Showing papers on "Tribology published in 2016"
TL;DR: Such lubrication in the light of very recent advances in the understanding of boundary effects in aqueous media based on the paradigms of hydration lubrication and of the synergism between different molecular components of the synovial joints (namely hyaluronan, lubricin, and phospholipids) in enabling this lubrication are discussed.
Abstract: The major synovial joints such as hips and knees are uniquely efficient tribological systems, able to articulate over a wide range of shear rates with a friction coefficient between the sliding cartilage surfaces as low as 0.001 up to pressures of more than 100 atm. No human-made material can match this. The means by which such surfaces maintain their very low friction has been intensively studied for decades and has been attributed to fluid-film and boundary lubrication. Here, we focus especially on the latter: the reduction of friction by molecular layers at the sliding cartilage surfaces. In particular, we discuss such lubrication in the light of very recent advances in our understanding of boundary effects in aqueous media based on the paradigms of hydration lubrication and of the synergism between different molecular components of the synovial joints (namely hyaluronan, lubricin, and phospholipids) in enabling this lubrication.
227 citations
TL;DR: For the first time to the authors' knowledge, such type of ultrafine particles made of crumpled, paper-ball–like graphene are reported, which indeed can self-disperse in lubricant oil, and exhibit stable and superior tribological performances.
Abstract: Ultrafine particles are often used as lubricant additives because they are capable of entering tribological contacts to reduce friction and protect surfaces from wear. They tend to be more stable than molecular additives under high thermal and mechanical stresses during rubbing. It is highly desirable for these particles to remain well dispersed in oil without relying on molecular ligands. Borrowing from the analogy that pieces of paper that are crumpled do not readily stick to each other (unlike flat sheets), we expect that ultrafine particles resembling miniaturized crumpled paper balls should self-disperse in oil and could act like nanoscale ball bearings to reduce friction and wear. Here we report the use of crumpled graphene balls as a high-performance additive that can significantly improve the lubrication properties of polyalphaolefin base oil. The tribological performance of crumpled graphene balls is only weakly dependent on their concentration in oil and readily exceeds that of other carbon additives such as graphite, reduced graphene oxide, and carbon black. Notably, polyalphaolefin base oil with only 0.01-0.1 wt % of crumpled graphene balls outperforms a fully formulated commercial lubricant in terms of friction and wear reduction.
167 citations
TL;DR: In this paper, the tribological behavior of in-situ exfoliated graphene for water-based lubricants is investigated, and the aqueous graphene dispersions show high stability due to the assistance of a non-ionic surfactant, Triton X-100.
154 citations
01 Jan 2016
TL;DR: The principles and applications of tribology is universally compatible with any devices to read and is available in the digital library an online access to it is set as public so you can get it instantly.
Abstract: Thank you for downloading principles and applications of tribology. As you may know, people have look hundreds times for their chosen novels like this principles and applications of tribology, but end up in infectious downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they cope with some infectious virus inside their laptop. principles and applications of tribology is available in our digital library an online access to it is set as public so you can get it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Merely said, the principles and applications of tribology is universally compatible with any devices to read.
116 citations
TL;DR: In this article, the influence of various factors such as material factors, graphite size and volume fraction, and mechanical factors, applied load and sliding speed on the tribological properties of self-lubricating aluminum composites, are discussed.
Abstract: Aluminum/graphite (Al/Gr) composites have been used as self-lubricating materials due to the superior lubricating effect of graphite during sliding. This paper summarizes various tribological aspects of self-lubricating aluminum composites. The influence of various factors such as (a) material factors, graphite size and volume fraction, and (b) mechanical factors, applied load and sliding speed on the tribological properties of self-lubricating aluminum composites, is discussed. Furthermore, the tribological properties of self-lubricating composites as a function of these parameters and the active wear mechanism involved in various systems are discussed. Bringing self-lubricating composites into different operating systems is a solution to reduce the use of external toxic petroleum-based lubricants in sliding contacts in a way to help the environment and reduce energy dissipation in industrial components for strategies toward sustainability and energy efficiency.
116 citations
TL;DR: In this paper, the tribological behavior of a commercial brake pad material, wear tested under dry sliding conditions against a cast iron counterface disc with a pin-on-disc apparatus, was investigated.
114 citations
TL;DR: In this article, an attempt is made in the development of a new material through powder metallurgy technique by the addition of molybdenum disulphide (MoS2), which acts as a solid lubricant.
