A Formation Mechanism and Tribological Properties of PTFE Transfer Film

2021 ◽  
Author(s):  
Hai Wang ◽  
Xiaowen Qi ◽  
Yu Dong ◽  
Bingli Fan ◽  
Changxin Liu ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Tribological Properties ◽  
Dry Friction ◽  
Evaluation Method ◽  
Transfer Film ◽  
Intermolecular Force ◽  
Test Load ◽  
General Evaluation

Abstract Polytetrafluoroethylene (PTFE), as one of the most widely used solid lubricating materials, is thought to be very efficient at forming transfer film because of terrific low intermolecular force. This work investigates the tribological properties of PTFE transfer film under dry friction, and further explores its formation process and evolution mechanism. The friction coefficient is the lowest when the transfer film thickness is in range of 8-12 μm. An evaluation method for transfer film is proposed. The results show that the quality of the transfer film is closely related to the test load and velocity. This method is expected to be a general evaluation method for polymer transfer film, which can further directly evaluate the wear state of polymers, and even directly predict the tribological properties of polymers and abrasion life.

Friction and Wear Behaviors of Solid Lubricants/Polyimide Composites in Liquid Mediums

2010 ◽  
Vol 654-656 ◽  
pp. 2763-2766 ◽  
Author(s):  
Li Wen Mu ◽  
Xin Feng ◽  
Yi Jun Shi ◽  
Huai Yuan Wang ◽  
Xiao Hua Lu
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Alkaline Solution ◽  
Dry Friction ◽  
Friction And Wear ◽  
Solid Lubricants ◽  
Polyimide Composites ◽  
Inorganic Fillers ◽  
Ptfe Composites

The tribological properties of polyimide (PI) composites reinforced with graphite or MoS2 sliding in liquid alkali and water as well as dry friction were investigated using a ring-on-ring tester. The results show that the friction coefficient (μ) and wear rate (W) for both graphite/PI and MoS2/PI composites in different liquid mediums are μdry>μwater >μalkali and Wwater>Wdry >Walkali. Results also indicate that the friction coefficient and wear rate of the PI composites filled with different solid lubricants are μMoS2 >μgraphite and W MoS2 >Wgraphite in different liquid mediums. In addition, the hydrophobic inorganic fillers are fit for the reinforcement of polymer-based composites sliding in liquid mediums. It is also concluded from the authors’ work that the wear rate and friction coefficient of polymer-based (such as PI, PTFE) composites in the alkali lubricated conditions is lowest among all the friction conditions. This may be attributed to the ionic hydration in the alkaline solution.

Tribological properties of the epoxy resin-based solid lubricant coating modified by Kevlar fibers

2018 ◽  
Vol 70 (9) ◽  
pp. 1706-1713 ◽  
Author(s):  
Guotao Zhang ◽  
Yanguo Yin ◽  
Ting Xie ◽  
Dan Li ◽  
Ming Xu ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Epoxy Resin ◽  
Tribological Properties ◽  
Dry Friction ◽  
Friction And Wear ◽  
Solid Lubricant ◽  
Transfer Film ◽  
Wear Properties ◽  
Content Type ◽  
Friction And Wear Properties

Purpose This paper aims to obtain high mechanical and good tribological properties of epoxy resin-based coatings under dry friction conditions. Design/methodology/approach Bonded solid lubricant coatings containing Kevlar fibres were prepared by a spraying method. The friction and wear properties of the coatings were experimentally investigated with a face-to-face tribometre under dry friction conditions. Scanning electron microscopy, energy dispersive X-ray spectroscopy and 3D laser scanning technologies were used to characterise the tribological properties. The action mechanism of the Kevlar fibres on a solid lubricant transfer film was also analysed. Findings Adding Kevlar fibres can significantly improve the wear resistance of the coatings. When the Kevlar fibre content increases, the tribological properties of the coatings improve and then worsen. Superior properties are obtained with 0.03 g of Kevlar fibres. Appropriately increasing the load or speed is beneficial to the removal of the outer epoxy resin and the formation of a lubricant film. During friction, the solid lubricants wrapped in the epoxy resin accumulate on the surface to form a transfer film that shows a good self-lubricating performance. In the later friction stage, fatigue cracks occur on the solid lubricant film but cannot connect to one another because of the high wear resistance and the entanglement of the rod-like Kevlar fibres. Thus, no large-area film falls from the matrix, thereby ensuring the long-term functioning of solid lubricant coatings. Originality/value Epoxy resin-based solid lubricant coatings modified by Kevlar fibres were prepared, and their friction and wear properties were investigated. Their tribological mechanisms were also proposed. This work provided a basis for the analysis of the tribological properties and design of bonded solid lubricant coatings containing Kevlar fibres.

