Lubricants

11 pages, 4883 KiB

Open AccessArticle

Tribological Properties of Protic Ionic Liquid as an Additive in Aqueous Glycerol Solution for Ruby-Bearing Steel Tribo-Contact

by Raimondas Kreivaitis, Milda Gumbytė, Artūras Kupčinskas, Jolanta Treinytė and Albinas Andriušis

Lubricants 2023, 11(1), 34; https://doi.org/10.3390/lubricants11010034 - 16 Jan 2023

Cited by 2 | Viewed by 1495

Abstract

Owing to their low cost and environmentally friendly nature, water-based lubricants have benefits over oil-based ones. However, the appropriate additive package is indispensable in improving its tribological properties. In the current study, we have investigated the friction and wear reduction ability of bis(2-hydroxyethyl) [...] Read more.

Owing to their low cost and environmentally friendly nature, water-based lubricants have benefits over oil-based ones. However, the appropriate additive package is indispensable in improving its tribological properties. In the current study, we have investigated the friction and wear reduction ability of bis(2-hydroxyethyl) ammonium oleate protic ionic liquid (PIL) in a glycerol aqueous lubricating fluid. The tribo-tests were performed using a ruby–steel friction pair acting in reciprocation mode. The coefficient of friction and wear were the main characteristics of the evaluation. Analysis of the physical properties of the investigated lubricating samples and worn surface analysis were performed to reveal a more detailed picture. The study shows that the investigated PIL can significantly reduce friction and wear. The most suitable concentration of PIL was 0.5%, where friction and wear were reduced 2.6 and 15.8 times, respectively. Using the investigated PIL facilitates a sliding coefficient of friction as low as 0.039. It was hypothesized that the formation of the adsorption layer and metal soap was responsible for this. Further studies could be directed toward higher load and speed applications. Full article

(This article belongs to the Special Issue New Developments and Future Trends of Ionic Liquids as Lubricants)

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21 pages, 8188 KiB

Open AccessArticle

Method for On-Line Remaining Useful Life and Wear Prediction for Adjustable Journal Bearings Utilizing a Combination of Physics-Based and Data-Driven Models: A Numerical Investigation

by Denis Shutin, Maxim Bondarenko, Roman Polyakov, Ivan Stebakov and Leonid Savin

Lubricants 2023, 11(1), 33; https://doi.org/10.3390/lubricants11010033 - 15 Jan 2023

Cited by 8 | Viewed by 2117

Abstract

RUL (remaining useful life) estimation is one of the main functions of the predictive analytics systems for rotary machines. Data-driven models based on large amounts of multisensory measurements data are usually utilized for this purpose. The use of adjustable bearings, on the one [...] Read more.

RUL (remaining useful life) estimation is one of the main functions of the predictive analytics systems for rotary machines. Data-driven models based on large amounts of multisensory measurements data are usually utilized for this purpose. The use of adjustable bearings, on the one hand, improves a machine’s performance. On the other hand, it requires considering the additional variability in the bearing parameters in order to obtain adequate RUL estimates. The present study proposes a hybrid approach to such prediction models involving the joint use of physics-based models of adjustable bearings and data-driven models for fast on-line prediction of their parameters. The approach provides a rather simple way of considering the variability of the properties caused by the control systems. It has been tested on highly loaded locomotive traction motor axle bearings for consideration and prediction of their wear and RUL. The proposed adjustable design of the bearings includes temperature control, resulting in an increase in their expected service life. The initial study of the system was implemented with a physics-based model using Archard’s law and Reynolds equation and considering load and thermal factors for wear rate calculation. The dataset generated by this model is used to train an ANN for high-speed on-line bearing RUL and wear prediction. The results show good qualitative and quantitative agreement with the statistics of operation of traction motor axle bearings. A number of recommendations for further improving the quality of predicting the parameters of active bearings are also made as a summary of the work. Full article

(This article belongs to the Special Issue Advances in Wear Predictive Models)

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15 pages, 4217 KiB

Open AccessArticle

Significance of Melting Heat Transfer and Brownian Motion on Flow of Powell–Eyring Fluid Conveying Nano-Sized Particles with Improved Energy Systems

by Hong Yang, Aaqib Majeed, Kamel Al-Khaled, Tasawar Abbas, Muhammad Naeem, Sami Ullah Khan and Munazza Saeed

Lubricants 2023, 11(1), 32; https://doi.org/10.3390/lubricants11010032 - 13 Jan 2023

Cited by 4 | Viewed by 1583

Abstract

The present study explores the characteristics of 2D MHD melting with reference to mass and heat transportation upon stagnation point Powell–Eyring nanofluid flow on an extensible surface. Melting is an important phenomenon that is involved in many procedures such as permafrost melting, solidification [...] Read more.

The present study explores the characteristics of 2D MHD melting with reference to mass and heat transportation upon stagnation point Powell–Eyring nanofluid flow on an extensible surface. Melting is an important phenomenon that is involved in many procedures such as permafrost melting, solidification of slag, defrosting frozen ground etc., all of which are examples of soil freezing and melting that involve heat trafficking through a coil in a grounded pump. A mathematical model is developed for the boundary layer flow. The differential equations are solved through a numerical algorithm which makes use of the boundary value problem solver bvp4c, applying MATLAB software. The numerical variations of embedded parameters on velocity lineation, temperature figuration, and concentration delineation are represented graphically, as are the width of the boundary layer value and the delineation rate for the increasing velocity parameter. The velocity function shows a decremental response for M while the opposite behavior is seen against the concentration field. Full article

(This article belongs to the Special Issue The Tribological Properties and Mathematical Analysis of Nanofluids)

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17 pages, 5740 KiB

Open AccessArticle

Spreading Behavior of Single Oil Droplet Impacting Surface with/without a Thin Liquid Film

by He Liang, Peiyi Yang, Wenzhong Wang, Yanfei Liu, Xiangyu Ge and Baohong Tong

Lubricants 2023, 11(1), 31; https://doi.org/10.3390/lubricants11010031 - 12 Jan 2023

Cited by 3 | Viewed by 1408

Abstract

When oil droplets impact a solid surface for oil-air lubrication, they may spread out to produce a thin oil layer on the surface, which serves as a significant source of lubrication. A test rig was constructed in this research to observe the spreading [...] Read more.

