Improved Tribological Performance of Polydopamine/Polytetrafluoroethylene Thin Coatings With Silica Nanoparticles Incorporated into the Polydopamine Underlayer

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Adedoyin Abe ◽  
Dipankar Choudhury ◽  
Min Zou
Keyword(s):  
Solid Lubricant ◽  
Silica Nanoparticle ◽  
Low Friction ◽  
Contact Conditions ◽  
Dry Contact ◽  
Delamination Resistance ◽  
Coating Durability ◽  
Steel Substrates ◽  
Increasing Load ◽  
Aqueous Silica

Abstract Polytetrafluoroethylene (PTFE) is a solid lubricant with low friction coefficient. However, it lacks durability as a thin coating. Prior studies have shown that a polydopamine (PDA) underlayer enhances the coating durability. In this study, 100, 200, and 300 µL of aqueous silica nanoparticle (NP) dispersions were added to a 15 mL PDA deposition solution. Stainless steel substrates were coated with PDA + silica in the mixed dispersions and then coated with PTFE layers to form thin PDA + silica/PTFE coatings. The coatings were tested in ball-on-flat linear reciprocating motion under dry contact conditions. The durability of the PDA/PTFE coating was improved by 70% when 100 µL of aqueous silica NP dispersion was added. The significant improvement in the durability was attributed to the increased adhesion of the PTFE coating to the PDA underlayer, the fragmented wear debris, and the enhanced counterface transfer film. These samples also showed enhanced resistance under linearly increasing load scratch testing with lower coefficient of friction (COF) and higher delamination resistance when compared to samples without silica.

Atomic-Scale Observation of Superlubricity

2005 ◽  
Author(s):  
M. Dienwiebel ◽  
G. S. Verhoeven ◽  
N. Pradeep ◽  
H. W. Zandbergen ◽  
J. W. M. Frenken
Keyword(s):  
Energy Dissipation ◽  
Frictional Force ◽  
Solid Lubricant ◽  
Atomic Scale ◽  
Three Dimensions ◽  
Low Friction ◽  
Friction Behavior ◽  
Rotational Angle ◽  
Dry Contact ◽  
Tungsten Tip

Graphite is known to be a good solid lubricant. The low-friction behavior is commonly ascribed to the low resistance to shear. Using a home-built frictional force microscope that is able to detect forces in three dimensions, we have studied the energy dissipation between a tungsten tip sliding over a graphite surface in dry contact. By measuring atomic-scale friction as a function of the rotational angle between two contacting bodies we show that the origin of the ultra-low friction of graphite lies in the incommensurability between rotated graphite layers, an effect proposed under the name of ‘superlubricity’.

scholarly journals Wear and Frictional Behaviour of Metals

2014 ◽  
Vol 893 ◽  
pp. 430-435
Author(s):  
J.G. Alotaibi ◽  
B.F. Yousif ◽  
T.F. Yusaf
Keyword(s):  
Stainless Steel ◽  
Thermal Loading ◽  
Operating Parameters ◽  
Thermal Imager ◽  
Contact Conditions ◽  
Dry Contact ◽  
Three Body Abrasion ◽  
Three Body ◽  
Worn Surface ◽  
Frictional Behaviour

In the current study, wear and frictional performances of different metals are investigated under different operating parameters against stainless steel counterface under dry contact conditions. The experiments performed using block on ring machine. Microscopy was used to examine the damage features on the worn surface and categorize the wear mechanism. Thermal imager was used to understand the thermal loading in the interface during the rubbing process. The results revealed that the operating parameters influence the wear and frictional behaviour of all the metals. Brass metal exhibited better wear and frictional behaviour compared to others. Three different wear mechanisms were observed, i.e. two body abrasion (Brass), three body abrasion (Aluminium) and adhesive (Mild Steel).

