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Article
Publication date: 12 March 2018

Hui Zhang, Guangneng Dong and Guozhong Dong

The main purpose of this paper is to present the effort on developing a mixed elastohydrodynamic lubrication (EHL) model to study the tribological effect of asperities on rough…

303

Abstract

Purpose

The main purpose of this paper is to present the effort on developing a mixed elastohydrodynamic lubrication (EHL) model to study the tribological effect of asperities on rough surface.

Design/methodology/approach

The model, with the use of the average flow Reynolds equation and the K-E elasto-plastic contact model, allows predictions of hydrodynamic pressure and contact pressure on the virtual rough surface, respectively. Then, the substrate elastic deformation is calculated by discrete convolution fast-Fourier transform (DC-FFT) method to modify the film thickness recursively. Afterwards, corresponding ball-on-disk tests are conducted and the validity of the model demonstrated. Moreover, the effects of asperity features, such as roughness, curvature radius and asperity pattern factor, on the tribological properties of EHL, are also discussed though plotting corresponding Stribeck curves and film thickness shapes.

Findings

It is demonstrated that the current model predicts very close data compared with corresponding experimental results. And it has the advantage of high accuracy comparing with other typical models. Furthermore, smaller roughness, bigger asperity radius and transverse rough surface pattern are found to have lower friction coefficients in mixed EHL models.

Originality/value

This paper contributes toward developing a mixed EHL model to investigate the effect of surface roughness, which may be helpful to better understand partial EHL.

Details

Industrial Lubrication and Tribology, vol. 70 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 29 October 2019

Yuquan Ni, Guangneng Dong, Qi Liu, Wei Wang and Yihong Li

Babbitt bush is easy to cause severe adhesive wear due to unexpected journal fall. This paper aims to improve wear resistance of Babbitt bush.

162

Abstract

Purpose

Babbitt bush is easy to cause severe adhesive wear due to unexpected journal fall. This paper aims to improve wear resistance of Babbitt bush.

Design/methodology/approach

A soft/hard hybrid surface mircoprofile of Babbitt alloy/steel was fabricated by a technology of laser texture combined with hot-pressing. The friction and wear performances of bare steel (steel-h), Babbitt bush on steel (steel-s) and Babbitt filled in dimples of steel (steel-hs) were conducted on a ball-on-disc tester under dry and lubricated conditions.

Findings

The results showed that wettability of steel-hs was enhanced by forming soft/hard hybrid surface. Compared with steel-s, the stability of friction coefficient curve of steel-hs was improved without increasing coefficient friction. The wear resistance of steel-hs was remarkably enhanced under dry and lubricated conditions.

Originality/value

The originality of this paper is as following: to improve the tribological properties and to prolong service life of steel-s, soft/hard hybrid surface of Babbitt filled in dimples of steel substrate was successfully fabricated by laser texturing combined with hot-pressing. This paper showed that the lipophilicity of steel-hs was best among those of steel-s and steel-h. Babbitt alloy as a soft filler on dimples of steel substrate improved anti-wear of steel-s remarkably. It provides a new way to fabricate Babbitt as bushing on steel substrate.

Details

Industrial Lubrication and Tribology, vol. 72 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 5 April 2022

Yuquan Ni, Nannan Sun, Guixiang Zhu, Shujie Liu, Jun Liu and Guangneng Dong

This paper aims to study different morphology Cu6Sn5 effect on Babbitt alloy tribological properties.

192

Abstract

Purpose

This paper aims to study different morphology Cu6Sn5 effect on Babbitt alloy tribological properties.

Design/methodology/approach

Different morphology Cu6Sn5 of Babbitt was conducted by different cooling modes. Bare Babbitt was marked by Babbitt-0, Babbitt modified by first cooling mode (marked by Babbitt-1) and Babbitt modified by second cooling mode (marked by Babbitt-2). The microstructure and microhardness of specimens were tested. Then, tribological properties of Babbitt-0, Babbitt-1 and Babbitt-2 were performed by reciprocating mode under lubricated condition.

Findings

The results showed that shape Cu6Sn5 of Babbitt was changed from mixed needle and star-like shape to short rod-like or granular shape. The microhardness of Babbitt-1 was highest than that of Babbitt-0 and Babbitt-2. Compared with Babbitt-0 and Babbitt-2, tribological properties of Babbitt-1 were better under lubricated condition due to short rod-like and sparse distribution of Cu6Sn5. Moreover, the simulation result of strain and stress of Babbitt-1 was lowest than that of Babbitt-0 and Babbitt-2.

