Observations of Depth-Sensing Reciprocating Scratch Tests of DLC and Nitrogenated-DLC Overcoats on Magnetic Disks

1998 ◽  
Vol 517 ◽  
Author(s):  
T.W. Scharf ◽  
R.D. Ott ◽  
D. Yang ◽  
J.A. Barnard
Keyword(s):  
Wear Resistance ◽  
Elastic Recovery ◽  
Normal Load ◽  
Thick Layer ◽  
Scratch Test ◽  
Film Structure ◽  
Diamond Like Carbon ◽  
Hard Disks ◽  
Depth Sensing ◽  
Scratch Tests

AbstractIn this investigation, the wear durability of existing and candidate protective overcoats and substrates was examined. Specifically, 5 nm thick diamond-like carbon (DLC) and nitrogenated diamond-like carbon (N-DLC) overcoats were deposited by sputtering onto glass, glass-ceramic, and NiP/AlMg substrates. The magnetic medium was a 15 nm thick layer of CoCrPt deposited on a 50 nm thick underlayer of CrV. The wear resistance of the hard disks was determined by a recently developed depth sensing reciprocating scratch test using the Nano Indenter© II. During the scratch tests, a constant normal load of 30 jtN was maintained at an indenter velocity of 2μm/sec. It was found the N-DLC/CoCrPt/CrV/glass disk exhibited the most wear resistance and least amount of plastic deformation after the last wear event. Conversely, the NDLC/CoCrPt/CrV/NiP/AiMg disk displayed the least wear resistance even though the magnitude of the elastic recovery was the greatest. This amount of recovery was influenced by the high elastic modulus of the NiP/AIMg substrate. Consequently, the scratch test failed to isolate the intrinsic properties of the overcoat, however it provided a very powerful means of quantitatively assessing the overall response of the whole magnetic disk. This is more relevant since it simulates the response the disks see in performance. In addition, a discrete amount of nitrogen up to 14 atomic % incorporated into the amorphous network resulted in an increase in overcoat durability compared to the DLC overcoat. This was attributed to an increase in the XPS determined number of N-sp3 C bonded sites in a predominantly N-sp2 C bonded matrix. However, with increasing nitrogen concentrations ≥18%, the film structure was weakened due to the micro-Raman spectroscopy determined formation of terminated sites in the amorphous carbon network since nitrogen failed to connect the sp2 domains within the network.

Evaluation of subsurface crack depth during scratch test for optical glass BK7

2011 ◽  
Vol 225 (12) ◽  
pp. 2767-2774 ◽  
Author(s):  
W Gu ◽  
Z Yao ◽  
K Li
Keyword(s):  
Optical Glass ◽  
Normal Load ◽  
Crack Depth ◽  
Scratch Test ◽  
Scratch Depth ◽  
Scratch Hardness ◽  
Deformation And Fracture ◽  
Constant Normal Load ◽  
Scratch Tests ◽  
Abrasive Process

To get insight into the deformation and fracture behavior of brittle materials during abrasive process, scratch tests with linearly increasing normal load and constant normal load were conducted on BK7 using Vickers indenters. The effect of the applied normal load on the characteristics of surface cracks as well as the square of the scratch depth was found insensitive to the two load conditions discussed here. By taking both scratch and residual depths into consideration, a model of scratch hardness for brittle material was developed. Based on this scratch hardness, the correlation between the depth of the subsurface cracks and the scratch depth was established and was found in general agreement with the experimental results.

scholarly journals Effect of Bulk Current Density on Tribological Properties of Fe-W, Co-W and Ni-W Coatings

2015 ◽  
Author(s):  
S.A. Silkin ◽  
A.V. Gotelyak ◽  
N. Tsyntsaru ◽  
A.I. Dikusar ◽  
R. Kreivaitis ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Coefficient Of Friction ◽  
Current Density ◽  
Dry Friction ◽  
Scratch Test ◽  
Tribological Behaviour ◽  
The Coefficient Of Friction ◽  
Current Densities ◽  
Scratch Tests ◽  
The Given

