Lubricants

In aerospace technology, angular contact ball bearings are required to exhibit extremely high operational precision, necessitating real-time monitoring of their wear status to conduct pre-failure analysis. Although extensive studies have been conducted on the wear characteristics of angular contact bearings, further in-depth research is still required to enhance the accuracy of bearing life predictions. To address the imprecision in wear life prediction for angular contact ball bearings, this article proposes a refined wear calculation model based on dynamic load distribution. The model calculates the dynamic load distribution between the inner and outer rings and the raceway under mixed lubrication conditions. Integrating the dynamic load distribution methodology with the wear calculation model, the dynamic contact characteristics of angular contact bearings can be more accurately characterized. Building on this foundation, a dynamic analysis model considering dynamic wear in the bearing contact zone is established. The vibration characteristics of bearings under varying loads are analyzed, and vibration experiments under different load conditions are conducted. Through vibration spectrum analysis, the influence patterns of wear characteristic frequency bands in the wear model on the pre-failure state of bearings are further elucidated. This study provides a theoretical basis for bearing wear life prediction analysis.

To improve the tribological performance of poly(ether ether ketone) (PEEK), a potassium titanate whisker/graphene multi-dimensional hybrid filler was proposed. Hybrid fillers with one-dimensional (1D) potassium titanate whiskers and two-dimensional (2D) graphene nanosheets in different ratios were fabricated using direct mixing and grafting methods. The potassium titanate whiskers and graphene nanosheets are an excellent combination, as confirmed by SEM and FTIR. Furthermore, PEEK/hybrid filler composites with different mass percentages of fillers were prepared and investigated systematically. It was found that introducing multi-dimensional hybrid PTWs–GNPs (volume ratio 1:3) fillers led to the wear rate being as low as 3.214 × 10−6 mm3N−1m−1, reduced by 60% compared with pure PEEK. In addition, the wear mechanism of PEEK composites was also investigated. The results demonstrate the superior tribological properties of the PEEK composites with multi-dimensional hybrid PTWs–GNPs fillers.

CoCrFeNiMn high-entropy alloy (HEA) composite coatings with 0, 10, and 20 wt% TiC are synthesized through laser cladding technology, and their corrosion and wear resistance are systematically investigated. The X-ray diffraction (XRD) results show that with the addition of TiC, the phases of TiC and M 23 C 6 are introduced, and lattice distortion occurs simultaneously (accompanied by the broadening and leftward shift of the main Face-Centered Cubic (FCC) peak). Scanning electron microscopy (SEM) reveals that the incompletely melted TiC particles in the coating (S2) are uniformly distributed in the matrix with 20 wt% TiC, while in the coating (S1) with 10 wt% TiC, due to gravitational sedimentation and decomposition during laser processing, the distribution of the reinforcing phase is insufficient. When rubbed against Si 3 N 4 , with the addition of TiC, S2 exhibits the lowest friction coefficient of 0.699 and wear volume of 0.0398 mm 3. The corrosion resistance of S2 is more prominent in the simulated seawater (3.5 wt% NaCl). S2 shows the best corrosion resistance: it has the largest self-corrosion voltage (−0.425 V vs. SCE), the lowest self-corrosion current density (1.119 × 10 −7 A/cm 2), and exhibits stable passivation behavior with a wide passivation region. Electrochemical impedance spectroscopy (EIS) confirms that its passivation film is denser. This study shows that the addition of 20 wt% TiC optimizes the microstructural homogeneity and synergistically enhances the mechanical strengthening and electrochemical stability of the coating, providing a new strategy for the making of HEA-based layers in harsh wear-corrosion coupling environments.