Originality/value

Different morphology (shape and distributed) of Cu6Sn5 was obtained by different cooling modes. Modulated different forms of Cu6Sn5 around SnSb was beneficial to improve Babbitt alloy tribological properties.

Details

Industrial Lubrication and Tribology, vol. 74 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 26 July 2021

Penghao Qi, Shijian Wang, Jing Li, Yue Li and Guangneng Dong

The purpose of this study is to reduce the use of Zinc dialkyl dithiophosphates (ZDDP) and improve the frictional properties and thermal oxidation stability of Perfluoropolyether…

213

Abstract

Purpose

The purpose of this study is to reduce the use of Zinc dialkyl dithiophosphates (ZDDP) and improve the frictional properties and thermal oxidation stability of Perfluoropolyether (PFPE) grease by adding antioxidant additives. The addition of antioxidants can reduce the consumption of ZDDP as an antioxidant, thus improving the anti-wear efficiency of ZDDP and reducing the excess phosphorus element in the grease.

Design/methodology/approach

In this study, an antioxidant with good comprehensive performance was selected from several antioxidants by tribological tests and high-temperature tests. Then, the effect of its combination additive with ZDDP on PFPE grease was investigated. The anti-wear property, anti-friction property, thermal oxidation stability and extreme pressure property of greases containing different proportions of ZDDP and antioxidant were tested by four-ball tester and synchronous thermal analyzer (STA). The effects of additives on properties of grease were analyzed by SEM, EDS, LSCM, XPS and FT-IR.

Findings

The research shows that 2,6-Di-tert-butyl-4-methylphenol (BHT) can be used as an antioxidant in combined additives to reduce the antioxidant reactions of ZDDP, thus improving the anti-wear efficiency of ZDDP and further enhancing the anti-wear performance of the grease. Moreover, BHT and ZDDP have a synergistic effect on the high temperature performance of the PFPE grease due to their different antioxidant mechanisms.

Social implications

In this paper, the problems related to PFPE grease are studied, which has a certain guiding effect on the industrial application of fluorine grease and the related formulation design.

Originality/value

In this paper, the properties of PFPE grease under different lubricating condition were studied. The synergistic lubrication effect of antioxidant and ZDDP are discussed. It provides experimental and theoretical support for reducing the content of ZDDP and improving the performance of additives.

Details

Industrial Lubrication and Tribology, vol. 73 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 15 October 2021

Liguo Qin, Hao Yang, Yuquan Ni and Guangneng Dong

This study aims to improve the tribological performance of Babbitt alloy under oil lubricant condition. Thus, the surface was treated into oleophobic state by modifying with low…

205

Abstract

Purpose

This study aims to improve the tribological performance of Babbitt alloy under oil lubricant condition. Thus, the surface was treated into oleophobic state by modifying with low surface energy fluorosilane (1H,1H,2H,2H-perfluorodecyltriethoxysilane). It is believed that the oleophobic surface offered excellent wear resistance of Babbitt-based tribo-pairs.

Design/methodology/approach

By modifying the Babbitt alloy with low surface energy fluorosilane and measuring the oil contact angle, the wetting behavior was evaluated. Using Pin on Disk tribometer, the tribological properties of bare Babbitt and modified Babbitt were quantified. The samples after the friction test were characterized by scanning electron microscope (SEM) and the anti-wear performance was evaluated under dry and oil lubrication conditions.

Findings

Results showed that oil contact angle of modified Babbitt was109° which was tripled compared to that of prime surface, which indicates the oleophobic behavior was greatly improved. Under dry conditions, the friction coefficient of the modified surface with different load conditions is slightly lower than that of the bare surface, while the friction coefficient of the modified surface under lubrication conditions is significantly decreased compared to that of the bare surface. Interestingly, under low load and high load, the wear rate of the modified Babbitt alloy surface is only 1/4 and 1/3 of that of the bare surface, respectively.

Originality/value

The work proposed an effective method to improve the Babbitt tribological performances and will lighten future ideas for the Babbitt alloy bearing with high wear resistance, which is beneficial to improve the service life of sliding bearings and has huge promotion and application value in the manufacture of sliding bearings.

