Knowledge

Welcome to our knowledge centre. Here you can find a selection of resources and articles on our products and industries we are involved with.

Paper

Study of Surface Roughness on Friction in Rolling/Sliding Contacts: Ball‑on‑Disc Versus Twin‑Disc

Although the efficiency of a gear pair is currently high, a better understanding of surface/lubricant contribution on efficiency is critical. …

Although the efficiency of a gear pair is currently high, a better understanding of surface/lubricant contribution on efficiency is critical. Electrified drivelines will, for example, impose higher speed and alternate loading, and it is expected that these new conditions will, to a greater extent, rely on the surface/lubricant characteristics. Phenomena taking place in the gear contact is often measured using ball-on-disc and twin-disc tribometers. In this study, these two test set-ups were compared in order to assess differences in the behaviour of surface/lubricant interactions. Results showed that ball-on-disc and twin disc set-ups refect the same friction trends. However, the friction results differed by a factor of roughly two, even though the tribometers were set-up to run at the same contact pressure. The wear mechanisms also differed: micropits occurred on discs used in the twin-disc set-up, whereas normal or no wear was found on the ball-on-disc specimens. The contact conditions for the two test set-ups were also analysed using a numerical model. The comparison of these two machines may aid gear designers in selecting the proper experimental set-up for their purpose.

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Paper

In Situ Microscopic Study of Tribology and Growth of ZDDP Antiwear Tribofilms on an Al–Si Alloy

Zincdialkyldithiophosphates (ZDDPs) form protective antiwear tribofilms but the growth mechanism and their contribution to friction on non-ferrous alloys are not …

Zincdialkyldithiophosphates (ZDDPs) form protective antiwear tribofilms but the growth mechanism and their contribution to friction on non-ferrous alloys are not well understood. Using a recently developed in situ AFM technique, we monitor the growth of ZDDP based tribofilms, friction, and wear, over Al matrix and Si phase of ADC12, sliding against a nonferrous alumina probe. Sliding tests performed at elevated temperature (110 °C), simultaneously over Al and Si phase, reveal tribofilm growth on both Al and Si regions without noticeable wear. However, the tribofilm thickness, density, and coefficient of friction on the Si phase are higher than on the Al matrix. Significant wear and increase in the coefficient of friction was observed when sliding within the Al matrix region alone.

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Paper

Gels and Oil-in-Water Emulsions: a Stepwise, Rheology- and Tribology-Focused Approach

Gels and oil-in-water emulsions are widely used in food, pharmaceutical, and personal care applications. In the case of emulsions, they …

Gels and oil-in-water emulsions are widely used in food, pharmaceutical, and personal care applications. In the case of emulsions, they can be either stabilized by an amphiphilic molecule, forming classical emulsions, or by colloidal particles, forming a Pickering emulsion. These systems exhibit rich rheological and frictional characteristics and factors such as component concentration and/or interactions can affect their final properties. Thus, their characterization is fundamental to understanding their performance from product development to final use. This dissertation provides insights on how to manipulate properties of multicomponent gels and emulsions based on their components, guiding the formulation of products with desired rheological and lubrication properties. For that, we focus on two groups of systems: 1) classical oil-in-water emulsions containing microgel-forming polymers and phospholipids as well as several simplified versions of these systems, and 2) Pickering emulsions stabilized by nanodiamond particles.

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Paper

Visualisation of Structured Lubricants in Tribological Contacts

The layered, lamellar phase of lyotropic liquid crystals display promising tribological properties possessing low shear strength between layers, solid like …

The layered, lamellar phase of lyotropic liquid crystals display promising tribological properties possessing low shear strength between layers, solid like elasticity and high load carrying capacity perpendicular to their layered structure. Being able to visualise and study the behaviour of LLC in high pressure contacts at a range of speed, slide-roll ratio (SRR) and temperature conditions can facilitate the understanding of the mechanism of action behind their low friction properties.

A microscope setup has been developed that is capable of collecting real time, high contrast videos of film formation, bulk alignment, and flow of liquid crystal containing lubricants in an EHD ultra-thin film tribometer. This project aims to describe an economic set of methods to evaluate qualitatively the behaviour of liquid crystals in and around tribological contacts.

This is demonstrated with two types of liquid crystals; lamellar lyotropic Oleic Acid/Triethanolamine and smectic thermotropic 8CB.

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Paper

Salivary Lubricity (Ex Vivo) Enhances Upon Moderate Exercise: A Pilot Study

This study sought to examine the effects of moderate intensity exercise on lubrication performance of saliva. We hypothesized that exercise …

This study sought to examine the effects of moderate intensity exercise on lubrication performance of saliva. We hypothesized that exercise would result in enhanced salivary lubricity by direct sympathetic stimulation of the salivary proteins…
In total, 11 healthy young pre-menopausal female participants (mean age: 24.4 ± 1.8 years, BMI: 22.1 ± 1.9 kg/m2) were included in a within-subjects repeated measures experimental design. Unstimulated whole saliva was collected at rest (S0), immediately after 45 min of moderate intensity cycling at ∼70 % maximum heart rate (mean: 133.4 ± 0.8 bpm) or time-match quiet rest (S1), and after a 60 min of recovery period (S2). Ex vivo salivary lubricity were measured using soft tribology. Total protein content, mucin (MUC5B) concentration, and α-amylase activity were determined.

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Paper

Composition Containing Heterocyclic Compounds And A Method Of Lubricating An Internal Combustion Engine

The present invention relates to a lubricating composition containing (a) an oil of lubricating viscosity; and (b) a compound selected …

The present invention relates to a lubricating composition containing (a) an oil of lubricating viscosity; and (b) a compound selected from the group consisting of: (i) an ester-containing heterocycle; (ii) an amide-containing heterocycle; and (iii) a pyrimidine, wherein the ester-containing heterocycle and the amide-containing heterocycle have a hydrocarbyl group containing 6 to 40 carbon atoms. The invention further provides for a method of supplying an internal combustion engine with the lubricating composition.

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Paper

Amino Acid Grafted Polymer with Soot Handling Properties

The present disclosure relates to lubricant additives such as dispersants and dispersant viscosity modifiers including acyl peptide grafted polymers and …

The present disclosure relates to lubricant additives such as dispersants and dispersant viscosity modifiers including acyl peptide grafted polymers and lubricating oil compositions comprising such additives. The disclosure also relates to the use of lubricant compositions comprising the additives herein for improving the soot or sludge handling characteristics of an engine lubricant composition and while minimizing the deterioration of engine's elastomer compatibility.

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Paper

Integrated Friction Reduction Technology to Improve Fuel Economy without Sacrificing Durability

This report describes the results of a study in response to the FY2014 Vehicle Technologies program DE-FOA-0000991 solicitation for fuel …

This report describes the results of a study in response to the FY2014 Vehicle Technologies program DE-FOA-0000991 solicitation for fuel economy improvement of cars and trucks (Area of interest 11: powertrain friction and wear reduction). It stated, “parasitic losses within vehicle engines and drivetrains are responsible for approximately two million barrels of oil consumption per day in the US. These losses are caused by friction between components, movement of components through fluids, and movement of fluids through components”. The objective of the study is to develop and demonstrate friction and wear reduction technologies for light duty vehicles that improve fuel efficiency of legacy vehicles by at least 2%, without adverse impacts on vehicle performance or durability.

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