Role of Al₂O₃ in Semi-Metallic Friction Materials and its Effects on Friction and Wear Performance

Abstract

In this work the semi-metallic friction composites with moderately increased content of Al 2 O 3 (0, 3.4, 5.6, 9.0, and 14.6 vol%) were successfully fabricated by casting technology and their tribological properties were evaluated. The character of friction surfaces was confirmed by SEM. The sample with 5.6 vol% of Al 2 O 3 offers the best tribological property among the prepared formulations, and is characterized by high and steady friction coefficient (about 0.45) and low wear. With the temperature increasing, the stibnite patches population on friction surface increases and individual steel fibers spread due to their plastic deformation to form larger primary contact plateaus. The area covered by contact primary plateaus decreases with the alumina content increasing.

Effects of walnut shells on friction and wear performance of eco-friendly brake friction composites

“…There are two basic categories of friction materials for an automotive brake lining application, semi-metallic and non-asbestos organic (NAO). 1,2 Asbestos has been used for a long time in brake linings, but strictly prohibited due to its carcinogenicity in recent years. 3 Semi-metallic friction composites, as the most common brake lining materials, usually consist of a high amount of metallic components (typically >50%), covering iron powders, copper fibers, brass chips, molybdenite, and so on.…”

Brake Pad Performance Characteristic Assessment Methods

“…Fu et al [40] evaluated the flax fibers, basalt fibers and the friction surfaces in SEM images of brake pads reinforced with flax fibers. Moreover, Fan et al [41] found that the most abrasion was observed in the SEM images of the sample with the highest Al2O3 content. According to the SEM images, with the increase in temperature, the stibnite patch population on the friction surface increased and individual steel fibers were deformed and spread.…”

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

“…On the other hand, the addition of Al2O3 in the friction material causes the sample to be less sensitive to temperature increases during sliding. Thus, it resulted in a stable friction coefficient [33]. Singh et al [34] reported that the presence of 5 wt.% Al2O3 in non-asbestos brake composite resulted in the highest friction stability (0.87) and friction variability (0.48).…”

“…In previous studies, materials such as ZrSiO4 [13], Al2O3 [14][15][16], SiO2 [17], SiC [13], h-BN [18,19], Sb2S3 [20], MoS2 [21], and graphite [22] have been studied. These studies only focused on understanding the individual effects of abrasives and solid lubricants on the brake friction performances experimentally.…”