Processing of Aluminium-Silicon Alloy with Metal Carbide as Reinforcement through Powder-Based Additive Manufacturing: A Critical Study

Powder-based additive manufacturing (PAM) is a potential fabrication approach in advancing state-of-the-art research to produce intricate components with high precision and accuracy in near-net form. In PAM, the raw materials are used in powder form, deposited on the surface layer by layer, and fused to produce the final product. PAM composite fabrication for biomedical implants, aircraft structure panels, and automotive brake rotary components is gaining popularity. In PAM composite fabrication, the aluminium cast alloy is widely preferred as a metal matrix for its unique properties, and different reinforcements are employed in the form of oxides, carbides, and nitrides. However, for enhancing the mechanical properties, the carbide form is predominantly considered. This comprehensive study focuses on contemporary research and reveals the effect of metal carbide’s (MCs) addition to the aluminium matrix processed through various PAM processes, challenges involved, and potential scopes to advance the research.

The Role of Graphitic Carbon Nitride in the Formulation of Copper-Free Friction Composites Designed for Automotive Brake Pads

In this study, graphitic carbon nitride (g-C3N4, labelled as gCN) was tested in the formulation of copper-free (Cu-free) friction mixtures, which are potentially interesting for brake pad manufacturing. Three formulations of friction composites were prepared starting from a common Cu-free master batch: (i) without graphite, (ii) with graphite and (iii) with gCN. The mixtures were pressed in the form of pins by hot-press moulding. The friction-wear performance of the prepared pins was investigated using a pin-on-disc (PoD) test at room temperature (RT), high temperature (HT) (400 °C) and, again, at room temperature (H-RT). The values of the friction coefficient (µ) for the composites with gCN (or graphite) were as follows: (i) RT test, µRT = 0.52 (0.47); (ii) HT test, µHT = 0.37 (0.37); (iii) RT after the HT tests, µH-RT = 0.49 (0.39). With respect to wear resistance, the samples with graphite performed better than the samples without this solid lubricant. To the best of our knowledge, this is the first report regarding the evaluation of the role of gCN in friction composites designed for automotive brake lining applications. The results indicate the main role of gCN as a soft abrasive.

Review of automotive brake lining materials and their tribological properties

Brake lining material properties are considered an essential aspect of the safe operation of vehicles. The presented paper aims to present a comprehensive review of brake lining materials and their tribological properties including the proposed materials, their advantages and disadvantages, analysis of results, and test rig experiments. The first section of the paper includes brief information on brake lining materials, friction modifier additives, and recent developments in friction additives. The second section discusses the tribological performance of brake lining materials. Furthermore, the key mechanisms of the friction layer produced on the worn brake lining surface have been explained microscopically (HRTEM). Part of this review is devoted to demonstrating current research gaps and challenges related to brake performance in automotive for further research. In brief, this review study is highly significant, as it provides more detailed information regarding the performance of brake lining materials.

New Developments in Carbon-Based Nanomaterials for Automotive Brake Pad Applications and Future Challenges

The proper functioning of automotive brake pads is of utmost importance to ensure the safety of passengers. Therefore, brake pad materials must be chosen with utmost precision and care to ensure their optimal functioning for long durations. Through a thorough literature review, it is found that the materials used currently for this purpose pose multiple discrepancies. Therefore, it is imperative to shift our focus towards nanomaterials, as they are one of the essential novel materials in this field. This study discusses the multiple constituents used in commercial brake pads, their role in improving and stabilizing their operation, and their desired properties to achieve optimal functioning. Parallelly, this study also reviews some of the potential organic and carbon nanomaterials that could prove to provide tough competition to currently utilized materials for brake pad applications. From this review, the major future commercial brake pad materials obtained include the likes of banana peel powder, crab shell powder, coconut fibers, stark corn fibers, metal oxide composites, metal nitride composites, multiwalled carbon nanotubes, and hybrid nanocomposites. These materials are studied on the basis of their performance under high-frictional force applications and analyzed by considering their mechanical, chemical, thermal, and tribological properties. Carbon nanotube-based composites showed improved tribological and braking performances making them more attractive than the materials in commercially available brake pads. In addition to these, the effects of usage of such nanomaterials on the environment and health are reviewed, in order to understand the feasibility of utilization of nanomaterials in automotive brake pad applications. From this analysis, this work suggests that there are a variety of nanomaterials that prove to be capable of automotive brake pad applications and, with further research and technological developments, would prove to be an asset to the automotive brake pad industry.

Prediction of squeal instabilities of a FEM automotive brake with uncertain structural and environmental parameters with a hybrid surrogate model

This study focuses on the prediction of the stability behaviour of an industrial automotive brake system under structural and environmental uncertainties. Uncertainties are modelled with a random distribution or an interval and are propagated with a hybrid surrogate model associating polynomial chaos and kriging. The objective is to create a surrogate model of each eigenvalue computed with the CEA. As the modes can be tracked only when unstable, the effective size of the training sets can become extremely small. Despite this limitation, it is shown the hybrid meta-model is still able to predict the stability of the brake system. Moreover, the hybrid meta-model gives a direct access to the mean and variance of the eigenvalues with respect to the design parameters without any additional MCS. By considering different PDF for the friction coefficient, it is shown it has a high influence on the stability and the latter should be accurately estimated.

Automotive Brake Disc Materials

The book reviews the current status of vehicle brake disc materials and technology. Topics covered include friction materials for braking systems, material characterization, mechanical properties, corrosion processes and methods for disc break investigations. The book references 158 original resources with their direct web links for in-depth reading.