High-temperature corrosion of spark plasma sintered Gd₂SiO₅ with volcanic ash for environmental barrier coatings

Hot corrosion behavior was evaluated by gadolinium monosilicate (Gd₂SiO₅) with volcanic ash for environmental barrier coatings (EBCs). Sintered Gd₂SiO₅ was prepared by the spark plasma sintering (SPS) method at 1400 °C for 20 min, and high-temperature corrosion resistance against of volcanic ash was evaluated at 1400 °C for 2 h, 12 h, and 48 h. The surface region of sintered Gd₂SiO₅ was partially dissolved in molten volcanic ash, creating a chemically reacted area. The formation of the elongated morphology of Ca₂Gd₈(SiO₄)₆O₂ grains observed in the reaction area is thicker with increasing heat-treatment time as the volcanic ash dissolves. In addition, high-temperature X-ray diffraction was carried out to identify the dynamics of phase evaluation in the volcanic ash and Gd₂SiO₅. According to the results, corrosion occurs due to reaction of the Gd₂SiO₅ phase and the Ca component of volcanic ash at 1300 °C, and the Ca₂Gd₈(SiO₄)₆O₂ phase is generated.