Considering the growing interest in substituting internal combustion engine vehicles with highly efficient electric vehicles around the world, this paper aims to contribute with a literature review ...about the current state and future improvement trends for optimization of critical tribological components used in passenger electric vehicles. The review gives an understanding of the most recent achievements in terms of tribological solutions applied to the critical components and the identification of research gaps for further developments and efficiency improvements for EVs through novel component designs, materials and lubricant technologies.
Up to date, most metalworking fluids (MWFs) are emulsions made of petroleum-derived oil bases and sodium petroleum sulphonate emulsifiers. They are not readily biodegradable, and their waste is ...hazardous for users and the environment. Therefore, green MWFs are required for achieving cleaner production processes. Recently, various MWFs have been developed using vegetable oil bases to meet biodegradability to some extent. However, the emulsifier has been scarcely replaced by a green product. This research aims to produce and evaluate Pickering emulsions made of Jatropha oil (JO) and partially deacetylated and fibrillated chitin (PDFC) as emulsifiers at different concentrations. JO is a non-edible biodegradable oil with remarkable lubricity properties, while PDFC is produced by extracting chitin from waste heads and shells of the shrimp species
, followed by partial deacetylation and further fibrillation, which improves wettability and stabilization. The prepared emulsions were characterized in terms of creaming index and size of emulsion droplets and evaluated as MWFs in actual turning operations of AISI 1018 steel bars via minimum quantity lubrication (MQL) technique. The findings suggest PDFC as a potential eco-friendly emulsifier to form green MWFs with acceptable stability generating low cutting forces and significant workpiece finishing and chips quality.
This work aims to determine the alteration of lubricity properties of Jatropha oil (SJO) due to thermal ageing caused by approached long-term use conditions as lubricant in engines. SJO, a mineral ...engine oil (EMO) and a blend made of 80%vol. of EMO and 20%vol. of SJO (B20) were tested. The oils were thermally aged at 160 °C for 30 and 60h. Oil ageing was characterized by measurement of oxidation, depletion of additives, kinematic viscosity and viscosity index. Ball-on-disk tests were conducted to evaluate friction coefficients and wear rates of disks samples from engine cylinder liners by using the oils. SJO was seriously oxidized compared to EMO and B20 by ageing, exhibiting high changes of viscosity from 58.8 to 1970 cSt at 26 °C and decrease of viscosity index from 262 to 200.4. The friction coefficients of SJO were not altered remaining in low values 0.06–0.07. The viscosity increase allowed a reduction of wear rates from 0.00065 to 0.0002 mm3/m. B20 exhibited better lubricity properties than EMO; and they even were improved after ageing. Thus, SJO could be blended with mineral oils in low concentrations to reduce friction and wear while promoting safe use of a renewable product in short and long-term uses in engines.
•Oxidation and lubricity of Jatropha oil due to thermal ageing was assessed.•Jatropha oil was seriously oxidized by thermal ageing.•Viscosity of Jatropha oil was highly raised by thermal ageing.•Friction coefficient of Jatropha oil was not altered by thermal ageing.•Wear produced by using Jatropha oil was reduced due to thermal ageing.
This work aims to determine the tensile set behavior of a silicone rubber under different stress magnitudes and temperatures through digital image correlation implemented in an improved creep ...experimental set-up. Creep-recovery strains were measured with time at 20, 40 and 60 °C under tensile strengths of 98.1, 196.2 and 394.3 kPa, respectively. The behavior of creep and recovery strain with time at the different stress magnitudes and temperatures was successfully obtained by the experiments. The corresponding elastic and viscous components of the material for each condition were determined from the results. Overall, all obtained creep behaviors matched with the behavior of a four-element model of creep-recovery. The increase of temperature generated an increase of creep compliance at the three loads, but the increase of tensile load produced a decrease of creep compliance for the three temperatures. The strain was not recovered entirely in any case for the test time stated.
•Tension set of a silicone rubber was successfully characterized via DIC.•Different tensile loads and temperature were tested effectively.•All found creep and recovery behaviors corresponded to a four-element model.•Elastic and viscous constants of silicone rubber were determined for the different conditions.•The test proposed in this work is simple and effective for creep strain measurement.
