Browse Topic: Lubricant additives
The intent of this SAE Aerospace Information Report (AIR) is to summarize and review the E34 committee’s efforts to educate the aerospace propulsion lubrication community on the science of micropitting, its consequences, and the various tribology evaluation methods that can be employed under aviation related conditions to differentiate formulation related aggravating factors
Lubricant additives have a strong influence on the tribological performance of internal combustion engine components, and it is currently one of the leading research driving forces within lubricant companies. However, the anti-friction and anti-wear additives work forming surface tribofilms may have their performance affected by ethanol or water contamination. As both ethanol and water are polar, they may compete on the surface with the additives, avoiding or delaying the additive tribofilm formation. In this work, the effect of ethanol and water on the performance of 4 different fully formulated SAE 0W-20 engine oils, differing only on the friction modifier (FM) additive technology employed, was investigated. In order to emulate fuel dilutions, three tests conditions were carried out for each engine oil: (i) fresh, (ii) in the presence of ethanol, and (iii) in the presence of ethanol and water. Friction and wear of actual piston ring and liner were evaluated in a reciprocating test
The acidification of lubricating oils during engine operation, and the subsequent additive neutralization, is an important challenge for Original Equipment Manufacturers and end-users. Often the decline in Total Base Number (TBN) and increase in Total Acid Number (TAN) is measured during engine operation as an indication of the oil’s condition and lifetime. This is clearly an oversimplification given that no consideration is given to the type of acid, how corrosive it is, or the type of base and how effective it is at neutralizing. Acids can be broadly categorized into mineral acids such as sulfuric/nitric and organic acids such as acetic. Traditionally, research has focused on understanding the effects of mineral acids such as sulfuric, which can be formed during the combustion of sulfur-containing fuel. However, emissions legislation has driven a reduction in sulfur levels, and there has been an increase in the use of biofuels, such as methanol and ethanol, which typically oxidase to
Pre-ignition remains a significant bottleneck to further downsizing and downspeeding technologies employed for reducing CO2 emissions in modern turbocharged spark-ignited engines. Pre-ignition, which occurs rarely, may lead to high peak pressures that auto-ignite the entire charge before TDC. The resulting high-pressure oscillations are known as super-knock, leading to sudden and permanent hardware damage to the engine. Over the years, numerous researchers have investigated the stochastic phenomenon’s source and concluded that there is a role of lubricant additives, deposits, gasoline properties, and hot surfaces in triggering pre-ignition. No single source has been identified; the research continues. Here, we take a different approach; rather than continue the search for the source(s) of super-knock, we explore mitigating super-knock by detecting pre-ignition early enough to take immediate evasive action. Such evasive action is expected to suppress knock intensity, thereby saving the
The purpose of this article is to study the antifriction and anti-wear effect of GCr15 bearing steel under paraffin base oil and the base oil with two additives of T405 sulfurized olefin and nano-MoS2 and compare the synergistic lubrication effect of two different additives (MoS2 and T405) in paraffin base oil. The tribological properties of GCr15 bearing steel under different lubrication conditions were tested on a ball-on-disk tribometer. The three-dimensional profile of disk’s worn surfaces and the scanning electron microscope (SEM) micrographs of corresponding steel balls were analyzed at the same time. The wettability of lubricating oils on the surface of friction pairs and the dispersibility of MoS2 in base oil were characterized. Furthermore, the Energy Dispersive X-ray Analysis (EDAX) of the disk’s worn surfaces under the nano-MoS2 base oil were measured by the Field Emission Environmental Scanning Electron Microscope to observe the variation of chemical elements on the worn
Particles generated from lubricant in a gasoline direct injection (*GDI) engine were investigated in detail with the aim to understand the influence of components in lubricant on the amount of particles generated as well as their size. Analytical approach employed in this study was real-time engine tests combined with X-ray spectroscopic and electron-microscopic analyses. Real-time engine tests where particle number (PN) and particle size distribution were consecutively measured with oil consumption for lubricants with different formulas enabled us to extract information regarding lubricant-derived particles. This can be achieved only when sulfur species in lubricant are used as a “tracer” and thus, sulfur-free fuel possessing low PM Index (i.e., isooctane) needs to be used for the measurements. It was revealed that the size of particles increased with an increase in oil consumption in the vicinity of 10 nm, and such particles were assumed to be mainly generated as a result of
The aim of this study is to investigate how lubricants used for transaxles in hybrid electric vehicles (HEVs) and electric vehicles (EVs) give an impact on the cooling performance for electric motors. As a result, reducing lubricant viscosity improve heat transfer in both natural and forced convection conditions. Quantitative analysis could reveal that kinetic viscosity and heat conductivity of fluids are highly influential on the cooling performance. In addition, we investigated the effect of lubricant additive on fatigue life in bearing components by using a thrust needle roller bearing tester. Extreme pressure agent could control a morphology of the bearing raceway surface, playing a role in extending a fatigue life of the bearing
This SAE Aerospace Information Report (AIR) establishes guidance for the specification of formulated lubricant properties which contribute to the lubricating function in bearings, gears, clutches, and seals of aviation propulsion and drive systems