Abstract: Aluminium ceramic composites with improved mechanical and chemical properties are essential and needed in aerospace and automotive application. The aluminium matrix composite reinforced with ceramic material of alumina (Al2O3) has good tribological properties. However, aluminium based ceramic composites require improvements in their lubrication properties. In this study an attempt is made in the development of a new material through powder metallurgy technique by the addition of molybdenum disulphide (MoS2), which acts as a solid lubricant. This molybdenum disulphide (MoS2) based solid lubricant has unique advantage that it can be used in vacuum space, but the same is not applicable in case of graphite. The microstructures, material combination, wear and friction properties were analysed by scanning electron microscopy, EDX, and pin-on-disc wear tester. The newly developed aluminium composite has significant improvements in tribological properties with a combination of 5% alumina (Al2O3) and 5% molybdenum disulphide (MoS2). The test reveals that sliding distance of 1000 m and sliding speed of 1.5 m/s with applied load of 5 N result in minimum wear loss of 0.0102 g and coefficient of friction as 0.117.
109 citations
TL;DR: In this paper, the authors summarized various features of Al/SiC/Gr hybrid composites that can be employed in different tribological applications, and showed that the addition of Gr particles helps in the formation of a thick and extensive tribolayer on the wear surface, thereby decreasing the wear rate under certain conditions.
Abstract: Improvement in surface properties and retainment of bulk properties are essential requirements for the design of components for wear resistance applications. This paper summarizes various features of Al/SiC/Gr hybrid composites that can be employed in different tribological applications. The study has revealed that the processing route plays a significant role in obtaining a homogeneous structure of these composites. In powder metallurgy, the selection of sizes of the matrix and reinforcement powders is crucial, whereas the wettability between the reinforcement particles and molten alloy is a major challenge in liquid metallurgy. The incorporation of SiC particles increases the mechanical strength and wear performance of Al composites. However, ejection of these particles can reduce the wear performance of Al composites under severe conditions. The addition of Gr particles helps in the formation of a thick and extensive tribolayer on the wear surface. This layer reduces direct contact between the rubbing surfaces, thereby decreasing the wear rate under certain conditions. Morphological analysis of worn surfaces has confirmed that the hybrid composites exhibit superior wear properties than the pure Al alloy and the ceramic-reinforced composite. However, increase in the Gr content beyond a limiting value can deteriorate the tribological properties of these composites. Therefore, true optimization of a tribosystem (of the hybrid composite and counterface) can be achieved by selecting appropriate reinforcement contents.
105 citations
TL;DR: In this article, the friction and wear of aluminum matrix composites reinforced with TiB2 micro particles processed through the stir casting method rather than in-situ techniques adopted by earlier studies was considered.
Abstract: The present study considers friction and wear of aluminium matrix composites reinforced with TiB2 micro particles processed through the stir casting method rather than in-situ techniques adopted by earlier studies. Different weight percentages of TiB2 powders having average sizes of 5 - 40 micron were incorporated into molten LM4 aluminium matrix by stir casting method. The friction and wear behavior were studied for Al-TiB2 composites prepared according to specific dimensions by using a block-on-roller type multi-tribotester at room temperature. Normal loads of 25 - 75 N and rotational speed of 400 – 600 rpm were used for determination of friction and wear behavior. It is found that friction and wear decrease with increase in percentage of TiB2 reinforcement in the composite, while friction and wear increase with applied load and speed. Scanning electron microscopy studies the reveal presence of both abrasive and adhesive wear mechanisms with abrasive wear being predominant.
102 citations
TL;DR: In this paper, the influence of incorporation of carbon based nano fillers, namely multi-walled carbon nanotubes and graphene oxide on the tribological behaviour of ultra-high molecular weight polyethylene was investigated in water lubricated sliding contacts.
97 citations
TL;DR: In this paper, the performance of textured surfaces under starved lubrication was investigated and the effect of the oil trapped in the texture features can be modeled clearly, and the simulation results show that the textured liner can obtain a steady benefit on the tribological properties.
TL;DR: In this paper, carbonaceous particles (graphite, carbon nanotubes and graphene) are reinforced in order to assess their effect on mechanical and tribological properties of FSP Al6061.
TL;DR: The role played by graphene in the friction and wear behavior of graphene/silicon carbide (SiC) composites, tested under dry sliding conditions and using silicon nitride balls as counterbodies, is investigated as a function of the graphene nanoplatelets (GNPs) content and the graphene source.
