A single step process to form in-situ an alumina foam/aluminide TBC system for alloys in extreme environments at high temperatures

► The presented coating opens a way to manufacture a complete TBC system by a simple and inexpensive method. ► The coating is based on a ceramic alumina hollow spheres top coat and an aluminum rich diffusion layer. ► The coating is produced by using a water based slurry containing spherical aluminum particles with a defined diameter. ► The investigation clarifies the coating manufacturing process and mechanisms. ► The observed diffusion layer phase transformations precede similarly as literature described pack diffusion coatings.