The effect of surface treatment on the corrosion behavior of a pure Ta sheet in an equimolar NaCl–KCl melt at 850°C in air. Part 1: Laser surface melting

Abstract

AbstractThe corrosion behavior of pure Ta and laser surface melting–treated Ta sheets was investigated in an equimolar NaCl–KCl melt at 850°C in air. The results show that the predominant factors involved in the consumption of materials were reactions that form sodium‐containing oxides and Ta2O5. High corrosion stress led to slip of the untreated Ta surface grains, further resulting in preferential corrosion along slip bands. The slip of surface grains substantially deteriorated the bonding between the corrosion scale and matrix, thus leading to rapid degradation of the corrosion scale. The melt layer consisted of a thin Ta2O5 film, and the inner dendrite layer demonstrated self‐healing characteristics during corrosion and presented a better hot corrosion resistance than the untreated Ta owing to the excellent bonding at the scale and melt layer interface.