Date/Time: 04-23-2019 - Tuesday - 05:00 PM - 07:00 PM
Zhidong Ding1 Mackenzie Ridley1 Jeroen Deijkers1 Md Shafkat Bin Hoque1 John Gaskins1 Patrick Hopkins1 Haydn Wadley1 Elizabeth Opila1 Keivan Esfarjani1

1, University of Virginia, Charlottesville, Virginia, United States

HfSiO4 (hafnon) can be used as a layer environmental barrier coating (EBC) materials placed between silicon dioxide and hafnia. Hafnon has a good lattice thermal expansion matching between silica and hafnia and can prevent oxygen diffusion in EBCs, thereby potentially lengthening the lifetime of EBCs. In this work, we conduct a comprehensive investigation of mechanical, thermodynamic and thermal transport properties of hafnon using first-principles density functional theory (DFT) calculations and compare our results to experiments performed on this material. The volumetric coefficients of thermal expansion (CTE) calculated by the quasi-harmonic approximation are in the range 9.18 - 19.07×10-6 K-1, when the temperature increases from 300 to 1500 K, in agreement with X-Ray Diffraction and dilatometer measurements. The thermal conductivity is nearly 10 Wm-1K-1 at room temperature (RT) using the Boltzmann transport theory. The time-domain thermoreflectance technique utilized to measure thermal conductivity yields 12.4 Wm-1K-1. The mechanical properties, such as bulk modulus and elastic constants are also compared between the first-principles calculations and the RT nanoindentation technique. This study validates our computational approach and can be used to further study thermomechanical properties of other high-temperature oxides.

Meeting Program

Symposium Sessions

5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)

PCC North, 300 Level, Exhibit Hall C-E