The compatibility of semi-synthetic engine oil with conventional diesel and biodiesel fuels

Recent trends to downsize diesel engines have increased the stress on lubricants. Oils naturally degrade during operation, undergoing continual reactions, changing chemically and physically, detracting in performance from initial specifications. This thesis investigates the role of fuel in the ageing of diesel engine oils, specifically Ultra Low Sulphur Diesel (ULSD) and Rapeseed Methyl Ester (RME – a common European biodiesel). Oil ageing is assessed distinctly with fuel dilution, the entrainment of exhaust gases; and the effects of soot loading. Results show fuel dilution has the greatest influence on oil performance. Effects are seen with an instant ‘dilution’ of properties, with the resultant blend performing as an amalgam of the fluids. This can be both positive and negative, depending on the property being measured, with the entrainment of biodiesel generally beneficial. The entrainment of exhaust gases in the oil leads to increased unburnt hydrocarbons and fuel content, with similar dilution effects. Soot loaded oil performance is heavily dependent on the respective fuel content. RME contamination has a positive influence which far outweighs its negligible soot production, whereas ULSD detracts from oil performance, also producing more soot. During an equivalent timeframe, the influence of RME is less detrimental than ULSD on overall performance

Potencial use of ionic liquids in tribology

228 p.Los líquidos iónico son una categoría de sales fundida con un punto de fusión relativamente bajo, lo que las haces especialmente interesantes desde un punto de vista de aplicaciones tecnológicas. En los últimos años, se les ha dedicados grande atención en muchos sectores por las buenas propiedades que presentan: baja presión de vapor, buena estabilidad térmica, elevada conductividad eléctrica, etc. Además de estas características, lo que mas de todo resulta muy atractivo de los líquidos iónicos es la posibilidad de combinar fácilmente propiedades del anión con propiedades del catión para obtener estructuras que presentan las características deseadas. En esta tesis, se han estudiado las propiedades tribológicas de diferentes tipos de líquidos iónicos y se han intentado explicar los procesos que llevan al desarrollo de tribo-capas protectoras y los fenómenos de degradación de los lubricante

Graphene-Based Lubrication for Tribological Applications: Nanolubricants and Self-lubricating Nanocomposites

