Evaluation of DLC Coatings for Foil Bearing Applications

2007 ◽  
Author(s):  
Said Jahanmir ◽  
Hooshang Heshmat ◽  
Crystal Heshmat ◽  
Osman Eryilmaz ◽  
Ali Erdemir
Keyword(s):  
Room Temperature ◽  
Excellent Performance ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Foil Bearings ◽  
Dlc Coating ◽  
Foil Bearing ◽  
Free Air ◽  
Flat Disk ◽  
Important Design

A critical component in oil-free air foil bearings is the tribological coating system that must be used on the journal/runner and the foil pads to ensure reliable operation during transient periods and start-stop cycles. The purpose of the present investigation was to evaluate the performance characteristics of hydrogenated diamond like carbon coatings (H-DLC) for foil bearing applications. Tribological tests were performed using a single thrust foil bearing in contact with a rotating flat disk at room temperature. While the performance of H-DLC coating on the foils tested against disks coated with MiTi® Korolon™ 900 was acceptable, the reverse coating combination provided an excellent performance. Although the H-DLC film had suffered some wear along narrow scratches, both coatings survived the 500 start/stop cycles. The liftoff speed, which is an important design parameter, was less than 1,000 rpm, much lower than uncoated foil and disk combination. It is, therefore, concluded that the combination of H-DLC foil coating with the Korolon™ 900 coating on the disk will provide excellent performance for foil bearing applications at room temperature.

Evaluation of DLC Coatings for High-Temperature Foil Bearing Applications

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Said Jahanmir ◽  
Hooshang Heshmat ◽  
Crystal Heshmat
Keyword(s):  
Carbon Film ◽  
Dlc Coatings ◽  
Foil Bearings ◽  
Dlc Coating ◽  
Foil Bearing ◽  
Flat Disk ◽  
Wide Range ◽  
Diamondlike Carbon ◽  
Powder Lubrication ◽  
Foil Thrust Bearing

Diamondlike carbon (DLC) coatings, particularly in the hydrogenated form, provide extremely low coefficients of friction in concentrated contacts. The objective of this investigation was to evaluate the performance of DLC coatings for potential application in foil bearings. Since in some applications the bearings experience a wide range of temperatures, tribological tests were performed using a single foil thrust bearing in contact with a rotating flat disk up to 500°C. The coatings deposited on the disks consisted of a hydrogenated diamondlike carbon film (H-DLC), a nonhydrogenated DLC, and a thin dense chrome deposited by the Electrolyzing™ process. The top foil pads were coated with a tungsten disulfide based solid lubricant (Korolon™ 900). All three disk coatings provided excellent performance at room temperature. However, the H-DLC coating proved to be unacceptable at 300°C due to lack of hydrodynamic lift, albeit the very low coefficient of friction when the foil pad and the disk were in contact during stop-start cycles. This phenomenon is explained by considering the effect of atmospheric moisture on the tribological behavior of H-DLC and using the quasihydrodynamic theory of powder lubrication.

Thermal Annealing Behavior of Si-DLC Ibad Coatings

1996 ◽  
Vol 438 ◽  
Author(s):  
C. G. Fountzoulas ◽  
J. D. Demaree ◽  
L. C. Sengupta ◽  
J. K. Hirvonen
Keyword(s):  
Room Temperature ◽  
Ion Beam ◽  
Silicon Substrates ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Annealing Behavior ◽  
Ion Beam Assisted Deposition ◽  
Disk Friction ◽  
Knoop Microhardness ◽  
Absorption Features

AbstractAmorphous, 700 nm thick, diamond-like carbon coatings containing silicon (Si-DLC), farmed by Ar+ ion beam assisted deposition (IBAD) on silicon substrates, were annealed in air at temperatures ranging from room temperature to 600°C for 30 minutes. RBS analysis showed that the composition of the films remained the same up to 200°C, but at higher temperatures the Si-DLC coatings began to oxidize at the outer surface of the coating, forming a surface layer of SiO2. After in-air annealing at 600°C the coating had been completely converted to SiO2, with no trace of carbon seen by RBS. FTIR spectra of the unannealed coatings showed a very broad mode typical of Si-DLC bonding as well as some absorption features associated with Si and SiO2. Above 200°C the transmission mode shifted to higher frequencies which may be caused by the growth of SiO2 and the decrease of the Si-DLC film thickness. The room temperature ball-on-disk friction coefficient of the coating against a 1/2′′ diameter 440 C steel ball at 1 N load ranged from 0.2 for the original coating up to 0.5 after a 100° anneal and returned to 0.2 after annealing at 200–400°C and fell to 0.12 after a 500°C exposure. The average Knoop microhardness (uncorrected for substrate effects) was 10 GPa (1,000 KHN) for coatings annealed at temperatures as high as 400°C. All coatings up to 500 °C passed the qualitative “Scotch Tape” test.