Details

Industrial Lubrication and Tribology, vol. 74 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 9 April 2018

Wei Yuan, Guangneng Dong, Kwai Sang Chin, Meng Hua and Qianjian Guo

Streak defect and dynamic harmonic excitation (DHE) loading play important roles in machine operating conditions. The purpose of this paper was to assess the effects of streak…

103

Abstract

Purpose

Streak defect and dynamic harmonic excitation (DHE) loading play important roles in machine operating conditions. The purpose of this paper was to assess the effects of streak defect and DHE loading on the tribological properties of surface-contact friction pairs, for example the differential gear end-face on the washer, via experimental investigation.

Design/methodology/approach

Streak defect was artificially introduced into the washer surface, which was loaded with DHE loads produced by a spring-connecting weight system. The wear scar of the washers and the monitored friction force signals were respectively scanned using scanning electron microscope (SEM) and analyzed using wavelet simulation.

Findings

The friction force curves, SEM images and discrete wavelet transform results indicate that DHE loading tends to increase friction force, to accelerate plowing damages and result in side-flow of material and plastic deformation on the surfaces of the washer. Whereas, streak oil-channel textures on washer specimen can be machined to modify the lubrication condition in the running-in stage so as to improve the tribological properties of the sliding pairs which were even subjected to DHE loading.

Originality/value

On the basis of this thesis research, the effect of streak defect and DHE loading on tribological performance of surface-contact sliding pairs is discussed. The results of wear form and friction state with the effect of streak defect and DHE loading facilitate to optimize the operating condition of mechanical parts.

Details

Industrial Lubrication and Tribology, vol. 70 no. 3
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 8 June 2015

Hui Zhang, Guangneng Dong, Meng Hua, Feifei Guo and Kwai Sang Chin

– The main purpose of this paper is to understand and model the hydrodynamic influence of surface textures on journal bearings.

856

Abstract

Purpose

The main purpose of this paper is to understand and model the hydrodynamic influence of surface textures on journal bearings.

Design/methodology/approach

In the model, a rectangular array of circle dimples is used to modify the film thickness expression. In full film and cavitation regions, classical Reynolds equation and Reynolds boundary condition are used as the governing equations, respectively. By setting high load bearing capacity as the main optimal goal, the influence of textures on tribological characteristics is studied to get the optimal distribution and parameters of textures.

Findings

The results suggest that the load bearing capacity of a journal bearing may be improved through appropriate arrangement of textures partially covering its sleeve. The reduction of the cavitation area may also be achieved by arranging the textures in divergent region. With a high density distribution of textures which have step depths varying linearly along the circumferential direction of the bearing, the load bearing capacity enhancement seems to give good performance. Comparing with smooth bearing, the load bearing capacity enhancement of such textures is about 56.1 per cent, although the influence of texture diameters for the same area density seems insignificant.

Originality/value

The paper shows how surface textures can be designed on journal bearing to improve its tribological performances.

Details

Industrial Lubrication and Tribology, vol. 67 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 14 September 2015

Wei Yuan, K. S. Chin, Guangneng Dong and Meng Hua

This paper aims to optimize the operating condition of mechanical parts, whose working surfaces have macro-crack defects, and surface wear properties with macro-cracks are…

484

Abstract

Purpose

This paper aims to optimize the operating condition of mechanical parts, whose working surfaces have macro-crack defects, and surface wear properties with macro-cracks are assessed through experimental investigation.

Design/methodology/approach

Macro-cracks perpendicular to the direction of sliding were manufactured on discs by electric discharge machining. Tribological tests under oil lubrication were conducted on a ball-on-disc test rig. Their wear processes were monitored with on-line visual ferrography. The cross-sectional profile and morphology of the wear track were analyzed using a T200 profilometer and a scanning electron microscope, respectively. Effects of different crack numbers and various applied normal loads on the wear behavior were studied.

Findings

The macro-cracks tend to promote plastic deformation on the contact disc surfaces, and material plastic deformation of the crack edges varies with the magnitude of applied normal loads. Relationship of the duration of running-in period and root mean square index of the particle coverage area with the numbers of crack is approximately linear.

Originality/value

The wear properties of surfaces with macro-cracks were assessed with various crack numbers and with different applied normal loads, and the relationship between the index of particle coverage area and the wear rate was established.

Details

Industrial Lubrication and Tribology, vol. 67 no. 6
Type: Research Article
ISSN: 0036-8792

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