The fibrous carbon material is then impregnated with a second thermosetting resin containing a boron compound and, optionally, a refractory metal capable of reacting with {HEAD ~ boron} to form {TAIL ~ a metal boride} 
The fibrous carbon material is then impregnated with a second thermosetting resin containing a boron compound and , optionally , a refractory metal capable of reacting with { HEAD ~ boron } to form { TAIL ~ a metal boride }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL