Thin-Walled HfN Components for KKV Divert and Attitude Control Systems

This proposal addresses BMDOOs requirement for enhancing the affordability and performance characteristics of kinetic kill vehicles (KKVs) by recommending a program to investigate the use of hafnium nitride-based divert and attitude control system (DACS)components. In this program, thin-walled HfN liners will be fabricated in net-shape fashion via gas phase nitridation of hafnium articles. Systematic variation of nitridation processing parameters will allow for controllable variation of nitride phasecontent, stoichiometry and morphology, thereby allowing the tailoring of constituent materials properties for specific mission requirements. Recent test results generated during simulated DACS propellant exposure at Thiokol indicates that HfN-basedmaterials fabricated by Exothermics may represent a cost-effective and viable alternative to rhenium, which is a very dense and costly metal. The fabrication of thin-walled liners is being carried out to support a new design concept for DACS and nozzleliner components which entails the use of thin refractory liners in conjunction with carbon foams and a structural outer shell. Exothermics team member Materials Research and design will augment empirical efforts in this program by analytically predictingthe thermomechanical response of various materials (HfN liner + foam thickness) combinations under simulated DACS exposure conditions.Commercial and DoD markets which could benefit from products made in support of the proposed work include: (1) aerospace/defense propulsion components (rocket nozzles, nozzle liners); (2) molten metals processing hardware (thin liners for minting andcasting operations); (3) specialty semiconductor components requiring thermal stability and excellent corrosion resistance.