The accurate characterization of wear debris is crucial for assessing the health of rotating engine components and for conducting simulation experiments in debris detection. This study proposed an intelligent recognition method for ferrography wear debris images, leveraging several improved Mask Region-based Convolutional Neural Network (Mask R-CNN) algorithms to quantitatively calculate both the number of debris particles and their coverage areas. The improvement on the Mask R-CNN focuses on two key aspects: enhancing feature extraction through the feature pyramid network structure and integrating attention mechanisms. The most suitable attention mechanism for wear debris detection was determined through ablation experiments. The improved Mask R-CNN combined with the Convolutional Block Attention Module achieves the best Mean Pixel Accuracy of 87.63% at a processing speed of 7.6 frames per second, demonstrating its high accuracy and efficiency in wear particle segmentation. Furthermore, the quantitative and qualitative analysis of wear debris, including the number and area of debris particles and their classification, provides valuable insights into the severity of wear. These insights are essential for understanding the extent of wear damage and guiding maintenance decisions.

This study explores the impact of a phosphonium-based IL (trihexyltetradecylphosphonium bis(2-ethylhexyl) phosphate, [P6,6,6,14][BEHP])) on the tribological performance of an automatic transmission fluid (ATF) when used as an additive. Tests were carried out under both non-electrified and electrified conditions in a reciprocating ball-on-flat tribometer. After tribological tests, the worn surfaces were subjected to extensive structural and surface analyses to understand the underlying friction and wear mechanisms. The addition of this ionic liquid improved the anti-wear protection of the ATF, although the wear rates were consistently higher than in non-electrified conditions. The tribofilm formed by the IL-containing ATF augmented the electrical resistance at the contact interface, thereby reducing the likelihood of electrification-induced wear. Our results point to the need for further improvements in the chemical formulation of the ionic liquids, like the one used in the present study, to enhance the protection of sliding surfaces against wear in future electric vehicle applications.

In many applications, it is necessary to optimise the performance of hydrodynamic (HD) bearings. Many studies have proposed different strategies, but there remains a lack of conclusive research on the suitability of various optimisation methods. This study evaluates the most commonly used algorithms, including the genetic (GA), particle swarm (PSWM), pattern search (PSCH) and surrogate (SURG) algorithms. The effectiveness of each algorithm in finding the global minimum is analysed, with attention to the parameter settings of each algorithm. The algorithms are assessed on HD journal and thrust bearings, using analytical and numerical solutions for friction moment, bearing load-carrying capacity and outlet lubricant flow rate under multiple operating conditions. The results indicate that the PSCH algorithm was the most efficient in all cases, excelling in both finding the global minimum and speed. While the PSWM algorithm also reliably found the global minimum, it exhibited lower speed in the defined problems. In contrast, genetic algorithms and the surrogate algorithm demonstrated significantly lower efficiency in the tested problems. Although the PSCH algorithm proved to be the most efficient, the PSWM algorithm is recommended as the best default choice due to its ease of use and minimal sensitivity to parameter settings.

This experimental study investigates the critical role and impact of additive concentration in enhancing the tribological performance of castor oil as a biolubricant for agricultural tractor engines. Friction and wear are major contributors to reduced engine efficiency , highlighting the need for effective lubrication strategies. While biolubricants like castor oil offer environmental benefits, they often require additives to achieve optimal performance. However, the concentration of these additives is crucial, as an imbalance can negatively impact the lubrication system, leading to a higher coefficient of friction, increased wear, and reduced engine efficiency and lifespan. This study examines the effects of varying concentrations of a mixture of propyl gallate (PG) and ionic liquid (IL) additives on the tribological performance of castor oil. The tribological behaviour of lubricated top compression piston ring and cylinder liner samples was evaluated under simulated engine conditions using a Bruker UMT Tribolab test rig, in accordance with the ASTM G181 standard. The experimental results revealed an influence of additive concentration on the coefficient of friction and wear behaviour. This emphasises the importance of optimising additive formulations to minimise engine wear and friction. Notably, a 0.5% volume concentration of the additive mixture led to a remarkable 34.8% reduction in the average coefficient of friction (COF) and a lower wear rate.

