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Article
Publication date: 5 May 2021

Fei Li, Yulin Yang, Laizhou Song and Lifen Liang

The purpose of this paper is to elucidate the tribology behavior of polytetrafluoroethylene (PTFE) incorporated with three types of nickel–phosphorus (Ni-P) particles…

Abstract

Purpose

The purpose of this paper is to elucidate the tribology behavior of polytetrafluoroethylene (PTFE) incorporated with three types of nickel–phosphorus (Ni-P) particles (i.e. low phosphorus [LP], medium phosphorus [MP] and high phosphorus [HP]) under dry sliding condition.

Design/methodology/approach

Ni-HP, Ni-MP and Ni-LP particles fabricated via an electroless plating process were incorporated into PTFE matrix with different additions to prepare Ni-P/PTFE composites (Ni-LP/PTFE, Ni-MP/PTFE and Ni-HP/PTFE). The tribology tests for these samples were carried out on a reciprocating ball-on-disc tribometer. The thermal stabilities, mechanical and tribological properties, morphologies and components of aforesaid Ni-P/PTFE composites were analyzed.

Findings

The marvelous effect of Ni-P incorporation on the simultaneous reduction in friction and wear of PTFE was corroborated.

Originality/value

Compared with that of pristine PTFE sample, the reduction on friction with a value of 27% and the reduction in wear about 94% for Ni-HP/PTFE composite is validated, which is probably related to the increased crystallinity and hardness due to the presence of Ni-P particles.

Details

Industrial Lubrication and Tribology, vol. 73 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 14 August 2009

Xue‐Bin Yang, Xin‐Qiao Jin, Zhi‐Min Du, Tian‐Sheng Cui and Shao‐Kan Yang

The purpose of this paper is to investigate the frictional behavior of polytetrafluoroethylene (PTFE) composites under oil‐free sliding conditions.

Abstract

Purpose

The purpose of this paper is to investigate the frictional behavior of polytetrafluoroethylene (PTFE) composites under oil‐free sliding conditions.

Design/methodology/approach

The friction force and power consumption of pressure packing seals, which were, respectively, made of common filled PTFE, 30 wt% CF (carbon fiber) + PTFE and C/C (carbon/carbon) + PTFE, are studied in a reciprocating oil‐free compressor arrangement. Their coefficient of friction is tested on a block‐on‐ring type tribometer.

Findings

The results indicate that influence of mean sliding velocity on filled PTFE composites is apparently more predominant than the others. The friction force curvilinear path of 30 wt% CF+PTFE is hardly influenced by changing crankshaft turn angle. For C/C+PTFE, the effect of mean piston velocity on friction force is not evident. The results also indicate that the friction coefficient of C/C+PTFE is lower than that of 30 wt% CF+PTFE if their applied normal force exceeds 9.8 N. Furthermore, their variation curve of friction force is little different and the power consumption of C/C+PTFE is slightly higher than that of 30 wt% CF+PTFE.

Research limitations/implications

Neither the effect of real contact area on friction coefficient measured in a tribometer nor the influence of the temperature on friction force and power tested in a compressor is not taken into consideration here.

Practical implications

Owing to its good mechanical performances and frictional behaviors, C/C+PTFE is an optimum and promising material under conditions with sealing pressure up to 10 MPa and sliding velocity exceeding 4.0 m/s.

Originality/value

A novel material called C/C+PTFE is considered to make packing rings for oil‐free reciprocating compressors and its friction behaviour is tested on a refitted compressor.

Details

Industrial Lubrication and Tribology, vol. 61 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 3 May 2011

Stanisław Krawiec

The purpose of this paper is to find a reason of a very high lubrication effectivity of a lithium grease filled with PTFE and copper powders when used as a lubricant…

Abstract

Purpose

The purpose of this paper is to find a reason of a very high lubrication effectivity of a lithium grease filled with PTFE and copper powders when used as a lubricant between contacting steel surfaces under mixed friction conditions.