When oil droplets impact a solid surface for oil-air lubrication, they may spread out to produce a thin oil layer on the surface, which serves as a significant source of lubrication. A test rig was constructed in this research to observe the spreading behavior of oil droplets impacting surfaces from both frontal and lateral views. From the frontal view, laser-induced fluorescence techniques are used to measure the thickness of the oil layer quantitatively during the spreading of oil droplets. While the lateral view can observe the shape evolution of the droplets. Oil droplet spreading patterns on the sheet with dry surfaces and with different thin liquid film thicknesses were studied, and the effect of viscosity and the thickness of the thin liquid film on spreading radius and spreading thickness is considered. The experimental findings demonstrate that the maximum spreading factor, the spreading central layer thickness, and the apparentness of retraction all increase as viscosity increases. The retraction is obviously impacted by thin liquid films, and the retraction weakens as the thin liquid film thickness increases. Full article

(This article belongs to the Special Issue Friction and Wear of Coatings/Films)

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17 pages, 3528 KiB

Open AccessArticle

Test Study of the Bridge Cable Corrosion Protection Mechanism Based on Impressed Current Cathodic Protection

by Guowen Yao, Xuanbo He, Jiawei Liu, Zengwei Guo and Pengyu Chen

Lubricants 2023, 11(1), 30; https://doi.org/10.3390/lubricants11010030 - 12 Jan 2023

Cited by 5 | Viewed by 1812

Abstract

The cable system is an important bearing element of a bridge with stay cables or slings and a matter of major concern in the safety of the bridge structure. Bridge cables are vulnerable to corrosion induced by leakage and soaking during their service [...] Read more.

The cable system is an important bearing element of a bridge with stay cables or slings and a matter of major concern in the safety of the bridge structure. Bridge cables are vulnerable to corrosion induced by leakage and soaking during their service life. To solve this problem, and based on the idea of proactive control by means of the impressed current cathodic protection (ICCP) of bridge cables, this study designs and develops an ICCP system device for bridge cable protection. In this study, an accelerated corrosion test was conducted to test the ICCP system of steel wires inside the cables and the cables under acid rain conditions. The corrosion protection behavior of ICCP was analyzed to reveal the corrosion protection mechanism of bridge cable ICCP. The results show that in the cable ICCP system, the impressed current generated by a more negative voltage may improve the efficiency of corrosion protection, but an excessively negative voltage may cause hydrogen embrittlement of the cable steel wire due to overprotection. The rational range of −1.13 V to −1.15 V was set as the result of the overall consideration. Within this range, the cable is subject to the joint protection of ICCP and sacrificial anode cathodic protection (SACP). Corrosive products can delay the development of cable corrosion to a certain degree; the SACP protection efficiency of the galvanized coat reduces gradually with corrosion development; and cable ICCP protection efficiency increases gradually. The ICCP for cable corrosion protection is transformed from joint protection using both a sacrificial anode and impressed current into protection, mainly using an impressed current. Full article

(This article belongs to the Special Issue Wire Rope Lubrication and Corrosion Protection)

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27 pages, 4386 KiB

Open AccessReview

Graphene as a Lubricant Additive for Reducing Friction and Wear in Its Liquid-Based Form

by Ab Rahman Marlinda, Gregory Soon How Thien, Mehmood Shahid, Ting Yang Ling, Abu Hashem, Kah-Yoong Chan and Mohd Rafie Johan

Lubricants 2023, 11(1), 29; https://doi.org/10.3390/lubricants11010029 - 11 Jan 2023

Cited by 10 | Viewed by 6263

Abstract

Graphene is a single atomic plane of sp²-bound carbon that has attracted considerable interest in various technologies. On the basis of its unique physical, mechanical, and chemical properties, graphene is a potentially strong candidate as a lubricant additive in its liquid-based [...] Read more.

Graphene is a single atomic plane of sp²-bound carbon that has attracted considerable interest in various technologies. On the basis of its unique physical, mechanical, and chemical properties, graphene is a potentially strong candidate as a lubricant additive in its liquid-based form to reduce friction and protect surfaces from degrading. Furthermore, graphene on wear performance acts as a heat dissipation source for liquid lubricants. This review explores and addresses the fundamental mechanisms illuminating the exceptional tribological behaviours of graphene family materials and their limitations. Although graphene additives were reported to improve friction coefficients and wear properties, several challenges remain a hindrance, such as production costs, dispersion stability, and lack of information regarding graphene optimisation. Thus, this review can provide a standard methodological framework for graphene additives in improving tribological performance. Moreover, this review provides an up-to-date review of current tribological experiments based on ultrafine particles incorporated with graphene as an additive for lubricating liquids. Full article

(This article belongs to the Special Issue Matching Ability and Anti-Wear Properties of Lubricants)

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18 pages, 6908 KiB

Open AccessArticle

Experimental Analysis of Frictional Performance of EN AW-2024-T3 Alclad Aluminium Alloy Sheet Metals in Sheet Metal Forming

by Tomasz Trzepieciński

Lubricants 2023, 11(1), 28; https://doi.org/10.3390/lubricants11010028 - 10 Jan 2023

Cited by 4 | Viewed by 1569

Abstract

Friction occurring in the area of contact between the sheet metal and the tool in sheet metal forming is one of the factors determining the quality of the surface of the drawpiece and the formability of the workpiece. Knowledge of the friction conditions [...] Read more.

Friction occurring in the area of contact between the sheet metal and the tool in sheet metal forming is one of the factors determining the quality of the surface of the drawpiece and the formability of the workpiece. Knowledge of the friction conditions allows the optimal forming conditions to be determined in terms of lubrication and applied pressures. The article presents the results of experimental studies of friction in EN AW-2024-T3 Alclad sheets using a special device simulating the sheet–tool contact in the blank-holder area during SMF. The friction tests were carried out at various pressures, under dry friction, and with the use of typical oils with a wide range of viscosity. The effect of the friction process parameters on the COF and surface roughness parameters Rsk and Rku was analysed using analysis of variance. The model F-values imply that the regression models for all the output parameters were significant. A monotonic decrease in the COF with an increase in the mean contact pressure and lubricant viscosity was observed for both dry and lubricated conditions. DELVAC 1340 engine oil with the highest viscosity significantly lowered the COF. The lubrication efficiency with LAN46 machine oil and LVH22 hydraulic oil showed an upward trend with an increasing mean contact pressure. In general, friction reduces the value of average roughness, Ra, and skewness, Rsk. Meanwhile, friction under contact pressures in the analysed range (4.4–11.7 MPa) causes an increase in kurtosis, Rku. Full article

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11 pages, 4055 KiB

Open AccessArticle

Effects of Hybrid Rockwool–Wood Fiber on the Performance of Asbestos-Free Brake Friction Composites

by Nan Wang, Hao Liu and Fei Huang

Lubricants 2023, 11(1), 27; https://doi.org/10.3390/lubricants11010027 - 10 Jan 2023

Cited by 3 | Viewed by 1256

Abstract

The present study explores the physical-mechanical and tribological properties of hybrid wood fiber and rockwool-reinforced asbestos-free resin-based friction materials. We developed asbestos-free brake friction composites with different contents of hybrid fiber (wood and rockwool fiber) at a total fixed fiber loading of 30%. [...] Read more.

