ABSTRACT
Oftenitisnotpracticaltoprepare,forexample,aone-inch longsample(asrequiredbythedesignofthesamplechamber). Aspacermadeoutofidenticalmaterialasthepushrodmaybe usedwithoutintroducingerror.Caremustbetakentoensure thatthespacermaterialhastheexactexpansionbehavioras thepushrodmaterial.Forexample,somemanufacturersmay usesinteringaidadditivesinthefabricationofpolycrystalline aluminawhichintroducesaglassyphaseintothegrainboundaries.Thiscontinuousglassyphasewillresultinadifferent expansionbehaviorofthismaterialascomparedtoalumina fabricated(sintered)withnoadditives.
