Abstract
The effects of silicon carbide (SiC) as an abrasive on friction and wear performance of nonasbestos organic brake friction composites were studied using a tailored series of samples with 0—14.6 vol.% SiC. Friction coefficient of the friction composites containing SiC increased with increasing SiC content; especially, the thermal fade of the friction material without SiC (SiC-0) improved. The specific wear rate of the friction composites containing SiC increased with SiC added up to 9.0 vol.% and then turned down, but the negative specific wear rate of SiC-0 obviously improved. With elevating friction temperature, an increase in both friction coefficient and wear of all the samples was observed. The extension evaluation method represents an effective tool to rank the friction composites. The ranking of five friction materials, described in the weighted average dependent degrees, was evaluated in the order from the best to the worst: SiC-3.4, SiC-14.6, SiC-5.6, SiC-0, and SiC-9.0. The formulation SiC-3.4 exhibited the best overall quality, and was recommended for future optimization of the brake friction composites. Microstructures of friction surfaces of the brake friction composites were characterized using scanning electron microscopy with energy dispersive X-ray microanalysis and electron microprobe analysis, and phase analysis was performed using X-ray powder diffraction methods. Formation and development of the friction layer were discussed. The friction layer, known as secondary plateaus, was easily formed and it grew among the adjacent or lined-up primary plateaus, which were helpful for improving the friction stability and wear resistance.
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