The present study explores the physical-mechanical and tribological properties of hybrid wood fiber and rockwool-reinforced asbestos-free resin-based friction materials. We developed asbestos-free brake friction composites with different contents of hybrid fiber (wood and rockwool fiber) at a total fixed fiber loading of 30%. Then, the developed composites were investigated on the physical, mechanical, and tribological properties according to the industry standards. The results show that, with the increase in wood fiber, the density, hardness, and strength decrease, and the water absorption increases. Meanwhile, rockwool fiber can improve the coefficient of friction and enhance friction stability, while wood fiber has a significant impact on wear resistance. The sample with 5% wood fiber and 25% rockwool fiber presented the best performance in terms of the coefficients of friction, wear rate, and fade–recovery behavior. It provides a new idea for the research of asbestos-free composites. Full article

(This article belongs to the Special Issue Tribology and Reliability of Mechanical Transmission)

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22 pages, 3359 KiB

Open AccessReview

A Review of Turbine and Compressor Aerodynamic Forces in Turbomachinery

by Luis San Andrés

Lubricants 2023, 11(1), 26; https://doi.org/10.3390/lubricants11010026 - 10 Jan 2023

Cited by 5 | Viewed by 3240

Abstract

Aerodynamic forces due to blade-tip clearance eccentricity are a known destabilizing source in rotating machinery with unshrouded impellers. Dynamic forces also appear in shrouded impellers, due to changes in the pressure in the gap between the impeller casing and its shroud. These are [...] Read more.

Aerodynamic forces due to blade-tip clearance eccentricity are a known destabilizing source in rotating machinery with unshrouded impellers. Dynamic forces also appear in shrouded impellers, due to changes in the pressure in the gap between the impeller casing and its shroud. These are load-dependent forces typically characterized by a cross-coupled stiffness coefficient (k > 0). This paper reviews the archival literature for quantification of blade-tip clearance induced forces and impeller-casing forces in both unshrouded and shrouded turbines and compressors. Most distinctive are the lack of experimental results and the indiscriminate application of simple formulas to predict k, including Alford’s and Wachel’s equations. The disparity in estimations of the destabilizing k extends to recent CFD models and results. Hence, rotordynamic predictions vary widely. This review reveals that engineering practice ignores accurate physical models that could bridge the gap between practice and theory. As the energy market shifts toward carbon capture and hydrogen compression, accurate knowledge of aerodynamic forces from unshrouded compressors and open impellers will become necessary in multi-stage rotors. Full article

(This article belongs to the Special Issue Fluid–Structure Interaction in Bearings and Seals)

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20 pages, 7090 KiB

Open AccessArticle

Influence of Nozzle Layouts on the Heat-Flow Coupled Characteristics for Oil-Jet Lubricated Spur Gears

by Duan Yang, He Liu, Jianfeng Zhong, Xiang Zhu and Yu Dai

Lubricants 2023, 11(1), 25; https://doi.org/10.3390/lubricants11010025 - 08 Jan 2023

Cited by 1 | Viewed by 1216

Abstract

Aiming to explore the influence of nozzle layouts on the lubrication and cooling performance of spur gears under oil jet lubrication conditions, this paper introduces a heat-flow coupled analysis method to predict the temperature field of the tooth surface with different nozzle layouts. [...] Read more.

Aiming to explore the influence of nozzle layouts on the lubrication and cooling performance of spur gears under oil jet lubrication conditions, this paper introduces a heat-flow coupled analysis method to predict the temperature field of the tooth surface with different nozzle layouts. Firstly, the friction heat formulas integrating the coefficient of friction and average contact stress are presented for calculating heat generation. We also present the impingement depth model, which considers the nozzle orientation parameters, jet velocity, and gear structure of the given spur gear pair for laying out the nozzle. Then, a heat-flow coupled finite element analysis method is exploited to resemble the jet lubrication process and gain the gear temperature characteristics. Finally, the numerical results of this model compare well with those of the experiments, showing that this heat-flow coupled model provides accurate temperature prediction, indicating that the nozzle layouts determined as a function of the oil jet height, deviation distance, and oil injection angle significantly influence the lubrication and cooling performance. Further, this study also reveals that the lubrication performance in cases where the nozzle approaches the side of the pinion is relatively superior. Full article

(This article belongs to the Special Issue Gear Load-Independent Power Losses)

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13 pages, 14430 KiB

Open AccessArticle

Influence of Al₂O₃ Nanoparticles Addition in ZA-27 Alloy-Based Nanocomposites and Soft Computing Prediction

by Aleksandar Vencl, Petr Svoboda, Simon Klančnik, Adrian But, Miloš Vorkapić, Marta Harničárová and Blaža Stojanović

Lubricants 2023, 11(1), 24; https://doi.org/10.3390/lubricants11010024 - 07 Jan 2023

Cited by 9 | Viewed by 1540

Abstract

Three different and very small amounts of alumina (0.2, 0.3 and 0.5 wt. %) in two sizes (approx. 25 and 100 nm) were used to enhance the wear characteristics of ZA-27 alloy-based nanocomposites. Production was realised through mechanical alloying in pre-processing and compocasting [...] Read more.

Three different and very small amounts of alumina (0.2, 0.3 and 0.5 wt. %) in two sizes (approx. 25 and 100 nm) were used to enhance the wear characteristics of ZA-27 alloy-based nanocomposites. Production was realised through mechanical alloying in pre-processing and compocasting processes. Wear tests were under lubricated sliding conditions on a block-on-disc tribometer, at two sliding speeds (0.25 and 1 m/s), two normal loads (40 and 100 N) and a sliding distance of 1000 m. Experimental results were analysed by applying the response surface methodology (RSM) and a suitable mathematical model for the wear rate of tested nanocomposites was developed. Appropriate wear maps were constructed and the wear mechanism is discussed in this paper. The accuracy of the prediction was evaluated with the use of an artificial neural network (ANN). The architecture of the used ANN was 4-5-1 and the obtained overall regression coefficient was 0.98729. The comparison of the predicting methods showed that ANN is more efficient in predicting wear. Full article

(This article belongs to the Special Issue Friction and Wear in Composite Materials)

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17 pages, 3433 KiB

Open AccessArticle

Stability Assessment of Polyvinyl-Ether-Based TiO₂, SiO₂, and Their Hybrid Nanolubricants

by Mohd Farid Ismail, Wan Hamzah Azmi, Rizalman Mamat, Korada Viswanatha Sharma and Nurul Nadia Mohd Zawawi

Lubricants 2023, 11(1), 23; https://doi.org/10.3390/lubricants11010023 - 07 Jan 2023

Cited by 3 | Viewed by 1530

Abstract

Poor characterisation of nanoparticle suspensions impedes the development of nanolubricants for use in refrigeration and air-conditioning systems. Chemical treatment techniques, such as surfactants, are inappropriate for enhancing the stability of nanolubricants intended for use in vapour-compression refrigeration (VCR) systems. Prior to incorporating nanolubricants [...] Read more.

