Metallic transfer between sliding metals: an autoradiographic study

1951 ◽  
Vol 208 (1095) ◽  
pp. 455-475 ◽  
Keyword(s):  
Coefficient Of Friction ◽  
Photographic Plate ◽  
Frictional Resistance ◽  
Autoradiographic Study ◽  
Lubricant Film ◽  
Small Range ◽  
Main Function ◽  
Boundary Lubricant ◽  
The Coefficient Of Friction ◽  
Higher Temperature

This paper describes a study of the friction and metallic transfer between sliding metal surfaces in the absence and in the presence of boundary lubricant films. One surface is made radioactive and is slid over the surface of a second, non-radioactive metal, the amount of metal transferred being detected by the blackening of a photographic plate placed in contact with the second surface. The results show that, in general, the metallic transfer or ‘pick-u p ’, consists of a relatively small number of discrete particles. For unlubricated surfaces the pick-up is about 40 times larger for similar than for dissimilar metals, although the coefficient of friction covers a relatively small range (μ ≈ 0.4 to μ ≈ 1). With well-lubricated surfaces the friction is reduced by a factor of not more than 20 (μ ≈0.05), whilst the ‘pick-u p ’ may be diminished by a factor of 20,000 or more. A simple analysis suggests that under these conditions the welded metallic junctions formed through the lubricant film play a very small part in determining the frictional resistance to motion. Consequently two lubricants possessing widely differing abilities to protect the surfaces may give essentially the same coefficient of friction. The lowest friction and ‘pick-up ’ are observed when the lubricant film is solid. As the temperature is raised a marked increase in friction and ‘pick -u p ’ occurs a t a temperature close to the melting-point of the film. A new observation is that at a somewhat higher temperature a further deterioration in lubricating properties occurs; although the surfaces are visibly covered with lubricant, the frictional behaviour and the metallic transfer are similar to those observed with unlubricated surfaces. These changes are reversible on cooling, and it is suggested that they correspond to changes in state of the lubricant film. The results provide direct support for the view that the friction between metals is due largely to the formation and shearing of metallic junctions, and that the main function of a boundary lubricant is to reduce the amount of metallic interaction. The investigation also shows that the metallic transfer is immensely more sensitive to changes in surface conditions than is the coefficient of friction.

Theoretical and experimental investigation of non-asbestos friction lining material applied in automotive drum brake

2019 ◽  
Vol 234 (6) ◽  
pp. 972-985
Author(s):  
Dinesh Subhash Shinde ◽  
KN Mistry ◽  
Mukesh Bulsara
Keyword(s):  
Coefficient Of Friction ◽  
Test Procedure ◽  
Frictional Resistance ◽  
Theoretical Models ◽  
Surface Phenomenon ◽  
Vehicle Speed ◽  
Lining Material ◽  
The Coefficient Of Friction ◽  
Brake Lining ◽  
Friction Lining

Automotive brakes are the important machine element which provides an artificial frictional resistance to control the speed of an automobile. In the present work, theoretical models for the coefficient of friction between brake drum and friction liner are generated and simulated using MATLAB Simulink. A test set up designed and manufactured according to the brake lining quality test procedure (SAE J661) is used to investigate tribological properties of a non-asbestos friction lining material having 11 different constituents, which is manufactured from one of the brake liner manufacturer. An experiment is designed using response surface methodology (RSM) with vehicle speed, braking force, and sliding distance as the input parameters, whereas coefficient of friction and wear as an output. It is found that vehicle speed is the most significant parameter among the three. Fade and recovery behavior of the friction lining material is also studied and it is found that the developed friction lining material satisfies the criteria specified in SAE J661. Scanning electron microscope (SEM) and energy dispersive spectoscopy (EDS) have revealed the significant surface phenomenon.

