Search Results (1,261)

High-entropy alloy (HEA) coatings have attracted wide scientific attention in academic research and industrial innovation. In the present paper, the NiCoCrAlY HEA coatings are successfully synthesized on the surface of M50 steel to improve the corrosion resistance and tribocorrosion resistance of M50 steel in salt-contaminated lubricating oil. The corrosion and tribocorrosion behaviors of M50 steel and NiCoCrAlY coatings are studied systemically under the same conditions. The experimental results show that NiCoCrAlY coatings have good, densified microstructures and improve effectively the corrosion resistance and tribocorrosion resistance of M50 steel because the protective passivation films and oxide films are formed on the surface of NiCoCrAlY coatings. NiCoCrAlY coatings have high corrosion potential, a low corrosion current density, and a corrosion rate that is comparable with M50 steel. The corrosion potential of M50 steel decreases and the corrosion current density increases with the increase in load due to wear-induced corrosion. The corrosion and tribocorrosion mechanisms of M50 steel and coatings are discussed in light of the experimental results. The wear mechanism of M50 steel is abrasive wear. It is accompanied by corrosion wear for M50 steel and oxidative wear for NiCoCrAlY coatings. Full article

In marine engineering, the daily management of mechanical equipment needs to ensure that the oil is normal. Oil plays the role of sealing, cooling, lubrication, and other functions in the equipment, and can also be used as hydraulic fluid to transfer energy. By analyzing the state of the oil, it is possible to obtain information about the operation of the equipment, such as judging the wear or failure of the equipment by detecting impurities in the oil. This paper proposes and designs a wireless triple-coil structure oil detection sensor for detecting metal particles in the oil circuit. The sensor consists of three coils placed concentrically with the same parameters. When the sensor detects metal particles in the oil, the ferromagnetic and non-ferromagnetic particles flowing through the sensor produce magnetization and eddy current effects, resulting in variable inductive signals that complete the detection of metal particles. This paper firstly explains the sensing principle of this triple coil sensor detection by formula derivation. Secondly, the simulation model of the sensor was established by using COMSOL 6.0 simulation software according to the scale of 1:1, and the magnetic field strength distribution law inside the coil of the triple-coil sensor was simulated. The experimental results showed that the sensor was able to detect iron particles at 73 µm and copper particles at 220 µm, moreover the obtained signal characteristics are obvious, with high detection sensitivity. The sensor is wireless and performs contactless detection of metal particles. This is important for the detection of metal particle contaminants in oil. Full article

Variable tooth thickness gears have significant effects on the characteristics of the flow field inside the gearbox and the lubrication efficiency under high-speed operating conditions due to their complex parameters, such as tooth profile, cone angle, rotational speed, and oil injection speed. To investigate the impact mechanism of oil injection velocity on the working flow field of high-speed variable tooth thickness gears under varying parameters, this paper establishes an oil injection lubrication model under high rotational speeds of variable tooth thickness gears, based on computational fluid dynamics (CFD) methods and the Volume of Fluid (VOF) model, combined with the dynamic mesh technique. This paper analyzes the lubrication issues at the initial oil injection moment of involute variable tooth thickness gears. By computing the lubricant distribution state at 0.1 s after the oil injection onset based on the stabilized flow field under no-oil-injection condition, discussions are conducted on the single-phase and two-phase flow fields within the gear casing at different cone angles and rotational speeds separately examining the flow states near the oil nozzle and the distribution patterns of lubricant at the meshing portions. The results indicate that, without oil injection, the pressure near the oil nozzle gradually increases with an increase in rotational speed and decreases with an increase in cone angle; at the initial oil injection moment, the lubricant volume fraction at the gear meshing portions gradually increases with an increase in rotational speed and rises with an increase in cone angle. Full article

The wettability of metal surfaces by different oils and water is a multifaceted phenomenon with significant implications for industrial processes, including lubrication, corrosion protection, and fluid transport; an understanding of the process is essential for optimizing the performance and durability of metallic components. The intermolecular interactions between oil molecules and the metal surface primarily influence the wetting of a metal surface by different types of oil. This paper introduces the concept of oil wetting on metal surfaces, exploring the factors influencing wetting behavior, the characterization techniques employed to assess wetting properties, and the implications for different industrial processes. This work aims to ascertain the contact angle of oil on various metal surfaces and subsequently establish a relationship between this contact angle and the attributes of the substrate. This is achieved through using the sessile drop technique. The results indicate that the wettability of petroleum was better than the hydraulic oil we used on all types of substrates (for example, on Ag surface, Θ-petroleum = 11°, but Θ-hydraulic oil = 20°). Also, we observed that the cosine of the oil/metal contact angle increases with the increase in the atomic radius of the pure metal substrate, and Becker’s broken bond model proved this linear relation. We then contrast this behavior with the wetting characteristics of water and glycerin on the same metals using the same conditions. Full article