Wear of metallic biomaterials is critical in controlling and determining the long-term clinical performance of total joint replacements. Apart of reduced biomaterial's life span by wear, debris can ...cause hazardous inflammation and damage to the bone supporting the implant. The micro-abrasion tester is broadly used to evaluate wear resistance of biomaterials by the effect of hard debris interacting at the sliding interface. However, this tester is only capable to reproduce micro-abrasion in unidirectional sliding, contrary to that occurring in actual knee joints where sliding is oscillatory. So, micro-abrasion testing under oscillating sliding would be more realistic for this kind of biomedical applications since different sliding motion can promote dissimilar micro-abrasion mechanisms and wear rates. Hence, this paper presents a novel micro-abrasion tester able to reproduce both unidirectional and oscillating sliding modes. To illustrate the methodology using the tester, an ASTM-F1537 CoCrMo alloy against an AISI 52100 steel countersurface was tested under unidirectional and oscillating sliding modes under rolling and grooving abrasion at different loads and sliding distances. The results obtained suggest similar wear rates and patterns for rolling abrasion but different for grooving for both sliding modes. Acceptable reproducibility, accuracy and versatility for micro-abrasion testing under different sliding modes were accomplished with this novel tester.
•A novel micro-abrasion tester for unidirectional and oscillating sliding is proposed.•The new tester can reproduce approached oscillating sliding motion to that of knee joint prostheses.•Rolling and grooving abrasion of a CoCrMo alloy in both sliding modes were compared.•Insignificant wear differences were formed by rolling abrasion for both sliding modes.•Different distinct wear rates, patterns and mechanisms were formed for unidirectional and oscillating grooving.
•A method for conducting micro-abrasion testing of materials in oscillating sliding is provided.•Oscillating parameters for micro-abrasion testing are given.•The method includes parameters for ...reproducing rolling abrasion and grooving in oscillating sliding.
Micro-abrasion is a kind of wear occurring on materials´ surfaces by action of three-body hard particles existing at the sliding interface. It is consistently reproduced by a popular laboratory method well-known as ball cratering test. Characteristically, it consists of wearing off a material sample by loading it against a ball that rotates continuously and unidirectionally under controlled conditions. A slurry containing a certain amount of hard micro-sized particles is dropped uninterruptedly onto the ball to get the particles enters the sliding contact by the ball´s rotary effect. The present method proposes a variant to the classic micro-abrasion methodology. It comprises changing the ball motion from a unidirectional to an oscillating for testing by considering new test parameters such as sliding arc lengths and frequency, which provides more realistic sliding conditions and wear rates for materials to be used in mechanical applications involving reciprocating and oscillating sliding.
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Bio-lubricants have emerged as a potential and viable way to replace, totally or partially, mineral oils due to their effectiveness in the boundary lubrication regime for different applications, ...including, automotive engine operation. However, the effect of thermo-oxidation caused by the long-term use of the bio-lubricants on their tribological properties has been scarcely analysed. In this work, the effect of thermo-oxidation of Jatropha oil (JO), an engine mineral oil (EMO) and a blend made up of 80%vol. EMO and 20%vol. JO (B20) on the tribological behaviour of a simulated piston ring/engine cylinder liner interface was studied in reciprocating friction tests at 26 and 100 °C. The oils were thermally oxidized and characterized in terms of carbonyl compounds, depletion of ZDDP additives, changes in kinematic viscosity and viscosity index. Friction coefficients, wear rates and scar morphologies were assessed. Thermo-oxidation resulted in significant viscosity increases in JO compared to EMO and B20. Also, it generated increased friction coefficients for JO and B20. However, they were lower than those for fresh and aged EMO. EMO increased the wear rate after thermo-oxidation in contrast to JO. Smearing was generated using most oil samples while severe scuffing was only produced by using fresh JO at 100 °C.
•Chemical and physical changes of Jatropha oil caused by ageing were analyzed.•Actual cylinder liner samples were tested by a reciprocating friction tester.•Friction and wear of Jatropha oil, a mineral oil and a blend were compared.•The effects of ageing on the lubricant properties of the oils were assessed.•Wear features on cylinder liner samples using the different oils are presented.
