Hot corrosion behavior of neodymium magnesium hexaaluminate by vanadium pentoxide in air

Hot corrosion due to molten salt attack is one of the main failure mechanisms of lanthanide magnesium hexaaluminate thermal barrier coating materials. Thermochemical attack of the NdMgAl₁₁O₁₉ ceramic by V₂O₅ was studied at different temperatures ranging from 650 to 950 °C using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The corrosion products of the NdMgAl₁₁O₁₉ ceramic by V₂O₅ depend mainly upon corrosion temperatures. At 650 °C, the corrosion products are mainly composed of AlVO₄ and NdVO₄. However, molten V₂O₅ reacts with NdMgAl₁₁O₁₉ to form NdVO₄, MgV₂O₆, a small amount of AlVO ₄ and alumina at 750 °C. At 850 °C, the corrosion products consist of Θ-Al₂O₃, NdVO₄ and a small amount of MgAl₂O₄. After hot corrosion at 950 °C, the corrosion products are composed of α-Al₂O₃, NdVO₄ and MgAl₂O₄.