Characterization of soot nanoparticle morphology can be used to develop understanding of nanoparticle interaction with engine lubricant oil and its additives. It can be used to help direct modelling of soot-induced thickening, and in a more general sense for combatting reductions in engine efficiency that occur with soot-laden oils. Traditional 2D transmission electron microscopy (TEM) characterization possesses several important shortcomings related to accuracy that have prompted development of an alternative 3D characterization technique utilizing electron tomography, known as 3D-TEM. This work details progress made towards facilitating semi-automated image acquisition and processing for location of structures of interest on the TEM grid. Samples were taken from a four cylinder 1.4 L gasoline turbocharged direct injection (GTDI) engine operated in typically extra-urban driving conditions for 20,284 km, with automatic cylinder deactivation enabled. Soot nanoparticles were extracted
Diesel particulate filter (DPF) is necessary for diesel engines to meet the increasingly stringent emission regulations. Many studies have demonstrated that the lubricant derived ash has a significant effect on DPF pressure drop and engine fuel economy, and this effect becomes more and more severe with the increasing of operating hours of the DPF because the ash accumulated in the DPF cannot be removed by regeneration. It is reported that most of the DPFs operated with more ash than soot in the filter for more than three quarters of the time during its lifetime [1]. In order to mitigate this problem, the original engine manufacturers (OEM) tend to use an oversized DPF for the engine. However, it will increase the costs of the DPF and reduce the compactness of the engine aftertreatment system. With the development of the lubricant additives technology, some OEMs and lubricant oil manufacturers are concerning that if there is any possibility to reduce DPF size using low ash lubricant oil
Numerous studies have attributed pre-ignition events in turbocharged spark ignited engines to the auto-ignition of lubricant oil-fuel mixture droplets. These droplets result from the interaction of the directly injected fuel spray on the lubricant oil film on the cylinder walls, causing fuel splashing to pull oil off the walls, forming droplets. The dilution of the oil by the fuel also changes lubricant oil droplet properties. Therefore, it is important to understand lubricating oils, with and without fuel dilution, as a possible ignition source in pre-ignition and super knock events. In this work, a constant volume (4 L) combustion chamber (CVCC) that allows the introduction of a single droplet of lubricating oil has been built. It is capable of operation at elevated pressures and temperatures. To simulate the droplet-induced pre-ignition event, a droplet injection system was incorporated into the vessel. The oil droplet was suspended on the junction of a thermocouple where the
Many studies on low speed pre-ignition have been published to investigate the impact of fuel properties and of lubricant properties. Fuels with high aromatic content or higher distillation temperatures have been shown to increase LSPI activity. The results have also shown that oil additives such as calcium sulfonate tend to increase the occurrence of LSPI while others such as magnesium sulfonate tend to decrease the occurrence. Very few studies have varied the fuel and oil properties at the same time. This approach is useful in isolating only the impact of the oil or the fuel, but both fluids impact the LSPI behavior of the engine simultaneously. To understand how the lubricant and fuel impacts on LSPI interact, a series of LSPI tests were performed with a matrix which combined fuels and lubricants with a range of LSPI activity. This study was intended to determine if a low activity lubricant could suppress the increased LSPI from a high activity fuel, and vice versa. The results
This index provides an overview of lubricants and symbols for the purpose of assisting the user in the identification of the appropriate product and relevant SAE specification. The aim is to better determine the best lubricant to be used for a particular application. If containers used for shipping lubricants are also to be marked, the same identification and symbols should be used. See also ISO 5169 Machine tools - Presentation of lubrication instructions
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The global trend to reduce CO2 emissions, combined with the popularity of Sport Utility Vehicles (SUV’s), has prompted automakers to design and manufacture lighter vehicles with suspension architectures that may require halfshafts (HS’s) to operate at higher continuous angles than in the past. Noise, Vibration and Harshness (NVH) characteristics of a halfshaft, as well as its durability, are functions of the operating angle and the lubricating grease in the joints. Newer vehicles require driveline solutions that can provide consistent dynamic performance over a wide range of operating angles. Tripot-type Constant Velocity Joints (CVJ’s) are commonly used as inboard joints in a halfshaft. Through proper grease selection, premium tripots may be lubricated with greases containing solid additives, which provide consistent dynamic performance and durability
Traditional methods for monitoring corrosion processes and mechanisms in real time can be both time consuming and challenging to interpret, especially when evaluations at multiple temperatures are required. Reported at SAE world congress 2017 by this author, a new method for measuring the change in resistance of a thin copper wire was applied to provide a way to monitor the corrosion of copper in situ. In this work, a copper alloy in thin wire form has been used to compare the corrosion rates to pure copper. New insights on the kinetics and mechanisms of corrosion in the presence of lubricant additives over a range of operating temperatures using the wire resistance test will be discussed. The corrosion processes observed here are highly dependent upon temperature. Making assessments of corrosion performance through elevated temperature differentiation testing can provide less optimal corrosion protection at the actual operating temperature condition. This work highlights how long
