Tantalum-Hafnium-Carbide and Tantalum-Hafnium-Carbonitride Materials for Boost Propulsion Nozzles

Advanced missile defense interceptors will provide our nation with the capability of defeating threats to our homeland and our deployed troops. However, the fielding of these advanced interceptors is strongly dependent upon technologies that enable production of interceptor boost nozzles capable of surviving extreme temperatures and corrosive environments with minimal erosion. Plasma Processes, Inc. (PPI) has already produced high quality vacuum plasma sprayed tantalum carbide (TaC) material. Analytical models predict that PPI’s TaC will survive subscale hot fire testing. In the proposed effort, the knowledge learned during the TaC studies will be applied to the development and characterization of materials superior to TaC, such as tantalum-hafnium-carbide (Ta4HfC5) and tantalum-hafnium-carbonitride (Ta4HfC3N2). Ta4HfC5 has a melting temperature up to 265°C higher than TaC, and Ta4HfC3N2 is less susceptible to thermal shock due to its expected higher thermal conductivity than TaC. Development, characterization, and testing of Ta4HfC5 and Ta4HfC3N2 is proposed to 1) increase the fundamental scientific knowledge of these ultrahigh temperature materials; 2) produce material property data to be utilized in existing performance models; and 3) determine if these materials are superior to TaC for employment as boost nozzle components. The proposed material development and low cost fabrication techniques will ultimately lead to improved performance and reduced costs for advanced missile defense interceptors.