Poor characterisation of nanoparticle suspensions impedes the development of nanolubricants for use in refrigeration and air-conditioning systems. Chemical treatment techniques, such as surfactants, are inappropriate for enhancing the stability of nanolubricants intended for use in vapour-compression refrigeration (VCR) systems. Prior to incorporating nanolubricants into the system, the stability of TiO₂ and SiO₂ nanoparticles dispersed in PVE was therefore investigated. The nanolubricants were prepared by a two-step method with the aid of an ultrasonication bath homogeniser. Visual observation and ultraviolet–visible (UV–Vis) spectrophotometric analysis were used, and zeta potential analysis was then performed to confirm the nanolubricants’ stability condition. The TiO₂/PVE nanolubricant was observed to be maintained at a 95% concentration ratio for up to 30 days of evaluation. The TiO₂/PVE, SiO_2/PVE, and SiO₂-TiO₂/PVE exhibited zeta potential values of 203.1 mV, 224.2 mV, and 105.3 mV, respectively, after 7 h of sonication. A high absolute value of zeta potential indicates that the electrostatic repulsive forces between nanoparticles are exceptionally strong, indicating an excellent stable suspension. The high values of zeta potentials validated the excellent stability conditions determined by UV–Vis analysis and visual observation. It can be concluded that ultrasonication times of 7 h produced the most stable state for mono- and hybrid nanolubricants. Full article

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17 pages, 4103 KiB

Open AccessArticle

Impact of Thermal and Activation Energies on Glauert Wall Jet (WJ) Heat and Mass Transfer Flows Induced by ZnO-SAE50 Nano Lubricants with Chemical Reaction: The Case of Brinkman-Extended Darcy Model

by Umair Khan, Aurang Zaib and Anuar Ishak

Lubricants 2023, 11(1), 22; https://doi.org/10.3390/lubricants11010022 - 07 Jan 2023

Cited by 4 | Viewed by 1162

Abstract

Heat transfer machinery or technology is rapidly expanding due to the need for effective cooling and heating systems in the requisite automotive, chemical, and aerospace industries. This study aims to provide a numerical solution to wall jet (WJ) flow with mass and heat [...] Read more.

Heat transfer machinery or technology is rapidly expanding due to the need for effective cooling and heating systems in the requisite automotive, chemical, and aerospace industries. This study aims to provide a numerical solution to wall jet (WJ) flow with mass and heat transport phenomenon comprising of the colloidal mixture of SAE50 and zinc oxide nanoparticles immersed in a Brinkman-extended Darcy model. The idea of WJ flow suggested by Glauert is further discussed along with the impact of the activation energy, thermal radiation, and binary chemical reaction. The leading equations are transformed into ordinary differential equations through proper similarity variables and then worked out numerically by employing a very efficient bvp4c method. The importance of pertaining quantities is illustrated and well explained through several tables and graphs. The major results suggest that the velocity profiles decline while the temperature and concentration augment due to the higher impact of nanoparticles volume fraction. In addition, the shear stress and heat transfer rate are accelerated by rising the volume fraction of nanoparticles while the Sherwood number declines with bigger impacts of nanoparticle volume fraction. In addition, the radiation factor progresses the quantitative outcomes of the heat transfer rate. Full article

(This article belongs to the Special Issue Nanolubrication and Superlubrication)

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10 pages, 2108 KiB

Open AccessArticle

Effect of Microstructure of TiN /TiCN Layer on the Structural, Mechanical and Tribological Properties of the Ti/TiN/TiCN Films

by Yanhong Lyu, Qiaoyu Zhang, Yang Liu, Xinrong Deng, Huilian Sun and Min Mo

Lubricants 2023, 11(1), 21; https://doi.org/10.3390/lubricants11010021 - 05 Jan 2023

Cited by 1 | Viewed by 1429

Abstract

A direct current magnetron sputtering (DCMS) system at room temperature was applied to deposit the Ti/TiN/TiCN films. In order to research the effect of the microstructure of the TiN/TiCN layer on the Ti/TiN/TiCN films, the deposition time ratio of the TiN/TiCN layer ranged [...] Read more.

A direct current magnetron sputtering (DCMS) system at room temperature was applied to deposit the Ti/TiN/TiCN films. In order to research the effect of the microstructure of the TiN/TiCN layer on the Ti/TiN/TiCN films, the deposition time ratio of the TiN/TiCN layer ranged from 28.57 to 200%, and the whole deposition time of the films and the deposition time of Ti layer were constant. In this work, the relationship between structure and mechanical properties of films were investigated. The research results showed that the composition and structure of the films only slightly changed, while the crystalline orientation of the TiCN layer was of significant variation with the deposition time of the TiN layer. It is shown that the adhesion strength and internal stresses were 18.6 ± 1.5 N and 140 MPa when the deposition time ratio was 50%. By adjusting the deposition time ratio, the films displayed significant improvement in tribological behaviors. The coefficients of friction (COF) for the films deposited under deposition time ratio of 50% were about only 0.139 when the value of COF was stabilized. This work can provide a good wear-resisting film prepared approach at room temperature. Full article

(This article belongs to the Topic Advanced Manufacturing and Surface Technology)

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20 pages, 12842 KiB

Open AccessArticle

Investigation of Microflow Effects in Textures on Hydrodynamic Performance of Journal Bearings Using CFD Simulations

by Yujun Wang, Georg Jacobs, Florian König, Shuo Zhang and Stephan von Goeldel

Lubricants 2023, 11(1), 20; https://doi.org/10.3390/lubricants11010020 - 05 Jan 2023

Cited by 10 | Viewed by 2175

Abstract

Adequately designed and positioned surface textures are recognized as a promising way to increase load-carrying capacity and reduce frictional losses of journal bearings. The aim of this work is to analyze the local lubrication mechanisms of textures in journal bearings from microflow perspective, [...] Read more.

Adequately designed and positioned surface textures are recognized as a promising way to increase load-carrying capacity and reduce frictional losses of journal bearings. The aim of this work is to analyze the local lubrication mechanisms of textures in journal bearings from microflow perspective, while considering the interactions between textures and the film formation in the whole bearing. For this purpose, hydrodynamic lubrication models of textured journal bearings are built. The results show that placing textures downstream of the high-pressure region leads to a reduced friction force, with a less severe loss of load-carrying capacity. The effects of textures on the load-carrying capacity include the positive micro-hydrodynamic pressure effect and the negative effect caused by the discontinuity of the high-pressure region. The micro-hydrodynamic pressure of textures can be generated on one hand by limiting pressure drop (cavitation) in the divergent gap and on the other hand by the inertia effect. For the friction, the vortex inside textures affects the friction force by influencing the maximum shear stress at the minimum oil film. In turn the vortex is influenced by the bearing lubrication film. The research provides the fundamental reference and theoretical basis for the design and optimization of textured journal bearings. Full article

(This article belongs to the Special Issue Multiscale and Modern Solutions in the Simulation of Lubricated Contacts)

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19 pages, 9213 KiB

Open AccessArticle

Thermal Fatigue Resistance Studies of Multilayer CrN and AlTiN Coatings Deposited on Plasma Nitrided H-13 Hot Work Steel

by Chetan Gurada, Rajesh Mundotia, Umesh Mhatre, Ashwin Kale and Dushyant Kothari

Lubricants 2023, 11(1), 19; https://doi.org/10.3390/lubricants11010019 - 05 Jan 2023

Viewed by 1252

Abstract

H-13 steel surface was duplex-treated using Plasma Nitriding (PN) and PVD coatings to solve the thermal fatigue problem faced in die-casting applications. Chromium-based multilayer CrN/Cr (m-CrN) coatings and multi-component aluminium–titanium-based AlTiN (m-AlTiN) coatings were deposited using a cathodic arc deposition technique after plasma [...] Read more.

