A STUDY OF MICROSTRUCTURE AND WEAR BEHAVIOUR OF TIB2/AL METAL MATRIX COMPOSITES

Abstract

TIB₂ REINFORCED ALUMINIUM METAL MATRIX COMPOSITES (MMCS) WITH 5, 10 AND 15% WERE MADE BY STIR CASTING TECHNIQUE. EFFECTS OF SLIDING VELOCITY ON THE WEAR BEHAVIOR AND TRIBOCHEMISTRY OF THE WORN SURFACES OF BOTH MATRIX AND COMPOSITES SLIDING AGAINST EN24 STEEL DISC HAVE BEEN INVESTIGATED UNDER DRY CONDITION. A PIN-ON-DISC WEAR TESTING MACHINE WAS USED TO FIND THE WEAR RATE, IN WHICH EN24 STEEL DISC WAS USED AS THE COUNTER FACE, LOADS OF 10-60N IN STEPS OF 10N AND SPEEDS OF 100, 200, 300, 400 AND 500 RPM WERE EMPLOYED. THE RESULTS SHOWED THAT THE WEAR RATE OF BOTH THE MATRIX ALLOY AND MMCS INCREASED WITH INCREASE IN LOAD AND SLIDING SPEEDS. HOWEVER, THE MMCS EXHIBITED LOWER WEAR RATE THAN THE MATRIX ALLOYS. THE RESULTS SHOWED A CRITICAL APPLIED LOAD, AT WHICH THERE EXISTS A TRANSITION FROM MILD TO SEVERE WEAR BOTH IN THE MATRIX ALLOY AND MMCS. THE TRANSITION LOADS FOR THE MMCS WERE MUCH HIGHER THAN THAT OF THE MATRIX ALLOY. THE TRANSITION LOADS INCREASED WITH THE INCREASE IN TIB₂, BUT DECREASE WITH THE INCREASE IN SLIDING SPEEDS. THE SEM AND EDS ANALYSES WERE UNDERTAKEN TO CLARIFY THE EFFECT OF TIB₂ PARTICLES ON THE WEAR MECHANISM FOR EACH CONDITION.