The Role of Hard Layers in Lubricated and Dry Sliding

1987 ◽  
Vol 109 (2) ◽  
pp. 223-231 ◽  
Author(s):  
K. Komvopoulos ◽  
N. Saka ◽  
N. P. Suh
Keyword(s):  
Deformation Mode ◽  
Interfacial Friction ◽  
Dry Sliding ◽  
Severe Damage ◽  
Low Friction ◽  
Element Analysis ◽  
Wear Rates ◽  
Tangential Surface ◽  
Steel Surfaces

Lubricated and dry experiments on titanium and steel surfaces with and without TiN sputtered coatings of various thicknesses have been conducted. The significance of the layer thickness, interfacial “friction”, magnitudes of normal and tangential surface tractions, and the mechanical properties of the layer and of the substrate (e.g., elastic modulus and hardness) are critically examined. The conditions under which the deformation mode at the solid-solid contacts is elastic or plastic are addressed in light of the experimental evidence and a finite element analysis. It is shown that surfaces with very low friction, especially for unlubricated sliding, and practically zero wear rates can be obtained in both lubricated and dry sliding by coating the surfaces with sufficiently thick TiN layers. Removal of the protective TiN layer resulted in plowing, severe damage, and delamination.

scholarly journals Effect of Different Lubricating Environment on the Tribological Performance of CNT Filled Glass Reinforced Polymer Composite

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2965
Author(s):  
Sandeep Agrawal ◽  
Nishant K. Singh ◽  
Rajeev Kumar Upadhyay ◽  
Gurminder Singh ◽  
Yashvir Singh ◽  
...  
Keyword(s):  
Tribological Performance ◽  
Hardened Steel ◽  
Dry Sliding ◽  
Gfrp Composites ◽  
Tribological Behaviour ◽  
Reinforced Polymer ◽  
Steel Surfaces ◽  
Lubrication Properties ◽  
Scanning Electron

In recent years, the engineering implications of carbon nanotubes (CNTs) have progressed enormously due to their versatile characteristics. In particular, the role of CNTs in improving the tribological performances of various engineering materials is well documented in the literature. In this work, an investigation has been conducted to study the tribological behaviour of CNTs filled with glass-reinforced polymer (GFRP) composites in dry sliding, oil-lubricated, and gaseous (argon) environments in comparison to unfilled GFRP composites. The tribological study has been conducted on hardened steel surfaces at different loading conditions. Further, the worn surfaces have been examined for a particular rate of wear. Field-emission scanning electron (FESEM) microscopy was used to observe wear behaviours. The results of this study explicitly demonstrate that adding CNTs to GFRP composites increases wear resistance while lowering friction coefficient in all sliding environments. This has also been due to the beneficial strengthening and self-lubrication properties caused by CNTs on GFRP composites, according to FESEM research.

Tribological Characteristics of AlMgB14 and Nanocomposite AlMgB14-TiB2 Superhard Coatings

2008 ◽  
Author(s):  
Jun Qu ◽  
Peter J. Blau ◽  
Dong Zhu ◽  
Bruce A. Cook ◽  
Alaa A. Elmoursi
Keyword(s):  
Physical Vapor Deposition ◽  
Nanocomposite Coating ◽  
Bearing Steel ◽  
Hard Coatings ◽  
Dry Sliding ◽  
Low Friction ◽  
Wear Rates ◽  
Aisi 52100 ◽  
Order Of Magnitude ◽  
Significant Extension

This study investigated the friction and wear characteristics of two super-hard coatings on M2 steel. One was AlMgB14, produced by pulsed laser deposition (PLD), and the other was a nanocomposite of AlMgB14-TiB2, produced by physical vapor deposition (PVD). Tests were conducted under unidirectional and reciprocating sliding against AISI 52100 bearing steel in both dry and oil-lubricated conditions. The AlMgB14 coating exhibited an encouraging but short-lived low friction stage (μ = 0.2) in dry sliding. The AlMgB14-TiB2 coating reduced the wear rates by one order of magnitude relative to the M2 steel and three orders of magnitude for the counterface in dry sliding. This nanocomposite coating also demonstrated significant extension (>2.5X) of the low friction (non-scuffing) stage when sliding under starved lubrication.

