Article
Engineering, Chemical
Bugao Lyu, Limin Zhang, Xianghui Meng, Chengen Wang
Summary: A boundary lubrication model considering tribofilms was developed in this study and validated through experiments. The results showed that the tribofilms can reduce friction force and wear depth, but their effects vary under different temperatures and loads.
Article
Engineering, Mechanical
Mengyu Lin, Aneta Nemcova, Andrey A. Voevodin, Andras Korenyi-Both, Tomasz W. Liskiewicz, Nicolas Laugel, Allan Matthews, Aleksey Yerokhin
Summary: The duplex coatings on AA6082 alloy exhibited significant improvement in fretting wear resistance and friction reduction compared to single-layer coatings. By reducing contact pressure, the topcoat's lubricating behavior was retained, resulting in high wear resistance and elimination of fatigue damage after 10^4 cycles.
TRIBOLOGY INTERNATIONAL
(2021)
Article
Engineering, Mechanical
Chunming Xu, Yuxing Peng, Zhencai Zhu, Wei Tang, Kun Huang
Summary: Mineral particles in mine air exacerbate wire rope wear, threatening its lifespan. Wear of steel wire under mixed grease conditions increases with loading force, while wear coefficient decreases. Wear mechanisms include abrasive, adhesive, and fatigue wear, with peak friction pair exhibiting more severe wear characteristics.
ENGINEERING FAILURE ANALYSIS
(2021)
Article
Engineering, Chemical
Linqing Bai, Yonggang Meng, Varian Zhang, Zulfiqar Ahmad Khan
Summary: Experimental investigations showed that surface topography significantly influences the critical time of ZDDP tribofilm formation and wear performance. Optimizing surface morphology design enhances anti-wear performance, leading to increased service life of interacting components and cost savings from reduced wear.
Article
Engineering, Mechanical
Guillaume Colas, Pierre-Henri Cornuault, Yann Michel, Romain Petre Bordenave
Summary: Fretting wear is a common problem in spacecraft launches, causing anomalies. A study was conducted on a CubSat satellite that got stuck in its dispenser during a preflight test. Due to limited time before the launch, no parts of the satellite could be replaced. Therefore, a fretting test campaign was carried out at a tribometer scale to propose a lubrication solution for the damaged contacts. The study successfully reproduced the damages and particles observed on the rail surfaces, and eventually, grease was chosen as the lubricant for the satellite.
Article
Engineering, Mechanical
Y. Kong, C. J. Bennett, C. J. Hyde
Summary: A method for simulating fretting wear using the Modified Simplex Method for contact solution has been developed, which optimized computational time by calculating force distributions and wear depths. The method was found to be viable for design and accurately simulated fretting wear in various practical applications.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Po Zhang, Liangcai Zeng, Xue Mi, Yan Lu, Shiyuan Luo, Wengzheng Zhai
Summary: This paper investigates the torsional-fretting wear properties of 7075 aluminum alloys under lubricated and dry conditions. The study explores the effects of lubricating medium, third body behavior, and contact configuration on fretting behavior, and observes abrasion wear, cracks, and delamination on worn surfaces. Corrosion pits and oxidation debris layer are also observed under different test conditions.
Article
Engineering, Mechanical
Yusong Lin, Ren He, Yongkun Xu, Jianjun Zhang, Bernd Wetzel, Ga Zhang
Summary: This study investigates the effect of nickel (Ni) particles on the tribological performance of polyimide (PI) and PI reinforced with carbon fiber (CF) materials. The results show that PI composites filled with Ni exhibit ultra-low friction and wear, surpassing the friction-reduction capabilities of CF. The researchers provide direct evidence for the formation of an extremely thin NiO glaze layer on the steel counterface, above which a uniform C-based tribofilm is formed. The NiO layer is believed to catalyze the dehydrogenation of oil molecules and promote the formation of the tribofilm. This work proposes a design concept of high-performance tribofilm for improving the boundary lubrication of motion components.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Engineering, Mechanical
S. Boedo
Summary: This study investigates the impact of surface ellipticity on self-acting partial arc journal bearings under steady load and sinusoidal oscillation, taking into account mass conserving cavitation. The computational efficiency is improved by using a generalized Warner bearing (GWB) formula. The results demonstrate that an elliptical sleeve can significantly improve bearing performance at small oscillation amplitudes commonly found in practical applications, and a fully hydrodynamic lubrication regime can be established through the wearing-in process of the sleeve surface.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Steven J. Thrush, Allen S. Comfort, James S. Dusenbury, Xue Han, Gary C. Barber, Xia Wang, Hongwei Qu
Summary: The study found that the sintered tribofilm formed with zirconia nanoparticle antiwear additive provided enduring protection for the substrate steel during wear, but exhibited cracks and mild abrasive wear. Without nanoparticle additive, wear occurred more rapidly and was more prone to scuffing.