H-13 steel surface was duplex-treated using Plasma Nitriding (PN) and PVD coatings to solve the thermal fatigue problem faced in die-casting applications. Chromium-based multilayer CrN/Cr (m-CrN) coatings and multi-component aluminium–titanium-based AlTiN (m-AlTiN) coatings were deposited using a cathodic arc deposition technique after plasma nitriding the H-13 steel surface with different case-depths of 50 µm and 200 µm. The structural, tribological, corrosion, and mechanical properties of the duplex-treated samples were studied. The thermal fatigue (TF) test was conducted by heating the sample to 600 °C and rapidly cooling it to room temperature, simulating the die-casting process conditions. After multiple cycles, it was observed that the oxide layer thickness formed was lower on duplex-treated samples compared to that on the uncoated plasma nitride sample. In addition, the mechanical properties were improved with the increase in PN diffusion depth. The duplex-treated samples showed better mechanical and thermal fatigue properties compared to untreated and only coated samples. The sample with m-AlTiN deposited on plasma nitrided H-13 with 200 µm case depth displays better thermal fatigue properties compared to the other samples. Full article

(This article belongs to the Special Issue Friction and Wear of Coatings/Films)

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20 pages, 4486 KiB

Open AccessArticle

Tribology Performance of Polyol-Ester Based TiO₂, SiO₂, and Their Hybrid Nanolubricants

by Abdul Hamid Hamisa, Wan Hamzah Azmi, Mohd Farid Ismail, Rosminazuin Ab Rahim and Hafiz Muhammad Ali

Lubricants 2023, 11(1), 18; https://doi.org/10.3390/lubricants11010018 - 05 Jan 2023

Cited by 12 | Viewed by 1439

Abstract

The tribology properties of TiO₂/POE, SiO₂/POE and TiO₂-SiO₂/POE nanolubricants were investigated for an automotive air-conditioning system with an electrically-driven compressor (EDC). A two-step preparation method was used in dispersing TiO₂ and SiO₂ nanoparticles [...] Read more.

The tribology properties of TiO₂/POE, SiO₂/POE and TiO₂-SiO₂/POE nanolubricants were investigated for an automotive air-conditioning system with an electrically-driven compressor (EDC). A two-step preparation method was used in dispersing TiO₂ and SiO₂ nanoparticles into Polyol-ester (POE)-based lubricant at different volume concentrations of 0.01 to 0.1%. The coefficient of friction (COF) and wear scar diameter (WSD) were investigated using a Koehler four-ball tribo tester and microscopes. For the TiO₂/POE, SiO₂/POE and TiO₂-SiO₂/POE nanolubricants, respectively, the lowest COFs with maximum reduction were attained at 37.5%, 33.5% and 31.6% each at volume concentrations of 0.05%, 0.01% and 0.03%. The highest WSD reduction for the TiO₂/POE and SiO₂/POE mono nanolubricants were attained at 12.5% and 26.4%, respectively, at the same volume concentration of 0.01%. Meanwhile, the maximum reduction of WSD for the TiO₂-SiO₂/POE hybrid nanolubricant was reached at 12.4% at 0.03% volume concentration. As a conclusion, mono and hybrid nanolubricants with volume concentrations of less than 0.05% are suggested for use in air-conditioning systems with EDC because of their outstanding tribology performances. Further performance investigation of nanolubricants in the air-conditioning system is required to extend the present work. Full article

(This article belongs to the Special Issue Nanolubrication and Superlubrication)

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16 pages, 1076 KiB

Open AccessArticle

Methodological Approach in the Simulation of the Robustness Boundaries of Tribosystems under the Conditions of Boundary Lubrication

by Tareq M. A. Al-Quraan, Fadi Alfaqs, Ibrahim F. S. Alrefo, Viktor Vojtov, Anton Voitov, Andrey Kravtsov, Oleksandr Miroshnyk, Andrii Kondratiev, Pavel Kučera and Václav Píštěk

Lubricants 2023, 11(1), 17; https://doi.org/10.3390/lubricants11010017 - 04 Jan 2023

Cited by 1 | Viewed by 1390

Abstract

In the presented work, a methodical approach was developed for determining rational operation modes of tribosystems, taking into account their design. This approach makes it possible in the designing stage, according to the predicted operating modes, to calculate the limits and margins of [...] Read more.

In the presented work, a methodical approach was developed for determining rational operation modes of tribosystems, taking into account their design. This approach makes it possible in the designing stage, according to the predicted operating modes, to calculate the limits and margins of stable work in operation. The definition of the robustness of the tribosystem and the criteria for assessing the robustness are formulated based on the theory of stability of technical systems. It is shown that such a methodical approach allows for determining the modes of the rational operation of the designed structures without damaging the friction surfaces. Experimental studies have proven that not all designs of tribosystems lose stability due to the appearance of friction surface burrs. There are designs where the loss of stability occurs upon the appearance of accelerated wear. The developed criteria take into account two options for the loss of stability. An experimental verification of the modes of loss of stability of tribosystems was performed by the appearance of a burr or the beginning of accelerated wear with the calculated values of the robustness criteria. The obtained results allow us to conclude that the modeling error is within 8.3–18.7%, which is a satisfactory result in the study of friction and wear processes. Robustness criteria is based on the coefficient of friction RR_f and wear rate RR_I, and must be used when designing new constructions of tribosystems. Theoretical calculations of such criteria and the dependence of their change on changing the predicted operating modes will allow for justifying rational operating modes within their stability. Full article

(This article belongs to the Special Issue Advances in Boundary Lubrication)

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30 pages, 11312 KiB

Open AccessArticle

Hard Turning Performance Investigation of AISI D2 Steel under a Dual Nozzle MQL Environment

by Rajashree Mallick, Ramanuj Kumar, Amlana Panda and Ashok Kumar Sahoo

Lubricants 2023, 11(1), 16; https://doi.org/10.3390/lubricants11010016 - 04 Jan 2023

Cited by 11 | Viewed by 2334

Abstract

In recent years, hard turning has emerged as a burgeoning cutting technology for producing high-quality finishing of cylindrical-shaped hardened steel for a variety of industrial applications. Hard turning under dry cutting was not accepted because of the generation of higher cutting temperatures which [...] Read more.