A common approach to optimising hydrodynamic journal bearings for power loss is to reduce the lubricant supply and direct the oil to specific bearing areas where it is needed to guarantee safe operation. This requires information on the processes in the gap and the surrounding pocket areas for both pre-design and simulation. In this paper, a system consisting of a total of eight cameras is used to determine the void fraction in deep grooves outside the lubricant film. The void fraction in the lubrication gap is determined using a novel method for the evaluation of two proximity measurements. While the variation of the deep groove void fraction is realised by a special oil supply and radially adjustable deep groove elements, the gap void fraction is adjusted by the oil supply in the lube oil pockets at the pad leading edges. On the one hand, the experimental investigations show that the void fraction of the deep groove areas has hardly any influence on the general operating behaviour. On the other hand, the void fraction in the lubrication gap can be measured quantitatively for the first time, and the operating point-dependent gas fractions can be visualised. It is also shown that gaseous cavitation is the main mechanism in partially filled regions of the lubrication gap. Full article

This study investigates the tribological effects of nano-sized metal oxides (ZrO₂, CuO, Y₂O₃ and TiO₂) in Group III type base oil containing 0.3% pour point depressant (PPD) and 5% viscosity modifier (VM) to enhance friction and wear performance. The homogenized lubricant samples with varying concentrations of oxide nanoparticles (0.1–0.5 wt%) on a linear oscillating tribometer performed static and dynamic frictional tests. Optical and confocal microscopy surface analysis evaluated the wear of the specimen, and SEM and EDX analyses characterized the wear tracks, nanoparticle distributions, and quantification. The cooperation between PPD and nanoparticles significantly improved friction and wear values; however, the worn surface suffered extensively from fatigue wear. The collaboration between VM and nanoparticles resulted in a nanoparticle-rich tribofilm on the contact surface, providing excellent wear resistance that protects the component while also favorably impacting friction reduction. This study found CuO reduced wear volume by 85% with PPD and 43% with VM at 0.5 wt%, while ZrO₂ achieved 80% and 63% reductions, respectively. Y₂O₃ reduced wear volume by 82% with PPD, and TiO₂ reduced friction by 20% with VM. These nanoparticles enhanced tribological performance at optimal concentrations, but high concentrations caused tribofilm instability, highlighting the need for precise optimization. Full article

In order to improve the anti-friction property of common mineral oil and develop a high-performance lubricant, MoS₂ and SiO₂ nano-additives were individually dispersed into the 350SN mineral oil at various weight percentages to prepare nanolubricants. Then, the viscosity, wettability, and tribological properties of the nanolubricants were measured and analyzed with a rotary viscometer, a contact angle measuring instrument, and a friction tester. Finally, the action mechanism of two nano-additives was explained based on the energy spectrum test results of the abrasion surface. The results show that MoS₂ and SiO₂ nano-additives could improve the viscosity of the base fluid and change its wettability, giving nanolubricants better anti-friction performance than the base fluid. Due to the difference in physical properties, SiO₂ and MoS₂ nanolubricants presented different friction reduction rules with the increase in nano-additive percentage. Under experimental conditions, SiO₂ nanolubricants showed better anti-friction effects than MoS₂ nanolubricants. When the SiO₂ percentage was 10 wt% and 15 wt%, the maximum friction coefficient was reduced to 0.06, which was about 1/3 of that with the base fluid. In this case, the abrasion surface quality was significantly improved, and the abrasion trace size was about half that of the base fluid. The energy spectrum test results show that the action mechanism of the MoS₂ nano-additive is the adsorption film effect and mending effect of nanoparticles, while the main action mechanism of the SiO₂ nano-additive should be the polishing effect and rolling effect of nanoparticles. Full article

