Effect of Silicon Carbide Nanoparticles on the Friction-Wear Properties of Copper-Based Friction Discs

To study the influence of nano-additives on the friction-wear characteristics of friction materials, the nano-sized silicon carbide particles which have excellent chemical and physical properties are considered to add in composite to form the modified friction material. The influence of the silicon carbide nanoparticles (SCN) on the friction-wear characteristics of copper-based friction materials (CBFM) is investigated via the SAE#2 (made in Hangzhou, China) clutch bench test with the applied pressure, rotating speed, and automatic transmission fluid (ATF) temperature taken into account. Moreover, the variations of friction torque and temperature are considered to evaluate the friction performance, and the variable coefficient is employed to describe the friction stability. The wear characteristics of friction materials are investigated by the disc changes in thickness and micro-morphology. The results show that the CBFM with SCN can provide a higher friction torque, which increased by 30% to 50% compared with CBFM. The variable coefficient of CBFM with SCN changes from 674 to 52 with the rotating speed raised from 600 rpm to 3000 rpm, which shows that the friction stability is relatively worse. Furthermore, the micromorphology shows that the CBFM with SCN has lower porosity and surface roughness, which increases the microscopic contact area and the coefficient of friction (COF). Simultaneously, the reduction in porosity also leads to a decrease in the cooling quality, bringing about a rapid temperature rise. Thus, the wear amount of CBFM with SCN increases significantly, especially for the friction disc in the axial middle position.

Brake friction composite materials: A review on classifications and influences of friction materials in braking performance with characterizations

Brake friction materials play an important role in automobiles to reduce speed and to stop the vehicles. Advances in friction materials were updated to ensure effective performances in braking systems and to provide the maximum safety and comfort. Presently eco-friendly friction materials have been used as a replacement for conventional friction materials. Many synthetic and natural products were identified and claimed as better alternatives to banned toxic materials like asbestos and copper. Friction materials developed from natural products are eco-friendly and assure a great promise when applied in modern vehicles. To develop innovative formulations, basic knowledge of common ingredients and their effects in friction materials was needed. This review focuses mainly on providing detailed information about the common ingredients used, processing methods and the characteristics of brake friction materials.

Effects of Particle Size and Composite Composition of Durian Peels and Banana Midribs' as Reinforcement Components on Resin-Based Brake Pad Performance

This study aims to determine the effect of particle size and material composition on the performance of resin-based brake pads. Experiments were carried out by mixing 75% UPR with durian peel and banana midribs fibers using ratios of 1/1, 3/2, and 2/3 at particle sizes of 104 and 250 μm. The experimental results shows that decreasing the particle size improves the mechanical properties of brake pads, but gives a high wear value and a low coefficient of friction. In addition, an increase in the percentage of banana midrib fibers as a whole provides better brake pad performance. The results of the comparison between commercial-based brake pads confirm that agricultural waste is potential as an alternative to friction materials in brake pads. Brake pad with a fiber ratio of 2/3 104 μm had highest values of hardness, wear and friction coefficient, namely 20.33 N/cm3, 2.02 x 10-4 g/s.mm2, and 0.2465. while the 1/1 250 μm and 3/2 250 μm had the lowest coefficient values and compressive strength of 0.1195 and 9.14 N/cm3. This study demonstrates the use of biomass waste as an alternative to friction material to overcome the dangerous problem of using asbestos in brake pads.

Synergistic Performance of Expanded Graphite – Mica amalgamation based Non-Asbestos Copper-Free Brake Friction Composites

Recent advancements in brake pad applications emphasise various friction compositions that exclude toxic components such as asbestos, copper etc., in order to provide superior performance without hurting the environment, human life and aquarium species. In this work, brake friction materials were fabricated by the conventional manufacturing process as standard brake pads using expanded graphite with the synergetic effect of thermal resistant material mica flakes. Six standard brake pads were produced based on varying the expanded graphite by 16, 14, 12, 8, 6 & 4 weight percentage, which is compensated using the Mica flakes by 4, 6, 8, 12, 14 & 16 weight percentage, fixing the composition of other ingredients and designated as BM01, BM02, BM03, BM04, BM05 and BM06. Physical, chemical and mechanical, characterisations of the formed friction materials were carried out in accordance with IS 2742 and ISO 6312. A full-scale inertia brake dynamometer was used to determine the fade, recovery characterisations with the pressure and speed sensitivity as of JASO-C-406. From the experimental observations, BM03 friction composites reveal excellent low fade and high recovery characteristics because of the integrated effect of expanded graphite (superior lubricity) & mica (good thermal stability). Worn surface analysis was studied with the help of a scanning electron microscope. The inclusion of expanded graphite-mica as a hybrid “lubricant-filler” combination in composite materials for friction braking application results in performance synergism.

