of simulated marine aerosols was studied. In-situ monitoring of droplet pH, volume loss measurements, identification and distribution of crystalline and amorphous phases from corrosion under different droplets were used to understand the role of acidification on atmospheric corrosion of Zn. Results for various droplet chemistries are discussed in terms of initiation mechanism, phase distribution and surface morphology in conjunction with chemical equilibrium calculations. Zn exposed to sulphate containing droplets had relatively small corrosion rates and greater coverage with Gordaite as compared to sulphate-free droplets where coupons have relatively more coverage with Simonkolleite.

Investigation of atmospheric corrosion of Zn using ac impedance and differential pressure meter

Investigation of atmospheric corrosion of Zn using ac impedance and differential pressure meter