The emergence of reflective thermal barrier coatings

Thermal barrier coatings to protect and extend the life of hot-end parts of gas turbine engine have come a long way from their introduction almost half a century ago, having been the subject of constant innovations determined to push their capabilities. The need for even more efficient next generation of gas turbines will require higher operating temperatures that results in an increased near-infrared radiative output. Unfortunately, the state-of-the-art yttria-stabilized zirconia is transparent to near-infrared leading to direct radiative heating of the substrate, significantly reducing its life. This opens up the requirement for advanced thermal barrier coatings that can optically reflect the incident radiation reducing overall thermal transport to the underlying super-alloy. The present review gives a thorough overview of the current state of research into the approaches employed to achieve thermal radiative barrier coatings for reflection of near-infrared radiation; either by modification of existing infrastructure or via completely novel approaches. Moreover, to complement the experimental research in this up-and-coming domain, an emphasis is laid on the modeling approaches to expedite further advancements.