The study of friction layer and tribological property of PI–matrix composites

2017 ◽  
Vol 69 (2) ◽  
pp. 267-275 ◽  
Author(s):  
Xiulin Xu ◽  
Xing Lu ◽  
Zuoxiang Qin ◽  
Dalong Yang
Keyword(s):  
Friction Coefficient ◽  
Tribological Property ◽  
Wear Debris ◽  
Friction Pair ◽  
Matrix Composites ◽  
Low Friction ◽  
Friction Layer ◽  
Content Type ◽  
Compact Zone ◽  
Pin On Disk

Purpose This paper aims to study the friction layer and tribological property of polyimide (PI)–matrix composites under different friction speeds. Design/methodology/approach Friction tests were conducted under friction speeds ranging from 20-120 km/h and pressure of 0.57 MPa by a pin-on-disk tribometer. Findings The results indicate that the friction coefficient decreases with the increasing of the friction speed. Under different friction speeds, the structure of the friction layer and debris are different, which affects the actual tribological performance of the composites. At low friction speed, the morphology of the friction layer is mainly particulate. The higher level of clenching action between the friction pair leads to a high friction coefficient, and the morphology of the particles in the particulate zone and the wear debris are mostly equiaxial particles. At high friction speed, the morphology of the friction layer is mainly a compact zone. The reduction of the surface roughness leads to a low friction coefficient. The debris collected on the counter surface at high friction speeds are mostly big sheets, and the morphology of the particles in the particulate zone is mostly rod-like. Controlling the conditions of the disk and the pin can reveal the influence of friction speed on the friction layer. The wear mechanisms at different friction speeds are also discussed. Originality/value By controlling the conditions of the disk and the pin to reveal the influence of friction speed on the friction layer, and the evolutions of the friction layer, wear debris were carefully inspected with the aim of demonstrating the relationship between friction speed and wear mechanism of PI–matrix composites.

Experimental study on the relationship between the friction coefficient and interference in locomotive axle press-fitting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ting Wang ◽  
Hanfei Guo ◽  
Jianjun Qiao ◽  
Xiaoxue Liu ◽  
Zhixin Fan
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Friction Pair ◽  
Rolling Stock ◽  
Content Type ◽  
Press Fitting ◽  
The Press ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Locomotive Wheels

PurposeTo address the lack of data in this field and determine the relationship between the coefficient of friction and the interference between locomotive wheels and axles, this study evaluates the theoretical relationship between the coefficient of friction and the interference under elastic deformation.Design/methodology/approachWhen using numerical analyses to study the mechanical state of the contacting components of the wheels and axle, the interference between the axle parts and the coefficient of friction between the axle parts are two important influencing factors. Currently, as the range of the coefficient of friction between the wheel and axle in interference remains unknown, it is generally considered that the coefficient of friction is only related to the materials of the friction pair; the relationship between the interference and the coefficient of friction is often neglected.FindingsA total of 520 press-fitting experiments were conducted for 130 sets of wheels and axles of the HXD2 locomotive with 4 types of interferences, in order to obtain the relationship between the coefficient of friction between the locomotive wheel and axle and the amount of interference. These results are expected to serve as a reference for selecting the coefficient of friction when designing axle structures with the rolling stock, research on the press-fitting process and evaluations of the fatigue life.Originality/valueThe study provides a basis for the selection of friction coefficient and interference amount in the design of locomotive wheels and axles.

Experimental investigation on Stribeck curves of different elastic modulus materials under oil and water lubrication conditions

2020 ◽  
Vol 72 (6) ◽  
pp. 805-810
Author(s):  
Hua Zhang ◽  
Guangwu Zhou ◽  
Ping Zhong ◽  
Kepeng Wu ◽  
Xingwu Ding
Keyword(s):  
Elastic Modulus ◽  
Friction Coefficient ◽  
Friction Pair ◽  
Water Lubrication ◽  
Contact Friction ◽  
Friction Coefficients ◽  
Content Type ◽  
Low Viscosity ◽  
Stribeck Curves ◽  
Lubrication Conditions