Compared to single-decker ball bearings, double-decker ball bearings offer advantages such as higher speed limits, greater load capacity, and better impact performance. However, the inclusion of an additional bearing and adapter ring structure increases its overall mass, limiting its applications. This study addresses the challenges of achieving lightweight design and impact resistance in double-decker ball bearings. Using bionic principles, this study analyzes the internal spatial structure and fiber distribution of loofah to guide the bionic design of the adapter ring in the double-decker ball bearing. A new bearing structure inspired by loofah characteristics is proposed, and a finite element model for its mechanical analysis is developed. The structural response of both the new and traditional double-decker ball bearings is analyzed under varying speeds and impact excitation conditions. The results indicate that the mass of the new adapter ring is reduced by 25.26%, with smaller stress variation and more uniform stress distribution in the bionic design. The overall performance of the new double-decker ball bearing outperforms the traditional design in terms of deformation, equivalent stress, equivalent strain, and contact stress. The proposed bionic loofah-inspired double-decker ball bearing meets both lightweight and impact resistance requirements. The findings provide a theoretical foundation for applying double-decker ball bearings in high-impact and lightweight applications.

A tapered roller bearing (TRB) is a specialized type of bearing with a high load-to-volume ratio, designed to support both radial and axial loads. Lubrication plays a crucial role in TRB operation by reducing friction and dissipating heat generated during rotation. However, it can also negatively impact TRB performance due to the viscous and inertial effects of the lubricant. Extensive research has been conducted to examine the role of lubrication in TRB performance. Lubrication primarily influences the frictional characteristics, thermal behavior, hydraulic losses, dynamic stability, and contact mechanics of TRBs. This paper aims to collect and classify the scientific literature on TRB lubrication based on these key aspects. Specifically, it explores the scope of research on the use of Newtonian and non-Newtonian lubricants in TRBs. Furthermore, this study analyzes research based on TRB size and type, considering both oil and grease as lubricants. The findings indicate that both numerical and experimental studies have been conducted to investigate Newtonian and non-Newtonian lubricants across various TRB sizes and types. However, the results highlight that limited research has focused on non-Newtonian lubricants in TRBs with an Outer Diameter (OD) exceeding 300 mm, i.e., those typically used in wind turbines, industrial gearboxes, and railways.

This paper presents an experimental study of uniform and variable texture patterns on a honed EN-GJS 400-15 spheroidal graphite cast iron surface. Textured samples were fabricated using a CNC electrochemical jet machining technique and tested against a 52100 G5 roller countersurface featuring a rectangular 1 mm × 13 mm contact area. Tribological tests were conducted in a fully flooded PAO4 lubricant bath at 30 °C on a TE-77 reciprocating sliding tribometer with a 25 mm stroke length. Frictional behaviour was assessed at test frequencies from 12 to 18 Hz under two loads, 11 N and 50 N, covering mixed and hydrodynamic lubrication regimes. Experimental results demonstrated that EJM textured surfaces were accurately fabricated within a ±2.50 µm standard error in depth, with chemical etching effects reducing the Rq roughness of initial grinding marks by 0.223 µm. Textured surfaces exhibited a more pronounced friction performance at 50 N than at 11 N, exhibiting a consistent friction reduction of up to 18.8% compared to the untextured surface. The variable textured surface outperformed the uniform textured surface under the mixed lubrication regime due to the enhanced secondary lubrication effect. Optical and SEM analyses revealed that textured surfaces reduced plastic deformation and two-body abrasion.

To optimize heat treatment of gears for high-end equipment and enhance their fatigue resistance, this paper studied the effects of Al, Mn and Cr content on surface microstructure, i.e., martensite, retained austenite, grain size, hardened layer depth and residual stress under different carburizing temperatures and low tempering of 20MnCr5 steel FZG gear. With numerical simulation combined with experimental verification, this paper establishes a simulation model for the carburizing process of 20MnCr5 steel FZG gear, analyzing the microstructure and retained austenite volume of the gear surface, after carburizing and quenching, by a scanning electronic microscope (SEM) and X-ray diffraction (XRD). In addition, the paper reveals the influence of the optimized heat treatment on the residual stress of the gear regulated with Al, Mn and Cr content in the meshing wear range of 200~280 µm. This study provides a guiding model theory and experimental verification for regulating proportions of alloying elements and optimizing the heat treatment process of low-carbon-alloy steel.