Dynamometric Investigation on Airborne Particulate Matter (PM) from Friction Materials for Automobile: Impact of Abrasive and Lubricant on PM Emission Factor

Reduction of non-exhaust airborne particulate matter (PM), leading to adverse effects in respiratory system, is an urgent task. In this work, we evaluated the impact of raw materials in friction materials on PM emission due to brake wear for passenger vehicle. Time- and temperature-dependent measurements using dynamometer were made for low-steel friction materials with varied abrasives and lubricant(graphite). The brake emission factor (BEF) for graphite of varied sizes ranged from 6.48 to 7.23 mg/km/vehicle. The number concentration indicates that smaller graphite (10 μm) produces more nano-sized particles than larger size (700 μm) by >50%. Depending on abrasives, BEF was found to be varied as large as by three-times, ranging from 4.37 to 14.41 mg/km/vehicle. As hardness of abrasive increases (SiC > Al2O3 > ZrSiO4), higher BEF was obtained, suggesting that abrasive wear directly contributes to emissions, evidenced by surface topology. Temperature-dependent data imply that particle emission for SiC abrasive is initiated at lower speed in WLTC cycle, where disc temperature (Tdisc) is ~100 °C, than that for ZrSiO4 (Tdisc >120 °C). Analysis of wear debris suggests that larger micron-sized particles include fragmented Fe lumps from disc, whereas smaller particles are, in part, formed by combination of oxidation and aggregation of nano-sized particles into small lumps.

Full-scale dynamometer tests of composite railway brake shoes: Effect of the resin-rubber ratio on friction performance and wear

Designing a friction material for a brake system entails considering the effects of each constituent and the interactions that they may present between them. In the present work, a characterization of the influence of the resin-rubber ratio in a brake block material is carried out. Railway brake shoes were produced and tested in a full-scale railway dynamometer in demanding conditions. The brake blocks had also their physical and mechanical properties tested. The progressive addition of resin was proven to heavily affect the friction level in dry and wet conditions. Interestingly, the use of 5% of resin showed significantly higher friction in wet conditions. This composition also presented more severe metal pick-up. The nature of the binder also affected wear rates (which were lower for lower resin contents), and the wear mechanism. The sample using only rubber presented thermal cracks and heavier delamination as specific failure modes. Differences on the microstructure of the friction materials were observed depending on the binder. A 5% of resin appears as a very interesting choice to avoid friction loss in wet environments without incurring in high wear rates, as long as metal pick-up is by different means diminished. Otherwise, a 100% of rubber as a binder grants the instantaneous friction stability that is often threaten by thermal fade.

Mechanisms of the copper third body as an interfacial media on copper matrix friction materials with different compositions

Purpose This paper aims to reveal the effects of the copper third body on different copper matrix friction materials with a novel experimental way called “exogenous powder.” Design/methodology/approach An accurate adding device of exogenous copper powder was designed to control the flow rate. The tribological properties with and without exogenous copper powder were investigated by a pin-on-disc tribometer during dry sliding. Findings Experimental results indicate that the Cu addition tends to increase the friction coefficient. For pure Cu material, the exogenous copper third body exhibits poor fluidity on the friction surface, causing serious adhesive wear on the friction interface. For the Cu 90% + 10% Gr material, the plasticity of exogenous copper powder may intensify the deformation of the third body of the surface, presenting layered accumulation distribution. For the pure Cu and Cu 95% + 5% SiO2 material, the Cu addition makes the composition and density of the third body uneven in the direction of depth. Originality/value The role of the copper component on different materials is revealed from a new perspective, and the relationship between the third body structure and the friction properties is explored.