Nowadays, biolubricants are being used to replace mineral lubricants totally or partially and it is of great importance due to interest in environmental protection. Jatropha oil is a good alternative ...as lubricant feedstock and combustible. Its production is cheap in comparison to other vegetable oils. In México, Jatropha curcas L. is widely distributed in more than 15 states, which makes a sustainable supply of this natural resource possible. The aim of this work was to investigate the frictional behavior of blends of automatic transmission fluid with vegetable oil tested in a pin-on-disk rig simulating the wet clutch operation. Two different friction materials were separately tested and used as pins against actual steel disks from a wet clutch. The frictional behavior results demonstrated that the mixtures presented antishudder characteristics. Thus, Jatropha oil could be potentially used as part of automatic transmission fluid (ATF) formulations to enhance their antishudder properties and increase the efficiency of the torque transferred of wet clutches with a controlled lock-up clutch system, which improves the full economy of vehicles.
Straight vegetable oils (SVO's) are currently used as renewable sources of fuel in diesel engines for electricity production, transport or agricultural mechanization. Despite various environmental ...benefits, the use of SVO's may result in shortcomings for the engine operation, in particular, degradation of seals and polymeric components. Thus, deterioration of seals into contact with SVO's in engines must be analyzed to make a safe use of these alternative fuels. In this work, the deterioration of silicone rubber (VMQ), fluoroelastomer/Viton® (FKM), ethylene-propylene-diene monomer (EPDM) and neoprene/chloroprene rubber (CR), upon exposure to straight Jatropha oil (SJO), diesel, and a blend 80% diesel-20% SJO (B20), respectively, was analyzed by immersion tests with measurements of changes in mass, volume, tensile and tear strengths, and hardness. Complementary measurements of changes in viscoelasticity, surface morphology, topography, and chemical composition provided further insight into the understanding of deterioration of the elastomers. Overall, the four elastomers exhibited negligible deterioration with SJO while only FKM exhibited minimal deterioration with diesel and B20. VMQ and FKM were the less deteriorated elastomers by SJO and diesel, respectively. These experimental results were found to be in good agreement with predictions of compatibility based on the use of the Hansen solubility theory.
•Deterioration of elastomers due to exposure to Jatropha oil and diesel was studied.•Changes in composition and physical and mechanical properties were assessed.•Standard tests suggest minimal deterioration of seals with Jatropha oil.•Silicone rubber is almost not affected by Jatropha oil.•FKM is the only seal almost not deteriorated by diesel.
Vegetable oils are potential alternative lubricants for the twofold purpose of achieving good tribological properties while protecting the environment. However, any intended use of bio-lubricants in ...machinery requires of a previous study of their compatibility with the involved sealing materials. In particular, Jatropha oil (JO) is inexpensive and easy to obtain, which make it a good candidate to be used as bio-lubricant in machinery. In this work, a compatibility study of four commercial sealing elastomers, namely, fluoroelastomer (FKM), silicone rubber (VMQ), neoprene/chloroprene (CR), and ethylene-propylene-diene monomer (EPDM) with JO, engine mineral oil (EMO) and a blend of EMO and JO (80-20%) (B20), for the purpose of comparison, was conducted. The analyses include the basic measurements comprised in the ASTM-D471 and ASTM-D7216 methods, namely, changes in mass, volume, tensile and tear resistance and hardness. In addition, non-standard measurements of creep compliance, surface morphology and topography, and chemical composition were performed to achieve a deeper evaluation of the interaction of JO with the elastomers. In general, good compatibility was found regarding the standard methods for the four elastomers with JO, VMQ being the most compatible sealing material. However, FKM, CR and EPDM showed changes in the creep compliance modulus and surface morphology when in contact with the three lubricants, which may considerably affect their sealing performance and decrease their useful life. Overall, pure JO generated much less physical changes on the elastomers than EMO and B20, which can be ascribed to the concentrations of free fatty acids contained in JO.
•The compatibility of common elastomers with Jatropha and engine oils was studied.•Standardized tests suggest that Jatropha oil is compatible with common elastomers.•The elastomers presented changes of creep and topography by using Jatropha oil.•Silicone rubber is almost not affected by Jatropha oil.
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