Simulation of thermal and mechanical performance of laser cladded disc brake rotors

Open access via Sage agreement Funding The authors received no financial support for the research, authorship and/or publication of this article. Acknowledgements The authors are grateful for the contributions provided by Fabrizio Girolimetti on simulation development.Peer reviewedPublisher PD

Microstructural and Mechanical Properties of Polylactic Acid /Tin Bronze Tensile Strength Bars Additive Manufactured by Fused Deposition Modelling

Tensile stress bar samples have been additive manufactured by fused deposition modelling (FDM) route by using polylactic acid (PLA)/tin bronze filament, thermal de-binding and air sintering. The samples reach sintered density of 7.42 g/cm3 or 85% of the relative density of the continuously casted CuSn10 reference. Tensile stress testing of the samples shows rather moderate mechanical properties, about half yield strength and one third maximal strength, elongation and hardness of the reference. Increase in the sample core density and elimination of large, agglomerated pores may result in largest improvement of the mechanical properties

Grey Cast Iron Brake Discs Laser Cladded with Nickel-Tungsten Carbide—\u80\u94Friction, Wear and Airborne Wear Particle Emission

Airborne wear particle emission has been investigated in a pin-on-disc tribometer equipped with particle analysis equipment. The pins are cut out from commercial powder metallurgy automotive brake pads as with and without copper content. The discs are cut out from a commercial grey cast iron automotive brake disc as cut out and as in addition to a laser cladded with a powder mix of Ni-self fluxing alloy + 60% spheroidized fused tungsten carbide and then fine-ground. Dry sliding wear testing runs under a contact pressure of 0.6 MPa, sliding velocity of 2 m/s and a total sliding distance of 14,400 m. The test results show both wear and particle emission improvement by using laser cladded discs. The laser cladded discs in comparison to the reference grey cast iron discs do not alter pin wear substantially but achieves halved mass loss and quartered specific wear. Comparing in the same way, the friction coefficient increases from 0.5 to 0.6, and the particle number concentration decreases from over 100 to some 70 (1/cm3) and the partition of particles below 7 µm is approximately halved. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Laser Cladding Treatment for Refurbishing Disc Brake Rotors : Environmental and Tribological Analysis

In this study, grey cast iron disc brake rotors are refurbished by adding a surface layer through laser cladding. Current methods to deal with replaced rotors mainly include remelting, with a minority fraction disposed in landfill. Both approaches result in a huge waste of resources and an increase in CO2 footprint. From a sustainable point of view, this study aims to evaluate the feasibility of refurbishing brake rotors by a combined environmental and tribological performance approach. A streamlined life cycle assessment is conducted to compare the environmental impacts between producing virgin grey cast iron brake rotors and refurbishing replaced brake rotors by laser cladding. It turns out that the energy consumption and CO2 footprint of the laser cladding refurbished brake rotors are 80% and 90% less than the virgin brake rotors. The results show that the refurbished brake rotor yields higher friction compared to the original cast iron utilizing the same pad material. The wear and particle emissions of the disc brake contact are in this study higher for the laser-cladded one compared to the original cast iron one

Influence of processing conditions on the microstructure and sliding wear of a promising Fe-based coating deposited by HVAF

Thermal spray is a versatile and cost-effective process to deposit wear and corrosion resistant coatings. In this work, a relatively new ‘Fe-based’ chemistry comprising boride and carbides, is explored as a ‘greener’ alternative to the relatively expensive and carcinogenic Co-based coatings to mitigate wear. The emergent thermal spray process of high-velocity air-fuel (HVAF) spraying was chosen to deposit the Fe-based coatings, with the high-velocity oxy-fuel (HVOF) also being employed solely for the purpose of preliminary comparison. Detailed characterization of the HVOF and HVAF sprayed Fe-based coatings was carried out. Microstructure, porosity, hardness and phase analysis results demonstrate the influence of processing conditions, where specific spray conditions yielded minimal undeformed particulates content, high hardness, low porosity and feedstock phase retention. Differences in microstructural features of the as-deposited coatings in relation to their processing conditions are discussed in detail. The coatings were subjected to ball-on-disc tribometry tests at different load conditions and their friction and wear performance were evaluated. The coefficient of friction results of investigated coatings concurred with their respective microstructural features. Post-mortem of the worn coating surface, the mating alumina ball surface and wear debris was performed using SEM/EDS analysis to understand the associated wear mechanisms and material transfer. This work provides new insights on identifying appropriate HVAF processing conditions to achieve acceptable microstructural features and phases in Fe-based coatings for improved wear performance