A SENSOR SYSTEM FOR HIGH-RESOLUTION IN-SITU ATMOSPHERIC CORROSIVITY MONITORING IN-FIELD ENVIRONMENT

In order to investigate episodic changes in atmospheric corrosivity wi th a high time resolution, a new sensor system for in situ field studi es has been developed. Atmospheric corrosivity probes, based on the qu artz crystal microbalance technique, are used together with probes for temperature and relative humidity and analyzers for H2S, SO2, NO2, an d O-3. To demonstrate the capability of the sensor system, an indoor f ield characterization has been conducted in an electrical control room within a pulp and paper factory. The characterization included simult aneous exposures of gold, silver, and copper together with gas analysi s during normal operation and simulated malfunctions of the air filtra tion system. The precision of in situ mass response measurements has a standard deviation of only +/-1 ng cm(-2), corresponding to a mass se nsitivity of less than one equivalent monolayer of corrosion products, e.g., Cu2O. The mass sensitivity enabled differences in mass increase rates of copper, silver, and gold to be detected within hours after e xposure start in normal operating conditions and on silver within minu tes after simulated malfunctions of the air filtration system.