This specification defines basic physical, chemical, and performance limits for 5 cSt grades of gas turbine engine lubricating oils used in aero and aero-derived marine and industrial applications, along with standard test methods and requirements for laboratories performing them. It also defines the quality control requirements to assure batch conformance and materials traceability, and the procedures to manage and communicate changes in oil formulation and brand. This specification invokes the Performance Review Institute (PRI) product qualification process. Requests for submittal information may be made to the PRI at the address in Appendix D Section D.2, referencing this specification. Products qualified to this specification are listed on a Qualified Products List (QPL) managed by the PRI. Additional tests and evaluations may be required by individual equipment builders before an oil is approved for use in their equipment. Approval and/or certification for use of a specific gas
See Table 1
ISO 7745 shall be used for providing detailing, operational characteristics, advantages, disadvantages, and factors affecting the choice to be made among fire-resistant fluids. HFAE, HFC, HFDR, HFDU and HETG oils are covered in this specification. HFAS, HFB and HFDS fluids are not addressed
This specification defines basic physical, chemical, and performance limits for 5 cSt grades of gas turbine engine lubricating oils used in aero and aero-derived marine and industrial applications, along with standard test methods and requirements for laboratories performing them. It also defines the quality control requirements to assure batch conformance and materials traceability, and the procedures to manage and communicate changes in oil formulation and brand. This specification invokes the Performance Review Institute (PRI) product qualification process. Requests for submittal information may be made to the PRI at the address in Appendix D Section D.2, referencing this specification. Products qualified to this specification are listed on a Qualified Products List (QPL) managed by the PRI. Additional tests and evaluations may be required by individual equipment builders before an oil is approved for use in their equipment. Approval and/or certification for use of a specific gas
Low speed pre-ignition (LSPI) is an undesirable combustion phenomenon that limits the fuel economy, drivability, emissions and durability performance of modern turbocharged engines. Because of the potential to catastrophically damage an engine after only a single pre-ignition event, the ability to reduce LSPI frequency has grown in importance over the last several years. This is evident in the significant increase in industry publications. It became apparent that certain engine oil components impact the frequency of LSPI events when evaluated in engine tests, notably calcium detergent, molybdenum and phosphorus. However, a close examination of the impact of other formulation additives is lacking. A systematic evaluation of the impact of the detergent package, including single-metal and bimetal detergent systems, ashless and ash-containing additives has been undertaken using a GM 2.0L Ecotec engine installed on a conventional engine dynamometer test stand. Consistent with previous
Hybrid drivetrain hardware combines an electric motor and a transmission, gear box, or hydraulic unit. With many hybrid electric vehicle (HEV) hardware designs the transmission fluid is in contact with the electric motor. Some OEMs and tier suppliers have concerns about the electrical properties of automatic transmission fluids (ATFs). Lubrizol has conducted a fundamental research project to better understand the electrical conductivity of ATFs. In this paper, we will present conductivity data as a function of temperature for a range of commercially available ATFs. All fluids had conductivities ranging from 0.9 to 8x10-9 S/cm at 100 °C and can be considered insulators with the ability to dissipate static charge. Next we will deconstruct one ATF to show the relative impact of the various classes of lubricant additives. We find that more polar additives have a larger effect on conductivity on a normalized (per weight %) basis. Finally, we will show conductivity data for ATFs taken from
Elastomer compatibility is an important property of lubricants. When seals degrade oil leakages may occur, which is a cause of concern for original equipment manufacturers (OEMs) because of warranty claims. Leakage is also a concern for environmental reasons. Most often, the mechanical properties and fitting of the oil seals is identified as the source of failure, but there are cases where the interaction between the lubricant and the seal material can be implicated. The performance of seal materials in tensile testing is a required method that must be passed in order to qualify lubricant additive packages. We conducted an extensive study of the interactions between these elastomeric materials and lubricant additive components, and their behavior over time. The physicochemical mechanisms that occur to cause seal failures will be discussed
There has been a global technology convergence by engine manufacturers as they strive to meet or exceed the ever-increasing fuel economy mandates that are intended to mitigate the trend in global warming associated with CO2 emissions. While turbocharging and direct-injection gasoline technologies are not new, when combined they create the opportunity for substantial increase in power output at lower engine speeds. Higher output at lower engine speeds is inherently more efficient, and this leads engine designers in the direction of overall smaller engines. Lubricants optimized for older engines may not have the expected level of durability with more operating time being spent at higher specific output levels. Additionally, a phenomenon that is called low-speed pre-ignition has become more prevalent with these engines. While more pre-ignition may be expected with highly-boosted engines, an especially destructive version of this has been found to be related to some of the essential
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