Variation with load of the coefficient of friction and metallic transfer under conditions of boundary lubrication

1952 ◽  
Vol 212 (1111) ◽  
pp. 516-519 ◽  
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
General Pattern ◽  
Copper Plate ◽  
Experimental Conditions ◽  
Average Hardness ◽  
Boundary Lubricant ◽  
The Coefficient Of Friction ◽  
Fixed Load ◽  
Molecular Layers

Several papers have been published recently which show for a number of metals that, under certain experimental conditions, several molecular layers of boundary lubricant are necessary to give effective lubrication, i.e. a coefficient of friction of 0.1 or less. Recent experiments by the authors suggest that these results represent parts of a more general pattern. In the previous work, the experiments were carried out at a fixed load; in the present, the load has been varied. The apparatus used was a copy of that described by Bowden & Leben (1939) for studying friction at low speeds of sliding. A hemispherical copper slider of radius 0-45 cm was caused to slide upon a flat copper plate at a speed of approximately 1 cm/min. Several specimens were used; their average hardness was 100 v .p .h .

XXIII.—On the Cohesion of Steel, and on the Relation between the Yield Points in Tension and in Compression.

1908 ◽  
Vol 28 ◽  
pp. 374-381 ◽  
Author(s):  
G. H. Gulliver
Keyword(s):  
Mild Steel ◽  
Yield Point ◽  
Coefficient Of Friction ◽  
External Load ◽  
Frictional Resistance ◽  
Experimental Results ◽  
Cohesive Force ◽  
Metallic Particles ◽  
Resistance To Deformation ◽  
The Coefficient Of Friction

SUMMARY(a) On the assumptions that resistance to deformation is due to simple friction, and that the coefficient of friction is independent of the load, the ratio of the yield point in tension to the yield point in compression, for what is ordinarily known as mild steel, is calculated as 2·384 to 3·384, or as 0·705 to 1. Experimental results so far obtained do not agree well with these figures, the value for the tensile yield point being relatively high, and that for compression relatively low.(b) On the further assumption that a cohesive force acting between the metallic particles gives rise to a frictional resistance which may be added (algebraically) to that due to the effect of the external load, the value of this cohesive force is deduced as equal to 3·384 times the stress which corresponds with the tension yield point, or to 2·384 times that corresponding with the compression yield point. Experimental results from a large number of tests agree very fairly with the calculated figures for the case of tension.

Part III. Boundary and extreme pressure lubrication - Mechanism of boundary lubrication

1952 ◽  
Vol 212 (1111) ◽  
pp. 498-505 ◽  
Keyword(s):  
Frictional Resistance ◽  
Surface Damage ◽  
Lubricant Film ◽  
Effect Of Temperature ◽  
Solid Boundary ◽  
Chemical Attack ◽  
Boundary Lubricant ◽  
Boundary Film ◽  
The Difference ◽  
Boundary Films

This paper shows how the theory of metallic friction, discussed in earlier papers, is modified in the presence of boundary films. Over the regions of contact the load is mainly supported by the boundary film, but some metallic interaction occurs through it with the formation of minute metallic junctions. These junctions contribute to the frictional resistance and play a major part in the wear of lubricated surfaces. The effect of temperature shows that the most effective lubrication is provided by a solid boundary film which possesses a close-packed strongly oriented structure. When the film melts, a marked increase in friction and metallic interaction occurs. For this reason fatty acids are generally more effective than hydrocarbons or alcohols, since they can react with the surface to form metallic soaps of relatively high melting-points. This chemical attack generally occurs via the metal oxide film which is present on the surface. The soap formation and the difference between a physically adsorbed and a chemically formed layer have been investigated by radioactive methods. A recent study has been made of the metal transference from one surface to the other as sliding takes place, using radioactive metals. The results again show that at the melting-point of the lubricant film a marked increase in pick-up and friction occurs. A new observation is that at still higher temperatures a second deterioration in lubricating properties occurs, corresponding to the desorption of the lubricant film. Although the surface is flooded with a lubricant the friction and surface damage are comparable with that observed with unlubricated surfaces. These effects are reversible on cooling and correspond to changes in state of the lubricant film. Similar changes are observed in electron diffraction studies of the structure and orientation of boundary films. The paper concludes with a discussion, based on these results, of the properties which a good boundary lubricant should possess.

