Repressing high‐temperature radiative heat transfer in thermal barrier coatings

Abstract

Photon diffusion in thermal barrier coatings (TBCs) significantly deteriorates the overall performance of gas turbines operating at high temperatures. This study presents the strategy of high‐temperature photon suppression, based on a ceramic composite consisting of the second component with a smaller refractive index and controlled particle size. Using the Mie theory, it is theoretically demonstrated that controlling the second component particle size closer/equal to the infrared radiation wavelength region (1–5 μm) could reduce photon diffusion. Ceramic composites comprised of 8 wt.% yttria‐stabilized zirconia (8YSZ, matrix) and corundum (second component) with different particle sizes were prepared. The total and the photon thermal conductivity of the 8YSZ/corundum composites are lower than pure 8YSZ by ∼48.9% and ∼96.4% at 1200°C, respectively. With the addition of corundum into 8YSZ, the thermal radiation transport of 8YSZ is significantly suppressed due to the photon scattering produced by the lower refractive index and proper particle size of the corundum. Besides, the fracture toughness and hardness of composites increased by ∼20% and ∼13%, respectively, compared to the 8YSZ. Composite with the corundum particles size of 1 μm displays the lowest values of total and photon thermal conductivity at high temperature.

Application of 3D Printing Technology and Porous Nano-Ceramic Decorative Sheet in Interior Landscape Design

“…Due to the poor conductivity, high hardness, and high melting point of ceramics, many complex shapes of high-strength and high-performance ceramic structural parts are difficult to directly form. Gel injection molding technology can not only obtain green embryos with high mechanical strength, but also not limited by complex molding shapes and sizes, but the limitation of mold dependence makes the product design cycle longer [ 15 ]. Gel injection molding technology can not only obtain high mechanical strength embryo but also be free from complicated shape and size.…”

A Promising Radiation Thermal Protection Coating Based on Lamellar Porous Ca‐Cr co‐Doped Y3NbO7 Ceramic

“…In contrast, the thermal diffusion coefficients of the niobate coating generally range from 2/3 to 3/4 of those exhibited by its full‐density bulk ceramic counterpart, spanning from room temperature to 1273 K. Additionally, the increasing pattern of the temperature‐dependent thermal diffusion coefficient is postponed until 1100 K, potentially due to the back‐scattering effect of infrared radiation by the micropores within the coating. [ 23 ] Overall, in comparison to the YSZ commercial thermal protection ceramic, the bulk niobate has successfully explored a 48.4% reduction in thermal conductivity via phonon engineering. However, the mechanism responsible for the additional 51.6% reduction in thermal conductivity through the implementation of a porous coating structure awaits further elucidation (Figure 4c).…”

Near‐Infrared Trapping by Surface Plasmons in Randomized Platinum–Ceramic Metamaterial for Thermal Barrier Coatings

“…Inspired by the previous researches, [46][47][48] we estimate the radiative thermal conductivity by experiment. In Figure 5a, the total thermal conductivities and phonon thermal conductivities of all samples are plotted.…”