Rocket Nozzle HfC Coatings and Structural Foams from Polymer Precursors

Innovative manufacturing processes to fabricate non-eroding rocket nozzles are fundamental technologies that could revolutionize nearly all core missions of the Missile Defense Agency. Coatings to protect graphite and C-C composite materials from erosionhave had limited success due to the high costs and inhomogenities in the structure and composition of the coatings produced using traditional plasma spray and chemical vapor deposition techniques. An innovative, low cost manufacturing process is proposedto produce HfC coatings and structural foam. A mixture of Hf and C containing polymer precursors are painted onto a graphite surface (C-C rocket nozzle for instance). The precursors after drying are then pyrolyzed at an intermediate temperature(1200-1400¿C) forming a HfC coating. Coatings made by this process are uniform in composition, show no presence of hafnium oxides, have excellent adhesion, exhibit no cracking and have good thermal shock resistance. Alternately the Hf containing polymercan be mixed with a C containing polymer and cast into shape using a mold. Upon pyrolysis a HfC structural foam is produced. The objective of this Phase I proposal is to establish proof-in-principal that usable HfC coatings and foams may be producedusing this innovative technique. This revolutionary manufacturing process would be used commercially to produce HfC coatings for the high temperature protection of automobile turbochargers/superchargers, electric power generation system steam turbinesand valve sealing surfaces for chemical and high temperature processing applications.