The present study uses a pin-on-disc tribometer to evaluate friction, wear, and airborne particle emissions for a rail-wheel contact. Test pins from UIC60 900A rail carbon steels were in contact with three types of test discs surfaces: R7 wheel carbon steel, laser cladding overlayed martensitic stainless steel, and laser cladding overlayed Ni-based-8% MnS self-lubricating alloy. Test results show about halving of the coefficient of friction, 0.42 to 0.22, and one ten-power lower specific pin and disc wear of discs with self-lubricating overlay compared to standard railway carbon steel contacts. Using stainless-steel overlayed discs also resulted in one ten-power lower specific disc wear, but pin wear is unchanged. Particle emission for the tests with discs with self-lubricating overlay is constant at almost 200 particles/cm3 while running in the distance is needed for the other tests. Almost all generated airborne wear particles were in the sub-100 nm range. The use of laser-cladded (LC) overlay reduced the number of airborne wear particles in the sub-100 nm range by more than a factor of 10. © 2023 Elsevier B.V.

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.

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 claddingrefurbished 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. © 2021, The Author(s).

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.

Studded tyres wear surfaces of winter roads, generating inhalable airborne particles. In this study, four concrete road materials and two stud geometries were investigated in terms of wear, road material hardness and airborne particle concentration. The sliding contactbetween studded tyres and road materials was studied using a pin-on-disc machine in a clean chamber. The results show that the normal load and the stud size have a large influence on the wear and particle emission. It was found that the wear and particle concentration are inversely proportional to the hardness of the aggregate in the road material and proportional to the sliding distance. The particle size distribution has peaks at 0.2 µm, 1 µm and 2 µm. © 2018 Elsevier B.V.

Sintered small-module gears have two important aspects that readily follow from the name: they are sintered and with a small module of 1.5875mm (DP 16). Both aspects are to date insufficiently described for gear designers despite an increased need for sintered small-module gears. This article reviews a decade of systematic experimental investigations with regard to pitting resistance of sintered small-module gears. Pitting resistance levels are listed for the common pressing/sintering/surface densification technologies of today. Currently the highest pitting resistance of 1300 MPa is achieved for pressed, sintered, rolled, re-sintered and case carburized low-alloy gears in comparison with 1800 MPa for the reference ground case-carburized 16MnCr5-wrought gears. This offset can, however, be compensated by selection of a relatively higher viscosity and lower operating temperature of the lubricating oil, if the application allows it. Thus, powder metal technology can once again contribute to a competitive total cost with high material utilization. © IMechE 2013

Sintered and sintered/gas nitrided cylinders made of low alloyed chromium steel Astaloy CrL + 0.45 Cat 7.25 g/cm3 density, have been tested for scuffing resistance and wear rate in a crossed cylinders testsetup lubricated with a commercial SAE 10W40 engine oil at 90 ◦ C. The results show large potential of1 h gas nitriding of the sintered chromium steel cylinders. The nitrided cylinders experienced safe wearat 1000 MPa and scuffing at 1100 MPa at 2.5 m/s. At 0.5 and 0.1 m/s at least up to 800 MPa the wear wasmild, as sintered chromium cylinders showed scuffing at pressure lower than 320 MPa and limited wearat 0.5 and 0.1 m/s.© 2011 Elsevier B.V. All rights reserved.