Solid–gas interface thermal conductance for the thermal barrier coating with surface roughness: The confinement effect

Abstract

The yttria-stabilized zirconia (YSZ) is a famous thermal barrier coating material to protect hot-end components of the engine. As a characteristic feature of the YSZ, the surface roughness shall play an important role in the interface thermal conductance between the YSZ and gas, considering that the gas is typically at an extremely high temperature. We investigate the effect of the surface roughness on the thermal conductance of the YSZ-gas interface with surface roughness described by nanoscale pores on the surface of the YSZ. We reveal two competitive mechanisms related to the microstructure of the pore, i.e., the actual contact area effect and the confinement effect. The increase of the pore depth will enlarge the actual contact area between the YSZ and gas, leading to the enhancement of the solid-gas interface thermal conductance. In contrast to the positive actual contact area effect, the geometry-induced confinement effect greatly reduces the interface thermal conductance. These findings shall offer some fundamental understandings for the microscopic mechanisms of the YSZ-gas interface thermal conductance.

Nanobubble-induced significant reduction of the interfacial thermal conductance for few-layer graphene

“…This phenomenon may arise from the fact that the ITC of the solid/gas interface is several orders of magnitude smaller than that of the solid/solid interface. 49–51 Therefore, the ITC of the bilayer graphene with bubble can be divided into two components 48 G = βG 1 + (1 − β ) G 2 ,where is the area ratio between the bubble and graphene layer. G 1 represents the ITC of the graphene/gas interface.…”

“…This phenomenon may arise from the fact that the ITC of the solid/gas interface is several orders of magnitude smaller than that of the solid/solid interface. [49][50][51] Therefore, the ITC of the bilayer graphene with bubble can be divided into two components 48…”

Wide frequency phonons manipulation in Si nanowire by introducing nanopillars and nanoparticles

“…Many important applications and devices such as thermoelectric conversion, thermal barrier coatings and insulating materials need to hinder phonon transport to further reduce TC. [1][2][3][4] Nanostructures have been widely used in the design of low TC materials, and the frequency range of phonons that significantly contributes to heat transport in nanostructured materials is generally in the sub-terahertz to tens of terahertz. [5] From a spectral point of view, the key question in obtaining low TC materials is how to suppress phonon transmission over a wider frequency range.…”