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1 – 10 of 361J. Landa, I. Illarramendi, N. Kelling, M. Woydt, A. Skopp and M. Hartelt
This paper aims to focus on the potential for substituting molybdenum‐based piston ring coatings, which are recognized as “allrounder” by other candidate metallurgies. Another…
Abstract
Purpose
This paper aims to focus on the potential for substituting molybdenum‐based piston ring coatings, which are recognized as “allrounder” by other candidate metallurgies. Another purpose is the tribological interaction of molybdenum‐based and new triboactive/reactive piston ring coatings with low SAP, polymer‐ and metal‐free as well as bionotox engine oils with high‐viscosity indices.
Design/methodology/approach
Substoichiometric titanium dioxide composed of the Magnéli‐types phases Ti4O7 (∼17 per cent), Ti5O9 (∼66 per cent), Ti6O11 (∼17 per cent) deposited by plasma spraying, a vacuum sprayed TiO1,93 and a plasma‐sprayed titanium‐molybdenum carbo‐nitride coated piston rings were compared to a state‐of‐the‐art molybdenum‐based piston ring. They were tribologically characterized by means of BAM and SRV tests lubed under mixed/boundary lubrication by factory fill engine oils, engine oils as blends of hydro‐carbons with esters as well as prototype engine oils based on esters and polyglycols.
Findings
Overall, the molybdenum‐ and titanium‐based ring coatings wore in the same order of magnitude. The ranking depends on the test used. The BAM test favours MKP81A (PL72) more, whereas the SRV methods favour the TinO2n−1 more. The different bionotox and low‐ash prototype engine oils with reduced additive contents displayed isoperformance regarding the tribological behaviour of common and triboreactive materials. They presented no visible weakness in wear resistance, coefficient of friction and extreme pressure properties.
Research limitations/implications
The next steps have to confirm functional properties by different engine and endurance tests.
Practical implications
Titanium‐based piston ring coatings are overall more attractive, as they are primarily refined from titania, which is cheap and not rated at stock exchanges, and they present at least an isoperformance when compared with molybdenum‐based ring coatings.
Originality/value
This supplier report displays the complete methodology in order to substitute molybdenum‐ by titanium‐based piston ring coatings as well as illuminating the beneficial interaction with alternative engine oils in existing engine architectures.
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Keywords
Feng Zhu, Jiujun Xu, Xiaoguang Han, Yan Shen and Mei Jin
The paper aims to investigate the friction and wear properties of three surface-modified piston rings matched with a chromium-plated cylinder liner.
Abstract
Purpose
The paper aims to investigate the friction and wear properties of three surface-modified piston rings matched with a chromium-plated cylinder liner.
Design/methodology/approach
Samples were taken from the chromium-plated cylinder liner, Cr-Al2O3 ring, CrN ring and Mo ring. Tribo-tests were conducted on a reciprocating sliding tribometer under fully formulated engine oils. Friction coefficients and wear depths of three friction pairs were tested. Surface morphologies of cylinder liners and piston rings before and after test were analyzed.
Findings
Experimental results show that in the Cr-Al2O3 piston ring, scuffing occurred easily when matched with the chromium-plated cylinder liner; compared with the Mo ring, the CrN ring could decrease the wear depth of the piston ring from 2.7 to 0.2 μm, and the wear depth of cylinder liner remained; however, the friction coefficient increased from 0.113 to 0.123. The tribological performances of three surface-modified piston rings were significantly different when they matched with chromium-plated cylinder liner.
Originality/value
Chromium-plated cylinder liner and the three kinds of surface-modified piston rings have excellent friction and wear properties, respectively. However, according to the systematic characteristics of internal combustion (IC) engine tribology, only the appropriate cylinder liner–piston ring can improve the tribological performance of the IC engine. This paper reports the tribological performance of three surface-modified piston rings matched with a chromium-plated cylinder liner. The results can be used as reference for the design of high-power-density diesel engine.