Based on the small perturbation method, the transient pressure control equation considering real gas effects was solved, and the fitting expression for the dynamic characteristic parameters of the gas film during the start-up process was obtained. Subsequently, the influence of structural parameters of spiral-groove dry-gas seals on the dynamic tracking of the stationary ring’s motion during the non-steady-state start-up process under three-degree-of-freedom perturbations was analyzed. The results show that when the stationary and rotating rings initially separate, the stationary ring exhibits good tracking performance for both axial and angular motions of the rotating ring, although the tracking capability varies significantly. As time and film thickness increase, the tracking capability gradually weakens, and for the working film thickness, the tracking parameters tend to stabilize when the working film thickness is reached. The larger the spiral angles and the deeper the dynamic pressure grooves, the poorer the axial and angular tracking performance of the sealing ring. The number of grooves has a minimal impact on the axial and angular tracking performance of the stationary ring. A higher balance coefficient improves the axial and angular tracking performance of the stationary ring.

Enhancing the durability and tribological performance of babbitt alloys is critical for high-stress applications in automotive, marine, and industrial machinery. The present study explores the electrodeposition of chromium coatings on SnSb11Cu6 alloys to improve their microstructural, mechanical, and tribological properties. The coatings were applied through an electrolytic process and systematically characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy to evaluate their morphology, composition, and wear performance. The chromium coating exhibited a uniform thickness of 20.2 µm and significantly improved the surface hardness to 715.2 HV, far surpassing the matrix and intermetallic phases of the uncoated alloy. Tribological testing under dry sliding conditions demonstrated a 44% reduction in the coefficient of friction (COF) and a 54% decrease in mass wear for the coated alloy, highlighting the protective role of the chromium layer against abrasive and adhesive wear. To further analyze the frictional behavior, a deep learning model based on a one-dimensional convolutional neural network was employed to predict COF trends over time, achieving excellent accuracy with R2 values of 0.9971 for validation and 0.9968 for testing. Feature importance analysis identified coating hardness as the most critical factor influencing COF and wear resistance, followed by matrix hardness near the coating. These findings underscore the effectiveness of chromium coatings in mitigating wear damage and improving the operational lifespan of SnSb11Cu6 alloys in high-stress applications. This study not only advances the understanding of chromium coatings for babbitt materials but also demonstrates the potential of machine learning in optimizing tribological performance.

Titanium alloys are widely used in medicine due to their unique properties, including inertness with respect to living tissues, light weight, high strength, and impact toughness. For successful implementation, titanium alloy implants should possess high wear resistance and hydrophilicity. This article investigates the surface modification process of VT-1 and VT-6 titanium alloys by electron-beam processing (EBP). The EBP effect on the modified surface′s wear resistance, roughness, and hydrophilicity was analyzed. The specimens were made by machining them at a CNC turning center. The specimen surfaces were modified at the SOLO facility by a submillisecond modulated electron beam with a controlled power density of thermal impact, allowing it to reach and stabilize 1400 °C in 400 µs and then maintain it on the surface for 600 µs. A friction machine with a counterbody was used to study the wear resistance of the specimen surface. The study revealed that EBP reduces the roughness parameters of the surface. EBP also decreases the contact angle of wetting, indicating an increase in hydrophilicity compared to the original surface. Experimentally, it was shown that the formation of a nanostructure consisting of needle-like α-strips induced by EBP improves the wear resistance of the surface layer.

