These sealing areas are preferably made by coating or impregnating these areas of the substrate with a silicon carbide powder bonded together with about 2% of Teflon or Teflon like {HEAD ~ polytetrafluoroethylene material} to hold {TAIL ~ the powdered material} in its compacted condition 
to hold
These sealing areas are preferably made by coating or impregnating these areas of the substrate with a silicon carbide powder bonded together with about 2 % of Teflon or Teflon like { HEAD ~ polytetrafluoroethylene material } to hold { TAIL ~ the powdered material } in its compacted condition
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