Joinery Of Ultra High Temperature Ceramics Inspired by Nature

Amy Wat | 23-FS-023

Project Overview

Ultra-high temperature ceramics (UHTCs) are critical for engineering applications in extreme environments found in new power generation technologies and aerospace applications. However, use of these materials is stymied by challenges in integrating these materials into the larger, metallic systems composed of very dissimilar materials. Current state-of-the-art approaches include brazing and mechanical fixturing, which introduce issues of coefficient of thermal expansion mismatches leading to premature failure and engineering constraints leading to bulkier designs. We aim to solve these issues by introducing a bio-inspired approach to joining dissimilar materials by incorporating a compliance interface within an interlocking surface design. This concept combines mechanical and chemical fixturing with the interlocking pattern enabling a mechanical means to lock the components together, but the compliant interface introduces a chemically bonded surface without using extra components. However, there is limited understanding on how to design these interdigitating teeth patterns to limit residual stresses introduced by thermal loads. In this work, we used a computational approach to show how the average stresses caused by coefficient of thermal expansion mismatch across the ceramic surface can be lowered at relevant temperatures by using a suture joint compared to a flat brazed joint. We have found using Livermore Design Optimization code that we can create new designs that would limit stresses in the compliant phase or the ceramic phase. This can enable new designs and inform experimental approaches to study this concept for national security needs.

Mission Impact

This project leveraged the High Performance Computing core competency to support Accelerated Materials and Manufacturing. Similar design concept has been of interest to the Department of Defense (DOD) as Defense Advanced Projects Research Agency (DARPA) has supported work on Mechanically Interlocked Materials. This concept may be of interest to address DOE's energy and environmental security missions because joining materials for extreme environments and conditions is relevant for materials in new power-generation capabilities. This work explored solutions to emerging security challenges associated with NNSA-relevant national security missions.

Publications, Presentations, and Patents

Wat, Amy, Travis Hu, and Mohsen Eshraghi. "Cal State La: An Example for Successful Dei Outcomes for Students." JOM 75, no. 9 (2023/09/01 2023): 3227-30.

Wat, Amy, Gabriella King, James Cahill, Joshua Kuntz, Wyatt Du Frane, Marcus Worsley, Logan Bekker, Xiaojie Xu, Yici Sun, Joshua Deotte. Compliant suture-based joinery. U.S. Patent US20230037628A1, filed 8 March 2021, and published 02 September 2023. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS- 1084064