Tribological Behavior of Phenolic Resin-Based Friction Composites Filled with Graphite

Abstract

In this paper, the influence of graphite (Gr) on the dry sliding tribological properties of phenolic resin (PF) composites was studied under different sliding speeds of 3.1–47.1 m/s. The wear mechanism was investigated by the observation of the morphology of the transfer layer during the dry sliding process. It was found that the addition of Gr could decrease the friction coefficient and wear rate effectively, and the friction coefficient and wear rate decreased with the increase of Gr content in the range of 10–30 vol.%. The dominant wear mechanisms of PF-based friction composites changed from adhesive wear to fatigue wear (in the form of peeling-off) in the high sliding speed condition after the addition of Gr. The addition of Gr effectively reduced the sensitivity of PF-based friction materials to sliding speeds, and thus enhanced the stability of the friction coefficient. When the content of Gr was above 20 vol.%, the stability of the friction coefficient was relatively steady.

Effect of Steel Surface Roughness and Expanded Graphite Condition on Sliding Layer Formation

“…In the initial stage of the research, graphite particles are anchored to the uppermost tips of the microcavities (1). Then, as a result of the movement, the amount of graphite material on the steel surface increases (2). After 5 min of work, the visible grooves of the indoor surface are filled with graphite.…”

“…The material transfer phenomenon in a graphite-metal pair consists of the transfer of the graphite to the metal surface, so that, with time, the pair can work in graphitegraphite configuration. The literature data on this phenomenon mainly refer to the material transfer of plastics containing graphite as filler [1,2]. The study shows that graphitemodified materials form a sliding layer on the metal surface, which is a factor retarding the destruction process on friction surfaces and increases the product value of pressures and speeds at which the exploitation of the tested materials is possible [3][4][5][6].…”

Tribological Performance and Thermal Stability of Nanorubber-Modified Polybenzoxazine Composites for Non-Asbestos Friction Materials

“…Polymer composite materials composed of different reinforcements and fillers into several engineering polymers to replace metallic and ceramics are currently used in structural applications such as automotive, construction, spacecraft, marine, etc. [ 1 , 2 , 3 ]. In automotive applications, friction polymer composites such as brake pads are a key brake part because they are the component that contacts and applies pressure and friction to a vehicle’s brake rotors, resulting in stopping the wheel; in consequence, the vehicles stop moving.…”

“…However, as a reason of eco-friendly environment, asbestos-free brake pads from polymer composite materials have been developed to replace asbestos ones. Polymer friction materials currently used as brake pads can contain more than 10 different ingredients, which are often categorized into four classes of ingredients, including binder, i.e., phenolic and epoxy resins (10–30 wt%), reinforcing fibers, i.e., glass fiber, aramid fiber, and metallic fiber (5–40 wt%), friction modifiers, i.e., graphite (synthetic and natural graphite), alumina powder and metal oxides (5–35 wt%), and fillers, i.e., barium sulfate, calcium carbonate, cashew dust, and rubber dust (40–80 wt%) [ 3 , 4 ].…”

Influence of Contact Plateaus Characteristics Formed on the Surface of Brake Friction Materials in Braking Performance through Experimental Tests

“…According to Xiao et al [ 14 ] and Zhang et al [ 15 ], when the brake is applied, the rough surfaces of the brake pad and brake disc are subjected to sliding. As the brake disc, which has much higher hardness than the pad, rotates at high speed, some friction materials are removed by cutting, forming wear debris.…”