| 1. |
- Ali, Nashit, et al.
(författare)
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Friction, wear, and airborne particle emissions from rail-wheel contact with laser cladded overlays-A pin-disc tribometer simulation
- 2023
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Ingår i: Wear. - Amsterdam : Elsevier BV. - 0043-1648 .- 1873-2577. ; 518
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Athanassiou, N., et al.
(författare)
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Simulation of thermal and mechanical performance of laser cladded disc brake rotors
- 2022
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - London : SAGE Publications Ltd. - 1350-6501 .- 2041-305X. ; 236:1, s. 3-14
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Tidskriftsartikel (refereegranskat)abstract
- Disc brakes wear during braking events and release airborne particulates. These particle emissions are currently one of the highest contributors to non-exhaust particle emissions and introduce health hazards as well as environmental contamination. To reduce this problem, wear and corrosion-resistant disc coatings have been implemented on grey cast iron brake disc rotors by using various deposition techniques such as thermal spraying and overlay welding. High thermal gradients during braking introduce risks of flaking off and cracking of thermally sprayed coatings with adhesive bonding to the substrate. Overlay welding by laser cladding offers metallurgical bonding of the coating to the substrate and other benefits that motivate laser cladding as a candidate for the coating of the grey cast iron brake discs. This study aims to investigate the effect of laser cladding on the thermal and thermo-structural performance of the coated grey cast iron brake discs. Therefore, thermal and thermo-stress analysis with COMSOL Multiphysics 5.6 software is performed on braking events of grey cast iron brake discs as non-coated – reference and laser cladding coated with stainless steel welding consumables. The Results demonstrated that surface temperatures were more localised, overall higher in the laser cladded coating with over three times the stresses attained of reference grey cast iron discs. The output of the simulations has been compared by tests found in the literature. Laser cladding presented higher reliability and braking performance, nonetheless requiring the evaluation of its thermal impact on other system components.
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| 3. |
- Bergseth, Ellen, 1979-, et al.
(författare)
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Effects of thrust washer bearing surface characteristics on planetary gear train wear
- 2019
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Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 432-433
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Tidskriftsartikel (refereegranskat)abstract
- Thrust washers in spur planetary gears are placed between the planet wheel and planet carrier and act as spacers and wear pads. Metal to metal sliding contact between the planet wheel – washer – carrier causes frictional power losses that, combined with starved lubrication, may cause high contact temperatures and thermo-mechanical effects that potentially trigger thermo-elastic instabilities and excessive local wear. The planetary gear system would benefit from a low-friction interface between the washer and the planet wheel. Five washers with different surface treatments were tested in a full-scale gear rig. These tests were also replicated as closely as possible in a pin-on-disc tribometer. The following types of finishing material treatments were studied: a chemical nickel coating plus polymer on a nitro-carburised surface, a combination of nitro-carburization and solid lubricant layers, electroless deposited chemical nickel coating plus polymer, nitro-carburizing, and manganese phosphating. The frictional results indicate that tribometer tests can be used to compare and classify new washer materials. Lab scale tests show that a new experimental self-lubricating tribomaterial that was applied with laser cladding has a promising potential to increase planetary gear train robustness and service life, especially if the surface is fine grinded.
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| 4. |
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| 5. |
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| 6. |
- Dizdar, Senad, 1965-, et al.
(författare)
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Friction and wear characterization of sintered low alloyed chromium steels for structural components
- 2011
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Ingår i: Wear. - Amsterdam : Elsevier. - 0043-1648 .- 1873-2577. ; 273:1, s. 17-22
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Dizdar, Senad, et al.
(författare)
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Grey Cast Iron Brake Discs Laser Cladded with Nickel-Tungsten Carbide-Friction, Wear and Airborne Wear Particle Emission
- 2020
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Ingår i: Atmosphere. - Basel : MDPI. - 2073-4433. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- 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/cm(3)) and the partition of particles below 7 mu m is approximately halved.
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| 8. |
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| 9. |
- Dizdar, Senad, 1965-, et al.
(författare)
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Microstructural and Mechanical Properties of Polylactic Acid /Tin Bronze Tensile Strength Bars Additive Manufactured by Fused Deposition Modelling
- 2022
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Ingår i: Advances in Transdisciplinary Engineering. - Amsterdam : IOS Press. - 9781643682686 - 9781643682693 ; , s. 566-579
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 10. |
- Dizdar, Senad, 1965-
(författare)
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Pitting resistance of sintered small-module gears
- 2013
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - London : Sage Publications. - 1350-6501 .- 2041-305X. ; 227:11, s. 1225-1240
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Tidskriftsartikel (refereegranskat)abstract
- 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
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