TRIBOLOGICAL STUDIES OF SILICON CARBIDE -TITANIUM CARBONITRIDE COMPOSITES

Abstract

SiC carbideceramicsarepromisingmaterialformechanical,specificallytribologicalapplicationsdue to theirhighhardnessandabilitytoretainstrengthathighertemperature.Thoughlowfracturetough- ness limitsitsapplication,useofcompositespreparedbyaddingvariousreinforcementsareattractive alternative.Inthiswork,fracturebehavior,slidingwearmechanismsanderosionwearmechanisms of Siliconcarbide-titaniumcarbonitridecompositesarereported.Fracturesurfacesofmonolithic silicon carbideshowedbrittlefracturebytransgranularmodeoffracturewhereastransgranularmode of fracturealongwithgrainpulloutandparticlepulloutwasobservedintitaniumcarbonitrideadded ceramic composite.Frictionandslidingwearpropertiesofcompositeswerestudiedunderunlu- bricated moderatelyhumidenvironmentatN,10N,20Nloadingconditions.Coefficientoffriction variedbetween0.2to0.4butlittleeffectofloadwasobserved.Significantreductioninslidingwear volumewasobservedbytheadditionoftitaniumnitrideunderhighloadingslidingwearconditions. At lowerloadsreductioninslidingwearvolumeinnotprominant.WornsurfaceanalysisandRaman spectroscopyrevealsinterplayoftwodifferentslidingwearmechanisms.Atlowerloadsmechanical brittle fractureisdominantwearmechanismbutathigherloadstribochemicalwearmechanismsare also prominent.Positiveeffectonerosionwearvolumeduetotitaniumcarbonitridepresenceisalso observed.Wornsurfaceanalysisshowsmechanicalfractureasdominantmechanismformaterial removal.WithTiCNcontentincrementplasticdeformationofcompositesisincreased.