scholarly journals Tribological Properties of Si3N4-hBN Composite Ceramics Bearing on GCr15 under Seawater Lubrication

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 635 ◽  
Author(s):  
Fang Han ◽  
Huaixing Wen ◽  
Jianjian Sun ◽  
Wei Wang ◽  
Yalong Fan ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Dry Friction ◽  
Pure Water ◽  
Water Environment ◽  
Surface Films ◽  
Seawater Lubrication ◽  
Pin On Disc ◽  
Worn Surface

This paper concerns a comparative study on the tribological properties of Si3N4-10 vol% hBN bearing on GCr15 steel under seawater lubrication and dry friction and fresh-water lubrication by using a pin-on-disc tribometer. The results showed that the lower friction coefficient (around 0.03) and wear rate (10−6 mm/Nm) of SN10/GCr15 tribopair were obtained under seawater condition. This might be caused by the comprehensive effects of hydrodynamics and boundary lubrication of surface films formed after the tribo-chemical reaction. Despite SN10/GCr15 tribopair having 0.07 friction coefficient in the pure-water environment, the wear mechanismsits were dominated by the adhesive wear and abrasive wear under the dry friction conditions, and delamination, plowing, and plastic deformation occured on the worn surface. The X-ray photoelectron spectroscopy analysis indicated that the products formed after tribo-chemaical reaction were Fe2O3, SiO2, and B2O3 and small amounts of salts from the seawater, and it was these deposits on the worn surface under seawater lubrication conditions that, served to lubricate and protect the wear surface.

scholarly journals Influence of Casting Conditions on Tribological Properties of A390.0 Alloy

2016 ◽  
Vol 16 (3) ◽  
pp. 95-98
Author(s):  
J. Piątkowski ◽  
R. Wieszała ◽  
A. Gontarczyk
Keyword(s):  
Cast Iron ◽  
Friction Coefficient ◽  
Tribological Properties ◽  
Dry Friction ◽  
Heat Removal ◽  
First Case ◽  
Cooling Speed ◽  
Grey Cast ◽  
Primary Crystals ◽  
Standard Tester

Abstract The paper presents tribological properties of A390.0 (AlSi17Cu5Mg) alloy coupled in abrasive action with EN-GJL-350 grey cast-iron. The silumin was prepared with the use of two different technologies which differed in terms of cooling speed. In the first case the alloy was modified with foundry alloy CuP10 and cast to a standard tester ATD and in case of second option the modified alloy was cast into steel casting die. Due to different speed of heat removal the silumins varied in structure, particularly with size of primary crystals of silicon and their distribution in matrix which had a significant influence of friction coefficient in conditions of dry friction.

The influence of laser surface texture on the tribological properties of friction layer materials in ultrasound motors

2021 ◽  
pp. 135065012110527
Author(s):  
Xijun Hua ◽  
Julius Caesar Puoza ◽  
Peiyun Zhang
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Tribological Properties ◽  
Dry Friction ◽  
Friction And Wear ◽  
Ultrasonic Motor ◽  
Area Ratio ◽  
Ultrasonic Motors ◽  
Increase Rate

Ultrasonic motors are typically driven by the dry friction force between the rotor and the stator; the friction pairs’ high friction coefficient and low wear rate are two essential elements for improving the operational stability with longer service life. In this research article, high-precision microgroove arrays were manufactured on the surfaces of the stator and rotor of the TRUSM60 ultrasonic motor using laser machining. Dry friction and wear tests between the stator and the rotor were carried out with pin-on-disc using HSR-2M high-speed reciprocating friction and wear tester to determine the tribological properties of the ultrasonic motor. According to a different distribution of microgrooves on the two contact surfaces, the influence of smooth surface, single-sided texture, and double-sided texture on the friction pair's friction performance were discussed. The results show that the textured surface can substantially increase the coefficient of friction of the contact surface and reduce the rate of wear. The one-sided textured phosphor bronze surface with a microgroove width of 200μm and an area ratio of 20% had the highest coefficient of friction of 0.334 and a friction increase rate of 36.3%. Similarly, the single-sided textured Polyimide surface attained the highest friction coefficient of 0.355 and friction increase rate of 44.9% when the groove width is 150μm and the area ratio is 30%. A higher friction coefficient of the double-sided texture can be obtained through reasonable parameter configuration than the single-sided texture. The included angle of 0° between the two textured surfaces produced the highest friction coefficient of 0.368 and the wear rate of the phosphor bronze and polyimide surfaces were 2.01 × 10−4 mm3/N-m and 1.949 × 10−3 mm3/N-m, respectively. The result provides an essential benchmark for enhancing the tribological performance of ultrasonic motors and increasing the output torque.