In this work, the effects of graphene nanoplatelets (GNPs) additives on tribological properties of aluminum are investigated. The objective of this research is to investigate and explain the enhancement mechanisms of GNPs at the contact surface during tribological testing. The graphene nanoplatelets are studied both as an oil additive (Chapter I) and as a reinforcement (Chapter II) experimentally. The coefficient of friction (COF) and wear rate were identified using a pin-on-disk test setup. Mineral, organic, and synthetic oils are not always efficient enough to satisfy the demands of a high-performance lubricant; therefore, mixing additives with base fluids is an approach to improve the lubrication ability and to reduce friction and wear. In chapter I, GNPs are used as lubricant additives to make nanolubricants. Then, the combined effect of the material’s variables (GNPs loading, size, and dispersion stability) and tribo test’s variable (applied normal load) are investigated on COF and wear rate of aluminum. Tribological studies are all carried out in the boundary lubrication regime. Three-dimensional surface metrology is performed using an optical profilometer. Various surface analyses, including Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Raman Spectroscopy are performed to assess the chemical elements on the tested surfaces. The experimental and theoretical analyses show that GNPs are effective in reducing friction and wear, although, this positive effect is more influential at higher loads. Also, it is demonstrated that there is a critical concentration of GNPs, below which a reduced wear rate is not sustained. The proposed mechanism to describe the effect of GNPs in boundary lubrication condition is “reduced direct metal-metal contact area” at the contact surface. In other words, a material which has low shear strength layers sits between two contacting surfaces and separates the two sliding metal surfaces with no actual contact between them. This means that there is less formation of asperity junctions between the two surfaces. Although liquid-based lubricants are efficient enough in most tribological applications, there are circumstances, such as extreme environmental conditions such as high or low temperatures, vacuum, radiation, and high contact pressure in some aerospace applications, where no liquid lubricants can be present. In addition, interminable providing of lubricant at the contact surface is another challenge ahead. In order to respond to these challenges of using liquid oil at extreme environmental conditions, in chapter II of this dissertation, the synthesis and performance of self-lubricating aluminum matrix nanocomposite are evaluated (Chapter II). Aluminum powder is mixed with varying concentrations of GNPs and alumina nanoparticles to form a hybrid metal matrix nanocomposite. High-energy ball milling is conducted at room temperature while powders are immersed and protected by benzene bath. Degassing is accomplished by heating to 135oC. Consolidation of the powders is conducted by single action cold compaction and single action hot compaction. Pin-on-disk experiments are conducted to investigate the tribological behavior of aluminum matrix composites reinforced by GNPs and compare them with unreinforced aluminum. Then, the combined effect of material’s variables (reinforcement type and loading) and tribo test’s variable (applied normal load) were investigated on COF and wear rate of aluminum. SEM and EDX were performed to assess the stoichiometry of the elements on the tribo surfaces. In addition, Raman Spectroscopy and Transmission Electron Microscopy (TEM) were also performed to identify the bonding/interactions between the phases on the surface. Results imply that the COF and wear rate of composites decrease by embedding graphene nanoparticles due to reduction the real contact area between the mating surfaces by forming the lubricant. Besides, the addition of alumina particles in Aluminum/GNPs composites can further improve COF and wear rate because of rolling effect of alumina nanoparticles. Increasing the loading of GNPs reduces the COF, while there is an optimum concentration of GNPs, above and below which the wear rate is increased. In addition, the COF and wear of all composites decreases by increasing normal load. Based on the observations, multiple mechanisms are proposed to describe the improved tribological behavior of the synthesized self-lubricating nanocomposites. In addition to the reduced direct metal-metal contact area at the contact surface, the fact that the layered GNPs structure is exposed to at the contact surface keeps the surface lubricated. In other words, under sliding conditions, the transfer layer formation of the GNPs on the tribo surfaces acts as a solid lubricant film, which prevents direct contact between the mating surfaces. Additionally, it is experimentally confirmed that GNPs prevent the surface from oxygen diffusion, thereby reducing the amount of oxides which are harder and more abrasive at the contact surface. “Load bearing” of added alumina nanoparticles, in addition to the increased hardness of the matrix, is another proposed mechanism of wear resistance enhancement. It has been shown that an effective lubricant layer forms when the solid lubricant has a strong adhesion to the bearing surface; otherwise, this lubricant layer can be easily rubbed away and tends to have a very short service life. Raman data confirms the formation of Al4C3 bonds on the tribo layer under certain test conditions

Stability and biological responses of zinc oxide metalworking nanofluids (ZnO MWnF™)

Zinc oxide nanoparticles (ZnO NPs) have demonstrated the ability to improve lubrication and thermal conductivity, and stand as promising metalworking lubricant and coolant additives due to their low cost compared to other NPs. While nanomaterials are a focus of research due to their potential to enable advanced technologies, little is known about their effects on the environment and human health. This research investigates two main characteristics of ZnO metalworking nanofluids (MWnF™). First, the stability of ZnO NPs (20nm) is investigated in mixtures of a microemulsion (TRIM® MicroSol® 585XT) and dispersants, all of which are commercially available. Second, toxicological assessments are conducted to survey the effect of ZnO NPs on MWnF™ safety. The results revealed that none of the dispersants enhanced the stability of ZnO NPs more than the prepared microemulsion alone. Research also revealed that ZnO MWnF™ had a significantly higher toxicity than the prepared microemulsion. This demonstrates the need for precautionary development of metalworking nanofluids.

Interdisciplinary Approach to Liquid Lubricant Technology

The proceedings of a conference of liquid lubricant technology are presented. The subjects discussed are: (1) requirements and functions of liquid lubricants, (2) mineral oils, (3) greases, (4) theory of rheology, (5) mechanics and thermodynamics in lubrication, (6) environmental capability of liquid lubricants, and (7) wear corrosion and erosion