scholarly journals Dry Sliding Behavior of an Aluminum Alloy after Innovative Hard Anodizing Treatments

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3281
Author(s):  
Chiara Soffritti ◽  
Annalisa Fortini ◽  
Anna Nastruzzi ◽  
Ramona Sola ◽  
Mattia Merlin ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Aluminum Substrate ◽  
Dry Sliding ◽  
Aluminum Oxides ◽  
Wear Rates ◽  
Anodic Aluminum ◽  
Hard Anodizing ◽  
Pin On Disc ◽  
Diffuse Reflectance Infrared ◽  
Wear Tests

This work evaluates the dry sliding behavior of anodic aluminum oxides (AAO) formed during one traditional hard anodizing treatment (HA) and two golden hard anodizing treatments (named G and GP, respectively) on a EN AW-6060 aluminum alloy. Three different thicknesses of AAO layers were selected: 25, 50, and 100 μm. Prior to wear tests, microstructure and mechanical properties were determined by scanning electron microscopy (VPSEM/EDS), X-ray diffractometry, diffuse reflectance infrared Fourier transform (DRIFT-FTIR) spectroscopy, roughness, microhardness, and scratch tests. Wear tests were carried out by a pin-on-disc tribometer using a steel disc as the counterpart material. The friction coefficient was provided by the equipment. Anodized pins were weighed before and after tests to assess the wear rate. Worn surfaces were analyzed by VPSEM/EDS and DRITF-FTIR. Based on the results, the GP-treated surfaces with a thickness of 50 μm exhibit the lowest friction coefficients and wear rates. In any case, a tribofilm is observed on the wear tracks. During sliding, its detachment leads to delamination of the underlying anodic aluminum oxides and to abrasion of the aluminum substrate. Finally, the best tribological performance of G- and GP-treated surfaces may be related to the existence of a thin Ag-rich film at the coating/aluminum substrate interfaces.

scholarly journals The Role of Hyaluronic Acid in Cartilage Boundary Lubrication

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1606 ◽  
Author(s):  
Weifeng Lin ◽  
Zhang Liu ◽  
Nir Kampf ◽  
Jacob Klein
Keyword(s):  
Hyaluronic Acid ◽  
Synovial Fluid ◽  
Surface Force ◽  
Force Balance ◽  
New Paradigm ◽  
Low Friction ◽  
Cartilage Surface ◽  
Boundary Lubricant ◽  
Lipid Layers

Hydration lubrication has emerged as a new paradigm for lubrication in aqueous and biological media, accounting especially for the extremely low friction (friction coefficients down to 0.001) of articular cartilage lubrication in joints. Among the ensemble of molecules acting in the joint, phosphatidylcholine (PC) lipids have been proposed as the key molecules forming, in a complex with other molecules including hyaluronic acid (HA), a robust layer on the outer surface of the cartilage. HA, ubiquitous in synovial joints, is not in itself a good boundary lubricant, but binds the PC lipids at the cartilage surface; these, in turn, massively reduce the friction via hydration lubrication at their exposed, highly hydrated phosphocholine headgroups. An important unresolved issue in this scenario is why the free HA molecules in the synovial fluid do not suppress the lubricity by adsorbing simultaneously to the opposing lipid layers, i.e., forming an adhesive, dissipative bridge between them, as they slide past each other during joint articulation. To address this question, we directly examined the friction between two hydrogenated soy PC (HSPC) lipid layers (in the form of liposomes) immersed in HA solution or two palmitoyl–oleoyl PC (POPC) lipid layers across HA–POPC solution using a surface force balance (SFB). The results show, clearly and surprisingly, that HA addition does not affect the outstanding lubrication provided by the PC lipid layers. A possible mechanism indicated by our data that may account for this is that multiple lipid layers form on each cartilage surface, so that the slip plane may move from the midplane between the opposing surfaces, which is bridged by the HA, to an HA-free interface within a multilayer, where hydration lubrication is freely active. Another possibility suggested by our model experiments is that lipids in synovial fluid may complex with HA, thereby inhibiting the HA molecules from adhering to the lipids on the cartilage surfaces.

