Effect of Carbon Content on Friction and Wear Properties of Copper Matrix Composites at High Speed Current-Carrying

Abstract

The copper matrix composites were prepared by spark plasma sintering (SPS). The current-carrying friction and wear tests were carried out on a self-made HST-100 high-speed current-carrying friction and wear tester, and the effect of the graphite content on the current-carrying friction and wear properties of the composite material was studied. The results show that with an increase in graphite content, the average friction coefficient and wear rate of the two materials decreased significantly, the fluctuation amplitude of the friction coefficient was also significantly reduced, and the average friction coefficient of copper-coated graphite composite with graphite content of 10 wt.% was 0.100; when the graphite content was the same and more than 5.0 wt.%, the average friction coefficient and wear rate of copper–graphite composites were slightly higher than copper–copper-coated graphite composites; the current-carrying efficiency and current-carrying stability of the copper matrix composite were obviously higher than that of copper material; there was a mechanical wear area and arc erosion area on the wear surface of the composites, with the increase in graphite content, the adherence and the tear of the mechanical wear area weakened, the rolling, plastic deformation increased, and the surface roughness decreased obviously. The surface roughness of the wear surface of copper–copper-coated graphite composites with graphite content of 10 wt.% was 3.17 μm. The forms of arc erosion included melting and splashing, and were mainly distributed in the friction exit area.

Effect of Rotation Speed on the Tribological and Conductive Behaviors of Rolling Current-Carrying Cu Pairs

“…In previous work of sliding current-carrying contact, the friction coefficient and the conductivity often worsen concurrently and had a strong coupling relationship. 26,27) However, in present results, the real-time current showed obvious pulse fluctuation while the friction coefficient still remained stable (Fig. 3 and Fig.…”

Friction Modifiers Optimization on Tribological Properties of Non-asbestos Organic (NAO) Brake Pad by DoE-Taguchi Method

“…C and O elements at a higher level indicate oxidation on the sample, which might occur from the thermal oxidation of organic and inorganic ingredients as graphite and MoS2. In previous studies, graphite decomposed into the gas at elevated temperature [35]. Whereas, MoS2 reacted with oxygen and transformed into oxide form (MoO3) at 540 °C [22,43].…”

“…In the previous studies, the increase in graphite content (0 -10 vol.%) in friction composite significantly reduces wear rates [31]. Yang et al [35] also reported that graphite enhancement (2.5 -10 wt.%) could reduce the average friction coefficient, friction fluctuation, and wear rate.…”

“…The low content of graphite in the friction material causes the occurrence of adhesion. It prevents the formation of the friction layer since only a few graphites may be distributed on the friction surface [35]. Thereby, the low content of graphite increases the roughness of the surface and instability of the friction coefficient.…”

“…This condition can prevent adhesion and contribute to forming a friction layer on the friction interface [36][37]. The friction layers prevent the hard particles from sticking in the friction interface [35] and inhibit the micro-welding of metallic ingredients [38], thereby protecting the surface from excessive wear [12,39].…”