Firstly, the Reynolds equation considering gas inertia force is theoretically deduced in the cylindrical coordinate system, and then a mathematical model of aerostatic thrust bearing with three degrees of freedom (3-DOF) is constructed. Secondly, the Reynolds equation and velocity control equation are solved by the finite difference method (FDM), and the characteristics of gas pressure and velocity distribution in the gas film under steady-state conditions are revealed. On this basis, in the single-factor analysis, the bearing capacity error and recovery torque error caused by the inertia force term are quantitatively analyzed. It is found that the bearing rotating speed has a significant influence on the inertial force error, and the bearing radius also has a certain influence on the inertial force error, while the initial clearance, gas supply pressure, and torsion angle have relatively little influence on the inertial force error. Finally, in the multi-factor analysis, the sample regression equation of relative error of bearing capacity and relative error of restoring torque is established by using the multiple regression analysis method. By comparing the estimated values with the simulation results, the validity of the constructed regression equation is verified.

A typical head–disk interface of hard drives can feature pressures exceeding 50 atmospheres, where the non-ideal gas effects can play an important role. One possible consequence is a change in the rate of water evaporation from the disk. This report describes a semi-analytical procedure that employs the concept of fugacity to investigate the non-ideal gas effects on the saturation pressure of water at an elevated temperature and pressure. A vapor–liquid equilibrium equation is solved to derive the saturation pressure. The results show a deviation from the ideal gas law, which is further examined through saturation pressure isotherms. At areas of low temperature and high pressure, lighter gases such as helium show about a 10% deviation from the ideal gas law, whereas heavier gases such as nitrogen deviate by up to 100%. As temperature increases, the differences between the gases decrease.

This study examines the flow dynamics of synovial fluid within a lubricated knee joint during movement, incorporating the effect of inertia and linear re-absorption at the synovial membrane. The fluid behavior is modeled using a couple-stress fluid framework, which accounts for mechanical phenomena and employs a lubricated membrane. synovial membrane plays a crucial role in reducing drag and enhancing joint lubrication for the formation of a uniform lubrication layer over the cartilage surfaces. The mathematical model of synovial fluid flow through the knee joint presents a set of non-linear partial differential equations solved by a recursive approach and inverse method through the software Mathematica 11. The results indicate that synovial fluid flow generates high pressure and shear stress away from the entry point due to the combined effects of inertial forces, linear re-absorption, and micro-rotation within the couple-stress fluid. Axial flow intensifies at the center of the knee joint during activity in the presence of linear re-absorption and molecular rotation, while transverse flow increases away from the center and near to synovium due to its permeability. These findings provide critical insights for biomedical engineers to quantify pressure and stress distributions in synovial fluid to design artificial joints.

This work studied the effect of self-protective paste nitriding (SPN) and ion plasma nitriding (IPN) on the surface chemistry, microstructure, and nanohardness of AISI 304 and 316L stainless steels, with both treated at 440 °C for 5 h. Surface modifications analyzed using SEM and nanoindentation revealed distinct outcomes. SPN induced an oxynitriding effect due to the oxidation properties of the pastes, forming Fe3O4 and FexC phases, while IPN produced an expanded austenite layer. Both methods enhanced surface nanohardness, but SPN showed superior results. For 316L SS, SPN increased nanohardness by 367.81% (6.83 GPa) compared to a 133.5% increase (3.41 GPa) with IPN. For 304 SS, SPN improved nanohardness by 26% (2.23 GPa), whereas IPN reduced it by 48% (0.92 GPa). These findings highlight SPN’s potential as an effective anti-wear treatment, particularly for 316L SS. The SPN process utilized a eutectic mixture of sodium cyanate and sodium carbonate, while IPN employed a N2:H2 (1:1) gas mixture. SEM analyses confirmed the formation of γ-Fe(N) phases, indicating dispersed iron nitrides (FeN, Fe3N, Fe4N). SPN’s simultaneous oxidation and nitrocarburization led to an oxide layer above the nitride diffusion layer, enhancing mechanical properties through iron oxides (Fe3O4) and carbides (FexC). Comparative analysis showed that AISI 316L exhibited better performance than AISI 304, underscoring SPN’s effectiveness for surface modification.

