Effect of bimodal size particles reinforcement on the wear, friction and mechanical properties of brake composites

Abstract

Novel bimodal size ranges of ceramic particles (SiC (115 μm)and SiO 2 (1.2 μm) (labelled as SIL)), SiC (115 μm) and mullite (4 μm) (labelled as MUL)) iron matrix composite structures were processed by powder metallurgy. The physical, mechanical and tribological properties were evaluated for these composites. The dry sliding wear and friction tests were conducted at ambient temperature and 60% humidity in a laboratory scale dynamometer for braking material applications. We have selected four braking speeds (5, 10, 15 and 20 m/s) and two braking loads (100 and 200 N) to cover the broad spectrum of braking conditions experienced in a typical automobile and military aircrafts. The particle morphology, microstructure, wear surface morphology and mechanisms were discussed based on the scanning electron microscopy equipped with energy-dispersive spectroscopy, optical microscope and stereoscope examinations. Our work provides the following important results: (1) bimodal particle structure composites can be easily fabricated using powder metallurgy, (2) the wear resistance and the braking performance of bimodal particle-reinforced composites is superior than the typical automobile asbestos or non asbestos, metallic, semi-metallic and Al/SiC composites based brake materials, (3) Between mullite and silica reinforcements, the mullite-reinforced bimodal composite (MUL) provides higher wear resistance, braking performance (high friction coefficient, stopping distance, stopping time), higher flexural strength, stiffness and hardness. These improvements are attributed to the better powder consolidation, high elastic modulus of mullite and better distribution of mullite in the iron matrix, (4) Increasing sliding speed decreases the wear rate and increases the friction coefficient in the MUL composites, whereas the variations in the wear rate and the friction coefficient are random in the SIL composites and (5) the combined effects of abrasive, delamination, oxidation and tribofilm-controlled wear mechanisms are observed to be operative at all sliding speeds and load conditions for both the composites.

Influence of abrasives and graphite on processing and properties of sintered metallic friction materials

“…With respect to normal pressure, there are not significant changes in μ when pressure increases. This behavior has also been found in other studies [18, 23].…”

Mechanical and Tribological Properties of Aluminum-Based Metal-Matrix Composites

“…The authors showed that a ratio of 3:1 (between the smaller size particles and bigger particles) resulted in the maximum nano-hardness and minimum wear rates. Prabhu [ 101 ] processed Fe-based composites where the Fe matrix was reinforced with bimodal-size dissimilar nature (SiC and SiO 2 ) particles through powder metallurgy. The author showed that the addition of bimodal-size particles improves the wear resistance of the composites significantly by comparison with single-size-particle reinforced composites.…”

Microstructural Evolution, Tensile Failure, Fatigue Behavior and Wear Properties of Al2O3 Reinforced Al2014 Alloy T6 Heat Treated Metal Composites

“…The maximum wear rate is observed in the un-heat treated Al2014 matrix alloy. The possible reason for this is extensive subsurface deformation, high adhesive metal-metal contact that assisted surface shear strain, and the absence of load-bearing particles [55][56][57]. The difference in wear rate of the Al2014 matrix alloy and Al2014-15 wt.% Al 2 O 3 composites before and after heat-treated conditions with variable loads is shown in Figure 8.…”

“…The maximum wear rate is observed in the un-heat treated Al2014 matrix alloy. The possible reason for this is extensive subsurface deformation, high adhesive metal-metal contact that assisted surface shear strain, and the absence of load-bearing particles [55][56][57].…”