Investigation of the Tribological Behaviour of Various AMC Surfaces against Brake Lining Material

Abstract

AlSi7Mg/SiCp aluminium matrix composites (AMCs) with a high ceramic content (35 vol.%) that were produced by using the field-assisted sintering technique (FAST) were subjected to tribological preconditioning and evaluated as a potential lightweight material to substitute grey cast iron brake discs. However, since an uncontrolled running-in process of the AMC surface can lead to severe wear and thus to failure of the friction system, AMC surfaces cannot be used directly after finishing and have to be preconditioned. A defined generation of a tribologically conditioned surface (tribosurface) is necessary, as was the aim in this study. To simulate tribological conditions in automotive brake systems, the prepared AMC samples were tested in a pin-on-disc configuration against conventional brake lining material under dry sliding conditions. The influence of the surface topography generated by face turning using different indexable inserts and feeds or an additional plasma electrolytic treatment was investigated at varied test pressures and sliding distances. The results showed that the coefficient of friction remained nearly constant when the set pressure was reached, whereas the initial topography of the samples studied by SEM varied substantially. A novel approach based on analysing the material ratio determined by 3D surface measurement was developed in order to obtain quantitative findings for industrial application.

Ultrasonic-Vibration-Superimposed Face Turning of Aluminium Matrix Composite Components for Enhancing Friction-Surface Preconditioning

“…Former investigations by the authors of this paper on AMC friction surfaces showed that the kinematic roughness generated by face turning influences the formation behaviour of the tribosurface [12,13]. The results showed that specimen surfaces with higher values for the roughness led more quickly to a homogeneously closed tribosurface.…”

“…The machined AMC specimens were prepared for the tribological test according to previous investigations [12,13]. The AMC specimens were fixed in a pin-on-disc test bench (SRV, Optimol Instruments Prüftechnik GmbH, Munich, Germany).…”

“…The number of rotations/local passages during the test duration was, therefore, about 3.700, and was similar for each conducted test. A detailed description of the setup and parameter identification has already been published ( [13]). To identify the differences between the surface microstructures generated by various face-turning parameters and tribosurface formation, the pin-on-disc test parameters were evaluated.…”

“…Firstly, the change in the length of the brake-lining material pin was documented. Secondly, the mean friction coefficient and the adjustment relevelling rate (AR rate, see [13]) were determined, as soon as the progressively increased test pressure, and thus, the systems' friction condition, were constant.…”

Towards Closed-Loop Recycling of Ceramic Particle-Reinforced Aluminium Alloys: Comparative Study of Resistance-Heating Sintered Primary and Solid-State Recycled Secondary SiCp/AlSi7Mg Composites

“…This trend already exists especially due to the beginning commercialisation of AMC brake discs, although mass production processes are currently lacking. Despite the nearly wear-free behaviour of highparticle-reinforced AMC in tribological contact with semi-metallic brake lining material [2], a significant amount of AMC scrap with a high content of ceramic hard phases is to be expected at the end of the latest car life cycle.…”