Effect of composition and milling time on mechanical and wear performance of copper–graphite composites processed by powder metallurgy route

Abstract

Copper–graphite (Cu–Gr) composites with 0, 5, 10 and 15 vol.-% graphite were processed via powder metallurgy route. The effect of composition and milling time on mechanical properties and wear resistance were studied. With increase in vol.-% of graphite, there was decrease in hardness of the composites. However, increasing milling time showed significant increase in hardness of the composites. Compressive strength of the composites containing 5 and 10 vol.-% of graphite was found to be 515 and 393 MPa respectively. The wear tests were carried out using a block-on-ring tribometer at a load of 30 N with varying sliding speed. The wear performance of the composites was found to be better with increase in milling time. The worn surfaces were analysed using FESEM. With increase in graphite content from 5 to 15 vol.-%, the coefficient of thermal expansion of the Cu–Gr composites decreased from 14·1 to 12·2×10⁻⁶/°C.

Keywords:

• Metal matrix composites (MMCs)
• Sintering
• Hardness
• Wear
• Graphite