Purpose The purpose of this paper is to study the influence of friction coefficient of materials with different elastic modulus on the variation of velocity and load under water lubrication and oil lubrication conditions. Design/methodology/approach Low-viscosity lubricating oil and water were used as lubricants to test the friction performance of the ball-disc contact friction pair in the lubrication state on the universal micro-tribometer multi-functional friction and wear test system. Findings In the same speed range, the lubrication states from soft to rigid materials are not necessarily similar to each other. Generally, the material with low elastic modulus is suitable in low-viscosity lubricant environments, while the material with high elastic modulus has relatively smaller friction coefficients in oil-lubricated environments compared with water lubrication. However, the coefficients of polyethylene, polytetrafluoroethylen and polyoxymethylene are exceeded by rubber’s coefficients under water lubrication in the same experiment environments, and their lubrication states are not affected by lubricants. The friction coefficient of the friction pair decreases with the increase of loads; however, it does not apply to all materials. The friction coefficients of materials with smaller elastic modulus such as rubber under high loads are rather large. Therefore, the elastic modulus of the material under high loads is a factor to be considered. Originality/value The Stribeck curves study of the ball-disk contact friction pair comprising soft and rigid materials, whose elastic modulus is from hundreds of GPa to a few of MPa, was carried out. The influence of different speeds, loads and lubricants on the friction coefficient of the friction pair was revealed, which provided a research basis for the selection and matching of friction pair materials.

Tribological behaviour of graphene oxide sheets as lubricating additives in bio-oil

2018 ◽  
Vol 70 (8) ◽  
pp. 1396-1401 ◽  
Author(s):  
Daoyi Wu ◽  
Yufu Xu ◽  
Lulu Yao ◽  
Tao You ◽  
Xianguo Hu
Keyword(s):  
Graphene Oxide ◽  
Friction Coefficient ◽  
Wear Loss ◽  
Tribological Behaviour ◽  
Low Friction ◽  
Content Type ◽  
Base Oil ◽  
Lubricating Film ◽  
Bio Oil ◽  
Practical Implications

Purpose This paper aims to study the upgradation of the lubricating performance of the renewable base oil , and to study the tribological behavior of graphene oxide (GO) sheets used as lubricating additives in bio-oil for iron/steel contact. Design/methodology/approach A multifunctional end-face tribometer was used to characterize the friction coefficient and wear loss of the tribosystem under different lubricants. Findings The experimental results show that GO sheets with small size benefit lubricating effects and the optimal concentration of GO sheets in bio-oil is 0.4-0.6 per cent, which can form a complete lubricating film on the frictional interfaces and obtain a low friction coefficient and wear loss. Higher concentration of GO sheets can result in a significant aggregation of the sheets, reducing the content of the lubricating components in the bio-oil, which results in the increase in friction and wear; at this stage, the main wear pattern was ascribed to adhesive wear. Practical implications These results show a promising prospect of improving the tribological performance of renewable base oil with the introduction of GO sheets as additives. Originality/value No literature has covered the tribological behaviour of GO sheets in bio-oil. This study contributes to accelerating the application of bio-oil.

Investigations on tribological behaviour of AA7075-TiO2 composites under dry sliding conditions

2019 ◽  
Vol 71 (9) ◽  
pp. 1064-1071 ◽  
Author(s):  
Alagarsamy S.V. ◽  
Ravichandran M.
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Applied Load ◽  
Weight Ratio ◽  
Specific Wear Rate ◽  
Dry Sliding ◽  
Matrix Composites ◽  
Content Type

Purpose Aluminium and its alloys are the most preferred material in aerospace and automotive industries because of their high strength-to-weight ratio. However, these alloys are found to be low wear resistance. Hence, the incorporation of ceramic particles with the aluminium alloy may be enhanced the mechanical and tribological properties. The purpose of this study is to optimize the specific wear rate and friction coefficient of titanium dioxide (TiO2) reinforced AA7075 matrix composites. The four wear control factors are considered, i.e. reinforcement (Wt.%), applied load (N), sliding velocity (m/s) and sliding distance (m). Design/methodology/approach The composites were fabricated through stir casting route with varying weight percentages (0, 5, 10 and 15 Wt.%) of TiO2 particulates. The mechanical properties of the composites were studied. The specific wear rate and friction coefficient of the newly prepared composites was determined by using a pin-on-disc apparatus under dry sliding conditions. Experiments were planned as per Taguchi’s L16 orthogonal design. Signal-to-noise ratio analysis was used to find the optimal combination of parameters. Findings The mechanical properties such as yield strength, tensile strength and hardness of the composites significantly improved with the addition of TiO2 particles. The analysis of variance result shows that the applied load and reinforcement Wt.% are the most influencing parameters on specific wear rate and friction coefficient during dry sliding conditions. The scanning electron microscope morphology of the worn surface shows that TiO2 particles protect the matrix from more removal of material at all conditions. Originality/value This paper provides a solution for optimal parameters on specific wear rate and friction coefficient of aluminium matrix composites (AMCs) using Taguchi methodology. The obtained results are useful in improving the wear resistance of the AA7075-TiO2 composites.

