The effect of porosity on the radiation component of the thermal conductivity of the thermal barrier coatings is studied. Heat transfer in the disordered porous structures as well as the porous photonic band-gap structures is investigated. The pores, which size is comparable with the characteristic radiation wavelength λmax=2897.8/T μm, were found to be most efficient obstacles for the heat radiation.

Recent progress in fabrication technology allows for the efficient control of electromagnetic waves by means of photonic devices. This could be attractive and promising also for high-temperature photonic structures to control electromagnetic heat transfer at temperatures above 1000 oC. We discuss the literature and present our own results on Fiber Matrix Composites (FMC), which could be superior to high-temperature metals or monolithic ceramics and can be designed for photonic applications. Possible applications include the protection of non-rotating components in high-temperature engines and turbines such as combustors and liners, coatings and parts for aerospace vehicles. Our discussion includes the material aspect and some relevant structure features. The use of woven fabrics to design new photonic band gap structures is discussed. An example of the use of the plane-wave expansion method for FMC design is given.