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Zeynep Burcu Acunaş Karagöz, Selman Demirtaş, Hakan Kaleli, Levent Yüksek and Emre Çıtak
This study aims to find out friction and wear characteristics of graphene and graphene coating deposited by the Chemical Vapor Deposition (CVD) process on Honda GX270 engine…
Abstract
Purpose
This study aims to find out friction and wear characteristics of graphene and graphene coating deposited by the Chemical Vapor Deposition (CVD) process on Honda GX270 engine (nodular cast iron) piston rings experimentally investigated under boundary lubricated conditions.
Design/methodology/approach
This study consists of two stages: tribotest and engine tests. First test was conducted through a reciprocating tribotest machine and second test was conducted through an engine bench with a duration of 75h. Engine piston ring was coated with graphene by two different methods: transfer method and direct CVD method.
Findings
Graphene has been demonstrated to be a potential and promising candidate for wear- and scratch-resistant coating because it is the thinnest, lightest and strongest known nanomaterial. In this case, the ability of a mono-layer graphene film to withstand high pressure differences (6 atm) indicates its mechanical robustness. It can effectively prevent or reduce mechanical failure by strengthening and toughening the loaded surface as well as by transferring the stress throughout the structure. The positive tribological outcomes of the graphene reinforced material under various dynamic loads revealed the potential of graphene-based coatings in macro - and micro-tribology.
Originality/value
This study fulfils an identified need to study for automotive industry a coating which is wear and scratch resistant.
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Anastasios Zavos and Pantelis Nikolakopoulos
Compression rings are the main sources of frictional losses in internal combustion engines. The present paper aims to present a thermo-mixed hydrodynamic analysis for coated top…
Abstract
Purpose
Compression rings are the main sources of frictional losses in internal combustion engines. The present paper aims to present a thermo-mixed hydrodynamic analysis for coated top compression rings. To understand the coating effects, the main tribological parameters are investigated into a ring-cylinder conjunction in a motorbike engine. Furthermore, flow simulations have been carried out on how different worn profiles on the cylinder inner liner affects friction, lubricant film and localized contact deformation of the coated compression rings.
Design/methodology/approach
In this paper, the basic geometrical dimensions of the top compression ring-cylinder system are obtained from a real motorbike engine. A 2D axisymmetric CFD/FLOTRAN model is created for coated compression rings. Flow simulations are performed by solving the Navier-Stokes and the energy equations. The load capacity of the asperities is also taken into account by Greenwood and Tripp contact model. Realistic boundary conditions are imposed to simulate the in-plane ring motion. The simulation model is validated with analytical and experimental data from the literature. Under thermal considerations, the contribution of worn cylinder profiles in conjunction with different coated compression rings is presented.
Findings
This research shows that because of thermal effects, the boundary friction is higher at reversals and the viscous friction is lower because of reduced oil viscosity. As regards to the isothermal case, the viscous friction is greater because of a higher lubricant viscosity. In the case of chromium-plated ring, boundary friction was 16 per cent lower than a grey cast iron ring taking into account thermal effects. Regarding the localized contact deformation, the coated compression rings showed lower values under different worn cylinder shapes. In particular, hard wear-resistant (Ni-Cr-Mo) coating showed the slighter local deformation. Therefore, the worn cylinder profiles promote boundary/mixed lubrication regime, whereas the lobed profile of cylinder inner liner becomes more wavy.
Originality/value
The solution of the thermo-mixed lubrication model, concerning the piston ring and worn cylinder tribo pair by taking into account the coating of the top compression ring.
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Mathias Woydt, Bernard Criqui, Gérard Desplanches and Tom Linneman
The purpose of this paper is to underline the future need for OEMs to receive lowSAP, polymer‐ and metal‐free engine oils with high‐viscosity indices and to illuminate for other…
Abstract
Purpose
The purpose of this paper is to underline the future need for OEMs to receive lowSAP, polymer‐ and metal‐free engine oils with high‐viscosity indices and to illuminate for other OEMs the technical feasibility for application of alternative engine oils based on esters or blends of hydrocarbons with esters or polyglycols.