Experimental study on the effect of load and rotation speed on dry sliding of silicon nitride

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zhishuang Wang ◽  
Songhua Li ◽  
Jian Sun ◽  
Junhai Wang ◽  
Yonghua Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Silicon Nitride ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Wear Mechanism ◽  
Rotation Speed ◽  
Friction Pair ◽  
Test Method ◽  
Dry Sliding ◽  
Content Type

Purpose The purpose of this study is to investigate the effects of load and rotation speed on dry sliding of silicon nitride, including a series of tribological behaviors (friction coefficient, wear rate, temperature rise, etc.) and wear mechanism. Through the analysis of the above characteristics, the influence law of load and speed on them and the internal relationship between them are determined, and then the best comprehensive performance parameters of silicon nitride full-ceramic spherical plain bearings in dry sliding are predicted, which can provide guidance for the operation condition of silicon nitride full-ceramic spherical plain bearings in dry sliding. Design/methodology/approach The experimental study of different loads and rotation speeds under dry friction conditions was carried out by the using ball-disk sliding test method. Findings With the increase of load, the friction coefficient of silicon nitride friction pair and the wear rate of silicon nitride ball decrease continuously. With the increase of rotation speed, the friction coefficient of silicon nitride friction pair first increases and then decreases, and the wear of silicon nitride ball first increases and then decreases. With the increase of load and rotation speed, the wear mechanism eventually changes to adhesive wear. Originality/value Because of the low timeliness and inefficiency of bearing experiments, this work adopts a simple ball-disk model to comprehensively explore the influence rules of different conditions, which provides a theoretical basis for the subsequent practical application of silicon nitride full-ceramic spherical plain bearings.

The Difficulty of Measuring Low Friction: Uncertainty Analysis for Friction Coefficient Measurements

2005 ◽  
Vol 127 (3) ◽  
pp. 673-678 ◽  
Author(s):  
Tony L. Schmitz, ◽  
Jason E. Action, ◽  
John C. Ziegert, and ◽  
W. Gregory Sawyer
Keyword(s):  
Friction Coefficient ◽  
Uncertainty Analysis ◽  
Cell Voltage ◽  
Load Cell ◽  
International Standards ◽  
Voltage Measurement ◽  
Low Friction ◽  
Laboratory Procedure ◽  
Friction Measurements ◽  
Pin On Disk

The experimental evaluation of friction coefficient is a common laboratory procedure; however, the corresponding measurement uncertainty is not widely discussed. This manuscript examines the experimental uncertainty associated with friction measurements by following the guidelines prescribed in international standards. The uncertainty contributors identified in this analysis include load cell calibration, load cell voltage measurement, and instrument geometry. A series of 20 tests, carried out under nominally identical conditions, was performed using a reciprocating pin-on-disk tribometer. A comparison between the experimental standard deviation and uncertainty analysis results is provided.

Fractal Prediction Model of Friction Coefficient in Dry Friction Pair

2011 ◽  
Vol 301-303 ◽  
pp. 315-320
Author(s):  
Jun Jie Zhou ◽  
Shi Hua Yuan ◽  
Chao Wei
Keyword(s):  
Friction Coefficient ◽  
Friction Pair ◽  
Surface Profile ◽  
Real Contact Area ◽  
Size Change ◽  
Contact Loads ◽  
Fractal Parameters ◽  
Dimension Change ◽  
Model Of Friction ◽  
Pin On Disk

To research the friction coefficient of rough surface under different contact loads. A mathematical model is proposed between the fractal parameters D and G and the non-dimensional real contact area based on M-B fractal contact model, surface profile curves are scanned by APE500 surface morphology, dimension change index k and size change index s are identified in tests, the model is verified on UMT-3 pin-on-disk wear apparatus. Results showed that the modeling method relying on limiting cases is feasible, this model could improve prediction accuracy of friction coefficient, and the experimental results are consistent with the theoretical prediction.

The problems of resistance to scuffing of heavily loaded lubricated friction joints with WC/C-coated parts

2014 ◽  
Vol 66 (3) ◽  
pp. 434-442 ◽  
Author(s):  
Remigiusz Michalczewski ◽  
Witold Piekoszewski ◽  
Waldemar Tuszynski ◽  
Marian Szczerek
Keyword(s):  
Design Methodology ◽  
Solid Lubricant ◽  
Vapour Deposition ◽  
Friction Pair ◽  
Low Friction ◽  
Friction Zone ◽  
Content Type ◽  
Steel Coating ◽  
Uncoated Steel ◽  
Practical Implications

