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.

Analysis of thermo-elastic and physical properties of recycled 2017 Aluminium Alloy/Gp composites: thermal management application

“…The appearance of porosity is in agreement with the results acquired in previous studies [38][39][40]. This behavior will affect the denser character of composites which is confirmed by the decrease of the sintered density As graphite content was increased to 10 wt% of Graphite ( figure 7(c)), the porosity will have a relevant number.…”

“…This can be attributed to the lower density of graphite compared to the 2017 Aluminium alloy. Furthermore, the addition of graphite particles reduce the contact area between 2017 Aluminium alloy particles which provides a poor network and a reduction of the sintered density agreeing with many researches [4,[38][39][40]. Also, by exploring the measured densities of composites as function of graphite content for different sintering time and temperature conditions and according to the equation (2), the porosity of composites is calculated and plotted in figure 5(b).…”

“…For instance, it is evident from the figure 5(b) that the porosity value after sintering at 550°C is only 16.4%, compared to 19% obtained after 450°C. This conclusion is justified by the diffusion phenomenon which is thermally activated according to many authors [4,39,40,42,43]. In this regard, they explained that the best particle bonding is taking place at a high temperature, and consequently, the pore reduction has a direct relationship with the sintering process.…”

Wear Behavior of Copper–Graphite Composites Processed by Field-Assisted Hot Pressing

“…Thus, copper-graphite composites constitute an attractive material for many applications, such as electrical brushes, bearings, and especially tribological engineering parts [1][2][3]. Several techniques have been used to produce copper-graphite composites, such as conventional powder metallurgy, microwave sintering, friction stir processing, and field-assisted sintering [4][5][6][7][8][9]. Generally, studies have shown that copper-graphite composites with finer particle sizes and better distribution exhibit higher load withstanding capacity and lower friction coefficient and wear rate due to a thick graphite layer that forms at the contact surface [5][6][7].…”

“…Then, a more continuous graphite layer which reduces the wear debris size is produced. D. Nayak and M. Debata [7] fabricated copper-graphite composites by the powder metallurgy route to study the effect of composition and milling time on the mechanical properties and wear resistance. They found that increasing the milling time yielded a better distribution and finer particle size, which led to a lower wear loss.…”