In recent years, hard turning has emerged as a burgeoning cutting technology for producing high-quality finishing of cylindrical-shaped hardened steel for a variety of industrial applications. Hard turning under dry cutting was not accepted because of the generation of higher cutting temperatures which accelerated tool wear and produced an inferior surface finish. Nowadays, minimum quantity lubrication (MQL) is widely accepted in hard turning to reduce the problems encountered in dry cutting. This research aimed to augment the MQL performance in the hard turning process of AISI D2 steel by applying a novel concept, namely, a dual jet nozzle MQL system that supplies the cutting fluid into the cutting zone from two different directions. The performances of hard turning are discussed using machinability indicator parameters, such as surface roughness, tool wear, cutting temperature, power consumption, noise emission, and chip morphology. The dual nozzle MQL greatly reduced the friction between contact surfaces in the cutting zone and provided improved surface quality (Ra = 0.448 to 1.265 µm). Furthermore, tool flank wear was found to be lower, in the range of 0.041 to 0.112 mm, with abrasion and adhesion being observed to be the main mode of wear mechanisms. The power consumption was greatly influenced by the depth of cut (46.69%), followed by cutting speed (40.76%) and feed (9.70%). The chip shapes were found to be helical, ribbon, and spiral c type, while the colors were a metallic, light blue, deep blue, and light golden. Full article

(This article belongs to the Special Issue Minimum Quantity Lubrication: Environmental Alternatives in Processing)

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14 pages, 5358 KiB

Open AccessArticle

Depletion of Reflectance of Silicon Surface Textured Using Nano Second Fiber Laser

by S. Oliver Nesa Raj and Sethuramalingam Prabhu

Lubricants 2023, 11(1), 15; https://doi.org/10.3390/lubricants11010015 - 03 Jan 2023

Cited by 1 | Viewed by 1544

Abstract

This paper characterizes the surface modification on silicon surfaces with different patterns (circle, pyramid) using a nanosecond fiber laser with different parameters, which enhances its anti-reflection property. The influence of textured and untextured silicon surfaces and their structural properties were evaluated. It has [...] Read more.

This paper characterizes the surface modification on silicon surfaces with different patterns (circle, pyramid) using a nanosecond fiber laser with different parameters, which enhances its anti-reflection property. The influence of textured and untextured silicon surfaces and their structural properties were evaluated. It has a long absorption path (200–1000 nm) and a rougher surface due to surface modifications, which results in a 40% decrease in incident light reflectance, especially in pyramid-shaped dimples with 70 µm size, helping to trap more light in solar cells where the anti-reflecting surface is a crucial need for devices used in optical and photovoltaic applications to operate more effectively. Scanning electron microscope (SEM) and atomic force microscopy (AFM) are used to examine the surface features to determine the process’s effectiveness and recognize the development of patterns that are deep enough to trap light. XRD and micro-Raman spectroscopy were used to examine the irradiated surface’s crystallographic structure and crystallinity change. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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33 pages, 6896 KiB

Open AccessReview

A Review of Research on Wind Turbine Bearings’ Failure Analysis and Fault Diagnosis

by Han Peng, Hai Zhang, Yisa Fan, Linjian Shangguan and Yang Yang

Lubricants 2023, 11(1), 14; https://doi.org/10.3390/lubricants11010014 - 31 Dec 2022

Cited by 14 | Viewed by 6162

Abstract

Bearings are crucial components that decide whether or not a wind turbine can work smoothly and that have a significant impact on the transmission efficiency and stability of the entire wind turbine’s life. However, wind power equipment operates in complex environments and under [...] Read more.

Bearings are crucial components that decide whether or not a wind turbine can work smoothly and that have a significant impact on the transmission efficiency and stability of the entire wind turbine’s life. However, wind power equipment operates in complex environments and under complex working conditions over long time periods. Thus, it is extremely prone to bearing wear failures, and this can cause the whole generator set to fail to work smoothly. This paper takes wind turbine bearings as the research object and provides an overview and analysis for realizing fault warnings, avoiding bearing failure, and prolonging bearing life. Firstly, a study of the typical failure modes of wind turbine bearings was conducted to provide a comprehensive overview of the tribological problems and the effects of the bearings. Secondly, the failure characteristics and diagnosis procedure for wind power bearings were examined, as well as the mechanism and procedure for failure diagnosis being explored. Finally, we summarize the application of fault diagnosis methods based on spectrum analysis, wavelet analysis, and artificial intelligence in wind turbine bearing fault diagnosis. In addition, the directions and challenges of wind turbine bearing failure analysis and fault diagnosis research are discussed. Full article

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15 pages, 8502 KiB

Open AccessArticle

Manufacturing of Aluminum Alloy Parts from Recycled Feedstock by PIG Die-Casting and Hot Stamping

by Tatsuhiko Aizawa, Takeshi Kurihara and Hiroki Sakayori

Lubricants 2023, 11(1), 13; https://doi.org/10.3390/lubricants11010013 - 30 Dec 2022

Cited by 2 | Viewed by 1996

Abstract

PIG (Pin-Injection-Gate) die-casting and hot stamping was developed for fabrication of small-sized and thin-walled aluminum alloy parts from the recycled feedstock. The pure aluminum and aluminum alloy granules were utilized as a feedstock model of recycled materials. The measured mass of granules with [...] Read more.

PIG (Pin-Injection-Gate) die-casting and hot stamping was developed for fabrication of small-sized and thin-walled aluminum alloy parts from the recycled feedstock. The pure aluminum and aluminum alloy granules were utilized as a feedstock model of recycled materials. The measured mass of granules with the estimated weight from 3D-CAD (Computer Aided Design) of products was poured into the PIG-nozzles before injection. After quickly melting by induction heating inside the PIG-nozzle units, the aluminum melts were injected into a die cavity through the PIG-nozzle. No furnaces and no crucibles were needed to store the melt aluminum stock in different from the conventional die-casting system. No clamping mechanism with huge loading machine was also needed to significantly reduce the energy consumption in casting. Much less wastes were yielded in these processes; the ratio of product to waste, or, the materials efficiency was nearly 100%. Nitrogen supersaturation and TiAlN coating were used to protect the PIG-nozzle and the stamping die surfaces from severe adhesion from aluminum melt. The pure aluminum gears and thin-walled mobile phone case were fabricated by this process. X-ray tomography proved that both products had no cavities, pores and shrinkages in their inside. Using the hot stamping unit, the micro-pillared pure aluminum heatsink was fabricated to investigate the holding temperature effect on the aspect ratio of micro-pillar height to width. Full article

(This article belongs to the Special Issue Tribology for Lightweighting)

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15 pages, 2691 KiB

Open AccessArticle

In Situ Observation of Hyaluronan Molecular Weight Effectiveness within Articular Cartilage Lubrication

by David Rebenda, Matúš Ranuša, Pavel Čípek, Evgeniy Toropitsyn and Martin Vrbka

Lubricants 2023, 11(1), 12; https://doi.org/10.3390/lubricants11010012 - 30 Dec 2022

Cited by 1 | Viewed by 1809

Abstract

Degradation of the articular cartilage (AC) structure due to osteoarthritis significantly influences its friction and lubrication mechanisms. Injection with exogenous hyaluronic acid (HA) is one of the ways to slow down the progress of these changes. The present paper aims to determine the [...] Read more.