Effects of single- and multi-shape laser-textured surfaces on tribological properties under dry friction

2019 ◽  
Vol 234 (7) ◽  
pp. 1382-1392
Author(s):  
Xianghua Zhan ◽  
Peng Yi ◽  
Yancong Liu ◽  
Peifa Xiao ◽  
Xiaoye Zhu ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Tribological Properties ◽  
Dry Friction ◽  
Nanosecond Laser ◽  
Textured Surface ◽  
Textured Surfaces ◽  
Wear Properties ◽  
Friction Tester ◽  
Pin On Disc ◽  
40Cr Steel

Textural morphology is an important factor influencing dry friction, and few studies have been conducted regarding the effects of single- and multi-shape textures on dry tribological properties. In this work, six types of textures including single- and multi-shape textures were produced on 40Cr steel samples by using a nanosecond laser. Reciprocating sliding tests under dry friction were conducted using a pin-on-disc friction tester. The influences of textured surfaces with different textures on tribological properties were investigated. Results showed that tribological properties were affected by different textural morphologies. The dimple-textured surface had the highest friction coefficient, followed by the groove-textured surface. The sinusoidal-textured surface had the lowest friction coefficient. The friction coefficients of multi-shape textured surfaces were lower than those of non-textured surfaces but higher than those of sinusoidal-textured surfaces. The wear properties of the tested surfaces were consistent with the friction-coefficient results. The sinusoidal- and sinusoidal–groove-textured surfaces can be considered as the optimum choices for dry reciprocating friction.

Tribological Properties of PM Cu-Based Dry Friction Clutch

2013 ◽  
Vol 545 ◽  
pp. 163-170 ◽  
Author(s):  
Jirapat Prapai ◽  
Monnapas Morakotjinda ◽  
Thanyaporn Yotkaew ◽  
Bhanu Vetayanukul ◽  
Ruangdaj Tongsri ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Dry Friction ◽  
Sintered Density ◽  
Sintering Temperature ◽  
Chemical Compositions ◽  
Friction Clutch ◽  
Frictional Materials ◽  
Dry Friction Clutch

Sintered Cu-based frictional materials were developed by using powder metallurgy (PM) method. The materials are aimed for application in a passenger car as a dry friction clutch. Effects of sintering temperature and composition on mechanical and tribological properties were determined. It was found that improper frictional material formulations caused inferior properties, particularly when the sintering temperatures were increased. Admixing of high Sn content (8 wt. %) resulted in decreases of sintered density and hardness with increasing sintering temperature. High Sn contents caused swelling of the sintered materials. Tribological properties (friction coefficient and wear rate) of the sintered specimens of the investigated materials were insensitive to sintering temperatures in the range of 800-950 °C but they were strongly influenced by chemical compositions. Addition of 3 wt. % graphite lowered the friction coefficient, which subsequently lowered the wear rate of the sintered material. To increase friction coefficient, one of the crucial properties of the dry friction clutch, of the sintered Cu-based frictional materials, two approaches were employed. In the first approach, substitution of graphite by SiO2 powders could improve the material friction coefficient. In the second approach, decreases of graphite content from 3 to 1 wt. % and of Sn content from 8 to 2 wt. % were conducted. The latter approach not only improved friction coefficient but also improved sintered density and hardness of the Cu-based frictional materials.