Article
Engineering, Mechanical
Krishnamurti Singh, Anirban Mahato, Mayank Tiwari
Summary: The transition from mixed stick-slip to gross-slip regime in advanced materials such as Zircaloy-4/Inconel-600, Ti6Al-4V/Inconel-600, and 9Cr-1Mo-steel/Ti-6Al-4V was explored in this study. Characterizations of worn surfaces showed sequential changes in contact state and associated chemical changes. Secondary cracks caused by low cycle fatigue in the plate material led to the movement of the stick-slip boundary and eventual transition of regimes over time.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Penghao Qi, Shijian Wang, Jing Li, Yue Li, Guangneng Dong
Summary: This study aims to reduce the use of Zinc dialkyl dithiophosphates (ZDDP) in Perfluoropolyether (PFPE) grease by adding antioxidant additives to improve its frictional properties and thermal oxidation stability. By selecting an antioxidant with good comprehensive performance, it was found that the combined use of BHT with ZDDP can enhance the anti-wear efficiency of ZDDP and improve the high temperature performance of PFPE grease.
INDUSTRIAL LUBRICATION AND TRIBOLOGY
(2021)
Article
Engineering, Mechanical
Shuoshuo Chen, Ningning Song, Shengmao Zhang, Yujuan Zhang, Laigui Yu, Pingyu Zhang
Summary: By modifying molybdenum oxide, molybdenum polyisobutylene succinimide-molybdenum oxide nanoparticles were obtained, which can effectively prevent the wear acceleration of diamond-like carbon (DLC) coating under boundary lubrication. The nanoparticles and zinc dialkyldithiophosphate (ZDDP) jointly participate in tribochemical reactions to form a composite tribofilm, significantly reducing the friction and wear of DLC coating.
Article
Engineering, Mechanical
Mao Ueda, Amir Kadiric, Hugh Spikes
Summary: This study found that adding other surface-active additives to lubricants can reduce DLC wear promoted by MoDTC, mainly by forming thick antiwear tribofilms, reducing the amount of MoO3, and competitive adsorption.
Article
Engineering, Multidisciplinary
Yang DongSheng, Chen WenYuan, Chen Jiao, Sun QiChun, Tan Hui, Cheng Jun
Summary: This study demonstrates that Ga-based liquid metal (GLM) can serve as a promising extreme pressure lubricant for steel-ceramic sliding pairs, forming a Ga-rich metallic tribofilm that provides good lubricity and bearing capability. The lubrication performance of GLM strongly depends on its composition and the contacting materials, with ternary Ga-In-Sn alloy showing superior lubrication compared to binary Ga-In alloy.
SCIENCE CHINA-TECHNOLOGICAL SCIENCES
(2022)
Article
Engineering, Chemical
Jie Zhang, Mao Ueda, Sophie Campen, Hugh Spikes
Summary: The boundary friction coefficients of ZDDP tribofilms depend on the alkyl structure, with linear alkyl chains giving lower friction than branched alkyl chains, and cyclohexylmethyl-based ZDDPs showing higher friction. These differences persist over long duration tests. In rolling-sliding conditions, boundary friction coefficient can range from 0.09 to 0.14 depending on alkyl structure.
Review
Engineering, Chemical
James P. Ewen, Hugh A. Spikes, Daniele Dini
Summary: The prediction of friction under elastohydrodynamic lubrication (EHL) conditions is a crucial and controversial area in tribology, and molecular dynamics (MD) simulation has been increasingly used to understand molecular behavior in EHL. MD simulation has shown quantitative agreement with experimental friction and viscosity results, making it a valuable tool to test and inform macro-scale models for EHL problems.
