Development of High Temperature Multi-Layer Laser Flash Artefacts

Ateeb Farooqui,Bruno Hay,Louise Wright,Michael Pekris,Theo Saunders,Mark J Whiting,Jiyu Wu,Roger Morrell

doi:10.1007/s10765-021-02928-4

Abstract

Delamination of the interlayers of multi-layer systems can cause a degradation in functionality, stability and life span of that system. This is even more pertinent for systems at high temperature. Laser flash analysis (LFA) has long been used for thermophysical properties measurements at high temperatures. Multi-layer reference artefacts, with and without, debonded regions are required for validating the thermal characterisation of such systems using LFA. Although some high-temperature bulk candidate reference materials were developed and studied, e.g. in the European Metrology Research Programme (EMRP) funded Joint Research Project (JRP) ENG08 Metrofission, they were not able to meet the requirements for validating thermal measurements of multi-layer systems using LFA. In the European Metrology Programme for Innovation and Research (EMPIR) funded JRP 17IND11 Hi-TRACE project, the National Physical Laboratory is developing multi-layer reference artefacts, including both fully bonded and partially de-bonded systems for validating thermal characterisation of multi-layer systems at temperatures from room temperature to above 1000 °C using LFA. This paper details the methodology of production, measurement and validation of isotropic graphite and hafnium based multi-layer systems with, and without, partial debonding. Reproducibility, thermal stability and sensitive parameters concerning the thermal response of the artefacts will be discussed, with recommendation on the usage criteria as LFA multi-layer reference artefacts.

Highlights

The laser flash method was first presented by Parker in 1961 [1] as a technique to measure the thermal diffusivity of a solid material
A technique that is able to determine the thermal effect of interface resistances and debonding at these temperatures would allow for better design of these critical components, and if used in conjunction with non-destructive debond detection techniques, would allow for users to determine if in-service components require maintenance or have to be replaced
This paper presents the details of the methodology of production, measurement and validation of isotropic graphite and hafnium based multi-layer systems both with, and without, partial debonding

Summary

Introduction

The laser flash method was first presented by Parker in 1961 [1] as a technique to measure the thermal diffusivity of a solid material. One benefit of LFA is that is can be used to measure the thermal diffusivity at temperatures as high as 3000 °C. For systems that are required to operate at high temperatures coatings are often employed to protect the substrate material from extreme conditions, creating a multilayer system. Factors such as the thermal resistance of the interface and the presence of a debond or delamination can cause a degradation in functionality, performance and lifespan of the system. A technique that is able to determine the thermal effect of interface resistances and debonding at these temperatures would allow for better design of these critical components, and if used in conjunction with non-destructive debond detection techniques, would allow for users to determine if in-service components require maintenance or have to be replaced

Methods

Results

Conclusion