Materials design of silicon based ceramic coatings for high temperature oxidation protection

To meet the rigorous thermal protection demands of state-of-the-art aircraft and aerospace systems, it is essential to implement comprehensive thermal oxidation shielding for the components exposed to extreme high temperature. Silicon based ceramic coating technology is an efficient way to improve the oxidation resistance of thermal structural materials, such as ceramic matrix composites (CMCs) and carbon/carbon (C/C) composites. Unfortunately, coating cracking under thermomechanical loads results in poor oxidation protection of the composite substrates. Two important perspectives to avoid the coating cracking are reviewed, namely i) crack healing and ii) toughening of the coating. Such two strategies can heal and inhibit the cracking of silicon based ceramic coatings to improve the service life-time. The strategies for the material design are appropriate for the fabrication of advanced silicon based ceramic coatings intended for the upcoming generation thermal structural components. And the outlook development of silicon-based ceramic coating systems is also summarized.