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