Hot corrosion behaviour of Nbss/Nb5Si3 in situ composites in the mixture of Na2SO4 and NaCl melts

• Hot corrosion behaviour of Nbss/Nb5Si3 in situ composites was investigated.
• Oxides with a loose and porous structure consisted mainly of TiO2 and CrNbO4.
• The presence of Na2SO4 + NaCl led to the formation of the loose and porous scale.

Hot corrosion behaviour of Nb–16Si–24Ti–6Cr–6Al–2Hf (at.%) in the mixture of Na2SO4 and NaCl melts at 900 °C was studied. The results show that the corrosion kinetics of the alloy fit parabolic law. The oxides consist of a loose and porous outer layer and an internal oxidation zone. Outer oxides are mainly composed of TiO2, TiNb2O7, Nb2O5, CrNbO4 and SiO2 while the internal oxidation zone is composed of TiO2. Hot corrosion mechanism of the alloy in the presence of Na2SO4 and NaCl deposits is discussed.

The oxide consisted of a porous outer layer and an internal oxidation zone, and the obvious spallation could be observed after hot corrosion for 100 h at 900 °C.Figure optionsDownload as PowerPoint slide