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Accelerated atmospheric corrosion testing is an integral part of determining a component's resistance to gaseous attack and is needed to enhance resistance to gaseous attack and subsequent degradation. An acrylic box of 28-L volume with no exposed internal metallic components serves as the basic chamber. All gas lines and fittings are inert. Air with less than 5-ppb total pollutant and a dew point of less than −50°C provides the starting point for air doping. Chamber air is exchanged at a rate of once per minute without a turbulent directed airstream. Chamber temperature is controlled at 30°C and relative humidity (RH) is held at 70%. Current studies utilize 10-ppb hydrogen sulfide (H2S), 10-ppb chloride (Cl2) and 200 ppb nitrogen dioxide (NO2). This environment can be expanded, reduced, or substituted to include other gases such as acid vapors, ozone, and hydrogen peroxide. Pollutant gases are added to the moist make up air at the chamber entrance. All gas flows are controlled through electronic flow meters. National Bureau of Standards (NBS) traceable pollutant standards are regularly scheduled to calibrate monitors. Computer data acquisition of system parameters and control of the electronic flow meters provides for recording and adjustment of system parameters. Spatial pollutant uniformity around the chamber is insured by continuous monitoring of film growth on four copper coated, quartz crystal, thin film monitors. Results of initial data on gold and copper surfaces are presented.
accelerated atmospheric corrosion, air pollutants, microbalances, quartz crystal oscillators, water adsorption, copper-chlorine interaction
Member of technical staff, Bell Communications Research, Inc., Red Bank, NJ