Design/methodology/approach
The strategic goal depends technically on the use of intrinsic properties of alternative base fluids, thus substituing some additives, like anti‐wear, extreme pressure and viscosity index improvers. The prone wear resistance of novel triboactive/‐reactive materials enables higher portions of mixed/boundary lubrication generated by oils with a lower viscosity.
Findings
Overall, the different bionotox and low‐ash prototype engine oils with reduced additive contents displayed isoperformance regarding the tribological behaviour against cast iron and triboreactive materials. APS‐Tin−2Cr2O2n−1 displayed an overall wear resistance comparable with grey cast iron with high‐carbon content and liner wear reduction of one order of magnitude when mated with Mo‐based rings. Both tests confirmed the potential for substituing molybdenum‐based rings by APS‐Tin−2Cr2O2n−1. The most significant reduction in “system wear” down to “zero wear” was demonstrated by mating the APS‐Tin−2Cr2O2n−1 coated piston rings with smooth machined HVOF‐(Ti,Mo)(C,N) liner coatings.
Research limitations/implications
As lubricants are today not part of the core business of automotive OEMs, the next steps have to be proposed by the petrochemical suppliers. It is recalled here that some OEMs in their history developed and produced lubricants.
Practical implications
The customer will appreciate any increase in longevity resulting in reduced maintenance. The OEM now owns, under increased solicitations, now a future‐oriented tool box in order to respond to environmental and CAFÉ demands with reasonable cost management.
Originality/value
This OEM report displays the complete methodology in order to adopt alternative engine oils in existing engine architectures.
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Thomas Wopelka, Ulrike Cihak-Bayr, Claudia Lenauer, Ferenc Ditrói, Sándor Takács, Johannes Sequard-Base and Martin Jech
This paper aims to investigate the wear behaviour of different materials for cylinder liners and piston rings in a linear reciprocating tribometer with special focus on the wear…
Abstract
Purpose
This paper aims to investigate the wear behaviour of different materials for cylinder liners and piston rings in a linear reciprocating tribometer with special focus on the wear of the cylinder liner in the boundary lubrication regime.
Design/methodology/approach
Conventional nitrided steel, as well as diamond-like carbon and chromium nitride-coated piston rings, were tested against cast iron, AlSi and Fe-coated AlSi cylinder liners. The experiments were carried out with samples produced from original engine parts to have the original surface topography available. Radioactive tracer isotopes were used to measure cylinder liner wear continuously, enabling separation of running-in and steady-state wear.
Findings
A ranking of the material pairings with respect to wear behaviour of the cylinder liner was found. Post-test inspection of the cylinder samples by scanning electron microscopy (SEM) revealed differences in the wear mechanisms for the different material combinations. The results show that the running-in and steady-state wear of the liners can be reduced by choosing the appropriate material for the piston ring.
Originality/value
The use of original engine parts in a closely controlled tribometer environment under realistic loading conditions, in conjunction with continuous and highly sensitive wear measurement methods and a detailed SEM analysis of the wear mechanisms, forms an intermediate step between engine testing and laboratory environment testing.
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Bifeng Yin, Xuefeng Wang, Bo Xu, Gongyin Huang and Xin Kuang
The purpose of this paper was to improve the frictional wear resistance properties of piston skirts caused by the low viscosity lubricant by studying the tribological performance…
Abstract
Purpose
The purpose of this paper was to improve the frictional wear resistance properties of piston skirts caused by the low viscosity lubricant by studying the tribological performance of three novel coating materials.
Design/methodology/approach
Comparative tribological examinations were performed in a tribological tester using the ring-block arrangement under two viscosity lubricants, the loading force was applied as 100 N, the speed was set to 60 r/min and the testing time was 180 min.