A novel composite groove array surface was fabricated using femtosecond laser ablation technology to enhance self-replenishment capability. Initially, the driving efficiency of droplets on the composite groove array surface was tested using a high-speed droplet transportation system, characterizing the effect of this surface on lubricant backflow characteristics. Simultaneously, measurement of lubricating film thickness was utilized to explore the lubrication enhancement effect of the composite groove array surface on oil film formation under reciprocating motion. The multidimensional gradient wettability, engineered through the composite groove array surface, demonstrated excellent efficiency in lubricant replenishment within the lubrication track. Oil droplet transportation testing demonstrated that the composite groove array surface, which induced gradient wettability at the boundary, attained a maximum driving speed of 123.5 mm/s. This innovative design significantly reduced the barriers associated with lubricant backflow, particularly those induced by cavitation expansion during high-frequency reciprocating motion. Furthermore, the results demonstrated that the film-forming capabilities of this composite groove array surface were enhanced, thereby optimizing the overall lubrication performance.

The novel forced wave generator (NFWG) is a critical component of the harmonic drive (HD) without a flexible bearing. Tribological design is required to increase the load-carrying capacity and reduce the frictional resistance in the elliptical sliding pairs (ESPs) between the flex spline (FS) and the NFWG. As the thin-walled FS operates under cyclic deformation with large displacement in the HD, this paper investigates the effects of the distribution region, depth, shape, and density of micro-dimple textures on the outer contour surface of the NFWG on the load-carrying capacity and the frictional resistance of the ESPs using the CFD method. The analysis reveals that the load capacity and lubrication performances of the ESPs are significantly enhanced when the micro-dimple textures are fully distributed on the outer contour surface of the NFWG, with a depth of 0.1 mm, a radius of 6 mm, and a distribution density of 3.9%. The results provide a reference for the practical design of ESPs in the HD under extreme mechanical transmission conditions.

Using the Rabinowitsch fluid model, the effects of dilatant fluids (a non-Newtonian factor less than 0) and pseudo-plastic fluids (a non-Newtonian factor greater than 0) on the non-linear stability of hydrodynamic journal bearings is discussed. The modified Reynolds equation is solved by the small perturbation method, and the stiffness and damping coefficients and threshold speed of hydrodynamic bearings are obtained. Through the fourth-order Runge–Kutta method, the trajectory of the journal center is traced and the non-linear stability boundary of hydrodynamic bearings with different non-Newtonian lubricants could be confirmed. The results show that the dilatant fluids could increase the threshold speed and enlarge the non-linear stability region of the hydrodynamic bearing, while the influence of pseudo-plastic fluids is positive. And for the lubricants with a larger non-Newtonian factor, the effect is more obvious. It could be confirmed that the stability of hydrodynamic bearings lubricated with dilatant fluids is better than that of bearings with Newtonian and pseudo-plastic lubricants. The results illustrate that selecting a more appropriate lubricant can enhance the stability of hydrodynamic bearings.

In this paper, the calculation model and method of the lubrication performance of the thrust bearing, which considers the thermal bomb deformation, are constructed based on the working characteristics of the main pump thrust of the nuclear power plant. The key design parameters of the tile package Angle θ are analyzed by taking the design parameters of the thrust-bearing tile as the variable. The circumferential fulcrum coefficient of tile, the influence of tile thickness B, and tile elastic modulus E on the lubrication performance of thrust bearing are analyzed to obtain improved design parameters. The lubrication performance of the thrust bearing includes the minimum oil film thickness hmin, the maximum temperature of oil film Tmax, total flow Qx, total power consumption W, maximum thermal deformation of axial bush δTmax, and the maximum elastic deformation of the axial bush δFmax. The scale test of the designed thrust bearing is carried out. The take-off speed of the bearing is tested and compared with the results of the theoretical analysis. The study results show that the influence is becoming more obvious from θo to hmin. Moreover, the impact becomes more obvious from Tmax to Qx, B to hmin, and Qx to δTmax and δFmax. Lastly, the impact is also obvious from E to Qx and δFmax.

