Degradation of perfluoropolyether lubricants on magnetic recording disks during sliding

1997 ◽  
Vol 211 (4) ◽  
pp. 279-288 ◽  
Author(s):  
Y Li ◽  
B Bhushan
Keyword(s):  
Coefficient Of Friction ◽  
Magnetic Recording ◽  
High Vacuum ◽  
Material Surface ◽  
Quadrupole Mass ◽  
Tribochemical Reaction ◽  
Gaseous Products ◽  
The Coefficient Of Friction ◽  
Fomblin Z ◽  
Sliding Distance

Degradation of perfluoropolyether lubricants (Fomblin Z-Dol and Fomblin AM 2001) on the magnetic recording thin-films disks are studied during sliding with an Al2O3-TiC slider under high vacuum. Gaseous products generated from the head/disk interfaces are detected and monitored as a function of sliding distance using a quadrupole mass spectrometer. Effects of overcoats and surface roughnesses of disks on degradation of lubricants and coefficient of friction were also studied. Experimental results show that the gaseous products generated from Z-Dol and AM 2001 lubricants during sliding are quite similar. Degradation of both lubricants is found to take place from the beginning of sliding, and the evolution rate of decomposition fragments decreases with the sliding distance. Removal of the lubricants is accompanied by a rapid rise in the coefficient of friction of the interfaces, followed by gaseous products from the tribochemical reaction of the overcoat material. Surface roughness of the disk has an effect on the sliding distance to failure, but little effect on the decomposition of lubricant.

The friction of clean crystal surfaces

1966 ◽  
Vol 295 (1442) ◽  
pp. 233-243 ◽  
Keyword(s):  
Coefficient Of Friction ◽  
High Surface ◽  
High Vacuum ◽  
Surface Films ◽  
Surface Adhesion ◽  
Crystal Surfaces ◽  
Deformation And Fracture ◽  
The Coefficient Of Friction ◽  
Molecular Layers ◽  
Frictional Behaviour

A study is made of the frictional behaviour of crystals (diamond, magnesium oxide, sapphire) sliding on themselves in high vacuum (10 -10 torr). The surface films normally present on these crystals are very tenacious but they may be worn away by repeated sliding in the same track. Under these conditions the friction of the clean crystals may increase by a factor of ten so that the coefficient of friction may rise to μ ≈ 1. The frictional rise is limited because of the elastic and brittle behaviour of the contact regions. Under these conditions subsurface deformation and fracture of the crystal occurs and this, combined with the high surface adhesion, causes pronounced wear. Adsorption of a few molecular layers of gas can again reduce the friction to a low value. The results are relevant to the operation of bearings and to the wear of surfaces in space.

scholarly journals Achieving Ultra-Low Friction with Diamond/Metal Systems in Extreme Environments

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3791
Author(s):  
Pantcho Stoyanov ◽  
Rolf Merz ◽  
Markus Stricker ◽  
Michael Kopnarski ◽  
Martin Dienwiebel
Keyword(s):  
Coefficient Of Friction ◽  
Wear Track ◽  
High Vacuum ◽  
Extreme Environments ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Low Friction ◽  
The Coefficient Of Friction ◽  
On Line ◽  
Low Wear

In the search for achieving ultra-low friction for applications in extreme environments, we evaluate the interfacial processes of diamond/tungsten sliding contacts using an on-line macro-tribometer and a micro-tribometer in an ultra-high vacuum. The coefficient of friction for the tests with the on-line tribometer remained considerably low for unlubricated sliding of tungsten, which correlated well with the relatively low wear rates and low roughness on the wear track throughout the sliding. Ex situ analysis was performed by means of XPS and SEM-FIB in order to better understand the underlying mechanisms of low friction and low-wear sliding. The analysis did not reveal any evidence of tribofilm or transferfilm formation on the counterface, indicating the absence of significant bonding between the diamond and tungsten surfaces, which correlated well with the low-friction values. The minimal adhesive interaction and material transfer can possibly be explained by the low initial roughness values as well as high cohesive bonding energies of the two materials. The appearance of the wear track as well as the relatively higher roughness perpendicular to the sliding indicated that abrasion was the main wear mechanism. In order to elucidate the low friction of this tribocouple, we performed micro-tribological experiments in ultra-high vacuum conditions. The results show that the friction coefficient was reduced significantly in UHV. In addition, subsequently to baking the chamber, the coefficient of friction approached ultra-low values. Based on the results obtained in this study, the diamond/tungsten tribocouple seems promising for tribological interfaces in spacecraft systems, which can improve the durability of the components.