Wear Characteristics of Conventional and Squeeze-Film Artificial Hip Joints

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
S. Boedo ◽  
S. A. Coots
Keyword(s):  
Implant Design ◽  
Squeeze Film ◽  
Linear Wear ◽  
Wear Depth ◽  
Element Analysis ◽  
Wear Characteristics ◽  
Wear Rates ◽  
Cycle Loading ◽  
Artificial Hip Joints ◽  
Elastic Elements

This paper investigates the wear characteristics of a novel squeeze-film hip implant design. Key features of the design are elastic elements attached to the cup which provide a mechanical means for ball separation during the swing phase of the gait loading cycle. An Archard-based wear formulation was implemented utilizing the ansys finite element analysis program which relates contact pressure and sliding distance to linear wear depth. It is found that low-modulus elastic elements with bonded high-modulus metal coatings offer significant predicted improvement in linear and volumetric wear rates when compared with conventional implant geometries for gait cycle loading and kinematic conditions found in practice.

Finite element analysis of hydrogen effects on superelastic NiTi shape memory alloys: Orthodontic application

2018 ◽  
Vol 29 (16) ◽  
pp. 3188-3198 ◽  
Author(s):  
Wissem Elkhal Letaief ◽  
Aroua Fathallah ◽  
Tarek Hassine ◽  
Fehmi Gamaoun
Keyword(s):  
Finite Element ◽  
Coupled Model ◽  
Element Model ◽  
Orthodontic Wires ◽  
Niti Wire ◽  
Element Analysis ◽  
Finite Element Software ◽  
Orthodontic Wire ◽  
Niti Shape Memory Alloys

Thanks to its greater flexibility and biocompatibility with human tissue, superelastic NiTi alloys have taken an important part in the market of orthodontic wires. However, wire fractures and superelasticity losses are notified after a few months from being fixed in the teeth. This behavior is due to the hydrogen presence in the oral cavity, which brittles the NiTi arch wire. In this article, a diffusion-mechanical coupled model is presented while considering the hydrogen influences on the NiTi superelasticity. The model is integrated in ABAQUS finite element software via a UMAT subroutine. Additionally, a finite element model of a deflected orthodontic NiTi wire within three teeth brackets is simulated in the presence of hydrogen. The numerical results demonstrate that the force applied to the tooth drops with respect to the increase in the hydrogen amount. This behavior is attributed to the expansion of the NiTi structure after absorbing hydrogen. In addition, it is shown that hydrogen induces a loss of superelasticity. Hence, it attenuates the role of the orthodontic wire on the correction tooth malposition.

Calculation and Simulation Azimuth Hydrostatic Thrust Bearing of a Large Alt-Azimuth Telescope

2013 ◽  
Vol 364 ◽  
pp. 28-32
Author(s):  
Long Huang ◽  
Wen Li Ma ◽  
Jin Long Huang
Keyword(s):  
Thrust Bearing ◽  
Structure Parameter ◽  
Tracking Accuracy ◽  
Low Friction ◽  
Element Analysis ◽  
Hydrostatic Bearing ◽  
Wide Range ◽  
And Performance ◽  
Large Telescopes ◽  
Main Factor

The use of hydrostatic bearing for support of telescope offers a number of potential performance advantages, but the structure parameter of bearing is the main factor which influence the bearing. The temperature rise of bearing is also important for the stiffnees of the telescope mount.In addition to the known benefit of mount stiffness and tracking accuracy from exceedingly low friction, the hydrostatic bearing provides a wide range of geometric possibilities for large telescopes [1].This paper analyzes various familiar hydrostatic bearing for the azimuth and elevation axes of telescope.Theoretical calculation and simulation show that the performance of bearing meets telescope’s design requirements.The principle and process of this work and Finite Element Analysis (FEA) are introduced in detail. According to the CFX result, the structure parameter and performance of bearing ,temperature field and pressure distribution have obtained.

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