High-temperature oxidation of transient-liquid phase bonded Ni-based alloys in 1 bar and 250 bar carbon dioxide

Abstract

ABSTRACT Compact microchannel heat exchanger designs for supercritical CO2 power cycles are valued for equipment size reduction and increased heat transfer. They can be fabricated via transient-liquid phase (TLP) bonding, which utilises a lower melting point interlayer for bonding facilitation of etched thin plates. Haynes 230 and 282 TLP bonded stacks were exposed to high-purity CO2 at 1 bar/700 °C to 4000 h and 250 bar/720 °C (supercritical) to 1500 h. All samples obeyed parabolic kinetics after an oxide build-up stage of 500–1000 h. Mass gains were similar for the base and TLP bonded alloys, and oxide thicknesses and scales did not significantly differ around the TLP bond regions. There were some slight oxide compositional differences for the H282 TLP samples at 250 bar. There was a slight pressure effect on mass gain, as samples exposed at the higher pressure experienced higher initial mass gains, but then slower continued oxide growth.