Degradation of the articular cartilage (AC) structure due to osteoarthritis significantly influences its friction and lubrication mechanisms. Injection with exogenous hyaluronic acid (HA) is one of the ways to slow down the progress of these changes. The present paper aims to determine the effect of HA on the friction and lubrication processes of the synovial joint model. The main emphasis is placed on the effect of HA molecular weight (MW) on the coefficient of friction (COF) and the interactions between HA and other constituents of synovial fluid (SF). Frictional measurements between the AC surface and the glass were performed with simultaneous in situ observation of the contact zone by fluorescence microscopy. Using this methodology, a decrease in AC COF with an increase in the fluorescence intensity emitted from contact with HA was observed, while the phenomenon was found to be MW-dependent. These findings demonstrate that high-MW HA is more effective within a resumption of healthy AC lubrication due to a better adhesion to the AC surface. Full article

(This article belongs to the Special Issue Synovial Lubricated Joints—Devices and Mechanical Behavior)

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14 pages, 3757 KiB

Open AccessArticle

Synergistic Lubrication and Antioxidation Efficacies of Graphene Oxide and Fullerenol as Biological Lubricant Additives for Artificial Joints

by Qian Wu, Honglin Li, Liangbin Wu, Zihan Bo, Changge Wang, Lei Cheng, Chao Wang, Chengjun Peng, Chuanrun Li, Xianguo Hu, Chuan Li and Bo Wu

Lubricants 2023, 11(1), 11; https://doi.org/10.3390/lubricants11010011 - 30 Dec 2022

Cited by 2 | Viewed by 1636

Abstract

The service life of artificial joints has gradually failed to meet the needs of patients. Herein, the synergistic lubrication and antioxidant efficacies of graphene oxide (GO) and fullerenol (Fol) as biological lubricant additives for artificial joints were investigated. The lubrication mechanisms of biological [...] Read more.

The service life of artificial joints has gradually failed to meet the needs of patients. Herein, the synergistic lubrication and antioxidant efficacies of graphene oxide (GO) and fullerenol (Fol) as biological lubricant additives for artificial joints were investigated. The lubrication mechanisms of biological lubricant containing GO and Fol at the friction interface of artificial joints were then revealed. Tribological tests showed that the average friction coefficients of Al₂O₃–Ti6Al4V pairs and Ti6Al4V–UHMWPE pairs for artificial joints could be reduced by 30% and 22%, respectively, when GO and Fol were used as biological lubricant additives simultaneously. The lubrication mechanism showed that some incommensurate sliding contact surfaces could be formed between the GO nanosheets and spherical Fol at the interface, which reduced the interaction forces of friction pairs. The maximum scavenging rates of •OH and DPPH free radicals by the biological lubricant containing GO and Fol were 35% and 45%, respectively, showing a good antioxidant efficacy of the biological lubricant. This can be attributed to the GO and Fol scavenging free radicals through electron transfer and hydrogen transfer. This study provides a theoretical basis for the development and application of carbon nanomaterials as biological lubricant additives for artificial joints in the future. Full article

(This article belongs to the Special Issue Tribology of 2D Nanomaterials)

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18 pages, 8451 KiB

Open AccessArticle

Surface Preparation for Coating and Erosion MRR of SS 304 Using Silicon Carbide Abrasive Jet

by Deb Kumar Adak, Vivekananda Pal, Santanu Das, Tina Ghara, Hillol Joardar, Nashmi Alrasheedi and Barun Haldar

Lubricants 2023, 11(1), 10; https://doi.org/10.3390/lubricants11010010 - 28 Dec 2022

Cited by 2 | Viewed by 2600

Abstract

The surface preparation of shiny stainless steels is a must for applying esthetic paints, effective functional plasma spray coating, laser cladding, welding, etc., applications. The current work aims for effective surface roughening and erosion MRR of SS 304 work surface using SiC abrasive [...] Read more.

The surface preparation of shiny stainless steels is a must for applying esthetic paints, effective functional plasma spray coating, laser cladding, welding, etc., applications. The current work aims for effective surface roughening and erosion MRR of SS 304 work surface using SiC abrasive jet erosion and optimization of the process parameters. The response surface approach is used to design and conduct the studies using the Box–Behnken design method. The surface topography of the eroded surfaces is examined by a 2D profilometer, 3D profilometer, and scanning electron microscope (SEM). The abrasive grit size and working gas pressure greatly affect the surface roughness of SS 304 samples. The influence of the process parameters on the variation of these topographical features is analyzed and confirmed. The working jet pressure is seen to significantly impact erosion MRR. The lower working gas pressure shows a typical influence on R_a (surface preparation) and as pressure increases, erosion MRR rises, and the surface preparation mode shifts to the erosion metal removal/cutting zone. The quality of SS 304 surface prepared from SiC abrasive jet impact is characterized by 3D profilometry. Full article

(This article belongs to the Special Issue Assessment of Abrasive Wear)

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11 pages, 1762 KiB

Open AccessCommunication

Rheological and Tribological Study of Polyethylsiloxane with SiO₂ Nanoparticles Additive

by Tuyana Dembelova, Badma Badmaev, Dagzama Makarova, Aleksandr Mashanov and Undrakh Mishigdorzhiyn

Lubricants 2023, 11(1), 9; https://doi.org/10.3390/lubricants11010009 - 26 Dec 2022

Cited by 4 | Viewed by 1846

Abstract

Nowadays, much attention is paid to the creation of high-performance lubricants with improved properties through the use of ultrafine nanopowders. The paper shows the results of studying the viscoelastic properties of samples of silicon dioxide nanoparticle suspensions based on polyethylsiloxane (silicone oil) by [...] Read more.

Nowadays, much attention is paid to the creation of high-performance lubricants with improved properties through the use of ultrafine nanopowders. The paper shows the results of studying the viscoelastic properties of samples of silicon dioxide nanoparticle suspensions based on polyethylsiloxane (silicone oil) by the acoustic resonance method. The method is based on a study of the additional coupling effect on the resonance characteristics of the piezoelectric resonator. The values of the shear modulus and the tangent of the mechanical loss angle were calculated. The interaction between polymer molecules and nanoparticles was characterized by infrared spectroscopy. The influence of silicon dioxide nanoparticles (as a nano-additive) on the performance characteristics of polyethylsiloxane lubricant is presented. The results of determining the friction coefficient from the sliding speed show an increase in the tear strength of the lubricating film, leading to improved tribological properties. Full article

(This article belongs to the Special Issue Advanced Industrial Lubricants and Future Development Trends of Tribo-Systems for Tribological Performance Evaluation)

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19 pages, 6749 KiB

Open AccessArticle

Influence of Deposition Temperature on the Structure and Current-Carrying Friction Performance of Cu Films by DC Magnetron Sputtering Technology

by Hao Zhang, Kai Le, Chen Wang, Jianbo Sun, Shusheng Xu and Weimin Liu

Lubricants 2023, 11(1), 8; https://doi.org/10.3390/lubricants11010008 - 26 Dec 2022

Cited by 3 | Viewed by 1668

Abstract

The structure and morphology of Cu films deposited by DC magnetron sputtering on silicon and stainless-steel substrates at different deposition temperatures of −140 °C, −95 °C, −55 °C, 25 °C (RT), 50 °C, and 200 °C were investigated by X-ray diffraction (XRD), scanning [...] Read more.

