On the Prediction of Running-In Behavior in Mixed-Lubrication Line Contact

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Saleh Akbarzadeh ◽  
M. M. Khonsari
Keyword(s):  
Wear Rate ◽  
Load Sharing ◽  
Mixed Lubrication ◽  
Surface Pattern ◽  
Stribeck Curve ◽  
Wear Volume ◽  
Line Contact ◽  
Arithmetic Average ◽  
Volume Wear ◽  
Surface Patterns

A model is presented, which enables one to predict the running-in performance of the rolling/sliding surfaces subjected to mixed-lubrication line contact. The load-sharing concept was used, in which it is assumed that both the fluid film and the asperities contribute in carrying the imposed load. The plastic deformation of asperities during the running-in is taken into consideration. In the application of the load-sharing method, it is often assumed that asperity heights have a Gaussian distribution. This assumption has been relaxed in this model. Prediction results for the variation in the arithmetic average of asperity heights (Ra) during the running-in period for contact of two rollers are compared with published experimental data. Also presented are the results for the variation in wear volume, wear rate, and friction coefficient during the running-in period. The effect of surface pattern, speed, and load on the running-in behavior is studied. The steady-state wear rate for different surface patterns calculated from this model is compared with the wear rate predicted by the thermal desorption model, and the results are in agreement both in trend and magnitude. The effect of running-in on the Stribeck curve for different surface pattern is discussed.

Friction Behavior for Micro-Scale Grooved Crosshatch Pattern under Lubricated Sliding Contact

2007 ◽  
Vol 345-346 ◽  
pp. 769-772 ◽  
Author(s):  
Young Hun Chae
Keyword(s):  
Friction Coefficient ◽  
Bearing Steel ◽  
Friction Reduction ◽  
Surface Pattern ◽  
Stribeck Curve ◽  
Friction Property ◽  
Friction Behavior ◽  
Groove Surface ◽  
Surface Patterns ◽  
Pin On Disk

Some surface patterns of tribological application are an attractive technology of engineered surface. Because of the friction reduction is considered to be necessary for improved efficiency of machine. This study was investigated for the effect of friction property for angles of micro-crosshatch groove surface pattern on bearing steel used pin-on-disk test. We obtain sample which can be fabricated by photolithography process. We discuss the friction property depended on an angle of crosshatch groove surface pattern. We can verify the lubrication mechanism as Stribeck curve which has a relationship between the friction coefficient and a dimensionless parameter under the lubrication condition. It was found that the friction coefficient was related to angle of crosshatch groove pattern on contact surface.

Wear Performance of GCr15 Friction Pairs with Effect of Initial Radial Micro-Grooves

2019 ◽  
Vol 11 (1) ◽  
pp. 56-61
Author(s):  
Wei Yuan ◽  
Shengkai Mei ◽  
Song Li ◽  
Zhiwen Wang ◽  
Jie Yu ◽  
...  
Keyword(s):  
Wear Rate ◽  
Abrasive Wear ◽  
Electrical Discharge Machining ◽  
Friction Pair ◽  
Wear Volume ◽  
Fatigue Wear ◽  
Wear Performance ◽  
Wear Process ◽  
Groove Test ◽  
On Line

Background: Grooves may inevitably occur on the surface of the friction pair caused by severe wear or residual stress, which will play an important role on the reliability of machine parts during operation. Objective: The effect of the micro-grooves perpendicular to sliding direction on the wear performance of the friction pairs should be studied. Method: Micro-grooves can be machined on discs of friction pairs using electrical discharge machining. On-line visual ferrograph method was used to monitor the wear process to research the wear rate changing characteristic. Profilemeter and metallurgical microscope were used to observe the wear scars. Results: Comparing to the non-groove test, i) in one-groove test, wear volume and rate were approximate the same, and the wear scar was smooth, ii) when the grooves more than 4, the test running-in stage will be obviously prolonged, particularly for the test with 8 grooves on the disc, the duration of running-in stage is 4 times than that without grooves on specimen, and the wear rate and volume increase significantly, and then decrease with fluctuation, iii) the abrasive wear can be avoid with the debris stagnating in the groove, however, fatigue wear will significantly emerge. Conclusion: Abrasive wear can be avoided and smooth running-in surfaces can be obtained with proper amount of initial radial micro-grooves.

