Determining the properties of a thermal barrier

Liebherr Aerospace wished to determine the thermal conductivity of a very thin ceramic coating deposited on an aluminium substrate. However, this characterization is highly complex. Indeed, traditional methods require to perform the measurement on the layer alone but how to do so if it can not be separated from its substrate?
Capacités’s experts developed a strategy which involved characterizing through the laser flash method the substrate by itself at first, then repeating the procedure on the assembly comprising the same substrate and the ceramic deposit.

To do so, the numerical model associated to the laser flash method was updated to take into account the multi layered material. The success of the operation also relied on the thorough characterization with temperature of additional properties which are mandatory to run the inverse algorithm: the specific heat and the thicknesses of each component. The procedure implemented by Capacités resulted in the successful identification of the thermal conductivity of the ceramic layer from ambient temperature to 400°C allowing Liebherr Aerospace to better ensure the mechanical strength of their multi-layered parts in a hot environment.

To complete this ambitious project, the Capacités’ experts benefited from support and technical equipment from the LTeN laboratory (Heat Transfer and Energy Laboratory), joint research unit of Université de Nantes and the CNRS.