File(s) under permanent embargo

Reason: Waiting on a pending patent and the material is PI for Rolls Royce

SURFACE ROUGHNESS AND SUPERHYDROPHOBICITY BEHAVIOR IN ELECTROCHEMICALLY-ETCHED FE- AND NI-BASED ALLOYS

thesis
posted on 09.12.2021, 23:32 by Benjamin P SmithBenjamin P Smith
Methods and techniques for tailoring the surface morphology of metallic surfaces are determined in part by the complex behavior of elemental interactions in conjunction with electrochemical reactions. In this work, we show how the surface morphology can be predicted based on experimental data resulting from polarization curves and compositional differences of Fe- and Ni-based superalloys. Electrochemical treatments utilizing NaCl as the electrolyte were adapted using parameters such as the pitting resistance equivalent (PRE) number and polarization curves to obtain both rough and smooth surfaces. Utilizing these metrics, we electrochemically etched Inconel 600, SS304, Inconel 718 and Inconel 625 obtaining average surface roughness values that ranged from 0.05 to 57.4 μm indicating the success of tailoring the technique to obtaining rough and smooth surfaces. The effect of current density, current pulsing, and temperature were varied to elucidate roughness and pitting behavior, and strong correlations to the PRE number and polarization curve properties of the alloy were observed. Heat treatments and subsequent evolution to the microstructure in the form of grain growth and precipitation altered the etching behavior. These techniques can be used in preventing corrosion failure and enhancing electrochemical machining

History

Degree Type

Master of Science

Department

Materials Engineering

Campus location

West Lafayette

Advisor/Supervisor/Committee Chair

Michael Titus

Advisor/Supervisor/Committee co-chair

Timothee Pourpoint

Additional Committee Member 2

Nikhilesh Chawla