Prediction of Wear Rate Dispersion in Mixed Lubrication

2005 ◽  
Author(s):  
F. Robbe-Valloire ◽  
R. Progri ◽  
B. Paffoni ◽  
R. Gras
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Boundary Lubrication ◽  
Mixed Lubrication ◽  
Tribological Behaviour ◽  
Low Friction ◽  
Local Boundary ◽  
Physico Chemical ◽  
Lubricant Films ◽  
Second Category

Mixed lubrication is usually related to the partition of contacts, and these latter may be divided into two categories. The first includes all asperities working in thin lubricated film (physico-chemical film) conditions. This situation corresponds to local boundary lubrication and is characterised by a local friction coefficient around 0.1. The second category contains all other asperity types. Due to the existence of a thick lubricant films asperities belonging to the second category exhibit a low friction coefficient. The global tribological behaviour for a given contact, however, is function of both categories, since it involves asperities from both categories.

Surface Replication and Structural Development in Micromolding for Micro/Nanocomposites

2007 ◽  
Author(s):  
H. Ito ◽  
K. Kazama ◽  
T. Kikutani
Keyword(s):  
Laser Scanning ◽  
Hexagonal Boron Nitride ◽  
Laser Scanning Microscopy ◽  
Surface Pattern ◽  
Confocal Laser ◽  
Order Structure ◽  
Structural Development ◽  
Molded Parts ◽  
Surface Patterns ◽  
Micro Features

Micromolding with micro-scale surface features of hexagonal boron nitride (h-BN) / polypropylene (PP) composites with different h-BN component was performed to improve molded parts’ heat diffusivity and processability. Effects of h-BN content and process parameters on processability, higher-order structure, and microscale surface patterns of molded parts were analyzed using SEM, WAXD, SPM, and confocal laser scanning microscopy. The replication ratio of the microscale surface pattern and flow length of composite molded parts was improved by compounding the h-BN filler. The replication ratio of the microscale surface pattern near the flow end became greater than 1.0 because of deformation of surface patterns during de-molding. The replication ratio and shape of surface patterns of molded parts were improved with the increase of the h-BN component. The h-BN platelet oriented inside surface micro-features; skin-shear-core structures were well observed in the molded parts.

scholarly journals Fretting wear rate of sulphur deficient MoSx coatings based on dissipated energy

2001 ◽  
Vol 16 (12) ◽  
pp. 3567-3574 ◽  
Author(s):  
Xiaoling Zhang ◽  
W. Lauwerens ◽  
L. Stals ◽  
Jiawen He ◽  
J-P. Celis
Keyword(s):  
Relative Humidity ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Contact Stress ◽  
Ambient Air ◽  
Fretting Wear ◽  
Dissipated Energy ◽  
Wear Volume ◽  
The Coefficient Of Friction ◽  
Crystallographic Orientations

The fretting wear of sulphur-deficient MoSx coatings with different crystallographic orientations has been investigated in ambient air of controlled relative humidity. The coefficient of friction and the wear rate of MoSx coatings sliding against corundum depend not only on fretting parameters like contact stress, fretting frequency, and relative humidity, but also strongly on the crystallographic orientation of the coatings. For randomly oriented MoSx coatings, the coefficient of friction and the wear rate increased significantly with increasing relative humidity. In contrast, basal-oriented MoSx coatings were less sensitive to relative humidity. The coefficient of friction of both types of MoSx coatings decreased on sliding against corundum with increasing contact stress and decreasing fretting frequency. A correlation between dissipated energy and wear volume is proposed. This approach allows detection in a simple way of differences in fretting wear resistance between random- and basal-oriented MoSx coatings tested in ambient air of different relative humidity.