Selected aspects of providing the chemmotological reliability of the engineering

Transport sector is an important component of the economy that have an impact on the development and prosperity of the population. Rational use of fuels and lubricants, energy efficiency, environmental safety are included into the list of the most important problems of the modern world. Solving these problems determines in a great manner the sustainable development of the world economy and keeping comfort conditions for human being. Efficiency, reliability of operation of vehicles, rational use of operational materials depend on their correct selection. According to its quality operational materials must conform to both the model and operating conditions of vehicles. The use of poor quality materials leads to a decrease in the durability and reliability of machinery and machine parts; the use of materials of higher quality than required causes unreasonable increase in costs. The knowledge of machinery suggest not only the knowledge of construction, kinematic, dynamic, and temperature characteristics but also physico-chemical properties of constituent materials that are necessary for analyzing and forecasting of physico-chemical processes during use of a Fuels or a Lubricants. Thus, the efficiency and reliability of vehicles operation depends not only on their structural characteristics, but also on the optimal selection of Fuels and Lubricants, Technical Liquids and other Operational Materials. Work professional activity of specialists dedicated to petroleum refinery, organizing of storage, transportation and distribution of products, assurance of correspondence between the properties of Fuels, Lubricants, Technical liquids and the conditions of operation of technology and engines aimed at obtaining maximum technical, economical, ecological and social effects is called usage of Fuels, Lubricants and Technical liquids. To know Fuels, Lubricants and Technical liquids is to clearly understand the interconnection of quality parameters with physico-chemical and energy processes, occurring in the process of their use under specific conditions, and also the connection with their chemical and group composition. The knowledge of technology suggest not only the knowledge of construction, kinematic, dynamic, and temperature characteristics but also physico-chemical properties of constituent materials that are necessary for analyzing and forecasting of physico-chemical processes during use of a Fuel or a Lubricant. The study of the essence, regularity (tendens) and connections of phenomena and the processes of use of Fuels, Lubricants, Technical liquids in Aviation Technology with the help of special methodological tools is the base of Aviation Chemmotology. Aviation Chemmotology is a part of Chemmotology that studies and solves the problems of ensuring the necessary quality and application requirements of Fuels and Lubricants used in Aviation Technology. Chemmotological reliability is a reliability of technology depending on the Quality of Fuels and Lubricants (the ability of technology to maintain good reliability when operated with Fuels and Lubricants grades that are of a economically reasonable quality level). This monograph as an intergative scientific work of many scholars is a striking example of the representation of these aspects and really illustrates the modern consolidated work of scientists and practitioners, trends in the development of scientific schools of different universities, different countries and science in general. Because, as is know, science does not have borders. Scientific achievements are global civilizational heritage

New advances in vehicular technology and automotive engineering

An automobile was seen as a simple accessory of luxury in the early years of the past century. Therefore, it was an expensive asset which none of the common citizen could afford. It was necessary to pass a long period and waiting for Henry Ford to establish the first plants with the series fabrication. This new industrial paradigm makes easy to the common American to acquire an automobile, either for running away or for working purposes. Since that date, the automotive research grown exponentially to the levels observed in the actuality. Now, the automobiles are indispensable goods; saying with other words, the automobile is a first necessity article in a wide number of aspects of living: for workers to allow them to move from their homes into their workplaces, for transportation of students, for allowing the domestic women in their home tasks, for ambulances to carry people with decease to the hospitals, for transportation of materials, and so on, the list don’t ends. The new goal pursued by the automotive industry is to provide electric vehicles at low cost and with high reliability. This commitment is justified by the oil’s peak extraction on 50s of this century and also by the necessity to reduce the emissions of CO2 to the atmosphere, as well as to reduce the needs of this even more valuable natural resource. In order to achieve this task and to improve the regular cars based on oil, the automotive industry is even more concerned on doing applied research on technology and on fundamental research of new materials. The most important idea to retain from the previous introduction is to clarify the minds of the potential readers for the direct and indirect penetration of the vehicles and the vehicular industry in the today’s life. In this sequence of ideas, this book tries not only to fill a gap by presenting fresh subjects related to the vehicular technology and to the automotive engineering but to provide guidelines for future research. This book account with valuable contributions from worldwide experts of automotive’s field. The amount and type of contributions were judiciously selected to cover a broad range of research. The reader can found the most recent and cutting-edge sources of information divided in four major groups: electronics (power, communications, optics, batteries, alternators and sensors), mechanics (suspension control, torque converters, deformation analysis, structural monitoring), materials (nanotechnology, nanocomposites, lubrificants, biodegradable, composites, structural monitoring) and manufacturing (supply chains). We are sure that you will enjoy this book and will profit with the technical and scientific contents. To finish, we are thankful to all of those who contributed to this book and who made it possible.info:eu-repo/semantics/publishedVersio

