Corrosion mechanism of Ti2AlC MAX phase coatings under the synergistic effects of water vapor and solid NaCl at 600 °C

Highlights: • Dense and high-purity Ti₂AlC coatings were fabricated by a facile two-step technique. • The mass gain per unit area of coatings was less than 1/6 of 1Cr11Ni2W2MoV substrates. • Corrosion mechanism of Ti₂AlC coatings under NaCl-H₂O was completely investigated. • Defects of corrosion scale were self-healed during corrosion by inert Al₂O₃ tissue. • Weakly-boned Al of Ti₂AlC coatings essentially favored their corrosion resistance. The corrosion behavior of Ti₂AlC MAX phase coatings coated on 1Cr11Ni2W2MoV substrates in NaCl deposit in water vapor at 600 °C has been fully investigated. The results demonstrated that the substrates underwent serious corrosion, but the coatings performed better. The mass gain per unit area of coatings was less than 1/6 of substrates, because of the formed compact and uniform corrosion scale. Such dense corrosion scale was composed of Na_xTi_yO_z fine grains with the size of 11 ± 0.4 nm and amorphous Al₂O₃ phases which self-healed the generated defects during corrosion, benefiting from the novel layered structure of MAX phase.