Abstract: The role played by graphene in the friction and wear behaviour of graphene/silicon carbide (SiC) composites, tested under dry sliding conditions and using silicon nitride balls as counterbodies, is investigated as a function of the graphene nanoplatelets (GNPs) content and the graphene source. GNPs composites show an enhanced wear resistance as compared to monolithic SiC, with maximum improvements of ∼70% for the material containing up to 20 vol.% of GNPs; whereas the friction performance depends on the sliding distance and GNPs content. The analysis of the wear debris by micro-Raman spectroscopy evidenced that the tribological behaviour of the GNPs/SiC materials is linked to the formation of an adhered lubricating and protecting tribofilm. Multilayered graphene fillers participate more actively in the protecting tribofilm than other graphene sources such as reduced graphene oxide or in-situ grown graphene flakes.
TL;DR: In this paper, a self-lubricating Ni-P-MoS2 composite coating has been successfully deposited on a mild steel substrate by electrodeposition, and the effects of MoS2 on the tribological coatings have been investigated.
Abstract: Tribological coatings with low coefficients of friction are in high demand by various industries since they can improve machine efficiency and have an environmental impact. A self-lubricating Ni-P-MoS2 composite coating has been successfully deposited on a mild steel substrate by electrodeposition. The effects of MoS2 on the tribological coatings have been investigated. Compared to a pure Ni-P coating, the Ni-P-MoS2 composite coating exhibited a dramatic reduction in friction coefficient against a bearing steel ball from 0.45 to 0.05. Examination and analysis of the worn surfaces and wear debris, the composite coating showed minimum wear and oxidation compared to the severe wear and oxidation observed in the pure Ni-P coating. The evolution of MoS2 particles in sliding wear has been elucidated.
TL;DR: In this paper, the UMT-2 tribotester was applied to a GCr15 steel ball and an RTCr2 alloy cast iron plate with various texture designs (original surface, dimple density of 22.1%, 19.6% and 44.2%).
TL;DR: In this paper, Ni-graphene composite coatings with different graphene addition amounts were prepared on 45 steel disk by using dipulse composite electrodeposition technology, and the influence of plating time, bath temperature and load on friction and wear of the coating was studied.
TL;DR: In this article, the tribological properties of polyimide (PI) and PI/fluorinated graphene (FG) nanocomposites, as a new class of graphene reinforced polymer, are investigated using a ball-on-disk configuration under different lubricated conditions of dry sliding, water lubrication and oil lubrication.
Abstract: The tribological properties of polyimide (PI) and PI/fluorinated graphene (FG) nanocomposites, as a new class of graphene reinforced polymer, are investigated using a ball-on-disk configuration under different lubricated conditions of dry sliding, water lubrication and oil lubrication. Experimental results reveal that single incorporation of FG can effectively improve the tribological performance of PI under all the three conditions. In addition, compared to the results under dry sliding, the phenomenon that the friction coefficient decreases while the wear rate increases under water lubrication condition is observed and researched in detail. The worst anti-wear performance under water-lubricated condition can be ascribed to the fact that the water can be adsorbed by the polar imide radicals of the PI and PI/FG nanocomposite, therefore leading to the property deterioration of the PI and PI/FG nanocomposite coatings.
TL;DR: In this article, the effects of graphene nanoplatelets (GNP) as additive in palm-oil trimethylolpropane (TMP) ester blended in polyalphaolefin were investigated.
Abstract: This paper investigates the effects of graphene nanoplatelets (GNPs) as additives in palm-oil trimethylolpropane (TMP) ester blended in polyalphaolefin. Different concentrations of GNPs that were ultrasonically homogenized in blended lubricants consist of 95 vol% polyalphaolefin and 5 vol% TMP ester. Physical properties of the nanolubricants were identified and tribological behaviors of GNP in blended lubricants were studied using standard fourball testing and surface analysis was done on the wear surfaces using scanning electron microscopy and energy-dispersive x-ray techniques. Addition of 0.05 wt% GNP in blended lubricant resulted in the lowest coefficient of friction and wear scar diameter, thus selected as the most suitable concentration of GNP in the blended lubricant. Friction and wear were reduced by 5 and 15% respectively, with the presence of 0.05 wt% GNP in the blended lubricant.
TL;DR: In this paper, the performance comparison of two conventional metal forming lubricants, CM202A press drawing oil and solid lubricant of zinc phosphate plus sodium soap, was made using two key factors of friction coefficient and deformation load.
TL;DR: A review of transfer film characterization methods for friction and wear control can be found in this article, where the state-of-the-art in solid lubricant transfer film literature is summarized.
Abstract: In dry sliding conditions, polytetrafluoroethylene (PTFE) composites can form thin, uniform, and protective transfer films on hard, metallic counterfaces that may play a significant role in friction and wear control. Qualitative characterizations of transfer film morphology, composition, and adhesion to the counterface suggest they are all good predictors of friction and, particularly, wear performance. However, a lack of quantitative transfer film characterization methods and uncertainty regarding specific mechanisms of friction and wear control make definitive conclusions about causal relationships between transfer film and tribological properties difficult. This paper reviews the state of the art in the solid lubricant transfer film literature and highlights recent advances in quantitative characterization thereof.
