Evaluation of thermal shock failure mechanism of arc-sprayed Fe-based coatings deposited on different substrates

Abstract

FeCrMoCBWNb coatings were fabricated on 65Mn and ASTM A238C steel via arc-spraying process to study the thermal shock behavior. To determine the influence of the substrate, the coatings' failure mechanisms were examined at 800 °C under different thermal cycles. The coating microstructure and mechanical properties were characterized. The crystallinity, peak intensity, mechanical properties, and surface roughness changed with the substrate type. The coating prepared on A238C steel presented improved resistance to thermal shock than the coating on 65Mn attributed to higher initial bonding strength. The mismatch of the mechanical properties between the coating and substrates influenced the adhesion and thermal shock properties of the coatings. The iron compounds and oxide layers at the interface and splat boundaries increased with the number of thermal cycles, resulting in internal cracking and de-bonding of the coatings.