Running-In of Metal-to-Metal Seals and its Influence on Sealing Ability:With application to the design of biodegradable thread compounds

Metal-to-metal sealing of casing connections is affected by running-in because it determines the topography of the gap between the contacting surfaces by wear and plastic deformation during assembly under the influence of the thread compound, coatings and the initial surface topography. The work in this thesis concerns the mechanisms related to these elements of the tribosystem and how they affect running-in of the metal-to-metal seal tribosystem and ultimately influence the sealing ability.The research was driven by a need to reduce costs in particular of the qualification of premium connections. Furthermore, increased understanding of the barriers in the well is important for well engineering. Understanding was needed on galling during assembly which is an often occurring failure mechanism as well as the protective mechanisms behind the applied coatings. In addition, the Oslo-Paris Convention for the protection of the Marine Environment of the North-East Atlantic (OSPAR) demands future substitution of mineral oils and the (heavy) metal additives used in the American Petroleum Institute (API) modified thread compound by biodegradable alternatives. To this end a combined experimental and modelling approach was applied.The existing thread compounds were shown, with pin-on-disc, anvil-on-strip and Shell Sealing Mock-Up Rig (SSMUR) tests, to provide relatively minor protection to initiation of galling in uncoated contacts. This was shown to be because of squeeze out of the formed tribofilms, limited adsorption of the additives and the lack of replenishment by the plan parallel contact configuration coming from the turned surface topography. These mechanisms only added 60mm of additional sliding length, before failure, with API modified thread compound compared to a plain mineral oil.In relation to the substitution of API modified for biodegradable alternatives, the elevated temperature degradation mechanisms of (environmentally acceptable) thread compounds were studied using Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), high temperature rheometry and pin-on-disc. Thread compounds were shown to fail because of evaporation and oxidation leading to starved lubrication conditions. The system subsequently enters a severe adhesive wear regime sometimes exacerbated by abrasive action of the hard metal oxide particles present in environmentally acceptable compounds. The found failure mechanisms and the developed test protocol were validated and successfully mitigated by the development of a prototype thread compound.The presence of phosphate conversion coatings proved to be a dominating factor in the running-in of the metal-to-metal seal. This was shown to be caused by two main mechanisms using various tribological experiments and analytical techniques. On the uncoated counter surface a durable tribofilm was formed by physical adsorption of phosphate debris particles through a shear stress activation mechanism. From the same debris particles a smooth glaze layer was generated on the phosphated surface which possesses a substantial hardness after dry sliding. However, this hardness was much lower after lubricated sliding and was shown to be related to the particle size which generated the glaze layer. The combination of these mechanisms resulted in a wear process that could satisfactorily be described by the energy dissipated in the sliding contact.Finally, it was shown with experimental data and a simple running-in model that the combination of plastic deformation of the waviness of the turned surface topography and wear of the phosphate coating determine the running-in behaviour. It was found that the surface runs-in within 40mm sliding length after which the wear regime transitioned to mild wear. The combination of severe initial wear by plastic deformation of the waviness and the generation of a smooth glaze layer created a conformal sealing configuration with multiple concentrated line contacts along the circumference. This created the most robust sealing configuration compared to configurations that did not have a distinct lay.<br/

Accelerated testing of space mechanisms

This report contains a review of various existing life prediction techniques used for a wide range of space mechanisms. Life prediction techniques utilized in other non-space fields such as turbine engine design are also reviewed for applicability to many space mechanism issues. The development of new concepts on how various tribological processes are involved in the life of the complex mechanisms used for space applications are examined. A 'roadmap' for the complete implementation of a tribological prediction approach for complex mechanical systems including standard procedures for test planning, analytical models for life prediction and experimental verification of the life prediction and accelerated testing techniques are discussed. A plan is presented to demonstrate a method for predicting the life and/or performance of a selected space mechanism mechanical component