TL;DR: In this paper, the friction and wear behaviors of 316L stainless steel processed both by selective laser melting and traditional methods have been investigated using a ring-on-disc rig under lubricated conditions.
TL;DR: In this article, a model based on movable cellular automata was applied for obtaining a better understanding of the sliding behavior of the nanostructured tribofilms, and it was shown that low friction and wear can be expected if the released particles are mixed with other wear products and form stable films at the disk surface thus preventing further severe oxidational wear.
TL;DR: In this paper, the tribological behavior of pure magnesium and its composites reinforced with 5, 10 and 15% SiC particulates with a mean diameter of 7.8µm was investigated under normal loads of 5-60 n at sliding speed of 0.4m/s and at wear temperatures of 25-200 n.
TL;DR: In this paper, the effect of laser surface texturing on the friction behavior and the lifetime of grey cast iron reciprocating under starved lubrication conditions was investigated using a design of experiments (DoE) approach.
TL;DR: The effect of roughness on the friction and wear of the tribological system was evaluated in this paper, where WC-CoCr coatings were prepared with different surface roughness and submitted to dry sliding wear tests against a commercial friction material using a pin-on-disc configuration.
01 Jan 2016
TL;DR: The contact mechanics in tribology is universally compatible with any devices to read, and is available in the digital library an online access to it is set as public so you can get it instantly.
Abstract: Thank you very much for downloading contact mechanics in tribology. As you may know, people have look numerous times for their favorite novels like this contact mechanics in tribology, but end up in malicious downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they juggled with some malicious virus inside their laptop. contact mechanics in tribology is available in our digital library an online access to it is set as public so you can get it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Merely said, the contact mechanics in tribology is universally compatible with any devices to read.
TL;DR: In this paper, infrared thermography was used to observe the full field temperature map of polyetheretherketone (PEEK) polymers against sapphire counterface during ball-on-disc sliding.
TL;DR: In this paper, the tribological properties of high-entropy alloys were studied in simulated rainwater and deionized water conditions against the Si3N4 ceramic ball at a series of different normal loads.
Abstract: In order to understand the environmental effect on the mechanical behavior of high-entropy alloys, the tribological properties of AlCrCuFeNi2 are studied systematically in dry, simulated rainwater, and deionized water conditions against the Si3N4 ceramic ball at a series of different normal loads. The present study shows that both the friction and wear rate in simulated rainwater are the lowest. The simulated rainwater plays a significant role in the tribological behavior with the effect of forming passive film, lubricating, cooling, cleaning, and corrosion. The wear mechanism in simulated rainwater is mainly adhesive wear accompanied by abrasive wear as well as corrosive wear. In contrast, those in dry condition and deionized water are abrasive wear, adhesive wear, and surface plastic deformation. Oxidation contributes to the wear behavior in dry condition but is prevented in liquid condition. In addition, the phase diagram of Al
x
CrCuFeNi2 is predicted using CALPHAD modeling, which is in good agreement with the literature report and the present study.
TL;DR: In this article, the femtosecond laser-induced surface texturing may remarkably improve friction and wear properties if the micro-groove were properly distributed and the inclination angles of micro-Groove were measured.
Abstract: Lubricated tribological properties of stainless steel were investigated by femtosecond laser surface texturing. Regular-arranged micro-grooved textures with different spacing and micro-groove inclination angles (between micro-groove path and sliding direction) were produced on AISI 304L steel surfaces by an 800 nm femtosecond laser. The spacing of micro-groove was varied from 25 to 300 μm, and the inclination angles of micro-groove were measured as 90° and 45°. The tribological properties of the smooth and textured surfaces with micro-grooves were investigated by reciprocating ball-on-flat tests against Al 2 O 3 ceramic balls under starved oil lubricated conditions. Results showed that the spacing of micro-grooves significantly affected the tribological property. With the increase of micro-groove spacing, the average friction coefficients and wear rates of textured surfaces initially decreased then increased. The tribological performance also depended on the inclination angles of micro-grooves. Among the investigated patterns, the micro-grooves perpendicular to the sliding direction exhibited the lowest average friction coefficient and wear rate to a certain extent. Femtosecond laser-induced surface texturing may remarkably improve friction and wear properties if the micro-grooves were properly distributed.
TL;DR: In this paper, a composite of SU-8+15-15-wt% graphite and 15-15 -wt% talc has been used for fabricating micro-electro-mechanical systems.