Wear Behavior of Commercial Copper-Based Aircraft Brake Pads Fabricated under Different SPS Conditions

Kyung Il Kim,Kyung Taek Kim,Kyu Hwan Oh,Jongbeom Kim,Hyunjong Lee

doi:10.3390/cryst11111298

Kyung Il Kim, Kyung Taek Kim + Show 3 more

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https://doi.org/10.3390/cryst11111298

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Abstract

Understanding the wear behavior of Cu-based brake pads, which are used in high-speed railway trains and aircraft, is essential for improving their design and safety. Therefore, the wear mechanism of these pads has been studied extensively. However, most studies have focused on the changes in their composition and not the effects of their manufacturing conditions. In this study, we fabricated commercial Cu-based brake pads containing Fe, graphite, Al2O3, and SiO2 using spark plasma sintering under different conditions. The microstructures and mechanical properties of the pads were investigated. The pads were tribo-evaluated using the ball-on-disc test under various load conditions. Their worn surfaces were analyzed using X-ray diffraction analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and confocal microscopy in order to elucidate their wear mechanism. In addition, the dynamometer test was performed to confirm whether their wear behavior would be similar under actual conditions. Finally, a comparative analysis was performed using the ball-on-disc test. The results indicated that the brake pads with the same composition but fabricated under different sintering conditions exhibited different wear characteristics. We believe that this research is of great significance for understanding the wear mechanism of Cu-based brake pads and improving their design and hence their performance.

Highlights

Cu-based sintered materials are the most widely used friction materials for aircraft and high-speed train brake systems owing to their high thermal conductivity, wear resistance, and thermal stability [1,2,3]
20 MPa (800-20), and 800 ◦ C–40 MPa (800-40), as these pads show high relative densities among all the pads fabricated under the different conditions
The matrix of the pad is composed of Cu, and SiO2, Al2 O3, graphite, and Fe phases are distributed within the Cu matrix

Summary

Introduction

Cu-based sintered materials are the most widely used friction materials for aircraft and high-speed train brake systems owing to their high thermal conductivity, wear resistance, and thermal stability [1,2,3]. Cu-based sintered materials suffer from low hardness and undergo mechanical softening during high-temperature wear [8,9]. To overcome these disadvantages, which can have an adverse effect on properties such as the heat conductivity, it has been proposed that abrasive components such as Fe, CrFe, SiO2 , Al2 O3 , and SiC particles, which show high hardness, be mixed in the metal matrix for mechanical strengthening and increasing the friction coefficient [3,10,11,12,13,14]. Cu-based sintered composites containing matrix-strengthening metallic phases, oxide abrasives, and graphite lubricants have been suggested for use in industrial-scale applications requiring high braking energy density (250–450 J/mm2 ) [18,19,20,21]

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