Friction is an unfavourable phenomenon in deep-drawing forming processes because it hinders the deformation processes and causes deterioration of the surface quality of drawpieces. One way to reduce the unfavourable effect of friction in deep-drawing processes is to use lubricants with the addition of hard particles. For this reason, this article presents the results of friction tests of dual-phase HCT600X+Z steel sheets using the flat die strip drawing test. Sunflower oil and rapeseed oil with the addition of 1, 5 and 10 wt.% of silicon dioxide (SiO₂) particles were used as lubricants. Tests were also carried out in dry friction conditions and lubricated conditions using SiO₂-modified oils and oils without the addition of particles, as a reference. Tests were carried out at different pressure values between 2 and 8 MPa. The effect of friction on the change in sheet surface roughness was also examined. For the entire range of pressures analysed, pure sunflower oil showed lower efficiency in reducing the coefficient of friction compared to pure rapeseed oil. In the pressure range of 4–8 MPa, the lubricants with 5 wt.% and 10 wt.% of particles were more effective in reducing friction than the biolubricant with the addition of 1 wt.% of SiO₂. The lowest average roughness was observed for lubrication with sunflower oil containing 5 wt.% of particles. In relation to rapeseed oil, the addition of 10 wt.% of SiO₂ provided a sheet surface with the lowest average roughness. Full article

Volatile and semi-volatile compounds, such as petroleum hydrocarbons and equipment lubricating oils, often contaminate soil due to accidents, posing significant ecological and health risks. Traditional soil remediation methods, such as thermal desorption and bioremediation, are time-consuming and resource-intensive, prompting researchers to explore more efficient alternatives. This study investigates the effectiveness of an in situ reactor for microwave-assisted soil remediation, specifically focusing on the impact of soil type and moisture content on pollutant removal efficiency. The reactor, designed to operate within a modified household microwave oven, provides direct microwave irradiation to the soil surface, enabling precise control of heating conditions. Experiments were conducted using soil samples of varying particle sizes and moisture levels under standardized conditions (1000 W microwave power, 2.45 GHz frequency). The results show that moisture content plays a critical role in pollutant removal efficiency, with an optimal moisture content of 10 wt % enhancing microwave absorption and energy transfer, thus improving pollutant recovery. In comparison with traditional resistive heating, microwave heating achieved a faster temperature rise and higher final temperatures, significantly improving pollutant removal efficiency in a shorter time frame. This study highlights the advantages of microwave heating, including its superior energy efficiency, faster pollutant volatilization, and the potential for optimized soil remediation in real-world applications. These findings provide valuable insights for the development of more sustainable and efficient soil remediation technologies. Full article

Currently, few studies have been conducted on the use of fluorocarbon resin (FEVE) and polytetrafluoroethylene (PTFE) as adhesive substrates and lubricating and anti-corrosion fillers, respectively, for the fabrication of PTFE-reinforced fluorocarbon composite coatings. In this paper, the tribological properties of polytetrafluoroethylene-reinforced fluorocarbon composite coatings were investigated through orthogonal tests under various operating conditions. The optimal configuration for coating preparation under dry friction and aqueous lubrication was thus obtained: the optimal filler particle size, mass ratio of FEVE to PTFE, spraying pressure, and curing agent content were 50 μm, 3:4.5, 0.3 MPa, and 0.3, respectively. Under oil lubrication, the corresponding optimal values were 5 μm, 3:4.5, 0.3 MPa, and 0.3, respectively. Tribological tests revealed that the best overall performance of the FEVE/PTFE coating was obtained when the mass ratio of FEVE to PTFE was 3:4.5, and the filler particle size also significantly affected the tribological properties under different environments, including the friction coefficients of the FEVE/50 μm-PTFE coating under both dry friction and aqueous lubrication, as well as the friction coefficient of the FEVE/5 μm-PTFE coating under oil lubrication. These coefficients were 0.067, 0.062, and 0.055, representing decreases of 86%, 92%, and 56%, respectively, compared to those of the pure FEVE coating under the same working conditions. This research was conducted with the goal of expanding the application of fluorocarbon coatings in the field of tribology. Full article

The cleanliness of lubricating oil plays a key role in determining the operational health of mechanical systems, serving as a critical metric that delineates the extent of equipment wear. In this study, we present a magnetic-core-type planar coil particle detection sensor. The detection accuracy and detection limit are improved by optimizing the magnetic field inside the sensor. The optimization of the magnetic field is achieved through the finite element simulation analysis of the coil and the magnetic core. First, the finite element simulation software COMSOL 6.0 is used to model the sensor in three dimensions (3D). Then, we study the distribution of the magnetic field under different coil radii, core conductivity levels, and other parameters. We obtain the sensor structure after optimizing the magnetic field. The sensor is made using experimental methods, and the iron particles and copper particles are detected. The results show that the lower limit of detection of iron particles can reach 46 μm, and the lower limit of detection of copper particles can reach 110 μm. Full article