Study on the tribological properties of titanium alloys sliding against WC-Co during the dry friction

2014 ◽  
Vol 66 (2) ◽  
pp. 202-208 ◽  
Author(s):  
Qiulin Niu ◽  
Xiaohu Zheng ◽  
Ming Chen ◽  
Weiwei Ming
Keyword(s):  
Titanium Alloy ◽  
Friction Coefficient ◽  
Tungsten Carbide ◽  
Titanium Alloys ◽  
Tribological Properties ◽  
Dry Friction ◽  
Sliding Friction ◽  
Friction Coefficients ◽  
Friction Forces ◽  
Content Type

Purpose – Titanium alloy has the excellent performance and been widely utilized in aeroengine and airframe manufacture. However, improving the understanding of all aspects of titanium alloy is necessary. The purpose of this paper is to investigate the tribological properties of two typical titanium alloys against tungsten carbide under dry friction. Design/methodology/approach – Reciprocating ball-disc friction tests were carried out at room temperature in different loading without lubricant to investigate the friction properties of TA19/WC-Co and TC18/WC-Co friction pairs. The influence of the load on the friction coefficient and friction force was analyzed. The worn surfaces of TA19 and TC18 specimens were observed by the digital microscopy and scanning electron microscopy (SEM). And the wear mechanism was discussed. Findings – The results show that the friction coefficients decreased with the increase in the normal load. However, the reduction in the friction coefficient for the TC18 alloy was less than that for the TA19 alloy. The dynamic friction forces with time were not quite coincident with the variation trend of the friction coefficients during the sliding friction. The results observed by the SEM and EDS revealed that several grooving were the main type of frictional wear causing the surfaces of the TA19 and TC18 alloys. Originality/value – It is shown in the paper that the tribological property of TA19 alloy was better than that of TC18 when sliding against tungsten carbide under the dry friction conditions. The main types of damage to the TA19/WC-Co friction pair were the ploughing, the delamination fatigue associate with abrasive wear and some diffusive wear. The ploughing and abrasion were the main wear mechanisms for the surface of TC18 alloy.

Environmental Impact Evaluation of Istanbul Wastewater Treatment and Marine Disposal Systems

1992 ◽  
Vol 25 (9) ◽  
pp. 85-92 ◽  
Author(s):  
I. Ozturk ◽  
T. Zambal ◽  
A. Samsunlu ◽  
E. Göknel
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Environmental Impact ◽  
Quality Parameters ◽  
Sea Of Marmara ◽  
General Evaluation ◽  
Marine Outfall ◽  
Secondary Stage ◽  
Pre Treatment

Metropolitan Istanbul Wastewater Treatment System contains 14 marine outfalls, seven of which include secondary stage biological treatment processes. The others have only mechanical treatment units including bar screens and grit chambers. Only one mechanical pre-treatment and marine disposal system, Yenikapi plant, has been operated since 1988 among these 14 plants and six of them are ready for construction. In this paper, the environmental impact of Yenikapi pretreatment and marine disposal system on the water quality of the Bosphorus and the Sea of Marmara has been investigated. Long term water quality measurements which were performed in pre-and post-dischange applications have been evaluated. Water quality parameters including pH, DO, BODs, TKN, P and total coliforms were measured at various sampling stations around the discharge points. A general evaluation of marine outfall systems to be constructed in the scope of Istanbul wastewater treatment project, on the water quality of the Sea of Marmara and the Bosphorus has been presented.

Influence of surface roughness, friction coefficient, and wrap angle on clinching joint strength and its correlation with belt friction phenomenon

2021 ◽  
pp. 135065012110253
Author(s):  
Santosh Kumar ◽  
Vimal Edachery ◽  
Swamybabu Velpula ◽  
Avinash Govindaraju ◽  
Sounak K. Choudhury ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Joint Strength ◽  
Joint Interface ◽  
Cross Sectional ◽  
Lap Shear ◽  
Mathematical Correlation ◽  
Mechanical Clinching ◽  
Wrap Angle

Clinching is an economical sheet joining technique that does not require any consumables. Besides, after its usage, the joints can be recycled without much difficulty, making clinching one of the most sustainable and eco-friendly manufacturing processes and a topic of high research potential. In this work, the influence of surface roughness on the load-bearing capacity (strength) of joints made by the mechanical clinching method in cross-tensile and lap-shear configuration is explored. Additionally, a correlating mathematical model is established between the joint strength and its surface parameters, namely, friction coefficient and wrap angle, based on the belt friction phenomenon. This correlation also explains the generally observed higher strength in lap-shear configuration compared to cross-tensile in clinching joints. From the mathematical correlation, through friction by increasing the average surface roughness, it is possible to increase the strength of the joint. The quality of the thus produced joint is analyzed by cross-sectional examination and comparison with simulation results. Experimentally, it is shown that an increment of >50% in the joint strength is achieved in lap-shear configuration by modifying the surface roughness and increasing the friction coefficient at the joint interface. Further, the same surface modification does not significantly affect the strength in cross-tensile configuration.

Sign in / Sign up

Export Citation Format

Share Document