scholarly journals Synergistic Regulation Mechanism of Inorganic Thermal Oxidation Coating and Poly (Vinylphosphonic Acid) (PVPA) Coating for High Load Bearing Superlubricity

2021 ◽  
Vol 11 (1) ◽  
pp. 416
Author(s):  
Mengmeng Liu ◽  
Zhifeng Liu ◽  
Junmin Chen ◽  
Liang Jiang ◽  
Caixia Zhang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Coating ◽  
Oxide Coating ◽  
Regulation Mechanism ◽  
Low Friction ◽  
Artificial Joints ◽  
Thermal Oxide ◽  
Vinylphosphonic Acid ◽  
Synergistic Regulation ◽  
Titanium Alloy Ti6al4v

A low friction coefficient and high bearing capacity can improve the service life of implants in the human body. In this study, we firstly investigate the mechanical properties of inorganic thermal oxide coatings on titanium alloy (Ti6Al4V). Tribological experiments were performed for different tribo-pairs under uniform conditions. The inorganic thermal oxide coating on Ti6Al4V formed at 300℃ was found to have excellent tribological properties and can effectively improve the bearing capacity of Ti6Al4V. The organic poly (vinylphosphonic acid) (PVPA) on Ti6Al4V has excellent anti-friction properties, which can help achieve superlubricity. An inorganic thermal oxide/organic PVPA composite coating was fabricated on Ti6Al4V to obtain a surface with low friction and high bearing capacity. It is found that the presence of the thermal oxide doubled the bearing capacity of the composite coating compared to that of the PVPA coating alone. This study can serve as a guide for the modification of artificial joints.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

Synergistic regulation mechanism of selectin and integrin on leukocyte adhesion under shear flow

2021 ◽  
pp. 1-32
Author(s):  
Wei Kang ◽  
Long Li ◽  
Jizeng Wang
Keyword(s):  
Shear Flow ◽  
Leukocyte Adhesion ◽  
Hydrodynamic Process ◽  
Regulation Mechanism ◽  
Leukocyte Rolling ◽  
Cooperative Effects ◽  
Inflammatory Site ◽  
Synergistic Regulation ◽  
Effective Phase ◽  
Kinetics Of

Abstract In the process of inflammation, the hydrodynamic process of circulating leukocyte recruitment to the inflammatory site requires the rolling adhesion of leukocytes in blood vessels mediated by selectin and integrin molecules. Although a number of experiments have demonstrated that cooperative effects exist between selectins and integrins in leukocyte rolling adhesion under shear flow, the mechanisms underlying how the mechanics of selectins and integrins synergistically may govern the dynamics of cell rolling is not yet fully resolved. Here we present a mechanical model on selectin- and integrin- jointly mediated rolling adhesion of leukocyte in shear flow, by considering two pairs' binding/unbinding events as Markov processes and describing kinetics of leukocyte by the approach of continuum mechanics. Through examining the dynamics of leukocyte rolling as a function of relative fraction of selectin and integrin pairs, we show that, during recruitment, the elongation of intermittent weak selectin bonds consuming the kinetic energy of rolling leukocyte decelerates the rolling speed and enables the integrin pairs to form strong bonds, therefore achieving the arrestment of leukocyte (firm adhesion). The coexistence of selectins and integrins may also be required for effective phase transition from firm adhesion to rolling adhesion, due to dynamic competition in pairs' formation and elongation. These results are verified by the relevant Monte Carlo simulations and related to reported experimental observations.

scholarly journals Characterisation of UHMWPE Polymer Powder for Laser Sintering

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3496 ◽  
Author(s):  
Yas Khalil ◽  
Neil Hopkinson ◽  
Adam Kowalski ◽  
John Patrick Anthony Fairclough
Keyword(s):  
Flow Characteristics ◽  
Laser Sintering ◽  
Polymer Chains ◽  
Low Friction ◽  
Artificial Joints ◽  
Suitable Material ◽  
Powder Properties ◽  
Sintering Behaviour ◽  
Ultra High Molecular Weight ◽  
Very High

Ultra-high molecular weight polyethylene (UHMWPE) is a thermoplastic semicrystalline polymer that has outstanding mechanical properties, low friction coefficient, excellent wear resistance, and is highly resistant to corrosive chemicals. UHMWPE is found in many applications including artificial joints and filtration. However, UHMWPE parts cannot be produced easily by traditional techniques, such as injection moulding and extrusion because of its very high melt viscosity owing to the extremely long polymer chains. Few attempts were made to process UHMWPE by additive manufacturing, particularly laser sintering. This is due to the lack of understanding of the powder properties of UHMWPE. Therefore, the aim of the powder characterisation process in this study is to gain a better understanding of the material requirements and provide a detailed insight on whether UHMWPE is a suitable material for laser sintering. The characterisation process includes powder morphological and flow characteristics, thermal behaviour and stability, and crystallinity of UHMWPE. The study reveals that the sintering behaviour of polymers is controlled by the morphology of the particles in addition to the viscous flow of UHMWPE. There are still difficulties of processing UHMWPE due to highly agglomerated structure of smaller particles with the presence of fibrils in the UHMWPE particles.