The structure and morphology of Cu films deposited by DC magnetron sputtering on silicon and stainless-steel substrates at different deposition temperatures of −140 °C, −95 °C, −55 °C, 25 °C (RT), 50 °C, and 200 °C were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was found that all Cu films presented strong orientation of the (111) and (200) peaks. The Cu films deposited at low temperatures (lower than −55 °C) showed the bilayer structures, in which the upper layer appeared to be a loose and porous structure and the lower layer near the substrate had a fine and dense structure that consisted of small grains. In addition, the Cu films deposited at low temperatures could be observed a large roughness. The roughness tended to decline and then increase with the rising of deposition temperature. The ball-on-disc reciprocating sliding tribometer was employed to evaluate the tribological behaviors of the Cu films at current-carrying levels of 0 A, 0.5 A, and 1.0 A. The results revealed that the Cu films deposited at low temperatures exhibited outstanding current-carrying friction performance and low electrical contact resistance (ECR), peeling only at 0.5 A and 1.0 A. Nevertheless, the Cu films deposited at the relatively high temperature exhibited oxidative wear caused by electric arc ablation at 0.5 A and 1.0 A. Additionally, the wear mechanism was discussed in terms of the structure and morphology of the wear track and formation of the tribo-film. Full article

(This article belongs to the Special Issue Friction and Wear of Coatings/Films)

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9 pages, 5308 KiB

Open AccessArticle

Fretting Wear Characteristics of SLM-Formed 316L Stainless Steel in Seawater

by Mingji Huang, Ping Chen and Xiaoxi Qiao

Lubricants 2023, 11(1), 7; https://doi.org/10.3390/lubricants11010007 - 26 Dec 2022

Viewed by 1327

Abstract

The fretting wear characteristics of two different energy density 316L stainless steels formed by selective laser melting (SLM) under different friction conditions are studied. The image method was used to study the porosity of two samples with different energy densities (46.88 J/mm³ [...] Read more.

The fretting wear characteristics of two different energy density 316L stainless steels formed by selective laser melting (SLM) under different friction conditions are studied. The image method was used to study the porosity of two samples with different energy densities (46.88 J/mm³, 98.96 J/mm³) formed by SLM. The dynamic wear test, respectively, evaluates its wear morphology and wear depth under three conditions: dry friction, distilled water, and an 3.5% NaCl solution. The porosity of the samples with SLM forming an energy density of 46.88 J/

{mm}^{3}

and 98.96 J/

{mm}^{3}

are 7.66% and 1.00%, respectively. Under the three conditions, the friction coefficient and wear depth of the samples with high energy density are smaller than those of the samples with low energy density; the friction of the samples with two energy densities in aqueous solution is faster than dry friction in air and tends to be stable. The friction coefficient in 3.5% NaCl solution is the smallest; when the energy density is constant, the wear depth of the fretting wear is the largest under dry friction and the smallest in distilled water. Under dry-friction conditions, the wear mechanisms of fretting wear are mainly oxidative wear and adhesive wear. In the fretting wear in the distilled water and the 3.5% NaCl solution, both wear mechanisms are abrasive wear and fatigue wear. Full article

(This article belongs to the Topic Advanced Manufacturing and Surface Technology)

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19 pages, 7640 KiB

Open AccessReview

A Review of Aviation Spline Research

by Guang Zhao, Xiangyang Zhao, Liting Qian, Yunbo Yuan, Song Ma and Mei Guo

Lubricants 2023, 11(1), 6; https://doi.org/10.3390/lubricants11010006 - 25 Dec 2022

Cited by 4 | Viewed by 3235

Abstract

Splines are irreplaceable in high-speed aviation fields due to their simplicity, reliability, and high specific power. Aviation splines are not only subjected to severe operating mechanical loads, but also sometimes operate under grease-lubricated and non-lubricated environments. All of this results in aviation splines [...] Read more.

Splines are irreplaceable in high-speed aviation fields due to their simplicity, reliability, and high specific power. Aviation splines are not only subjected to severe operating mechanical loads, but also sometimes operate under grease-lubricated and non-lubricated environments. All of this results in aviation splines suffering widespread failures. Since the 1960s, many researchers have carried out much research on aviation splines. The wide range of research topics demonstrates the technical challenges of understanding aviation spline. This paper reviews the research of aviation spline from the aspects of failure form, fatigue strength, surface contact stress, effects of lubrication, and misalignment on wear, as well as experiments. Relevant research shows crowned splines can mitigate the spline wear process induced by angular misalignment, and oil-lubricating splines experience almost no wear. This paper also looks forward to the future development directions of aviation splines. Full article

(This article belongs to the Special Issue Wear Prediction in Aeroengine Rotor System)

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19 pages, 10237 KiB

Open AccessArticle

Ecofriendly Protic Ionic Liquid Lubricants for Ti6Al4V

by Ana-Eva Jiménez, María-Dolores Avilés, Ramón Pamies, María-Dolores Bermúdez, Francisco-José Carrión-Vilches and José Sanes

Lubricants 2023, 11(1), 5; https://doi.org/10.3390/lubricants11010005 - 22 Dec 2022

Cited by 2 | Viewed by 2334

Abstract

Three diprotic ionic liquids (PILs) containing bis(2-hydroxyethyl) ammonium cations and citrate (DCi), lactate (DL), or salycilate (DSa) hydroxy/carboxylate anions were studied as lubricants for Ti6Al4V–sapphire contact. At room temperature, the neat PILs are non-Newtonian fluids, which show up to a 70% friction coefficient [...] Read more.

Three diprotic ionic liquids (PILs) containing bis(2-hydroxyethyl) ammonium cations and citrate (DCi), lactate (DL), or salycilate (DSa) hydroxy/carboxylate anions were studied as lubricants for Ti6Al4V–sapphire contact. At room temperature, the neat PILs are non-Newtonian fluids, which show up to a 70% friction coefficient reduction with respect to water. New aqueous lubricants were developed using PILs as 1 wt.% additives in water. The new (Water + 1 wt.% PILs) lubricants showed friction reductions of higher than 50% with respect to water at room temperature. The lowest friction coefficients at room temperature were achieved with thin lubricant layers deposited on Ti6Al4V using Water + 1 wt.% PIL after water evaporation. At 100 °C, the best tribological performance, with the lowest friction coefficients and wear rates, was obtained for the PILs containing aliphatic anions: DCi, and DL. The surface layers of the sapphire balls with mild adhesion and abrasion wear mechanisms were observed via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Full article

(This article belongs to the Special Issue Green Tribology: New Insights toward a Sustainable World 2023)

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Lubricants, Volume 11, Issue 1 (January 2023) – 34 articles

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