60384 - Experimental Analysis and Material Characterization of Ultra High Temperature Ceramic Composites 

Experimental Analysis and Material Characterization of Ultra High Temperature Ceramic Composites

Dr. Anindya Ghoshal¹, Dr. Michael J. Walock¹, Dr. Andy Nieto², Dr. Muthuvel Murugan¹, Dr. Clara Hofmeister-Mock¹, Mr. Marc Pepi¹, Dr. Luis Bravo¹,  Mr. Andrew Wright³, and Prof Jian Luo³

¹U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland

² Naval Postgraduate School, Monterrey, California

³University of California, San Diego, California

Ultra high temperature ceramic (UHTC) materials have attracted attention for hypersonic applications. Currently there’s lot of interest in possible gas turbine engine applications of UHTC composites. However, many of these materials, such as hafnium carbide, zirconium carbide, and zirconium diboride, have significant oxidation resistance and toughness limitations.  In addition, these materials are very difficult to manufacture.  In many cases, SiC powder is mixed with UHTC powders to improve manufacturability.  This can also improve the materials’ oxidation resistance at moderately high temperatures.  For example, ZrB₂-SiC composites show very good oxidation resistance up to 1700 °C, due to the formation of SiO₂ and ZrO₂ scales.  While this may limit its application to hypersonic applications (due to reduced thermal conductivity and oxidation resistance at higher temperatures), these UHTC-SiC composites may find applications in turbomachinery. 

The US Army Research Laboratory (ARL), the Naval Postgraduate School (NPS), and the University of California – San Diego (UCSD) are developing tough UHTC composites with high durability and oxidation resistance.  For this paper, UHTC-SiC composites, high-entropy fluorite oxides, and high-entropy metal borides were developed using planetary and high-energy ball milling and consolidated using spark plasma sintering; these materials were evaluated for their oxidation-resistance, ablation-resistance, and thermal cycling behavior under a DoD/OSD-funded Laboratory University Collaborative Initiative (LUCI) Fellowship and DoD Vannevar Bush Fellowship Program. In this paper experimental results and post-test material characterization of SPS sintered ZrB2, ZrB2+SiC, ZrB2+SiC+HfC, HfC+SiC, and HfC+ZrB2 pellets subjected to ablation test will be presented.