This research follows closely previous findings in flow characteristics and phenomena that take place in the piston ring and cylinder liner interface during motoring and firing engine operation, and also compares results between different optical engine set-ups. Cavitation visualisation in a simulating lubrication single-ring test rig and oil transport and cavitation visualisation in custom made cylinder assemblies of optical engines are the tools used to quantify the transport process under the piston ring and cylinder liner. Simplification of the interface is an essential technique that enhances the researcher’s confidence in results interpretation. Engine complexity and severe oil starvation are impeding the analysis of the experimental results. Visualisation experiments constitute an effective way to test various lubricant types and assess their overall performance characteristics, including their properties and cavitation behaviour. The repeatability of the visualisation method establishes the parametric study effects and offers valuable experimental results. As a further step towards the lubricant composition effect, a link between the lubricant formulation and the operating conditions could be established as the oil performance is assessed with a view to its transport behaviour. Image processing is used to quantify the impact of cavitation on piston ring lubrication in conjunction with varied operating and lubricant parameters. The characteristics of the lubricant and the working environment have an impact on these types of cavities. Viscosity, cavitation, oil film thickness (OFT), lubricant shear-thinning characteristics and friction are all linked. Full article

Research on and the development of bio-based lubricants as alternatives to mineral-based lubricants have been encouraged worldwide owing to environmental concerns and the possible depletion of oil reserves. This study explored the use of grape seed oil (GSO), a byproduct of wine production, as a raw material for biolubricant synthesis. GSO contains a triglyceride molecule rich in unsaturated fatty acids, which is ideal for obtaining biolubricants. This study addresses the technical challenges of converting GSO into a lubricant by synthesizing methyl esters (FAME) via transesterification with 2-ethylhexanol to produce a biolubricant (BL) sample. The obtained products were characterized using Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy to confirm the conversion of the molecules. The density, kinematic viscosity, and viscosity index were determined using the parameters established by ASTM. The tribological characteristics of BL were evaluated using a four-ball tribometer configuration. BL exhibited physicochemical characteristics comparable with those of an ISO VG 10 lubricant, a friction coefficient (FC) 40.82% lower than that of a hydrotreated mineral oil sample, and a smoother wear surface. These results indicate that the polarity of the ester functional group was efficient in producing a protective film on metal surfaces. Full article

This study is related to producing a set of fatty acid esters from different vegetable oils and C1–C12 alcohols. A total of 66 products were synthesized. The obtained esters were characterized by fatty acid composition, density, viscosity, saponification value, acid value, iodine value, low-temperature properties, and oxidative stability. It was established that the fatty acid composition, as well as alcohol, used has a significant impact on esters properties. Comparing physicochemical properties of fatty acid esters with existing standards and specifications, it was proposed to use esters for different industrial applications. In particular, rapeseed oil fatty acid methyl esters are an ideal candidate for application as biodiesel, while transesterification of soybean oil, sunflower oil, rapeseed oil, and coconut oil with higher alcohols led to products with promising properties as bio-lubricants. Castor oil alkyl esters could potentially be utilized as base oils due to their excellent viscosity and low-temperature properties. Full article

To enhance the sliding tribological performance between PTFE and 40#steel (AISI 1040) under full film lubrication conditions, laser surface texturing (LST) technology was employed to prepare micro-dimples on the contact surfaces of 40# steel discs. The Box–Behnken design response surface methodology (BBD-RSM) was applied to optimize the micro-dimple parameters. Coefficients of friction (COFs), wear losses and worn contact surfaces of the PTFE–40# steel tribo-pairs were researched through repeated wear tests, as lubricated with sufficient anti-wear hydraulic oil. The influencing mechanism of micro-dimples on the tribological behavior of tribo-pairs was also discussed. The results proved that micro-dimples can significantly improve the tribological properties of PTFE–40#steel tribo-pairs. The deviation between the final obtained average COF and the prediction by the BBD-RSM regression model was only 0.0023. Following optimization, the average COF of the PTFE–40# steel tribo-pair was reduced by 39.34% compared to the smooth reference. The wear losses of the PTFE ring and 40# steel disc decreased by 91.8% and 30.3%, respectively. This study would offer a valuable reference for the optimal design of key seals used in hydraulic cylinders. Full article