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This study aims to investigate the tribological characteristics of a Napier-type second piston ring against a cylinder liner in the presence of graphene nano-additives mixed into 5W40 fully synthetic engine oil.

Wear tests were carried out in the boundary lubrication condition using a reciprocating tribometer, and real engine tests were performed using a single spark ignition Honda GX 270 test engine for a duration of 75 h.

The experimental results of the tribometer tests revealed that the nano-additives formed a layer on the rubbed surfaces of both the piston ring and the cylinder liner. However, this layer was only formed at the top dead center of the cylinder liner during the engine tests. The accumulation of carbon (C) from the graphene was heavily detected on the rubbed surface of piston ring/cylinder liner, mixed with other additive elements such as Ca, Zn, S and P. Overall, the use of graphene nano-additives in engine oil was found to improve the frictional behavior in the boundary and mixed lubrication regimes. Abrasive wear was found to be the main mechanism occurring on the surface of both piston rings and cylinder liners.

Though many researchers have discussed the potential benefits of graphene as a nano-additive in oil to reduce the friction and wear in laboratory tests using tribometers, to date, no actual engine tests have been performed. In this paper, both tribometer and real engine tests were performed on a piston ring and cylinder liner using a fully formulated oil with and without graphene nano-additives in the boundary lubrication condition. It was found that a graphene nano-additive plays an active role in lowering the coefficient of friction and increasing surface protection and lubrication by forming a protective layer on the rubbing surfaces.

The purpose of this paper is to present an approach to compute accurately the distributions of the frictional heat generated, contact pressure and thermal stresses at any instant during the sliding period (heating phase) of the single-disc friction clutch system works in the dry condition and the complex interaction among them.

Numerical work was achieved using the developed elastic and thermal finite element models (axisymmetric models) to simulate the engagement of the single-disc friction clutch system.

The change of distribution of contact pressure during the sliding period (heating phase) affects significantly the magnitude and distribution of the produced thermal stress. The high local heat generated appeared in the contacting surfaces because of the non-uniformity of the distribution of contact pressure during the heating phase (sliding time) and this will dramatically increase the thermal stresses.

Sequentially coupled thermal-mechanical approach was developed to investigate the thermal stresses problem in automotive clutches under dry conditions. This approach is considered a promising approach to investigate the effect of material, sliding time, torque function, etc., on the thermal stresses of different types of friction clutch.

Wear on internal combustion engines is a loss of material that occurs with the rubbing of the materials in contact with each other and significantly reduces the economic life of the engine. Even the smallest precaution that can be taken to prevent friction and wear in the engines can provide economical savings in very large quantities. Internal combustion engines are widely utilized in modem automobiles. Around 10 per cent of the total fuel energy is dissipated to heat due to mechanical friction, among which 20 per cent is caused by the contact between the cylinder liner and the piston rings.

In this study, real piston ring-cylinder specimens were tested with reciprocating tribometer by using five different nanoparticles added to engine oil to investigate their wear and friction behavior.

With regard to the experiments, it has been found that the best results were determined by TiO₂ and single-walled carbon nanotubes according to boron nitride, multi-walled carbon nanotubes and graphene nanoparticles added to the engine oil, respectively. At the end of the tests, different wear mechanisms have been determined after the surface analyses on the piston ring and cylinder liner surface, and abrasive wear has been observed as the main wear mechanism.

This paper has an originality with regard to adding different nanoparticles into the commercial engine oil.

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.

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.

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.

This study fulfils an identified need to study for automotive industry a coating which is wear and scratch resistant.

This study aims to evaluate and compare by 100 hours engine bench tests the tribological performances of two types of lubrication oils, which were sulfur-based, boron succinimide-containing antiwear package (NP-3) oil and conventional zinc dialkyldithiophosphate (ZDDP)-containing (R-1) oil.

The tribological performances of the oils were evaluated in three main contexts, including engine tests, physical/chemical changes and surface analysis.

Results showed that NP-3 lubrication oil, which was environment- and catalyst-friendly, can be an alternative lubrication oil with its tribological performance due to similar antiwear characteristics with the ZDDP.