Research on Lubrication and Wear-Resistant Mechanism of Ni60A/MoS2 Composite Coating

2011 ◽  
Vol 189-193 ◽  
pp. 231-235
Author(s):  
Yun Cai Zhao ◽  
Li Wang
Keyword(s):  
Friction Coefficient ◽  
Composite Coating ◽  
Friction Surface ◽  
Testing Machine ◽  
The Self ◽  
Wear Testing ◽  
Friction Property ◽  
Low Friction ◽  
Coverage Area ◽  
Lubricating Film

The influence of MoS2 lubrication phase on the tribological properties of the Ni60A/MoS2 composite coating was conducted on UMT-2 micro-wear testing machine (USA), discussing the self-lubricating effect and mechanism. The result shows that with the increasing content of MoS2, the friction coefficient of the coating which changed with the increasing content of the MoS2 presents firstly decreases then increases, and the value reach the minimum when the quality percent of MoS2 wrapped with Nickel is 35%. Low-friction property of the Ni60A/MoS2 composite coating is due to the forming of MoS2 lubricating film in friction surface. The decreasing of the friction coefficient of the coating is in proportion to the coverage area of MoS2 lubricating film.

scholarly journals Roles of polymer brushes in biological applications

2021 ◽  
Vol 2 (1) ◽  
pp. 12-23
Author(s):  
Ajinkya Raut ◽  
◽  
Peter Renner ◽  
Rick Wang ◽  
Serge Kazadi ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Polymer Brushes ◽  
Selective Adsorption ◽  
Polymer Chains ◽  
Biological Applications ◽  
Low Friction ◽  
Binding Properties ◽  
Artificial Joints ◽  
Adhesion Protein ◽  
Functionalized Surfaces

Polymer brushes are macromolecular structures with polymer chains tethered to a surface resembling a brush. They have shown variety of uses in biological applications. Because of the nature of crafted polymers, the functionalized surfaces exhibit unique functions such as low friction, altered adhesion, protein binding and selective adsorption. Functionalization can be controlled by changing parameters such as grafting densities, chemical configurations, shapes and thickness. In this review, a particular emphasis has been provided for studies related to biological applications of polymer brushes based on their ultra-low friction, hydrophilic elongated surfaces, and binding properties. It provides useful information for researches and labs working on finding better solutions for drug delivery, arthritis, artificial joints, antibiofouling coatings and protein immobilization and purification.

Study on Tribological Properties of n-SiO2/FeS Solid Lubrication Composite Coating

2011 ◽  
Vol 694 ◽  
pp. 914-918
Author(s):  
Yu Qiang Zhao ◽  
Yan Zang ◽  
Yu Lin Qiao ◽  
Shan Lin Yang
Keyword(s):  
Friction Coefficient ◽  
Composite Coating ◽  
Tribological Properties ◽  
Treatment Process ◽  
Solid Lubrication ◽  
Vacuum Impregnation ◽  
Comprehensive Treatment ◽  
Low Friction ◽  
Duplex Coating ◽  
Lubrication Mechanisms

The n-SiO2/FeS solid lubrication composite coating is prepared by means of the comprehensive treatment process of gridded laser quenching, low temperature ion sulfuration and vacuum impregnation technology. The tribological properties of n-SiO2/FeS solid lubrication composite coating are investigated under the condition of dry sliding, and the lubrication mechanisms are also preliminary discussed. The experiment results reveal that the friction coefficient of the coating is in the range of 0.065~0.10 when tested in 4067 minutes. Furthermore, its wear rate is only 6% of FeS solid lubrication duplex coating. This is testified that the n-SiO2/FeS solid lubrication composite coating is durable with low friction coefficient and wear resistance.

Low Friction Achieved Using Repulsive Van Der Waals Forces: A Nanotribology Study With Colloid Probe AFM

2005 ◽  
Author(s):  
A. A. Feiler ◽  
L. Bergstro¨m ◽  
M. W. Rutland
Keyword(s):  
Friction Coefficient ◽  
Bearing Capacity ◽  
Atomic Force Microscope ◽  
Contact Surface ◽  
Van Der Waals ◽  
Surface Force ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Atomic Force ◽  
Almost All

We show that extremely low friction can be achieved with the use of a divergent, pre-contact “surface force” — the repulsive, so called van der Waals force. In almost all cases this force is attractive, but for certain combinations of materials it manifests repulsively and at short separations (of the order of molecular distances) the load bearing capacity provided by the force is large. We have used the Atomic Force Microscope (AFM) in colloid probe mode to measure the friction between sub-microscopic contacts in the presence of such a force and have achieved a friction coefficient of the order of 0.0002.

scholarly journals Synergies in lubrication

2017 ◽  
Vol 19 (35) ◽  
pp. 23677-23689 ◽  
Author(s):  
Andra Dėdinaitė ◽  
Per M. Claesson
Keyword(s):  
Bearing Capacity ◽  
Aqueous Medium ◽  
Water Layer ◽  
High Load ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Friction Forces ◽  
Load Bearing ◽  
Living Organisms

In living organisms the aqueous medium is used for providing low friction forces. This is achieved by synergistic actions of different biomolecules that together accomplish a high load bearing capacity and sustain an easily sheared water layer.

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