Brian Marx

Corrosion Assessment and Characterization of Aerospace-Bearing Steels in Seawater and Ester-Based Lubricants

The corrosion behavior of bearing steels was screened using potentiodynamic scans in seawater. The results of electrochemical testing provided a relative ranking of the bearing steels when tested in aqueous chloride-containing solution. The corrosion behavior of bearing steels in the lubricant environment has been observed to be quite different than in aqueous solution. Both the amount of water contamination in oil and chloride content of the water impact the observed corrosion rates in oil-water mixtures. All steel compositions tested demonstrated localized corrosion damage when exposed to oil with water added; however, inherently less corrosion-resistant alloys had more widespread shallow attack, whereas higher Cr-containing alloys displayed more localized severe attack. The mechanism of corrosion in the two-phase, oil plus aqueous phase system appears to be controlled by an aqueous corrosion process dependent on steel microstructure and emulsified or free water and likely limited by oxygen availability...

Miniature Multi-Electrode Electrochemical Cell in LTCC

The miniaturization of analytical instruments and packaging of novel sensors is an area that has attracted significant research interest and offers many opportunities for product commercialization. Electrochemical sensors have been used to detect a wide variety of compounds including toxic gases. A miniature electrochemical cell has been designed, constructed, and tested for functionality. The cell will be used in identifying and selecting chemical species in solutions. The cell was constructed of low temperature co-fired ceramic (LTCC) material using gold for the electrodes. Tests performed in sulfuric acid and sea water solutions show that the cell is functioning based on cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis. Miniaturization allows the cell to be deployed as a sensor in many different environments.

Micro-sensor for monitoring oils

An electrochemical sensor has been constructed for detecting changes in the electrical responses of oil/metal systems. The sensor was used to make electrochemical impedance spectroscopy (EIS) measurements and the impedance responses are compared as a function of oil additive. This work uses the base stock oil (no additives) as the baseline for comparison of the various additives. Of the four additives tested, only the metal deactivator additive was found to increase the impedance. The full formulation oil (containing all additives) displays the lowest impedance, indicating possible additive interaction. A basic Randles circuit was used to fit the impedance data. This type of fit provides information pertaining to the properties of the bulk oil and contributions due to the interactions at the oil/metal interface