Effect of PTFE Retainer on Friction Coefficient in Polymer Thrust Bearings under Dry Contact

2013 ◽  
Vol 683 ◽  
pp. 90-93 ◽  
Author(s):  
Koshiro Mizobe ◽  
Takashi Honda ◽  
Hitonobu Koike ◽  
Edson Costa Santos ◽  
Yuji Kashima ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Low Friction ◽  
Friction Forces ◽  
Thrust Bearings ◽  
Dry Contact

Polyetheretherketone (PEEK) is a tough semi-crystalline thermoplastic polymer with excellent mechanical properties. While abilities of polyphenylenesulfide (PPS) are similar to PEEK, former material cost was lower than later. Polytetrafluoroethylene (PTFE) is well known because of its low friction coefficient and self lubrication ability. The objective of this study is to observe the friction coefficient of hybrid bearings, PTFE retainer sandwiched with PPS-races or PEEK-races. Rolling contact fatigue tests were performed and in situ friction forces wear measured. It is concluded that the PTFE retainer reduced friction coefficient.

scholarly journals Understanding the Unique Role of Phospholipids in the Lubrication of Natural Joints: An Interfacial Tension Study

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 264 ◽  
Author(s):  
Aneta D. Petelska ◽  
Katarzyna Kazimierska-Drobny ◽  
Katarzyna Janicka ◽  
Tomasz Majewski ◽  
Wiesław Urbaniak
Keyword(s):  
Interfacial Tension ◽  
Lipid Bilayers ◽  
Solid Lubricant ◽  
Solid Lubricants ◽  
Phospholipid Bilayer ◽  
Low Friction ◽  
Unique Role ◽  
Lamellar Phases ◽  
Chemical Inertness

Some solid lubricants are characterized by a layered structure with weak (van der Waals) inter-interlayer forces which allow for easy, low-strength shearing. Solid lubricants in natural lubrication are characterized by phospholipid bilayers in the articular joints and phospholipid lamellar phases in synovial fluid. The influence of the acid–base properties of the phospholipid bilayer on the wettability and properties of the surface have been explained by studying the interfacial tension of spherical lipid bilayers based on a model membrane. In this paper, we show that the phospholipid multi-bilayer can act as an effective solid lubricant in every aspect, ranging from a ‘corrosion inhibitor’ in the stomach to a load-bearing lubricant in bovine joints. We present evidence of the outstanding performance of phospholipids and argue that this is due to their chemical inertness and hydrophilic–hydrophobic structure, which makes them amphoteric and provides them with the ability to form lamellar structures that can facilitate functional sliding. Moreover, the friction coefficient can significantly change for a given phospholipid bilayer so it leads to a lamellar-repulsive mechanism under highly charged conditions. After this, it is quickly transformed to result in stable low-friction conditions.

Report Paper 3: Elastohydrodynamic Lubrication of ‘O’ Ring Seals

1969 ◽  
Vol 184 (12) ◽  
pp. 197-200
Author(s):  
I. A. Gibson ◽  
C. J. Hooke ◽  
J. P. O'Donoghue
Keyword(s):  
Theoretical Analysis ◽  
Film Thickness ◽  
Pressure Gradient ◽  
Contact Zone ◽  
Elastohydrodynamic Lubrication ◽  
Iterative Solution ◽  
Contact Conditions ◽  
Dry Contact

This report gives details of a theoretical analysis of the lubrication of ‘O’ ring seals. Under dry contact conditions the pressure gradient at inlet to the contact zone is infinite, and an iterative solution has been developed to determine the inlet sweep of pressure under conditions of elastohydrodynamic lubrication. The exit film thickness and pressures have also been determined for conditions of variable outlet viscosity and pressure gradient. Typical results for an ‘O’ ring are given for a standard seal section.

Low friction states for thin solid lubricant film of MoS2

2018 ◽  
Vol 70 (4) ◽  
pp. 639-644 ◽  
Author(s):  
Kwang-Hua R. Chu
Keyword(s):  
Thin Films ◽  
Solid Lubricant ◽  
Activation Volume ◽  
High Vacuum ◽  
Low Friction ◽  
Friction Behavior ◽  
Stick Slip ◽  
Content Type ◽  
Term Operation

