Radiative Transfer and its Impact on Determination of Thermal Diffusivity in Thin Films

TL;DR

This paper enhances the Front Face Flash Method to measure thermal diffusivity in thin films with small optical thickness, considering radiative transfer effects through simulations and finite element modeling.

Contribution

It extends the method to partially transparent samples and integrates radiative transfer modeling with conduction analysis in a finite element framework.

Findings

Successful application to ZrO2 and SiC samples

Demonstrates the method's potential for thin film thermal property analysis

Provides a tool for coupled conduction and radiation heat transfer studies

Abstract

This paper extends the recently introduced Front Face Flash Method for extraction of thermal diffusivity of thin films to samples of small optical thickness. The paper discusses the principal question whether diffusivity is uniquely defined in case a heated ceramic, thin film sample is non- or only partly transparent to radiation. The paper applies radiative Monte Carlo and Two-Flux simulations to numerically solve the Equation of Radiative Transfer. Both methods are integrated in a Finite Element scheme, with conduction coupled to radiation, to investigate heat transfer under strongly transient and non-linear conditions. In this paper, the Front Face Flash method is successfully applied to ZrO2- and SiC samples. It thus provides a promising tool to also investigate the thermal transport properties of thin film superconductors, but applicability still has to be demonstrated. The approach is particularly suitable for analysis of coupled conduction/radiation processes.