Design/methodology/approach

The paper presents the results of the differential thermal analysis (DTA) of a lithium grease lubricant filled with 6 wt% PTFE and 6 wt% Cu and of a 1:1 mass mixture of PTFE and copper powders alone. The chemical composition analysis of post‐DTA residual substances was carried out using the x‐ray microanalysis. The same method was employed for the examination of the chemical composition of the post‐test friction area in the balls of a four‐ball apparatus. The balls were lubricated with three greases: without any fillers (the base 1S lithium grease), with one filler (6 wt% Cu), and with two fillers (6 wt% PTFE and 6 wt% Cu). For the latter compound, the load was 500 daN, for the remaining compositions, the load was 126 daN.

Findings

The results of the analyses done confirmed a thesis that the synergism of PTFE and Cu in the tested grease under mixed friction conditions is possible due to the thermal decomposition of PTFE and creation – as a result of a reaction of this decomposition products with an earlier formed platering layer – of new layers that are (to a high probability) complexes containing copper, fluorine, and sulphur.

Practical implications

PTFE and copper powders when used as fillers for a lithium grease form a very effective lubrication compound for steel sliding pairs. The application of this compound results in an overall reduction of friction and wear that is greater than a simple summation of gains obtained when using these two additives separately.

Originality/value

It was proved that a dominant factor contributing to the synergistic effect of PTFE and copper in a lithium grease when used for the lubrication of steel surfaces is the fluorine that originate from the thermal disintegration of PTFE and not sulphur from the base grease.

Details

Industrial Lubrication and Tribology, vol. 63 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 29 September 2021

TCSM Gupta, Ajay Kumar and Babu Prasad

The purpose of this paper is to formulate heavy-duty lithium complex grease using low molecular weight poly tetra fluoro ethylene (PTFE) micro-particles as extreme…

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Abstract

Purpose

The purpose of this paper is to formulate heavy-duty lithium complex grease using low molecular weight poly tetra fluoro ethylene (PTFE) micro-particles as extreme pressure (EP) additive manufactured by E-beam scissoring and ultra-high speed grinding process of pre-sintered PTFE scrap.

Design/methodology/approach

Lithium complex grease is formulated with PTFE micro-particles, and optimum treat rate was studied by standard bench tests by ASTM D 2266 and IP-239 for tribological properties and compared with commercially available Molybdenum Di sulphide (Moly)-based lithium complex grease. The performance of the grease was further evaluated by a cyclic load test at varying speeds and loads to simulate the operational field conditions.

Findings

The lithium complex PTFE grease was manufactured using PTFE micro-particles as EP additive. The PTFE micro-particles dispersed in the lithium complex grease significantly improve the anti-wear performance and load bearing properties. Further, when the product was tested under a cyclic load conditions on standard tribological bench test against commercially available Moly lithium complex grease, shows stable anti-wear properties and reduced coefficient of friction.

Originality/value

The low molecular weight PTFE micro-particles, manufactured in the in-house electron beam (E-beam) and ultra-high speed micronizer facility from a pre-sintered PTFE scrap has been used as EP additive for grease applications for the first time. The results on the cyclic load tests indicate significant performance improvement in retaining the anti-wear and friction properties. Thus, value addition is done in formulating superior performance grease and evaluating under cyclic load conditions similar to field operating conditions and also in creating value added additives by converting the pre-sintered PTFE scarp which is environmental hazard due to poor biodegradability, creating a cyclic economy and a sustainable concept.

Details

Industrial Lubrication and Tribology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 6 August 2020

Wei Feng, Lei Yin, Yanfeng Han, Jiaxu Wang, Ke Xiao and Junyang Li

This paper aims to explore the possibility of converting the nitrile butadiene rubber (NBR) water-lubricated bearing material into a self-lubricating bearing material by…

Abstract

Purpose

This paper aims to explore the possibility of converting the nitrile butadiene rubber (NBR) water-lubricated bearing material into a self-lubricating bearing material by the action of polytetrafluoroethylene (PTFE) particles and water lubrication.