Purpose During the operation of Wendelstein 7-X (W7-X), any mechanical disturbance such as stick-slip may cause quenching of superconducting (SC) coils. The friction behavior of MoS2 lubrication (thin film) for narrow support elements between the SC coils in W7-X is rather important, as there is a design requirement for a coefficient of friction (COF) 0.05 between the sliding surfaces to control the stress contribution (from friction). Design/methodology/approach The author has carried out intensive calibrations or verifications using verified models considering previous friction tests on various samples which measured the COF in 4.2 K, 77 K and room temperature conditions (at high vacuum) to simulate the actual working condition. Findings The author has given useful explanations and diagnosis for previous anomalous scattered data. To improve the performance of MoS2, the author has predicted its better COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS2 thin films considering the long-term operation requirement W7-X. Originality/value In this paper, the author has adopted Eyring’s approach to predict the low COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS2 thin films considering the long-term operation requirement W7-X. Finally, some recent progresses about the possible few-layer MoS2 role in the electromagnetic loads have been provided.

Controlling aqueous silica nanoparticle synthesis in the 10–100 nm range

2015 ◽  
Vol 51 (98) ◽  
pp. 17420-17423 ◽  
Author(s):  
Delyan R. Hristov ◽  
Eugene Mahon ◽  
Kenneth A. Dawson
Keyword(s):  
Nanoparticle Synthesis ◽  
Silica Nanoparticle ◽  
Single Step ◽  
Generation Rate ◽  
Nm Range ◽  
Aqueous Silica

Controlling monomer generation rate in different ways, we broaden the range of sizes attainable for single step aqueous silica nanoparticle synthesis.

High temperature friction and wear properties of graphene oxide/polytetrafluoroethylene composite coatings deposited on stainless steel

RSC Advances ◽  
2016 ◽  
Vol 6 (7) ◽  
pp. 5977-5987 ◽  
Author(s):  
N. Nemati ◽  
M. Emamy ◽  
S. Yau ◽  
J.-K. Kim ◽  
D.-E. Kim
Keyword(s):  
Stainless Steel ◽  
Graphene Oxide ◽  
Friction And Wear ◽  
Solid Lubricant ◽  
Composite Coatings ◽  
Friction Material ◽  
Wear Properties ◽  
Low Friction ◽  
Solid Lubricant Coating ◽  
Friction And Wear Properties

Polytetrafluoroethylene (PTFE) coating is known as a low friction material that is often used as a solid lubricant coating.

scholarly journals The mechanics of snow friction as revealed by micro-scale interface observations

2017 ◽  
Vol 64 (243) ◽  
pp. 27-36 ◽  
Author(s):  
JAMES H. LEVER ◽  
SUSAN TAYLOR ◽  
ARNOLD J. SONG ◽  
ZOE R. COURVILLE ◽  
ROSS LIEBLAPPEN ◽  
...  
Keyword(s):  
Melting Point ◽  
High Resolution ◽  
Real Contact Area ◽  
Kinetic Friction ◽  
Low Friction ◽  
Dominant Mechanism ◽  
Micro Scale ◽  
Real Contact ◽  
Dry Contact ◽  
Air Pockets

ABSTRACTThe mechanics of snow friction are central to competitive skiing, safe winter driving and efficient polar sleds. For nearly 80 years, prevailing theory has postulated that self-lubrication accounts for low kinetic friction on snow: dry-contact sliding warms snow grains to the melting point, and further sliding produces meltwater layers that lubricate the interface. We sought to verify that self-lubrication occurs at the grain scale and to quantify the evolution of real contact area to aid modeling. We used high-resolution (15 µm) infrared thermography to observe the warming of stationary snow under a rotating polyethylene slider. Surprisingly, we did not observe melting at contacting snow grains despite low friction values. In some cases, slider shear failed inter-granular bonds and produced widespread snow movement with no persistent contacts to melt (μ < 0.03). When the snow grains did not move and persistent contacts evolved, the slider abraded rather than melted the grains at low resistance (μ < 0.05). Optical microscopy revealed that the abraded particles deposited in air pockets between grains and thereby carried heat away from the interface, a process not included in current models. Overall, our results challenge whether self-lubrication is indeed the dominant mechanism underlying low snow kinetic friction.

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