Corrosion behavior of volcanic ash on sintered mullite for environmental barrier coatings

The high-temperature corrosion behavior of volcanic ash(VA) in attacking sintered mullite was investigated, and the corrosion resistibility of mullite environmental barrier coatings (EBCs) to VA was predicted. Sintered mullite specimens were prepared by using the spark plasma sintering method. These specimens were subjected to a hot corrosive environment—molten Icelandic VA at 1400 °C—for three different duration times (2, 12, and 48 h). The microstructure and phase of the specimens were analyzed by using a scanning electron microscope equipped with an accessory system for energy dispersive spectroscopy and X-ray diffraction. In addition, in-situ high-temperature X-ray diffraction was carried out to identify the dynamics of phase evaluation in the volcanic ash and mullite mixture powders. Results show that a reaction layer was generated and continuously dissolved into the melted volcanic ash. The primary incursive component is iron; however, a minimal amount of sodium plays a more important role in disintegrating sintered mullite.