Evaluation of tribological behaviour of Fe-W, Ni-W and Co-W coatings produced by electrodeposition at various bulk current densities (BCD) was under investigation in the given study. BCD does not have essential effect on the microhardness and wear characteristics of Fe-W and Co-W coatings. But the scratch tests reveal the presence of such influence. These tests showed superior wear resistance for the coatings obtained at low BCD. It was found that BCD has influence on wear resistance of Ni-W coatings under dry friction conditions. The BCD also has an influence on the coefficient of friction of Fe-W and Ni-W coatings at dry friction conditions. However, such an effect is opposite to that, observed at the scratch test.

scholarly journals Comparative Study of Tribomechanical Properties of HiPIMS with Positive Pulses DLC Coatings on Different Tools Steels

Coatings ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 28
Author(s):  
Adrián Claver ◽  
Emilio Jiménez-Piqué ◽  
José F. Palacio ◽  
Eluxka Almandoz ◽  
Jonathan Fernández de Ara ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Scratch Test ◽  
Industrial Applications ◽  
Diamond Like Carbon ◽  
Low Friction ◽  
Dlc Coatings ◽  
Tetrahedral Amorphous Carbon ◽  
Useful Life ◽  
Resistance To Wear ◽  
Tribomechanical Properties

Diamond-like carbon (DLC) coatings are very interesting due to their extraordinary properties; their excellent wear resistance, very low friction coefficient, great hardness, high elastic modulus or biocompatibility can be highlighted, as can their multifunctionality. Because of this, over recent decades they have been widely used in tribological applications, improving the performance and the useful life of machining tools in an effective way. However, these coatings have a disadvantage compared to other coatings deposited by commercially available techniques—their resultant adhesion is worse than that of other techniques and limits their industrial applications. In this work, tribological results of a scratch test, wear resistance and nanoindentation of tetrahedral amorphous carbon (ta-C) and tungsten carbide:carbon (WC:C) DLC coatings deposited by means of novel high-power impulse magnetron sputtering (HiPIMS) technology with positive pulses are reported. The coatings were deposited in three different tools steels: K360, vanadis 4 and vancron. These tools’ steels are very interesting because of their great and wide industrial applicability. Experimental results showed excellent tribological properties, such as resistance to wear or adhesion, in the two types of DLC coatings.

scholarly journals A Comparative Study in the Tribological Behavior of DLC Coatings Deposited by HiPIMS Technology with Positive Pulses

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 174 ◽  
Author(s):  
Jose A. García ◽  
Pedro J. Rivero ◽  
Eneko Barba ◽  
Ivan Fernández ◽  
Jose A. Santiago ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Tribological Behavior ◽  
High Hardness ◽  
Scratch Test ◽  
Low Friction ◽  
Dlc Coatings ◽  
Useful Life ◽  
Scratch Tests ◽  
Deposition Techniques

During the last few decades, diamond-like carbon (DLC) coatings were widely used for tribological applications, being an effective tool for improving the performance and the useful life of different machining tools. Despite its excellent properties, among which stand out a high hardness, a very low friction coefficient, and even an excellent wear resistance, one of the main drawbacks which limits its corresponding industrial applicability is the resultant adhesion in comparison with other commercially available deposition techniques. In this work, it is reported the tribological results of a scratch test, wear resistance, and nanoindentation of ta-C and WC:C DLC coatings deposited by means of a novel high-power impulse magnetron sputtering (HiPIMS) technology with “positive pulses”. The coatings were deposited on 1.2379 tool steel which is of a high interest due to its great and wide industrial applicability. Finally, experimental results showed a considerable improvement in the tribological properties such as wear resistance and adhesion of both types of DLC coatings. In addition, it was also observed that the role of doping with W enables a significant enhancement on the adhesion for extremely high critical loads in the scratch tests.

EVALUATION OF TRANSFORMED LAYER HARDNESS OF DLC COATING AFTER FRICTION TEST

2016 ◽  
Vol 78 (10-3) ◽  
Author(s):  
Nor Azmmi Masripan ◽  
Yosuke Tsukiyama ◽  
Kenji Ohara ◽  
Noritsugu Umehara ◽  
Hiroyuki Kousaka ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Scratch Test ◽  
Tribological Performance ◽  
Diamond Like Carbon ◽  
Friction Test ◽  
Friction Behavior ◽  
Sliding Interface ◽  
Dlc Coating

Diamond-like carbon (DLC) provide very excellence performance in term of friction coefficient and wear resistance under boundary   lubrication. the  nano characteristic of the transformed  layer has not  been studied  in terms  of its  hardness  which is believed to  have a significant  effect in the tribological  performance. This study presented the scratch test of the DLC transformed layer was obtained from the AFM scratch test that governs the friction behavior of DLC. As a result, the hardness of the DLC transformed layer depends on the oil temperature, where the sliding interface of DLC softened during the friction test due to graphitization process

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.

Experimental and Three-Dimensional Finite Element Study of Scratch Test of Polymers at Large Deformations

2004 ◽  
Vol 126 (2) ◽  
pp. 372-379 ◽  
Author(s):  
J. L. Bucaille ◽  
E. Felder ◽  
G. Hochstetter
Keyword(s):  
Strain Hardening ◽  
Penetration Depth ◽  
Large Deformations ◽  
Numerical Study ◽  
Scratch Test ◽  
Scratch Resistance ◽  
Plastic Strains ◽  
Thermosetting Polymer ◽  
Scratch Tests ◽  
Hardening Coefficient

An experimental and numerical study of the scratch test on polymers near their surface is presented. The elastoplastic response of three polymers is compared during scratch tests at large deformations: polycarbonate, a thermosetting polymer and a sol-gel hard coating composed of a hybrid matrix (thermosetting polymer-mineral) reinforced with oxide nanoparticles. The experiments were performed using a nanoindenter with a conical diamond tip having an included angle of 30 deg and a spherical radius of 600 nm. The observations obtained revealed that thermosetting polymers have a larger elastic recovery and a higher hardness than polycarbonate. The origin of this difference in scratch resistance was investigated with numerical modelling of the scratch test in three dimensions. Starting from results obtained by Bucaille (J. Mat. Sci., 37, pp. 3999–4011, 2002) using an inverse analysis of the indentation test, the mechanical behavior of polymers is modeled with Young’s modulus for the elastic part and with the G’sell-Jonas’ law with an exponential strain hardening for the viscoplastic part. The strain hardening coefficient is the main characteristic parameter differentiating the three studied polymers. Its value is equal to 0.5, 4.5, and 35, for polycarbonate, the thermosetting polymer and the reinforced thermosetting polymer, respectively. Firstly, simulations reveals that plastic strains are higher in scratch tests than in indentation tests, and that the magnitude of the plastic strains decreases as the strain hardening increases. For scratching on polycarbonate and for a penetration depth of 0.5 μm of the indenter mentioned above, the representative strain is equal to 124%. Secondly, in agreement with experimental results, numerical modeling shows that an increase in the strain hardening coefficient reduces the penetration depth of the indenter into the material and decreases the depth of the residual groove, which means an improvement in the scratch resistance.

scholarly journals Analysis of depth-sensing indentation tests with a Knoop indenter

2001 ◽  
Vol 16 (6) ◽  
pp. 1660-1667 ◽  
Author(s):  
L. Riester ◽  
T. J. Bell ◽  
A. C. Fischer-Cripps
Keyword(s):  
Elastic Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
New Method ◽  
Short Axis ◽  
Depth Sensing ◽  
Specimen Material ◽  
Indentation Tests ◽  
Conventional Methods ◽  
Knoop Indenter

The present work shows how data obtained in a depth-sensing indentation test using a Knoop indenter may be analyzed to provide elastic modulus and hardness of the specimen material. The method takes into account the elastic recovery along the direction of the short axis of the residual impression as the indenter is removed. If elastic recovery is not accounted for, the elastic modulus and hardness are overestimated by an amount that depends on the ratio of E/H of the specimen material. The new method of analysis expresses the elastic recovery of the short diagonal of the residual impression into an equivalent face angle for one side of the Knoop indenter. Conventional methods of analysis using this corrected angle provide results for modulus and hardness that are consistent with those obtained with other types of indenters.

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