Uneven inter-stage pressure drops of the common two-stage brush seal (CBS) lead to a problem that the second stage bristles bear excessive pressure load, and this problem leads to the premature failure of the brush seal. In this paper, a novel two-stage brush seal (NBS) with the backing plate holes of the second stage was proposed, and a three-dimensional numerical model of the NBS was established. Then, the effects of the pressure-equalizing (PE) hole on the inter-stage pressure drop distribution of the NBS were numerically analyzed, and an optimal structure was obtained. Finally, the leakage flow characteristics of this optimal structure were studied. The results showed that the NBS with PE hole increased the passage area of the downstream, and so effectively improved the uneven pressure drops of the CBS, and the pressure drop balance ratio of the NBS was obviously smaller than that of the CBS. For the structural parameters studied in this paper, the pressure drop balance ratio of the NBS was improved by 45.6~67.9% compared to the CBS. Moreover, when PE holes were 0.4 mm in diameter, 5.95 mm in height, and the number of rows was 1, the NBS had the best pressure drop balance and its leakage was only 8.7% higher than that of the CBS.

Anisotropic microstructures and wear resistance are caused by large thermal gradients during selective laser melting (SLM). Investigating the wear resistance in different planes of SLM specimens is crucial. Hence, the effect of heat treatment on the anisotropy of the microstructure, density, microhardness, and wear resistance of SLM 316L stainless steel was studied. Specimens subjected to solution + aging treatment exhibited γ austenite and α ferrite phases with lower microstrain, as determined via X-ray diffraction (XRD) analysis. Microstructure observations demonstrated that SLM 316L appears as intersecting melt pools on the XOY plane and fish scale-like melt pools on the XOZ plane. After heat treatment, the melt boundaries disappeared, carbides (M23C6) precipitated at grain boundaries and within the grains, and the microstructures coarsened and became more uniform. The microhardness and wear resistance of the XOY plane were shown to be superior to those of the XOZ plane, and the microhardness decreased following heat treatment. Compared with SLM 316L, the microhardness of the XOY and XOZ planes of the specimen subjected to solution + aging treatment decreased by 5.96% and 4.98%. The friction and wear test results revealed that the specimen after solution + aging treatment had the lowest friction coefficient and the smallest wear rate. The wear rates of specimens from the XOY and XOZ planes after solution + aging treatment were 21.1% and 27.1% lower than that of SLM 316L, exhibiting the best wear resistance.

The automotive industry faces increasing challenges due to fuel scarcity and pollutant emissions, necessitating the implementation of strategies that optimize engine performance while minimizing the environmental impact. This study aimed to analyze the influence of oil viscosity and fuel quality on the engine performance and pollutant emissions in an internal combustion engine. A Response Surface Methodology (RSM)-based experimental design was employed. Three oil viscosity levels (SAE 5W-30, 10W-30, and 20W-50) and three fuel quality levels (87, 92, and 95 octane) were evaluated using a Chevrolet Grand Vitara 2.0L (General Motors, Quito, Ecuador) tested on a dynamometer. The oil grades were selected to represent a practical range of viscosities commonly used in commercial vehicles operating under local conditions. The results indicate that using lower-viscosity oil (SAE 5W-30) increased the engine power by up to 6.25% compared to when using SAE 20W-50. Additionally, using higher-octane fuel led to an average power increase of 1.49%, attributed to improved combustion stability and the ability to operate at a more advanced ignition timing without knocking. The emissions analysis revealed that high-viscosity oil at high RPMs increased CO2 emissions to 14.4% vol, whereas low-viscosity oil at low RPMs reduced CO2 emissions to 13.4% vol. Statistical analysis confirmed that the engine speed (RPM) was the most influential factor in emissions (F = 163.11 and p < 0.0001 for CO2; F = 247.02 and p < 0.0001 for NOx), while fuel quality also played a significant role. These findings suggest that optimizing the oil viscosity and selecting the appropriate fuel can enhance engine efficiency and reduce emissions, thereby contributing to the development of more sustainable automotive technologies. Future research should explore the use of ultra-low-viscosity lubricants (SAE 0W-20) and assess their long-term effects on engine wear.