PhD abstract Sina Sheikholeslami
Long-term Field-Performance of Waterborne Coatings
PhD Student: Sina Sheikholeslami, Supervisors: Wei Gao, David Williams
The long-term field performance of several environmental-friendly coating systems was evaluated via both conventional methods and a newly-developed test. We used the full waterborne non-hazardous Chrome-free materials which were developed by Fletcher Steel in NZ with Beckers Group in the UK to substitute Chrome-contained roofing products in Australasia. The new corrosion evaluation process was designed to be a rapid assessment technique, involving a modified Damage Tolerance Test (DTT) developed by NASA, the Scanning Vibrating Electrode Technique (SVET), and natural exposure at Muriwai Beach, Auckland.
Our modified DTT was capable of ranking the coating systems regarding their corrosion performance in only 7 days. Electrochemical Impedance Spectroscopy (EIS) and Open Circuit Potentiometric (OCP) investigations illustrated that our modified DTT could have superior or inferior corrosion performance of Cr containing coatings with different organic layers, substrates, corrosion inhibitors, and thicknesses. Cut-edge corrosion comparison of these coatings was also successfully conducted via a novel approach of SVET technique, which gives the time-lapse current density mapping and corrosion mass loss of cut-edges. Most importantly, the ranking order and performance evaluation using our modified DTT and SVET tests matched the same trend with samples exposed at Muriwai Beach for 24 months, showed this technique is promise as a predictive and rapid indicator of real-world corrosion performance.