scholarly journals Investigate the Drag Resistance of Antifouling Self-Adhesive Film

2020 ◽  
Vol 77 (2) ◽  
pp. 13-22
Author(s):  
Khor Wei-Hann ◽  
Siow Chee Loon ◽  
Adi Maimun Abdul Malik ◽  
Arifah Ali ◽  
Mohammad Nabil Jainal ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Resistance ◽  
Percentage Increase ◽  
Ansys Fluent ◽  
Adhesive Film ◽  
Ship Model ◽  
Ship Resistance ◽  
Lack Of Information ◽  
The Coefficient Of Friction ◽  
Rotor Apparatus

Fouling has always been a common issue for ships as fouling drastically increases the surface roughness and ship resistance. The microfiber self-adhesive antifouling film is claimed to be effective up to 5 years and is environmentally friendly. However, there is lack of information about the drag characteristics of the antifouling material. Thus, this project is conducted based on an experimental study to determine the drag characteristics of the surface installed with microfiber self-adhesive antifouling film. The rotor apparatus is used to study the coefficient of friction of the microfiber surface. From the experimental results, a flat plate simulation using ANSYS-Fluent is conducted to further estimate the coefficient of friction up to Reynolds number of 109 and to evaluate the total ship resistance for the Semi-SWATH (fast vessel) and KVLCC (slow trading ships). The results show that the percentage increase in total ship resistance for the KVLCC is about 80%, which is more than the Semi-SWATH of 30%, as frictional resistance has high significance for slow trading ships. The speed drop experienced by the ship model installed with the microfiber antifouling is 2 knots for the KVLCC and 1 knot for the Semi-SWATH if the power remained the same for both models.

scholarly journals An Experimental Study of the Frictional Properties of Steel Sheets Using the Drawbead Simulator Test

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4037 ◽  
Author(s):  
Trzepiecinski ◽  
Kubit ◽  
Slota ◽  
Fejkiel
Keyword(s):  
Coefficient Of Friction ◽  
Extreme Values ◽  
Rolling Direction ◽  
Frictional Resistance ◽  
Friction Reduction ◽  
Experimental Investigations ◽  
Sheet Rolling ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
Lubrication Conditions

This article presents the results of an experimental investigation of the frictional resistance arising in a drawbead during sheet metal forming. The frictional characterization of DC04 deep drawing quality steels commonly used in the automotive industry is carried out using a friction simulator. The effects of some parameters of the friction process on the value of the coefficient of friction have been considered in the experimental investigations. The friction tests have been conducted on different strip specimens, lubrication conditions, heights of drawbead and specimen orientations in relation to the sheet rolling direction. The results of drawbead simulator tests demonstrate the relationship that the value of the coefficient of friction of the test sheets without lubrication is higher than in the case of lubricated sheets. The lubricant reduces the coefficient of friction, but the effectiveness of its reduction depends on the drawbead height and lubrication conditions. Moreover, the effectiveness of the reduction of the coefficient of friction by the lubricant depends on the specimen orientation according to the sheet rolling direction. In the drawbead test, the specimens oriented along the rolling direction demonstrate a higher value of coefficient of friction when compared to the samples cut transverse to the rolling direction. The smaller the width of the specimen, the lower the coefficient of friction observed. The difference in the coefficient of friction for the extreme values of the widths of the specimens was about 0.03–0.05. The use of machine oil reduced the coefficient of friction by 0.02–0.03 over the whole range of drawbead heights. Heavy duty lubricant even reduced the frictional resistances by over 50% compared to dry friction conditions. The effectiveness of friction reduction by machine oil does not exceed 30%.

scholarly journals A Comparison of the Frictional Characteristics of Five Initial Alignment Wires and Stainless Steel Brackets at Three Bracket to Wire Angulations—an in Vitro Study