Surface Patterning of Stainless Steel in Prevention of Fouling in Heat Transfer Equipment

2013 ◽  
Vol 762 ◽  
pp. 493-500 ◽  
Author(s):  
Tiina M. Pääkkönen ◽  
Ulla Ojaniemi ◽  
Markus Riihimäki ◽  
Esa Muurinen ◽  
Carey J. Simonson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Thermal Conditions ◽  
Surface Patterning ◽  
Surface Pattern ◽  
Stainless Steel Surface ◽  
Cfd Modelling ◽  
Carbonate Solutions ◽  
Wide Range ◽  
Surface Patterns

Fouling of surfaces is a major challenge in design and operation of many industrial heat transfer equipment. Fouling causes significant energy, material and production losses, which increase the environmental impact and decrease economic profitability of processes. Even small improvements in prevention of fouling would lead to significant savings in a wide range of heat transfer applications. In this study, crystallization fouling of aqueous calcium carbonate solutions on a heated stainless steel surface is used to investigate the prevention of fouling in heat transfer equipment by physical surface modifications. Fouling behaviour of different surface patterns are studied experimentally in a laboratory scale fouling test apparatus. CFD modelling is used to study hydrodynamic and thermal conditions near surfaces with different patterns. In addition, the effect of surface pattern on the removal of particles is studied numerically. Surface patterning is found to affect the hydrodynamic and thermal conditions near the wall, and therefore to change the conditions for fouling layer build-up and removal, when compared to a flat heat transfer surface. The most promising surface pattern includes curved shapes, and it seems to create flow conditions in which improved convective heat transfer decreases the driving force for crystallization fouling. In addition, curved surfaces increase the shear forces at the wall, which prevents adhesion of the foulants to the surface and increases resuspension.

Role of Si(100) Surface Patterns in the Phase Separation of Cu/Sn Thin Films

2001 ◽  
Vol 672 ◽  
Author(s):  
Qin Hu ◽  
Martin Zinke–Allmang ◽  
Ian V. Mitchell
Keyword(s):  
Thin Film ◽  
Thermal Decomposition ◽  
Phase Separation ◽  
Ex Situ ◽  
Surface Pattern ◽  
Length Scale ◽  
Thermal Decomposition Process ◽  
Surface Patterns ◽  
Initial Pattern

ABSTRACTWe report on the competitive phase separation of copper and tin thin film deposits on a pre–patterned Si(100) surface. The initial pattern on Si(100) was achieved through a thermal decomposition process of an ex–situ grown oxide film. Copper and tin phase separation on silicon is a competitive process with Cu forming preferrably silicide. Sn is observed to cover the silicide clusters when present in a sufficient amount. The pre–patterning of the surface introduces a new length scale in the problem. Our data suggest that this length scale plays a role while the clustering (ripening) length scale is of the same order, i.e., during nucleation and the early phase separation, but that both length scales become independent once the length scale of ripening significantly exceeds the length scale of the surface pattern.

TRIBOLOGICAL CHARACTERISTICS OF RADIAL JOURNAL BEARINGS BY ULTRASONIC NANOCRYSTAL SURFACE MODIFICATION TECHNOLOGY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3011-3016 ◽  
Author(s):  
YOUNG SHIK PYOUN ◽  
JEONG HYUN PARK ◽  
CHANG MIN SUH ◽  
INHO CHO ◽  
CHANG-SOON LEE ◽  
...  
Keyword(s):  
Surface Modification ◽  
Boundary Lubrication ◽  
Transition Period ◽  
Hydrodynamic Lubrication ◽  
Peak Torque ◽  
Bearing Steel ◽  
Journal Bearings ◽  
Mixed Lubrication ◽  
Stribeck Curve ◽  
Lubrication Condition

Ultrasonic nanocrystal surface modification (UNSM) has applied to a radial journal bearings made of bearing steel SUJ2. Mechanical characteristics are compared between UNSM treated and untreated bearings. Friction torque is measured at the boundary lubrication condition, the mixed lubrication condition, and the full hydrodynamic lubrication condition. The peak torque at the boundary lubrication condition and the transition period to mixed lubrication condition on the UNSM treated samples are reduced. These effects are very useful to improve the service life of journal bearings. The Stribeck curve at the mixed and full hydrodynamic lubrication is derived and compared. The friction coefficient at these two regimes is reduced by more than 50%, which will do effective role for improvement of energy efficiency. The major effects for this reduction at three lubrication regimes could be explained in the terms of micro dimple surface.

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