Mo(Al Si1−)2 healing particles for high temperature ceramics and encapsulation by selective oxidation of aluminium

To prevent premature triggering of the healing reaction in Mo-Si containing self-healing thermal barrier coating system, an oxygen impenetrable shell (α-Al2O3) around sacrificial particles (MoSi2) is desired. Here encapsulation method presented through selective oxidation Al Mo(AlxSi1-x)2 particles. Healing designed terms alumina thickness, particle size and fraction dissolved. By replacing Si by MoSi2 up to maximum solubility (x = 0.65) a strong crack ability maintained (relative volume expansion ≥ 40 %). The formed exclusive α-Al2O3, featuring two-layered structure, results from counter-diffusion process along grain boundaries, its kinetics fits well with 3D diffusion-Jander model. After 16 h exposure gaseous ambient pO2 5 × 10-10 atm. at 1100 °C, closed dense α-Al2O3 thickness about 1.3 µm. oxide produced under this condition provided significantly improved stability upon high 0.2 °C for 50 h. after feature inner core completely consumed α-Al2O3.