Design/methodology/approach

A group of experimental studies was carried out on a ring-on-block friction test. The physical properties, tribological properties and interface structure of PTFE-NBR self-lubricating composites filled with different percentages of PTFE particles were investigated.

Findings

The experimental results indicated that the reduction in friction and wear is a result of the formation of the lubricating film on the surface of the composites. The lubricating film was formed of a large amount of PTFE particles continuously supplied under water lubrication conditions and the PTFE particles here can greatly enhance the load capacity and lubrication performance.

Originality/value

In this study, the tribological properties of PTFE particles added to the NBR water-lubricated bearing materials under water lubrication were investigated experimentally, and the research was carried out by a ring-on-block friction test. It is believed that this study can provide some guidance for the application of PTFE-NBR self-lubricating.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0187/

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 9 March 2015

Shibo Wang, Bo Cao and Bing Teng

The purpose of this paper is to investigate the effect of hexagonal boron nitride (h-BN) and poly (phenyl p-hydroxybenzoate) (PHBA) on improving the torsional tribological…

Abstract

Purpose

The purpose of this paper is to investigate the effect of hexagonal boron nitride (h-BN) and poly (phenyl p-hydroxybenzoate) (PHBA) on improving the torsional tribological behavior of polytetrafluoroethylene (PTFE).

Design/methodology/approach

This paper investigates the torsional tribological behavior of PTFE composites filled with h-BN and PHBA under different angular displacements with a plane-on-plane torsional friction tester. The worn surface of PTFE composites was investigated by using a scanning electron microscope.

Findings

The shape of T–Θ curves of PTFE composites was influenced by both content fillers and torsional angule. The material with a higher coefficient of sliding friction exhibited the larger torsional angle under which the torsional regime transited from a partial slip to a gross slip. PTFE composites filled with 20 weight per cent PHBA and 10 weight per cent h-BN showed the best anti-wear properties. The specific wear rate of composites exhibits a negative correlation with material hardness. The wear volume loss presents a positive correlation with friction dissipation energy. The specific wear rate of all composites decreased with increasing torsional angle. The dominant wear mechanism of pure PTFE was adhesive wear. The slight plastic flow and plowing occurred on the worn surfaces of PTFE composites because of the higher hardness of composites and the lubrication of h-BN particles with layer crystal structure.

Originality/value

This paper put forward a kind of PTFE composite with low torsional wear rate, which can be used in the sliding slewing bearing or the center plate of a bogie.

Details

Industrial Lubrication and Tribology, vol. 67 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 8 February 2016

Shun Wang, Qingchang Tan and Zunquan Kou

The purpose of this paper was to construct lubrication model closer to the fact of thrust bearings and to calculate the bearings characteristics of lubrication for…

Abstract

Purpose

The purpose of this paper was to construct lubrication model closer to the fact of thrust bearings and to calculate the bearings characteristics of lubrication for understanding how structures influence bearings performances and, importantly, what can be the most beneficial. Large-scale composite thrust bearings with Polytetrafluoroethylene (PTFE)-faced sector pad backed by steel base are used increasingly in equipment. But there are plenty of puzzled problems in design and application.

Design/methodology/approach

The authors established a 3D thermal elastohydrodynamic lubrication (TEHL) model. Oil film was formulated by Reynolds equation for pressure, and by energy equation for temperature varying through oil film thickness. Meanwhile, pad temperature was formulated by solid heat transfer equation. Elastic and thermal deformations of pad surface were calculated. Viscosity and density of oil were valued separately under different pressure and temperature. Load balance was considered as well as overturning moment balance. Finite difference method was applied to discrete these equations.

Findings

PTFE layer and steel base have either helpful or detrimental impact on contact strength and full film lubrication of thrust bearing depending on their relationship in thickness. Temperature lag between middle layer of steel base and pad surface depends on PTFE layer, but not on the steel base. PTFE layer thickness should be considered when alarming threshold value of the bearings temperature is chosen.