Effect of Micro-Size Cenosphere Content on Friction and Dry Sliding Wear Behavior of Vinylester Composites – A Taguchi Method

2012 ◽  
Vol 585 ◽  
pp. 569-573 ◽  
Author(s):  
S.R. Chauhan ◽  
Sunil Thakur
Keyword(s):  
Wear Rate ◽  
Coefficient Of Friction ◽  
Sliding Wear ◽  
Friction And Wear ◽  
Normal Load ◽  
Dry Sliding ◽  
Sliding Speed ◽  
Applied Normal Load ◽  
The Coefficient Of Friction ◽  
Sliding Distance

In this paper the friction and wear characteristics of vinylester and vinylester composites have been investigated under dry sliding conditions for different applied normal load, sliding speed and sliding distance. The experiments have been carried on a pin on disc arrangement at normal room temperature conditions. The influence of friction and wear parameters like normal load, speed, sliding distance and percentage of filler content on the friction and wear rate has been investigated. In this study, a plan of experiments based on the techniques of Taguchi was performed to acquire data in a controlled way. An orthogonal array L27 (313) and Analysis of variance (ANOVA) were applied to investigate the influence of process parameters on the coefficient of friction and sliding wear behaviour of these composites. The Taguchi design of experiment approach eliminates the need for repeated experiments and thus saves time, material and cost. The results showed that with increase in the applied normal load and sliding speed the coefficient of friction and specific wear rate decreases under dry sliding conditions. It is also found that a thin film formed on the counterface seems to be effective in improving the tribological characteristics. The results showed that the inclusion of cenosphere as filler materials in vinylester composites will increase the wear resistance of the composite significantly.

TiCN coating tribology for the circular economy of textile industries

2021 ◽  
pp. 152808372110257
Author(s):  
Abrar Hussain ◽  
Vitali Podgursky ◽  
Maksim Antonov ◽  
Mart Viljus ◽  
Dmitri Goljandin
Keyword(s):  
Surface Modification ◽  
Cotton Fabric ◽  
Coefficient Of Friction ◽  
Circular Economy ◽  
Ticn Coating ◽  
The Coefficient Of Friction ◽  
Textile Industries ◽  
And Performance ◽  
Sliding Distance ◽  
Textile Products

The circular economy is still a hypothetical field in Europe. Different shredding and manufacturing machinery parts in textile industries are presumed to enhance product quality and performance. The quality and performance of recycled textile products play a vital role in the development of textile recycling technologies. The quality is principally associated with the mechanical and tribological properties of machinery parts. In this article, TiCN Coating is used to determine the coefficient of friction of post-consumer cotton fabric. The scanning electron microscope, optical and mechanical profilometer, and tribometer were used for surface and tribological evaluations. The TiCN coating was found smooth and homogeneous. The average coating surface roughness parameters Rmax, Rz, Rp were 0.24 µm, 0.21 µm, and 0.20 µm, respectively. The dynamic coefficient of friction values was found 0.38 to 0.30 in the warp and 0.33 to 0.28 in weft directions. The increase in sliding distance is used for industrial applications and evaluations. The increase in distance deformed and fractured cotton fabric surface. The coefficient of friction and deformation becomes constant after 40 m of sliding distance. Based on coefficient of friction values, permanent deformation, fracture, and morphologies evaluations TiCN coatings could be used operationally for surface modification of textile machinery parts. The surface modification of textile machinery parts with TiCN coating can enhance the quality and performance of textile products.

Effects of Floor Material, Surface Condition, and Foot Moving Speed on the Coefficient of Friction on the Floor

2013 ◽  
Vol 303-306 ◽  
pp. 2704-2707
Author(s):  
Kai Way Li ◽  
Chan Chi Lin
Keyword(s):  
Coefficient Of Friction ◽  
Surface Condition ◽  
Reaction Force ◽  
Force Platform ◽  
Material Surface ◽  
Sliding Speed ◽  
The Coefficient Of Friction ◽  
Male Subjects ◽  
Floor Material ◽  
Moving Speed

A laboratory study was conducted to measure the coefficient of friction between the foot and the floor under three surface and two foot sliding speed conditions. A force platform was adopted to measure the ground reaction force (GRF) of the foot on the floor. The coefficient of friction was calculated as the ratio of vertical and horizontal GRF. Five male subjects were recruited. They were requested to slide their right foot on the tested floor which was mounted on the force platform. The results indicated that floor material, surface condition, and foot sliding speed were all significant factor affecting the COF. Ceramic tile had lower COF under all surface and sliding speed conditions as compared to steel, wood, and vinyl tiles.