Purpose – The purpose of this paper was to explore the mechanisms of scuffing propagation of heavily loaded lubricated friction pair elements coated with low-friction WC/C coating for various material combinations. Design/methodology/approach – The investigations were performed for low-friction coatings WC/C (a-C:H:W) deposited by the reactive sputtering physical vapour deposition (PVD) process. Experiments were carried out using a four-ball tester with continuously increasing loads. Tests were conducted for the following four material combinations: steel/steel tribosystem (all balls uncoated); steel/coating tribosystem (one upper ball uncoated/three lower balls WC/C-coated); coating/steel tribosystem (one upper ball WC/C-coated/three lower balls uncoated); and coating/coating tribosystem (all balls WC/C-coated). Findings – The better scuffing resistance is achieved by coating only one element (coating/steel tribosystem) than all elements (coating/coating tribosystem). The description of scuffing propagation for all investigated tribosystems was done. The high scuffing resistance of the coating/steel tribosystem resulted from reducing the adhesion between rubbing surfaces due to low chemical affinity (similarities) between the steel and the coating material and the presence of solid lubricant in the friction zone. Practical implications – In all cases, when a coating is applied, an increase in scuffing resistance is observed. However, it is better to coat only one element than all. Furthermore, the scuffing resistance for the coating/steel tribosystem is significantly higher than for the steel/coating tribosystem. Originality/value – The main value of this paper is description of scuffing propagation and revealing the new aspects in application of low-friction WC/C coating for heavily loaded lubricated friction pair elements. The overlapping ratio has been defined as an important factor influencing the scuffing resistance of the coated tribosystems.

Boundary Lubricated Friction Experiments With Coarse Surface Texture

2005 ◽  
Author(s):  
Jorn Larsen-Basse ◽  
Lewis Ives ◽  
Stephen M. Hsu
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Contact Area ◽  
Surface Texture ◽  
304 Stainless Steel ◽  
Low Friction ◽  
Partial Removal ◽  
Coarse Texture ◽  
Coarse Surface ◽  
Pin On Disk

Low-speed friction experiments were conducted under boundary lubrication in a pin-on-disk tester. The 304 stainless steel disk had smooth areas alternating with areas of coarse surface texture consisting of indents or macroscopic grooves, 0.3–0.4 mm in size and in area fractions varying between 25 and 70%. The 3.2 mm flat pin was also SS304. The coarse texture has detrimental effects. For each pattern the friction coefficient is greater than for the smooth areas. It becomes independent of load as boundary conditions set in. In comparing various patterns it is noted that this friction coefficient increases with pressure or with the amount of area removed to form the texture. It is suggested that partial removal of surface area to form the texture reduces the number of trapped liquid patches, which otherwise can provide low-friction load support. The coarse texture may also conduct lubricant away from the contact area.

Microstructure and tribological property of self-lubrication CBN abrasive composites containing molybdenum disulfide

2019 ◽  
Vol 71 (5) ◽  
pp. 712-717 ◽  
Author(s):  
Biao Zhao ◽  
Wenfeng Ding ◽  
Weijie Kuang ◽  
Yucan Fu
Keyword(s):  
Friction Coefficient ◽  
Flexural Strength ◽  
Molybdenum Disulfide ◽  
Tribological Property ◽  
Cubic Boron Nitride ◽  
Three Dimensional ◽  
Optical Microscope ◽  
Transgranular Fracture ◽  
Vacuum Sintering ◽  
Content Type

Purpose This paper aims to evaluate the influence of molybdenum disulfide (MoS2) concentrations (5, 7.5, 10, 12.5 and 15 Wt.%) on the microstructure and tribological property of the self-lubrication cubic boron nitride (CBN) abrasive composites. Design/methodology/approach Three point bending method and rotating sliding test are used to evaluate the flexural strength and tribological property of self-lubricating CBN abrasive composites. Microstructure, wear morphology of the ball and scratch are supported by scanning electron microscopy, optical microscope and three-dimensional confocal microscopy, etc. Findings The MoS2 concentration has a significant influence on the interface microstructure between CBN abrasives and matrix alloys, and thus, affects the flexural strength of CBN abrasive composites. The grain fracture modes of CBN abrasive composites are transformed from the transgranular fracture into intergranular fracture as the MoS2 concentrations increase. Additionally, the friction coefficient of as-sintered samples decreases with the MoS2 concentrations. The MoS2 concentrations of 10 Wt.% are final determined to fabricate self-lubricating composites in basis of the mechanical and lubricating property. Originality/value The ball is fabricated under vacuum sintering process. The tribological property of self-lubricating CBN abrasive composites is evaluated in terms of the friction coefficient and morphologies of the ball and scratches after rotating sliding tests.

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