Assessing the applied normal load during contact mode AFM: An issue with the conventional approach

2016 ◽  
Author(s):  
Raheem Sadoon Jamel Al-Musawi ◽  
Emmanuel Brousseau
Keyword(s):  
Normal Load ◽  
Conventional Approach ◽  
Contact Mode ◽  
Applied Normal Load

An Extension to a Cohesive Zone Solution for Adhesive Cylinders

2004 ◽  
Author(s):  
Clint A. Morrow ◽  
Michael R. Lovell
Keyword(s):  
Cohesive Zone ◽  
Normal Load ◽  
Adhesive Contact ◽  
Physical Contact ◽  
Contact Radius ◽  
Intimate Contact ◽  
Contact Behavior ◽  
Micro Scale ◽  
Applied Normal Load ◽  
Adhesive Forces

When adhesive forces are taken into consideration, contacting asperities can still interact after intimate contact is broken. Current theories that predict the contact behavior of adhesive cylindrical asperities fail to capture the forces in this regime. In the present investigation, prior solutions for adhesive cylindrical asperities will be extended to include the condition where the asperities are not in physical contact but are still interacting through adhesive forces. In the extended results, relationships between the adhesive contact radius and the applied normal load will be developed and discussed with respect to the design of micro-scale components.

Characterisation of Plasticity Response for Reciprocating Sliding Wear Test of Ti-6Al-4V under Variables Normal Load

2015 ◽  
Vol 1087 ◽  
pp. 350-354 ◽  
Author(s):  
D. Harun ◽  
Abdul Latif Mohd Tobi ◽  
A. Singh Chaal ◽  
Ramdziah Md. Nasir
Keyword(s):  
Plastic Deformation ◽  
Sliding Wear ◽  
Wear Track ◽  
Normal Load ◽  
Surface Profile ◽  
Wear Test ◽  
Wear Scar ◽  
Reciprocating Sliding ◽  
Applied Normal Load ◽  
Reciprocating Sliding Wear

Reciprocating sliding wear test of uncoated titanium alloy, Ti-6Al-4V is investigated using pin-on-flat arrangement under variable applied normal load. The wear scar produced by the reciprocating sliding wear test is analysed by surface profile examination using 2D and 3D optical microscope (OM) and Scanning Electron Microscope (SEM). Through SEM, the energy-dispersive X-ray spectroscopy (EDX) is used to characterise the composition of the substance on the worn surface. The hardness value of the wear scar is investigated at three regions which are; worn, unworn and the end of the wear track using Micro Vickers Hardness Test. The presence of moderate oxygen composition and the increasing in hardness value at the end of wear track suggesting evidence of plastic deformation. The increase in hardness value at the end of wear track indicates increase in plastic deformation with increasing applied normal load.

Correlation between morphology and local mechanical and electrical properties of van der Waals heterostructures

2021 ◽  
Author(s):  
Borislav Vasic ◽  
Uros Ralevic ◽  
Sonja Aškrabić ◽  
Davor Čapeta ◽  
Marko Kralj
Keyword(s):  
Charge Transfer ◽  
Close Contact ◽  
Normal Load ◽  
Van Der Waals ◽  
Contact Potential Difference ◽  
Electrical Current ◽  
Potential Difference ◽  
Electrical Measurements ◽  
Contact Potential ◽  
Contact Mode

Abstract Properties of van der Waals (vdW) heterostructures strongly depend on the quality of the interface between two dimensional (2D) layers. Instead of having atomically flat, clean, and chemically inert interfaces without dangling bonds, top-down vdW heterostructures are associated with bubbles and intercalated layers (ILs) which trap contaminations appeared during fabrication process. We investigate their influence on local electrical and mechanical properties of MoS2/WS2 heterostructures using atomic force microscopy (AFM) based methods. It is demonstrated that domains containing bubbles and ILs are locally softer, with increased friction and energy dissipation. Since they prevent sharp interfaces and efficient charge transfer between 2D layers, electrical current and contact potential difference are strongly decreased. In order to reestablish a close contact between MoS2 and WS 2 layers, vdW heterostructures were locally flattened by scanning with AFM tip in contact mode or just locally pressed with an increased normal load. Subsequent electrical measurements reveal that the contact potential difference between two layers strongly increases due to enabled charge transfer, while local I/V curves exhibit increased conductivity without undesired potential barriers.

scholarly journals Effect of different rubber materials on husking dynamics of paddy rice

2012 ◽  
Vol 226 (6) ◽  
pp. 516-528
Author(s):  
A Baker ◽  
RS Dwyer-Joyce ◽  
C Briggs ◽  
M Brockfeld
Keyword(s):  
Shear Stress ◽  
High Speed ◽  
Sliding Friction ◽  
Normal Load ◽  
Normal Pressure ◽  
Applied Normal Load ◽  
Limiting Shear Stress ◽  
Governing Factor ◽  
The Coefficient Of Friction ◽  
Husk Rice