Originality/value

Three-dimensional TEHL model of large-scale composite thrust bearings was established, which included more factors close to the actual. Conclusions were drawn. These proposals are helpful to design the bearings.

Details

Industrial Lubrication and Tribology, vol. 68 no. 1
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 10 July 2017

Joao Luiz do Vale, Carlos Henrique da Silva and Carlos M.G. da Silva Cruz

The purpose of this article is to discuss the tribological behavior of polytetrafluoroethylene (PTFE) and property changes imposed by wear tests.

Abstract

Purpose

The purpose of this article is to discuss the tribological behavior of polytetrafluoroethylene (PTFE) and property changes imposed by wear tests.

Design/methodology/approach

Long-duration dry wear tests were carried out in a sliding bearing on shaft tribometer. Differential Scanning Calorimetry (DSC) and Fourier Transformed Infrared Spectroscopy (FTIR) analyses were performed in the PTFE in its original condition and after the tests.

Findings

The wear products merged in multilayer films and were expelled out of the test sequence. Through DSC and FTIR analyses in the polymeric material, before and after tests, it was possible to verify an increase of the crystallinity degree of PTFE, as well as absence of crystalline fusion of the material. The wear products presented changes in the infrared spectra, which suggests the occurrence of some bonds of hydrogen and oxygen.

Originality/value

It was verified on correlation that fibril mechanism, which occurred during PTFE wear, and its crystallinity degree increase. Also, analysis of PTFE wear products showed CO and CH bonds, which were imposed by wear test.

Details

Industrial Lubrication and Tribology, vol. 69 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 2 March 2012

Chen Jiguo

The purpose of this paper is to study, analyze and present the lubricating mechanism and tribological properties of two types of oil‐based titanium complex grease…

Abstract

Purpose

The purpose of this paper is to study, analyze and present the lubricating mechanism and tribological properties of two types of oil‐based titanium complex grease containing Polytetrafluoroethylene (PTFE).

Design/methodology/approach

Two types of oil‐based sebacic acid/stearic acid titanium complex greases containing PTFE additive were synthesized using 3 L reaction vessel, and the base oils including neopentyl polyol ester and mixed oil of 650SN and neopentyl polyol (1:1.8). Friction‐reduction, antiwear, and load‐carrying properties of greases were evaluated using a four‐ball tester, and their dropping point and penetration were characterized using relevant ASTM standards. Morphologies of wear scar and chemical states of typical elements on worn surfaces were characterized by means of scanning electron microscope and X‐ray photoelectron spectroscopy, respectively.

Findings

Tribological results show that titanium complex grease containing PTFE had better friction‐reduction and antiwear properties than base grease. However, PTFE could not improve the load‐carrying capacity of base grease. Moreover, a synergistic effect between deposited film and adsorptive film contributes to good tribological properties of titanium complex grease.

Practical implications

Such a very useful lubricating material could be used in industrial applications including steel plants, power plants, packaging, and fertilizer industries.

Originality/value

The lubricating mechanism of titanium complex grease containing PTFE was proposed by tribochemical analysis of worn surfaces. The mechanism should become the direction of the theoretical and applied research of grease in the future.

Details

Industrial Lubrication and Tribology, vol. 64 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 February 2001

Yanchun Han, Stefan Schmitt and Klaus Friedrich

The lateral force mode of atomic force microscopy (AFM) was applied to conduct friction tests on a filled PTFE/PPS‐composite blend. This method distinguishes between the…

Abstract

The lateral force mode of atomic force microscopy (AFM) was applied to conduct friction tests on a filled PTFE/PPS‐composite blend. This method distinguishes between the individual phases of the blend, i.e. carbon fibers, PPS‐particles, PTFE‐matrix and graphite flakes. The relative frictional behaviours of the different filler types were compared and the law of microfriction was discussed.

Details

Industrial Lubrication and Tribology, vol. 53 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

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