Nano-Hardness, Nano-Friction and Nano-Wear of Ultra-Thin Overcoats

1994 ◽  
Vol 356 ◽  
Author(s):  
D. B. Bogy ◽  
Zhaoguo Jiang
Keyword(s):  
Critical Load ◽  
Normal Load ◽  
Wear Test ◽  
Indentation Hardness ◽  
Fatigue Wear ◽  
A Value ◽  
Hardness Tests ◽  
The Coefficient Of Friction ◽  
Protective Overcoats ◽  
Made In

AbstractThin film magnetic disks require protective overcoats, usually some form of carbon, to guard against corrosion and wear from interaction with the read/write transducer. In current products these films are less than 25 nm in thickness. This paper summarizes developments using scanning probe microscopes with sharp diamond tips (15 – 100 nm radius) to obtain indentation hardness tests with 5 nm deep indentations. We discuss an accelerated wear test that can measure wear at depths on the order of 1 nm. Finally material characterizations related to friction over sub-micron scans are discussed.A novel observation has been made when studying the dependence of friction coefficient on normal load: below a critical load, which is material and tip dependent, no observable wear occurs, and the coefficient of friction is about 0.05. Above the critical load the coefficient is load dependent and increases to a value more usually associated with the materials being tested. A study of fatigue wear was made in the “no-wear” regime with three different results. For some materials, fatigue wear occurred with multiple passes, when none was apparent for a single pass. Other materials showed no fatigue wear, and one material, silicon, showed a build-up or “negative-wear” under multiple passes. Interpretations and implications of these results are discussed.

The frictional anisotropy of diamond

1981 ◽  
Vol 373 (1755) ◽  
pp. 405-417 ◽  
Keyword(s):  
Critical Load ◽  
Surface Damage ◽  
Diamond Surface ◽  
Radius Of Curvature ◽  
Type I ◽  
Diamond Surfaces ◽  
A Value ◽  
The Coefficient Of Friction ◽  
Contact Pressures ◽  
Critical Contact

This paper describes a study of the friction, in air, of a spherically tipped diamond stylus over the {100} face of a flat diamond surface. The results show that in general the friction is greater when sliding occurs along the <100> direction than along the <110> direction. This cannot be explained in terms of a Coulomb frictional mechanism where the friction is attributed to the climbing of one surface over the asperities on the other, for in that case the coefficient of friction is determined solely by the surface topography and is independent of load. By contrast, the experiments described in this paper show that below a critical load Wc the frictional anisotropy virtually disappears. This critical load is proportional to R 2 , where R is the radius of curvature of the stylus, implying, for Hertzian deformation, a critical contact pressure. For both type I and type II diamonds this critical pressure has a value of the order of 20 GN m -2 . At these and larger contact pressures cathodoluminescent studies of the flat diamond surfaces indicate that the frictional anisotropy is largely due to surface and sub-surface damage produced in preferred crystallographic directions by the sliding process itself. The results are discussed in terms of crack formation and plastic deformation. However, the results do not, as yet, provide an unequivocal account of the mechanism of energy dissipation.

scholarly journals The Effect of Disc Surface Topography on the Dry Gross Fretting Wear of an Equal-Hardness Steel Pair

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3250 ◽  
Author(s):  
Lenart ◽  
Pawlus ◽  
Dzierwa
Keyword(s):  
Relative Humidity ◽  
Normal Load ◽  
Fretting Wear ◽  
Experimental Investigations ◽  
Disc Surface ◽  
Hardness Tests ◽  
Total Wear ◽  
The Coefficient Of Friction ◽  
Constant Normal Load ◽  
Number Of Cycles

Experimental investigations were carried out with an Optimol SRV5 tribological tester in a flat-on-sphere scheme. The balls co-acted with the discs in a gross sliding fretting regime. The balls and discs were made from the same steel with a very similar hardness. Tests were conducted at 25–35% relative humidity, 30 °C, and a constant normal load and number of cycles (18,000). The discs had different textures after various machining treatments. It was found that the total wear level of the tribological assembly was proportional to the disc surface amplitude. The influence of the disc roughness on the coefficient of friction was evident only for the smallest stroke of 0.1 mm, and the frequency of oscillation affected this dependency.

Mechanical Characterization Of Ultra-Thin, Hard-Disk Overcoats Using Scratch Testing And Depth-Sensing Indentation

1997 ◽  
Vol 505 ◽  
Author(s):  
J. L. Hay ◽  
R. L. White ◽  
B. N. Lucas ◽  
W. C. Oliver
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
Wear Test ◽  
Constant Load ◽  
Indentation Hardness ◽  
Depth Sensing ◽  
Small Constant ◽  
Residual Damage ◽  
20 Nm ◽  
Scratch Tests

ABSTRACTTwo series of five diamond-like carbon (DLC) coatings were sputtered under nominally identical conditions, but to different film thicknesses of 20 nm and 105 nm. First, the hardness of each sample was determined by depth-sensing indentation. Hardness measurements were substrate-affected to some extent for all samples but especially so for the 20 nm coatings. Two types of scratch tests were performed in an attempt to isolate and characterize the top coatings. The first was a wear test, which consisted of moving the sample back and forth repeatedly under a small constant load. The residual damage was inconsistent, but appeared to be a function of the composite, or substrate-affected hardness. The second test was a single-pass scratch in which the normal load was ramped linearly. For all samples, the friction coefficient was approximately constant as a function of load. Furthermore, samples with the same top coats yielded similar friction coefficients, regardless of the coating thicknesses. Friction coefficient decreased with hydrogen content and to some extent, increased with hardness, as measured on the 105 nm samples. The friction coefficient measured during a ramp-load scratch offers an alternative for characterizing ultra-thin films, when indentation alone yields measurements that are significantly affected by the substrate.

Wear Characteristics of Manganese Phosphate Coating with Oil Lubricant

2011 ◽  
Vol 110-116 ◽  
pp. 616-620 ◽  
Author(s):  
S. Ilaiyavel ◽  
A. Venkatesan ◽  
N. Nallusamy ◽  
T. Sornakumar
Keyword(s):  
Coefficient Of Friction ◽  
Normal Load ◽  
Wear Test ◽  
Wear Loss ◽  
Manganese Phosphate ◽  
Industrial Coating ◽  
Pin On Disc ◽  
Aisi D2 ◽  
The Coefficient Of Friction ◽  
Pin On Disk

Manganese Phosphate is an Industrial coating used to reduce friction and improve lubrication in sliding components. In this study, the tribology behavior of uncoated, manganese phosphate coated, Manganese Phosphate with oil lubricant AISI D2 steels was investigated. The Surface morphology of manganese phosphate coatings was examined by scanning electron microscope (SEM) and Energy dispersive X-ray Spectroscopy (EDX) .The wear tests were performed in a pin on disk apparatus as per ASTM G-99 Standard. The wear resistance of the coated steel were evaluated through pin on disc test using a sliding velocity of 0.35 m/s under normal load of 5 to35 N and controlled condition of temperature and humidity. The Coefficient of friction and wear loss were evaluated. Based on the results of the wear test, the manganese phosphate with lubricant exhibited the lowest average coefficient of friction 0.13 and the lowest wear loss 0.4 mm3under 35 N load.

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.

Self-Lubricating and Wear Resistant Epoxy Composites Incorporated With Microencapsulated Wax

2014 ◽  
Vol 81 (7) ◽  
Author(s):  
N. W. Khun ◽  
H. Zhang ◽  
C. Y. Yue ◽  
J. L. Yang
Keyword(s):  
Tribological Properties ◽  
Friction And Wear ◽  
Normal Load ◽  
Wear Test ◽  
Epoxy Composites ◽  
Wear Resistant ◽  
Working Parameters

Self-lubricating and wear resistant epoxy composites were developed via incorporation of wax-containing microcapsules. The effects of microcapsule size and content and working parameters on the tribological properties of epoxy composites were systematically investigated. The incorporation of microcapsules dramatically decreased the friction and wear of the composites from those of the epoxy. The increased microcapsule content or the incorporation of larger microcapsules decreased the friction and wear of the epoxy composites due to the larger amount of released wax lubricant via the rupture of microcapsules during the wear test. The friction of the composites decreased with increased normal load as a result of the promoted wear of the composites and the increased release of the wax lubricant.

IONIZATION ENERGY AND IMPURITY BAND CONDUCTION OF SHALLOW DONORS IN n-GALLIUM ARSENIDE

1967 ◽  
Vol 45 (1) ◽  
pp. 119-126 ◽  
Author(s):  
J. Basinski ◽  
R. Olivier
Keyword(s):  
Ionization Energy ◽  
Impurity Band ◽  
Shallow Donor ◽  
Band Model ◽  
A Value ◽  
Transition Concentration ◽  
Temperature Electron ◽  
Two Band Model ◽  
Band Conduction ◽  
Made In

Hall effect and resistivity measurements have been made in the temperature range 4.2–360 °K on several samples of n-type GaAs grown under oxygen atmosphere and without any other intentional dopings. The principal shallow donor in this material is considered to be Si. All samples exhibited impurity-band conduction at low temperature. Electron concentrations in the conduction band were calculated, using a two-band model, and then fitted to the usual equation expressing charge neutrality. A value of 2.3 × 10−3 eV was obtained for the ionization energy of the donors, for donor concentration ranging from 5 × 1015 cm−3 to 2 × 1016 cm−3. The conduction in the impurity band was of the hopping type for these concentrations. A value of 3.5 × 1016 cm−3 was obtained for the critical transition concentration of the impurity-band conduction to the metallic type.

Change in Backlash of Humanoid Robot Joints under High Load

2013 ◽  
Vol 372 ◽  
pp. 507-511
Author(s):  
Hitonobu Koike ◽  
Kenji Kanemasu ◽  
Kiyoto Itakura ◽  
Shota Okazaki ◽  
Masahiro Takamiya ◽  
...  
Keyword(s):  
Evaluation System ◽  
Humanoid Robot ◽  
Wear Test ◽  
Transmission Error ◽  
High Load ◽  
Fatigue Wear ◽  
Load Torque ◽  
Ether Ether Ketone ◽  
Poly Ether Ether Ketone ◽  
Joint Evaluation

In this work, wear of reinforced poly-ether-ether-ketone (PEEK) polymer bushes in friction against 7075 aluminium alloy cam plates or titanium crankshafts is investigated in order to establish the application possibilities in transmission parts in humanoid robot joints under high load torque. The PEEK bush wear requires close examination as well as the input axis-output axis transmission error (backlash). Sliding wear tests were performed on bushes under 4000 kgfcm (392 Nm) load torque, while the cam plate oscillated in the humanoid robot leg joint evaluation system. The robot joint using PEEK bush achieved quite small backlash after the fatigue wear test.

Sliding behavior of silica ball-shale rock contact under polyacrylamide aqueous solutions

2021 ◽  
pp. 1-25
Author(s):  
Huijie Zhang ◽  
Shuhai Liu
Keyword(s):  
Adverse Effect ◽  
Shale Gas ◽  
Normal Load ◽  
Gas Production ◽  
Wear Depth ◽  
Brine Solution ◽  
Shale Rock ◽  
Different Types ◽  
The Coefficient Of Friction ◽  
Specific Speed

Abstract The tribological properties of proppant particle sliding on shale rock determine the shale gas production. This work focuses on investigating the impacts of sliding speed on the coefficient of friction (COF) and wear of the silica ball-shale rock contact, which was lubricated by water or different types of polyacrylamide (PAM) aqueous or brine solution. The experimental results show that both boundary and mixed lubrication occur under specific speed and normal load. COF and wear depth of shale rock under water are higher than those under PAM solution due to superior lubrication of PAM. COF of shale rock under PAM brine solution increases and the wear of the rock is more serious, attributed to the corrosion of shale rock and adverse effect on lubrication of PAM by brine.

scholarly journals On the precise measurement capability of the direct microscopic measurement method for wear volume characterization

2018 ◽  
Vol 188 ◽  
pp. 02007
Author(s):  
Enbiya Türedi
Keyword(s):  
Normal Load ◽  
Wear Test ◽  
Optical Microscope ◽  
Bearing Steel ◽  
Wear Scar ◽  
Wear Volume ◽  
Measurement Capability ◽  
Comparison Results ◽  
Novel Method ◽  
Microscopic Measurement

There are plenty of methods for determining the wear volume after a wear test. Due to the geometrical assumptions, some of them could unfortunately lead to mistaken results. It has been shown that a novel method, the direct microscopic measurement, is able to calculate the wear volume on a specimen surface very precisely and accurately [1-2]. It is based on creating a series of line profiles perpendicular to the wear scar. This novel method, however, needs to be characterized in terms of measurement limitations and minimum detectable volume capability. For example, how small or how shallow a wear scar could be calculated or measured with this method, must be determined. For this purpose, it has been prepared a series of wear test specimens exposed to the different amounts of wear in a “pin-on-disk” type test rig. As specimens, two different non-ferrous mold materials, Al bronze alloys, were selected and prepared metallographically. Counterpart materials were inox steel and bearing steel balls with diameter of 6 mm. Normal load was set to 5 N. Test configurations were set to 1, 5, 10 and 100 m of sliding distance values, in turn. Wear tests were conducted in according to ASTM G99 standard. Wear volume results were determined both direct microscopic measurement and also a 3D optical microscope methods. Comparison results showed that the novel method could be successfully used for wear volume calculations even with small amounts of wear volume conditions.

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