Correction
Engineering, Chemical
Jie Zhang, Mao Ueda, Sophie Campen, Hugh Spikes
Summary: There was a formatting mistake in the placement of tables and figures in the original version of the article.
Article
Engineering, Mechanical
Mao Ueda, Amir Kadiric, Hugh Spikes
Summary: This study found that adding other surface-active additives to lubricants can reduce DLC wear promoted by MoDTC, mainly by forming thick antiwear tribofilms, reducing the amount of MoO3, and competitive adsorption.
Article
Multidisciplinary Sciences
Carlos E. Garcia, Mao Ueda, Hugh Spikes, Janet S. S. Wong
Summary: The formation process of MoS2 tribofilm under different temperature and shear stress conditions was investigated using Raman spectroscopy and a tribometer. The results showed that increasing shear stress promotes MoS2 formation, and the nature of the tribofilm is temperature-dependent, with higher temperature tribofilms having higher friction coefficients.
SCIENTIFIC REPORTS
(2021)
Article
Engineering, Mechanical
Jie Zhang, Sophie Campen, Janet Wong, Hugh Spikes
Summary: The study demonstrates that lubricant plays a crucial role in reducing wear and friction in inert gas atmospheres, while an increase in oxygen content leads to an increase in both wear and friction. The presence of a carbon film on rubbed surfaces in inert atmospheres and at low oxygen levels is observed, highlighting the importance of lubricant in forming a protective boundary film.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Mao Ueda, Hugh Spikes, Amir Kadiric
Summary: The study confirms the effectiveness of black oxide coatings in preventing micropitting and identifies the main mechanism behind it. BO coating, with one-quarter the hardness of steel, rapidly reduces surface roughness to prevent surface fatigue cracks, while not suppressing tribofilm growth to protect against adhesive wear and promote micropitting prevention.
TRIBOLOGY TRANSACTIONS
(2022)
Article
Engineering, Mechanical
Mao Ueda, Benjamin Wainwright, Hugh Spikes, Amir Kadiric
Summary: Micropitting is a surface fatigue damage that occurs in rolling-sliding contacts under thin oil film conditions and is poorly understood, Friction has a very significant impact on micropitting, reducing friction can mitigate crack initiation and propagation.
Article
Engineering, Chemical
Mao Ueda, Hugh Spikes, Amir Kadiric
Summary: The role of lubricant additives in forming tribofilms is crucial for surface protection against scuffing. The initial sliding speed has a significant impact on scuffing performance and the formation of tribofilms. Additives like ZDDPs and triphenyl phosphate can form thicker tribofilms, providing effective protection. However, these protective tribofilms are gradually removed at higher sliding speeds, leading to scuffing.
Article
Engineering, Mechanical
R. Taylor, I Sherrington
Summary: A new equation is proposed to calculate the proportion of mixed/boundary friction in a contact based on experimental data, and it is revealed that some commonly used rough surface contact models underestimate this type of friction. The new model suggests treating rough surface contact modeling as a growth/decay process, and the consequences of this approach are discussed.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Mao Ueda, Amir Kadiric, Hugh Spikes
Summary: This study found that some PMAs can greatly enhance the anti-scuffing performance of AW/EP additives by forming thick, adsorbed boundary films to protect the rubbing surfaces.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Mao Ueda, Janet S. S. Wong, Hugh Spikes
Summary: This paper investigates the influence of appropriate blends of PAOs and PIBs on micropitting. The findings show that these blends can provide thick oil film thicknesses and reduce micropitting while maintaining low viscosity.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Chemistry, Physical
Jie Zhang, James P. Ewen, Hugh A. Spikes
Summary: Mechanochemistry plays a crucial role in the function of lubricant additives. By modifying the molecular structure of additives, such as chain length and substituents, the mechanochemical response can be tailored to optimize their performance. This study provides insights into the relationship between structure and performance of lubricant additives.
MOLECULAR SYSTEMS DESIGN & ENGINEERING
(2022)
Review
Engineering, Mechanical
Robert Ian Taylor
Summary: Amontons' law has been experimentally shown to hold true for more than 500 years, and researchers have studied the contact of rough surfaces under different deformation conditions. With the increasing focus on energy efficiency, research on mixed/boundary lubrication and friction prediction is becoming important.