The conventional way to husk rice is to pass it between two rubber rollers that are rotating with a surface speed differential. The resulting normal pressure and shear stress causes the husk to be peeled away from the kernel. The process is suited to high-rice flow rates, but is energy intensive and can result in considerable wear to the surfaces of the rollers. The operating parameters for machines of this design are usually determined and set empirically. In this article, some experiments and calculations had been carried out in order to explore the mechanisms involved in husking rice grains using this method. A simple sliding friction rig with load cell and high-speed camera was used to observe the mechanisms that occur during husking. The husking performance of different rubbers was compared for changes in the applied normal load. It was found that grains rotate between the rubber counterfaces on initial motion before being husked. In addition, harder rubbers were found to husk a higher proportion of entrained grains at lower applied normal load. By measuring the coefficient of friction between rice and rubber samples, the shear force required to husk a given percentage of grains could be calculated and was shown to be constant regardless of rubber type. Based on the mechanism seen in the high-speed video, it was evident that there was a limiting shear stress that was the governing factor over the husked ratio.

Investigation of Friction and Wear Properties of Electroless Ni–P–Cu Coating Under Dry Condition

2016 ◽  
Vol 04 (04) ◽  
pp. 1640013 ◽  
Author(s):  
Santanu Duari ◽  
Arkadeb Mukhopadhyay ◽  
Tapan Kr. Barman ◽  
Prasanta Sahoo
Keyword(s):  
Heat Treatment ◽  
Surface Morphology ◽  
Normal Load ◽  
Wear Depth ◽  
Wear Properties ◽  
Sliding Speed ◽  
Applied Normal Load ◽  
Heat Treated ◽  
Pin On Disc ◽  
Electroless Ni

This study presents the deposition and tribological characterization of electroless Ni–P–Cu coatings deposited on AISI 1040 steel specimens. After deposition, coatings are heat treated at 500[Formula: see text]C for 1[Formula: see text]h. Surface morphology study of the coatings reveals its typical cauliflower like appearance. Composition study of the coatings using energy dispersive X-ray analysis indicates that the deposit lies in the high phosphorus range. The coatings undergo crystallization on heat treatment. A significant improvement in microhardness of the coatings is also observed on heat treatment due to the precipitation of hard crystalline phases. The heat-treated coatings are subjected to sliding wear tests on a pin-on-disc type tribo-tester under dry condition by varying the applied normal load, sliding speed and sliding duration. The coefficient of friction (COF) increases with an increase in the applied normal load while it decreases with an increase in the sliding speed. The wear depth on the other hand increases with an increase in applied normal load as well as sliding speed. The worn surface morphology mainly indicates fracture of the nodules.

Development of a Fretting Wear Evaluation Method in the Nuclear Fuel Fretting by Using a Wear Scar Shape

2007 ◽  
Vol 26-28 ◽  
pp. 1231-1234
Author(s):  
Young Ho Lee ◽  
Hyung Kyu Kim
Keyword(s):  
Nuclear Fuel ◽  
Evaluation Method ◽  
Normal Load ◽  
Wear Scar ◽  
Wear Volume ◽  
Critical Ratio ◽  
Applied Normal Load ◽  
Scar Size ◽  
The Relationship ◽  
Wear Tests

In order to evaluate the effects of a variation of a supporting springs' shape on the wear behavior of a nuclear fuel rod, sliding wear tests have been performed in room temperature air and water. The objective of the tests is to quantitatively evaluate the relationship between a worn area and a wear volume, and the formation behavior of a worn area with a variation of the slip amplitudes, applied normal loads and supporting spring shapes. The results indicated that the variation behavior of the volume and the wear scar size was influenced by the contact shape between the springs and the fuel rods. Also, it was found to be possible to evaluate a critical ratio (Tc) for each spring shape and test condition when the T was defined as the ratio of an applied normal load (Ln) to a wear scar size (At). Below this Tc, the wear volume was rapidly increased and the Tc was determined by a variation of the At under the same applied normal load condition. This result enables us to evaluate a wear resistant spring shape by using an analysis of a wear scar after wear tests have been completed. Based on the above results, the relationship between At and a worn area (Aw), a wear mechanism and an evaluation method for a wear resistance were discussed.

scholarly journals Nanodiamond Particles as Secondary Additive for Polyalphaolefin Oil Lubrication of Steel–Aluminium Contact

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1438
Author(s):  
Ankush Raina ◽  
Mir Irfan Ul Haq ◽  
Ankush Anand ◽  
Sanjay Mohan ◽  
Rajiv Kumar ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Hexagonal Boron Nitride ◽  
Normal Load ◽  
Lubricant Additive ◽  
Oil Lubrication ◽  
Volumetric Wear ◽  
Base Oil ◽  
Applied Normal Load ◽  
Lubrication Performance ◽  
The Coefficient Of Friction

