Friction and Wear Study of Fe-Cu-C-CaF2 Self-lubricating Composite at High Speed and High Temperature

Abstract

A novel Fe-Cu-C based self-lubricating composite is developed, wherein Calcium fluoride (CaF2) has been used as a solid lubricant. CaF2 is added in varying weight percentages of 3, 6, 9 and 12% to the base matrix comprising of Iron, Copper and Graphite (Fe-2Cu-0.8C). The composites were fabricated through Powder Metallurgy using uni-axial compaction and sintering. The developed composites were tested for friction and wear characteristics using a pin-on-disc configuration, conducted at a speed and load of 10 m/s and 20 N respectively. All tests were conducted at high temperature of 500°C for a constant sliding distance of 4000 m. Results show low coefficient of friction for the composites with 3-9 wt% CaF2 making them self-lubricating. Due to testing at high temperature, weight gain was observed in all the composites because of oxidation. The increase in weight gain was observed to be dependent on the CaF2 content. Adhesion, ploughing and delamination were identified to be the prominent wear mechanisms of the developed self-lubricating composites as revealed by SEM analysis.