Improving oxidation resistance of MoSi2 coating by reinforced with Al2O3 whiskers

To improve the toughness and oxidation resistance of MoSi2 coating, Al2O3 whiskers and Al2O3 particles were introduced respectively. The geometry of Al2O3 significantly influence the toughening effect on suppressing crack extension. After oxidation at 1450 °C for 76 h, MoSi2 coating reinforced with 1% Al2O3 whiskers lost mass of only 0.17% and remained integrity, compared to the particles with 0.70% and destroyed by penetrative cracks, exhibiting favorable oxidation resistance. The improved property resulted from the crack-healing by Al2O3·21SiO2 glass occurred during oxidation and better toughening effect by the whiskers to restrain crack growth. Noticeable, increased Al2O3 content made the coatings porous remarkably, and also decrease the crack resistance during oxidation, led to degradation of the ability to resist accelerated oxidation erosion.