1994 ◽  
Vol 21 (1) ◽  
pp. 15-22 ◽  
Author(s):  
J. A. S. Dickson ◽  
S. P. Jones ◽  
E. H. Davies
Keyword(s):  
Stainless Steel ◽  
Coefficient Of Friction ◽  
In Vitro Study ◽  
Frictional Resistance ◽  
Vitro Study ◽  
Coated Steel ◽  
Fibre Optic ◽  
Initial Alignment ◽  
The Coefficient Of Friction

The study investigated static planar frictional resistance between five initial alignment wires and stainless steel brackets at three brackets to wire angulations (0, 5 and 10 degrees). It was demonstrated that static frictional resistance increased significantly with increasing bracket to wire angulation due to binding within the system. Epoxy-coated steel had the highest static frictional resistance and coaxial stainless steel the lowest. Fibre-optic glass (Optiflex®) had low frictional resistance. The coefficient of friction followed the trends of static frictional resistance in all respects.

The Efficiency of Involute Spur Gears

1981 ◽  
Vol 103 (1) ◽  
pp. 160-169 ◽  
Author(s):  
K. F. Martin
Keyword(s):  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Experimental Tests ◽  
Rolling Friction ◽  
Gear Train ◽  
Small Range ◽  
Load Effect ◽  
Coefficient Of Sliding Friction ◽  
The Coefficient Of Friction ◽  
Basic Characteristics

Approximate equations produced by Trachman |15| are used to predict the coefficient of sliding friction between the gear teeth. These equations apply when the lubrication regime is elastohydrodynamic; this is true during many gear contacts. The equations, which require only certain basic characteristics of the lubricant and the gears, are relatively simple and produce values for the coefficient of friction which are acceptable. The use of this coefficient of friction, together with a calculation for the rolling friction force allows the calculation of instantaneous and overall efficiency of the gear train. Contact ratios greater than one are accounted for and the load is assumed to be shared equally between the pairs of teeth. The computed values show that the load torque has a significant effect on both coefficient of friction and efficiency; as the load increases the coefficient of friction increases and the efficiency decreases. The effect of speed does not, over the small range of computations made, have as much significance as load, although it appears that efficiency will probably increase as the speed increases. Comparison of these predicted results with the few experimental tests which are relevant indicates some support, especially for the load effect.

Sliding Friction Analysis of Phosphatidylcholine as a Boundary Lubricant for Articular Cartilage

1993 ◽  
Vol 207 (1) ◽  
pp. 59-66 ◽  
Author(s):  
P F Williams ◽  
G L Powell ◽  
M LaBerge
Keyword(s):  
Articular Cartilage ◽  
Coefficient Of Friction ◽  
Relative Velocity ◽  
Sliding Friction ◽  
Weight Bearing ◽  
Contact Geometry ◽  
Synovial Joint ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Boundary Lubricant ◽  
The Coefficient Of Friction

Dipalmitoyl phosphatidylcholine (DPPC), the major lipidic component of the synovial fluid (45 per cent), has been implicated in previous studies in synovial joint lubrication as a potential boundary lubricant for articular cartilage. The purpose of this study was to evaluate the effectiveness of DPPC as a boundary lubricant at physiological stresses experienced by weight-bearing joints (up to 7.5 MPa). The sliding coefficients of static and kinetic friction for glass surfaces coated with DPPC layers of physiological thickness (70 nm) were measured as a function of average contact stress, contact geometry (point and line), applied load and relative velocity (from 25 to 0 mm/s) and compared to the coefficient of friction for clean glass in the same conditions. The coefficient of friction for DPPC-lubricated surfaces was dependent on contact geometry, obeyed Amonton's law (not dependent on axial load or contact area), was dependent on relative velocity within the range stated and was an effective lubricant at physiological stresses. This study showed that dipalmitoyl phosphatidylcholine can be an effective boundary lubricant at stresses observed in load-bearing joints. Because of their surface-active nature, these adsorbed molecules might also act as a protective layer for the articular surfaces.

Sign in / Sign up

Export Citation Format

Share Document