Findings
Under low viscosity lubricant, the friction coefficient and wear of the three coatings all increase, and the friction coefficient and wear of the PTFE coating are the largest, while the MoS2 coating has the lowest friction coefficient and wear. Under low viscosity lubricant, the friction coefficient of the MoS2 coating is 2.1%–5.4% and 20.0%–24.3% lower than that of the SiO2 and PTFE coating, respectively. The friction coefficient and wear fluctuation rate of the MoS2 coating is the smallest when the lubricant viscosity decreases, which indicates that the MoS2 coating has excellent stability and adaptability under low viscosity lubricant.
Originality/value
To reduce the piston skirt wear caused by low viscosity lubricant in heavy-duty diesel engines, the friction and wear adaptability of three novel composite coating materials for piston skirts were compared under 0 W-20 low viscosity lubricant, which could provide a guidance for the application of wear-resistant materials for heavy-duty diesel engine piston skirt.
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The ring seal under consideration has come out as a result of the complex research such as the numerical simulation research, introductory quality research involving a real…
Abstract
The ring seal under consideration has come out as a result of the complex research such as the numerical simulation research, introductory quality research involving a real object, comparative research on a tribotester and fundamental research on the real object. It has been found that the essence of excellent tribological properties of the new ring seal lies, in its low value of surface free energy (SFE) of titanium nitride coating on the piston ring and in its high value of energy which is the characteristic of the nitrided surface of the cast iron cylinder sleeve. As a result, when the motion of the ring on the sleeve surface ceases, especially in the outer dead centre (ODC) in expansion stroke, the boundary layer of oil on the sleeve surface prevents metallic contact. In general, it has been found that the SFE can be an important index of material selection for cutting pairs, especially for those working in the reciprocating motion.
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There must always be a danger that condition monitoring techniques aimed at the wear products of one particular couple may find interference, or even be blanketed by the products…
Abstract
There must always be a danger that condition monitoring techniques aimed at the wear products of one particular couple may find interference, or even be blanketed by the products of another couple. It is therefore essential for those in such work to recognize what new materials may have been introduced, but not infrequently component makers are unwilling to disclose at any early date the “secrets” of their new coatings. By reviewing the traditional materials, and both the developments and trends in purposely structured materials used in modern piston ring/liner technology it is hoped that some value will result to those engaged in the development of condition monitoring techniques.
Ferric and ferrous oxides are used for coating of piston rings in order to obtain the layer, facilitating their wearing‐in at the beginning of work. This paper aims to present…
Abstract
Purpose
Ferric and ferrous oxides are used for coating of piston rings in order to obtain the layer, facilitating their wearing‐in at the beginning of work. This paper aims to present study and the implementation of the anti‐wear technology of piston rings production with the application of ferrous oxides. Those rings are intended for two‐stroke self‐ignited diesel engines used for driving the diesel locomotives.
Design/methodology/approach
It was decided to use magnetite, Fe3O4, together with a binding agent, sodium metasilicate. Working out the adequate technology of filling the grooves of piston rings required performing a broad research range. It is possible to apply three different technologies. In order to find out which of the three methods of filling grooves gives the best results, the series of experiments were planned.
Findings
Experimental results cover the variability intervals of input factors enabling the selection of their best combination by the analysis of the regression function. The paper describes the experimental plan for the wet technology with water‐glass, since it occurred to be the best considering the equipment of the factory in which it was implemented. In order to cover the variability field of input factors, the multifactor Hartley's plan was applied. On the basis of the performed investigations, it was found that all input factors are significantly influencing the filling quality of ring grooves on piston rings.
Practical implications
This technology in one of the Polish factories in piston rings production was implemented. The implemented technology allows the production of approximately 500,000 rings annually.
Originality/value
The paper presented a new anti‐wear technology of the sealing piston rings for diesel.
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