Effects of Gaseous Pollution and Thermal Conditions on the Corrosion Rates of Copper and Silver in Data Centre Environment: A Literature Review

The objectives of the present review are to: 1) summarize the existing knowledge on the mechanisms of the corrosion, identify and analyze the major factors affecting the corrosion of copper and silver; 2) compare various measurement techniques for the study of atmospheric corrosion and models of corrosion; 3) identify knowledge gaps for atmospheric corrosion; 4) recommend “realistic worst case” pollution levels for laboratory testing of humidity and temperature effects on corrosion and assessment of datacom equipment reliability in data centers. This review focuses on the five pollutants: SO2, NO2, H2S, O3 and Cl2. Results of the review include: the pollution levels and thermal environmental conditions in data centers; fundamental mechanisms of corrosion; current knowledge of the major factors affecting the corrosion rates of copper and silver; the techniques (QCM, Coulometric Reduction, SEM, XPS, FTIR and EIS) for the measurement of corrosion levels. It was found that the “realistic worst-case” concentrations for H2S, NO2, SO2, Cl2 and O3 are 10 ppb, 80 ppb, 40 ppb, 2 ppb and 60 ppb, respectively. Different levels and combinations of contaminants, temperature, relative humidity and air velocity cause different corrosion on the metal. Chloride, Nitrogen dioxide and Sulfur dioxide are the common corrosive gases for the datacom equipment. Hydrogen sulfides and ozone are very important gaseous contamination in data center environment. Each of them alone can damage the equipment, and their synergistic effects with the other compounds and humidity can cause significantly more damages, but a mechanistic model is lacking for predicting the synergistic effects and better design of the thermal environment to ensure equipment reliability while improve the energy efficiency through the use of outdoor air for free cooling