Review: Thermal ceramic coatings as energy saving alternatives for high temperature processes

Abstract

Reductions in energy consumption for high temperature processes are an important research topic, especially due to the ongoing energy crisis scenario. Based on the several possibilities of saving it, thermal coatings are an economical and technical viable possibility of tailoring the optical properties of a material surface. Although many studies have been published on the benefits of high emissivity and high reflectivity ceramic coatings, there is still a lack of a clear understanding on the correlation between thermal radiation heat transfer, solid state physics, and material science technology. This study aims to create a connection between these areas in order to provide basic guidelines for the correct use of thermal ceramic coatings, leading to achieving the maximum decrease in energy consumption by their use.

Radiation heat transfer during hypersonic flight: A review of emissivity measurement and enhancement approaches of ultra‐high temperature ceramics

“…In ceramics, ionic, and electronic polarization are responsible for intrinsic optical properties (absorptivity, reflectivity, transmissivity) as the ions, and electron cloud can resonate with the photons of incident IR radiation. 14 Absorptance and reflectance, on the contrary, are surfacespecific properties and can be optimized by controlling the surface roughness and microstructure of the material. Emittance is the outcome of such extrinsic modifications of a material.…”

Repressing high‐temperature radiative heat transfer in thermal barrier coatings

“…5 To date, only a few reports have addressed the reduction in photon diffusion or photon thermal conductivity of the TBCs. [6][7][8][9] As the demand for operating temperature of gas turbines increases (over 1723 K), 10 it becomes essential to increase the hightemperature thermal insulation efficiency of the TBCs.…”

“…Therefore, this study proposes the 8YSZ‐based ceramic composite to suppress its photon thermal conductivity. Since producing the spatial refractive index modulation in the microstructure of ceramics can lead to increased photon scattering 9 . Therefore, the fundamental strategy for designing composite is to generate a network of refractive index discontinuity by adding the second component with a much smaller refractive index than the 8YSZ.…”

“…However, the insulation performance of TBCs deteriorates above 1000°C by the thermal radiation transport, which becomes a significant portion of the total thermal conductivity 5 . To date, only a few reports have addressed the reduction in photon diffusion or photon thermal conductivity of the TBCs 6–9 . As the demand for operating temperature of gas turbines increases (over 1723 K), 10 it becomes essential to increase the high‐temperature thermal insulation efficiency of the TBCs.…”

“…Since producing the spatial refractive index modulation in the microstructure of ceramics can lead to increased photon scattering. 9 Therefore, the fundamental strategy for designing composite is to generate a network of refractive index discontinuity by adding the second component with a much smaller refractive index than the 8YSZ. In addition, controlling the second component particle size closer/equal to the IR wavelength of 1-5 μm is also essential.…”