H 3915 (OTTO) Hafnium(IV) carbide, 99.8% Cas 12069-85-1 - used in rocket nozzle, especially for re-entry space rocket nose cone. H 3915 (OTTO) Hafnium(IV) carbide, 99.8% Cas 12069-85-1 - used in coatings. H 3915 (OTTO) Hafnium(IV) carbide, 99.8% Cas 12069-85-1 - used for preparation of ultra-high temperature ceramics.