Projects / Programmes
Novel design of EHL contacts by employing solid-liquid interface phenomena
| Code |
Science |
Field |
Subfield |
| 2.11.03 |
Engineering sciences and technologies |
Mechanical design |
Special development know-how |
| Code |
Science |
Field |
| T210 |
Technological sciences |
Mechanical engineering, hydraulics, vacuum technology, vibration and acoustic engineering |
| Code |
Science |
Field |
| 2.03 |
Engineering and Technology |
Mechanical engineering |
TRIBOLOGY, FRICTION, ELASTO-HYDRODYNAMIC LUBRICATION, DIAMOND-LIKE CARBON COATINGS, ENERGY LOSSES, WETTING, SOLID-LIQUID SLIP
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
33657 |
PhD Marko Polajnar |
Mechanical design |
Head |
2019 - 2021 |
105 |
Organisations (1)
Abstract
Prosed project focuses on the design of novel and innovative elasto-hydrodynamic (EHD) contacts that provide remarkably low energy losses due to significantly reduced friction at the solid-liquid interfaces in fully-realistic lubrication conditions.
Namely, in the last years, we succeeded to make one of the major lubrication step-changes and present an immensely reduced friction due to a completely new lubrication phenomena at the macro-scale EHD contacts; i.e. the lubricant slip at the surface wall. We were the first to report on almost 50 % reduction of friction in EHL contacts – by changing the wetting and polar surface energy of solid surfaces and tailoring them for a lubricants surface tension. This paramount achievement gained great attention in scientific and industrial community. However, this breath-taking phenomenon has only been confirmed in pure base oils, while for the success in industrial and automotive applications, it has to be confirmed in realistic oils, namely fully formulated oils. Due to additives competition and even stronger “passivation” of the surfaces, the outcome of this project is very promising and may completely change the future additive technology and result in an immensely reduced energy consumption due to friction, which in total accounts for 25 % of all energy produced world-wide.
In this project, we will innovatively design extremely-efficient EHD contacts, with taking into an account interactions and phenomena at the solid-liquid interface that significantly effect EHD friction. To achieve this, low-surface energy, slip-inducing DLC coatings will be combined with formulated-oils by employing both, the coatings and oils that are commonly used in automotive and industrial applications. To provide proof-of-concept for this project, we already possess supporting results with some DLC coatings and some formulated oils, but this has to be systematically and scientifically confirmed in a broad range of contact conditions and materials used. Therefore, for actual industrial implementation, this concept should be proven for several commonly used formulated oils, DLC and other surfaces, together with complete and in-depth understanding of the effect of all the additives in formulation on solid-liquid interactions. Proposed project will thus address a paramount scientific goal: to find fundamental understanding and synergistic effect of additives and DLC coatings, on lubricant-DLC interactions to achieve solid-liquid slip that will provide significant EHD friction reduction in real-engineering contacts.
To achieve this goal following tasks will be tackled in the proposed project:
1. The effect of oil additives on surface properties of oils will reveal how oil surface tension that significantly define the strength of solid-liquid interactions is influenced by different additives in formulated oils.
2. Surface energy determination of selected surfaces will reveal the effect of additives adsorption on surface chemistry changes.
3. Iterative wetting analysis of different solid-liquid interfaces will provide the best surface-oil combination to induce maximum solid-liquid slip.
These tasks, together with the new concept of EHD contact design, represent world novelties that have never been achieved so far. They will enable a step-change in future EHD contact design, with significant impact on economic, environmental and social aspects.
Significance for science
Several of the proposed solutions in the project are completely new and represent a scientific breakthrough in the field of EHD lubrication with formulated oils and DLC coatings. To achieve this:
1. For the first time the effect of state-of-the-art additives on surface tension of oils will be investigated.
2. Surface energy changes due to adsorption of relevant state-of-the-art additives onto the steel and DLC surfaces will be determined and for the first time this effect on EHD friction will be established.
3. For the first time carefully performed wetting experiments will be performed to investigate the wetting of steel and various DLC coatings with formulated oils in terms of understanding the simultaneous effect of additives on oil’s and surface’s interfacial properties.
4. Thermal and slip effect on EHD friction will be addressed simultaneously as mechanisms for EHD friction reduction when using DLC coatings, by solid-liquid interface characterization and EHD modelling, what will enable for the first time determination the magnitude of each effect.
5. With separation of slip and thermal effect on EHD friction we will be able to determine the range of operating conditions where certain effect prevails.
6. DLC coatings as slip inducing surfaces and formulated oils will be studied in the full-range of macroscopic tribological parameters, validating the efficiency of the proposed concept for EHD friction reduction and providing optimised solid-liquid interface design, which will represent a step change in future EHD contact design, if successful.
Significance for the country
Several of the proposed solutions in the project are completely new and represent a scientific breakthrough in the field of EHD lubrication with formulated oils and DLC coatings. To achieve this:
1. For the first time the effect of state-of-the-art additives on surface tension of oils will be investigated.
2. Surface energy changes due to adsorption of relevant state-of-the-art additives onto the steel and DLC surfaces will be determined and for the first time this effect on EHD friction will be established.
3. For the first time carefully performed wetting experiments will be performed to investigate the wetting of steel and various DLC coatings with formulated oils in terms of understanding the simultaneous effect of additives on oil’s and surface’s interfacial properties.
4. Thermal and slip effect on EHD friction will be addressed simultaneously as mechanisms for EHD friction reduction when using DLC coatings, by solid-liquid interface characterization and EHD modelling, what will enable for the first time determination the magnitude of each effect.
5. With separation of slip and thermal effect on EHD friction we will be able to determine the range of operating conditions where certain effect prevails.
6. DLC coatings as slip inducing surfaces and formulated oils will be studied in the full-range of macroscopic tribological parameters, validating the efficiency of the proposed concept for EHD friction reduction and providing optimised solid-liquid interface design, which will represent a step change in future EHD contact design, if successful.
Most important scientific results
Interim report
Most important socioeconomically and culturally relevant results
