The High Melt Coating system is applied to a carbon-carbon structure and embeds HfC, ZrB2 in the outer layers. ACC High Melt builds on the time tested base material system of T-300 fibers, impregnated with phenolic resin, pyrolyzed, densified, and SiC Conversion coated For Phase 2, C-CAT proposes to team with Pratt and Whitney Rocketdyne to fully develop High Melt into a material system that when combined with the appropriate design will produce nozzle extensions for future NASA spacecraft. PWR will supply the designs for a notional nozzle extension for a 2000 lbf LOX/LCH4 lunar descent engine and a nozzle extension for a notional lunar ascent engine sized at 5500 lbf LOX/LCH4. Objectives: C-CAT engineering will work with PWR designers to insure that the nozzle extension design for each prototype is both manufacturable and will meet the technical requirements. C-CAT engineering will design and C-CAT will fabricate lay-up tools that will take into account ply shrinkage distortion and still maintain dimensional tolerances during processing. Lay-up the nozzle extensions without defects Process each nozzle extension through pyrolysis, heat treatment and coating without defects. Apply SiC Conversion Coating to the ACC High Melt material without spalling.