Recent Advances in Reactive Monitoring of Air Corrosivity

Knowledge of the rates at which an atmosphere will corrode metals has benefits. Corrosion rate is an indirect, though reliable indication of the concentrations of corrosive gases in the air. Today’s data centers require that for computers to work reliably, the corrosion rates of copper and silver foils, in terms of the rates of growth of corrosion products, be less than 300 and 200 A/month, respectively. One of the industry standard size of metal foils used for reactive monitoring of air corrosivity is 25x50 mm. The thickness of the corrosion products on the foils is measured using coulometric reduction. The other means of measuring corrosion rates is electrical resistance increase of metal serpentine thin films. Serpentine thin films have smaller surface areas, finer grain sizes and higher mechanical stresses compared to metal foils. Both these factors increase corrosion rates. This paper compares the corrosion rates of metal films and foils. The corrosion rates of two different area metal foils were measured using coulometric reduction and compared with the corrosion rates of metal serpentine thin films using resistance increase and coulometric reduction techniques.