Attempts to develop catalysis- and environment-friendly antiwear additive packages have not presented popular or commonly used ZDDP-free products for the vehicle industry. This study presents tribological characterization of a newly developed ZDDP-free lubricating oil by engine bench tests.

The more frequently an engine oil is changed, the more the overhaul life of the engine is extended but with an increase in the cost both of the oil and of the oil drain services. If engine oil is changed less frequently the associated costs will decrease. In order to find the optimum drain interval, it is necessary to establish the relationship between the cost of the oil and oil drain services and the cost of more frequent overhauls. Presents an investigation into the degradation of a proprietary lubricant marketed in Turkey, and the wear rate of a petrol engine driven in urban traffic. Lubricant samples were examined approximately every 2,000km for deterioration of the lubricant and evidence of wear of the engine components. From the experimental results, determines the optimum oil drain period of the engine.

The purpose of this technical paper is to investigate the friction and wear behavior of inexpensive and durable cutting tools, developed for wood machining using duplex treatment.

Cr–(WC–Co) coatings were deposited onto carburized low-alloy steel substrate by a reactive magnetron sputtering. The total coating thickness was approximately 2 μm. Unlubricated wear tests have been performed using a disc sample sliding against an alumina ball (Al₂O₃) and a wood (beech) pin.

The paper provides information about the effect of duplex treatment on the surface properties of low-alloy steel against wood and offers practical help for the researchers in coating topic.

Experimental results showed that sliding wear properties of the selected coatings are strongly dependent on the counter-face material. When tested against alumina balls, the wear mechanisms are oxidative wear followed by a combination of adhesive and abrasive wear, while a combination of an oxidative and adhesive wear was the main wear mechanism observed against a wood pin.

The role that lubricating oils play is, first of all, to reduce energy loss and keep the wear and seizure to a minimum, or, in a broader sense, to improve the friction characteristics. Resistance to deterioration and prevention of rust development on metals are demanded as secondary functions. The time during which lubricating oil retains its ability to prevent any possible damage to a body in motion should be considered as its lifetime. Many functions that are provided by base oil alone are insufficient; therefore, special additives are dissolved in them. The additives for lubricating oils are of many types, and their functions are diverse and many. Those additives that are used with the purpose of improving friction characteristics are generally called oiliness improvers or friction modifiers. In this study, the protective additive's layers formed on rubbed surfaces of pins, plates and discs were investigated using pin‐on‐disc and reciprocating pin‐on‐plate test rigs. Wear tracks were examined using optical and electron microscopy with X‐ray diffraction analysis.

Two 5W‐30 synthetic‐base phosphorus containing (commercial) and phosphorus‐free (P‐free) crankcase oils were tested for engine performance characteristics, engine emissions and poisoning effects of oil additives on a three‐way catalytic converter using engine dynamometer. The emission data of the two oils taken during engine operation were compared in the absence and presence of the catalytic converter. Surface characterization was used to determine the poisoning catalyst effect accumulated from the oil additives in the ceramic washcoat. Oil analyses were also used to examine the condition of the lubricant occurred during engine performance testing operation. The experimental engine performance tests indicated that the catalytic converter diminished the torque and power for the commercial and P‐free oils, whereas the specific fuel consumption increased for both oils in the presence of the catalytic converter.

This paper aims to investigate the wear mechanisms, formations and effectiveness of tribofilms of new developed, antiwear additive which is called mercapthocarboxylate. The mercapthocarboxylate is a sulphur-based and non-phosphorus additive.

The effectiveness of the additive was examined through a set of laboratory endurance tests that applied with single cylinder spark ignition engine. Two types of lubricants were used to compare the engine tests which were thiophosphate (ZDDP) containing engine lubricant (phosphorus containing) and mercapthocarboxylate containing non-phosphorus and non-ash crankcase oil. Lubricants were tested under identical operating conditions for 100 hrs. The surfaces of cylinder liner and piston rings were inspected through optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques.

Catalysis-friendly and sulphur-based mercapthocarboxylate additive can be an alternative antiwear additive package for lubrication oil due to better wear performance when compared to ZDDP.

Sulphur-based mercapthocarboxylate is a new developed antiwear additive and was applied to lubrication oil in this study. This lubrication oil was tested in the real engine environment by using 100-hr engine bench tests.