Nanodiamond (ND) particles are effective lubricant additives. Attention of research has shifted towards investigating the particles as secondary additives. ND particles provide more benefits as secondary additives than as the sole lubricant additive for steel–steel contacts. In this work, the influence of ND particles as secondary additives on oil lubrication of steel–aluminium tribopair (hard–soft contact) was examined. AISI 52100 steel balls were slid against AA2024 aluminium alloy discs, in the presence of polyalphaolefin (PAO) base oil, in boundary lubrication regime (applied normal load: 10 N to 50 N). Primary additives were copper oxide (CuO) and hexagonal boron nitride (h-BN) nanoparticles. The addition of ND particles to PAO, with CuO and h-BN as primary additives, at the lowest applied normal load of 10 N: (i) decreased the volumetric wear of the aluminium discs by 28% and 63%, respectively, and (ii) decreased the coefficient of friction by 15% and 33%, respectively. At the highest applied normal load of 50 N, it: (i) decreased the volumetric wear of the aluminium discs by 20% and 38%, respectively, and (ii) decreased the coefficient of friction by 5.4% and 8%, respectively. ND particles as secondary additives significantly reduce energy loss and power loss as a consequence of an effective reduction in friction during sliding. Unique characteristics of ND particles—such as their (a) physicochemical and thermal properties, (b) ball bearing and polishing effects and (c) synergistic interaction with primary additives to form stable tribofilms—enhance the lubrication performance of steel–aluminium contact. ND particles in combination with h-BN nanoparticles showed the best performance, due to better synergy between the primary additive and the secondary additive. Results from the investigation indicate that ND particles taken as secondary additives in small amount (0.2 wt%) can improve oil lubrication performance of hard–soft contacts in engineering systems.

An Elastic Adhesion Model for Contacting Cylinder and Perfectly Wetted Plane in the Presence of Meniscus

2007 ◽  
Vol 129 (2) ◽  
pp. 231-234 ◽  
Author(s):  
Y. F. Peng ◽  
G. X. Li
Keyword(s):  
Relative Humidity ◽  
Normal Load ◽  
Adhesive Contact ◽  
Laplace Pressure ◽  
Contact Radius ◽  
Adhesive Interaction ◽  
Applied Normal Load ◽  
Adhesion Model ◽  
The Relationship

The present research concerns the elastic contacting adhesion of a cylinder with a perfectly wetted plane in the presence of a meniscus. The Laplace pressure due to the meniscus is simplified utilizing Maugis–Dugdale approximation. Then the Baney and Hui solution and its extension are used to solve the adhesive interaction of the cylinder and the plane. Simulations of the relationship between the adhesive contact radius and the applied normal load are performed, and the influence of the relative humidity on the relationship is also discussed.

Effect of Micro-Size Cenosphere Content on Friction and Dry Sliding Wear Behavior of Vinylester Composites – A Taguchi Method

2012 ◽  
Vol 585 ◽  
pp. 569-573 ◽  
Author(s):  
S.R. Chauhan ◽  
Sunil Thakur
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Sliding Wear ◽  
Friction And Wear ◽  
Normal Load ◽  
Dry Sliding ◽  
Sliding Speed ◽  
Applied Normal Load ◽  
The Coefficient Of Friction ◽  
Sliding Distance

In this paper the friction and wear characteristics of vinylester and vinylester composites have been investigated under dry sliding conditions for different applied normal load, sliding speed and sliding distance. The experiments have been carried on a pin on disc arrangement at normal room temperature conditions. The influence of friction and wear parameters like normal load, speed, sliding distance and percentage of filler content on the friction and wear rate has been investigated. In this study, a plan of experiments based on the techniques of Taguchi was performed to acquire data in a controlled way. An orthogonal array L27 (313) and Analysis of variance (ANOVA) were applied to investigate the influence of process parameters on the coefficient of friction and sliding wear behaviour of these composites. The Taguchi design of experiment approach eliminates the need for repeated experiments and thus saves time, material and cost. The results showed that with increase in the applied normal load and sliding speed the coefficient of friction and specific wear rate decreases under dry sliding conditions. It is also found that a thin film formed on the counterface seems to be effective in improving the tribological characteristics. The results showed that the inclusion of cenosphere as filler materials in vinylester composites will increase the wear resistance of the composite significantly.

Zero-Load Friction at Nanowire-Silicon Interfaces

2008 ◽  
Author(s):  
Mohan Manoharan ◽  
Aman Haque
Keyword(s):  
Normal Load ◽  
Static Friction ◽  
Force Sensor ◽  
Silicon Substrates ◽  
Ambient Conditions ◽  
Friction Forces ◽  
Oxide Nanowires ◽  
Applied Normal Load ◽  
Adhesion Friction ◽  
Adhesive Forces

The dominance of adhesive forces at the nanoscale implies that significant friction forces can be generated at the interface even with no externally applied normal load. We have nanofabricated an adhesion-friction force sensor to characterize friction in zinc oxide nanowires on silicon substrates. Experimental results show static friction coefficients for zero externally applied normal load can be as high as 45. This behavior is observed to be strongly influenced by the ambient conditions and we propose that the presence of molecularly thin moisture layers is responsible for the observed pseudo-static friction. The findings of this study will provide valuable input to nanoscale interfacial systems such as nanowires and nanotube based sensors and nanocomposites.

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