The Dependency of Takeoff Velocity and Friction on Head Geometry and Drive Configuration

1995 ◽  
Vol 117 (2) ◽  
pp. 350-357 ◽  
Author(s):  
Jerry J. K. Lee ◽  
J. Enguero ◽  
M. Smallen ◽  
A. Chao ◽  
E. Cha
Keyword(s):  
Thin Film ◽  
Coefficient Of Friction ◽  
Air Bearing ◽  
Head Disk Interface ◽  
Skew Angle ◽  
Lower Mass ◽  
Frictional Drag ◽  
Disk Interface ◽  
The Coefficient Of Friction ◽  
Sliding Distance

Wear at the head-disk interface of magnetic recording devices is dependent on the contact sliding distance between the head and disk. The sliding distance is dependent on the head takeoff velocity and frictional drag. In this study, the dependence of takeoff velocity and friction on selected head parameters was measured with an air bearing spindle equipped with a strain gauge. For the thin film head, crown had the greatest influence on takeoff velocity, followed by bolt pattern runout, suspension preload, camber, skew angle, and rail width in decreasing order. For the metal-ingap head, ski jump had the greatest influence. The rest of the parameters followed in the same order as they did for the thin film head. Twist and edge blend did not affect takeoff velocity, but larger edge blends did improve contact start-stop performance. Lower mass disk stacks did better in contact start-stop tests because of their shorter sliding distance before reaching the takeoff velocity or after achieving the landing velocity. Finally, both crown and skew angle affected the coefficient of friction between the head and disk. Heads with a more positive crown or zero skew angle had the lowest coefficient of friction.

Experimental Investigation of aluminum doping crumb rubber/epoxy composite in reciprocating motion

2015 ◽  
Vol 3 ◽  
pp. 1
Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak
Keyword(s):  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Epoxy Composite ◽  
Normal Load ◽  
Crumb Rubber ◽  
The Other ◽  
Reciprocating Motion ◽  
Molding Process ◽  
Friction Tester ◽  
The Coefficient Of Friction

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

scholarly journals Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Applied Load ◽  
Practical Significance ◽  
Tribological Characteristics ◽  
M 10 ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

scholarly journals Influence of Beam Power on Young’s Modulus and Friction Coefficient of Ti–Ta Alloys Formed by Electron-Beam Surface Alloying

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1246
Author(s):  
Stefan Valkov ◽  
Dimitar Dechev ◽  
Nikolay Ivanov ◽  
Ruslan Bezdushnyi ◽  
Maria Ormanova ◽  
...  
Keyword(s):  
Electron Beam ◽  
Young’S Modulus ◽  
Coefficient Of Friction ◽  
Young's Modulus ◽  
Beam Power ◽  
Surface Alloying ◽  
Surface Alloys ◽  
X Ray ◽  
The Coefficient Of Friction ◽  
Beam Surface

In this study, we present the results of Young’s modulus and coefficient of friction (COF) of Ti–Ta surface alloys formed by electron-beam surface alloying by a scanning electron beam. Ta films were deposited on the top of Ti substrates, and the specimens were then electron-beam surface alloyed, where the beam power was varied from 750 to 1750 W. The structure of the samples was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Young’s modulus was studied by a nanoindentation test. The coefficient of friction was studied by a micromechanical wear experiment. It was found that at 750 W, the Ta film remained undissolved on the top of the Ti, and no alloyed zone was observed. By an increase in the beam power to 1250 and 1750 W, a distinguished alloyed zone is formed, where it is much thicker in the case of 1750 W. The structure of the obtained surface alloys is in the form of double-phase α’and β. In both surface alloys formed by a beam power of 1250 and 1750 W, respectively, Young’s modulus decreases about two times due to different reasons: in the case of alloying by 1250 W, the observed drop is attributed to the larger amount of the β phase, while at 1750 W is it due to the weaker binding forces between the atoms. The results obtained for the COF show that the formation of the Ti–Ta surface alloy on the top of Ti substrate leads to a decrease in the coefficient of friction, where the effect is more pronounced in the case of the formation of Ti–Ta surface alloys by a beam power of 1250 W.

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