Evaluation of Damage Tolerance for TSA-Coated Steel in a Simulated Marine Environment (C2026-00305)

Adriana Vargas, Shiladitya Paul

Thermal Spray Aluminium (TSA) coatings are widely used to protect steel structures in marine environments due to their ability to provide long-term cathodic protection and their low self-corrosion rates. Even when mechanically damaged, TSA remains effective, as aluminium is galvanically more active than steel. However, the extent of damage that can be tolerated without compromising performance is not fully understood. This study investigates the electrochemical performance of TSA-coated steel with 30% (TSA_30) and 50% (TSA_50) exposed steel surfaces. The TSA coating (300 µm thick, 1050 AA) was applied using the twin-wire arc spray method. Samples were immersed for 30 days in synthetic seawater (ASTM D1141-98, without heavy metals) under stagnant conditions at 18 °C. Results showed that both TSA_30 and TSA_50 provided effective cathodic protection throughout the exposure period. After removing the calcareous deposits from the exposed steel, rapid reformation of aragonite was observed, resulting in a reduction in the coating's corrosion rate. The findings emphasise the coating's high damage tolerance and its capability to maintain protective performance even when a significant defect is present. This study suggests that TSA coatings offer a robust safety margin, which could help reduce inspection frequency and maintenance costs in marine applications.