Fracture toughness of diamondlike carbon coatings

1999 ◽  
Vol 14 (5) ◽  
pp. 2173-2180 ◽  
Author(s):  
M. Nastasi ◽  
P. Kodali ◽  
K. C. Walter ◽  
J. D. Embury ◽  
R. Raj ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Length ◽  
Total Work ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Si Substrates ◽  
Dlc Coating ◽  
Diamondlike Carbon ◽  
Radial Cracks ◽  
Work Of Fracture

The fracture behavior of diamondlike carbon (DLC) coatings on Si substrates has been examined using microindentation. The presence of DLC coatings reduces the radial crack length to less than one-half the crack length observed in uncoated Si at the same indenter load. A total work of fracture analysis of the radial cracks formed in the DLC-coating/Si-substrate system gives 10.1 MPa m1/2 as the average fracture toughness for DLC alone. A bond-breaking calculation for DLC suggests that the elastic limit fracture toughness should be 1.5 MPa (m)1/2. The higher value obtained from experiment and total work analysis suggests that plastic work and/or a tortuous path crack evolution occurred during DLC fracture process.

Sliding Wear of Non-Hydrogenated Diamond-Like Carbon Coatings Against Al, Cu and Ti

2005 ◽  
Author(s):  
E. Konca ◽  
Y. T. Cheng ◽  
A. T. Alpas
Keyword(s):  
Sliding Wear ◽  
Ambient Air ◽  
Inert Atmosphere ◽  
Diamond Like Carbon ◽  
Severe Damage ◽  
Material Transfer ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Dlc Coating ◽  
Pin On Disc

Magnetron sputtered non-hydrogenated diamond-like carbon (DLC) coatings were tested against Al, Cu and Ti pins using a vacuum pin-on-disc tribometer. The objective was to compare Al, Ti, and Cu transfer to DLC coatings in air (29% RH) and an inert atmosphere (argon). In argon, a significant amount of adhesion and material transfer occurred from the Al and Ti pins to the DLC coating surfaces inflicting severe damage to the coatings. Wear and material transfer of the DLC coating against Cu were negligible in argon. Compared to tests in argon, the tribological performance of the DLC coatings against Al and Ti improved significantly in ambient air. In contrast, the wear rate of the DLC coatings against Cu was much higher in ambient air compared to that in argon.

scholarly journals Berkovich indentation of diamondlike carbon coatings on silicon substrates

2008 ◽  
Vol 23 (7) ◽  
pp. 1862-1869 ◽  
Author(s):  
Ayesha J. Haq ◽  
P.R. Munroe ◽  
M. Hoffman ◽  
P.J. Martin ◽  
A. Bendavid
Keyword(s):  
Plastic Deformation ◽  
Cross Sections ◽  
Silicon Substrate ◽  
Chemical Vapor ◽  
Silicon Substrates ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Dlc Coating ◽  
Vapor Deposition Technique ◽  
Diamondlike Carbon

The deformation behavior of diamondlike carbon (DLC) coatings on silicon substrates induced by Berkovich indentation has been investigated. DLC coatings deposited by a plasma-assisted chemical vapor deposition technique were subjected to nanoindentation with a Berkovich indenter over a range of maximum loads from 100 to 300 mN. Distinct pop-ins were observed for loads greater than 150 mN. However, no pop-out was observed for the loads studied. The top surface of the indents showed annular cracks with associated fragmented material. The cross sections showed up to 20% localized reduction in thickness of the DLC coating beneath the indenter tip. Cracking, {111} slip, stacking faults, and localized phase transformations were observed in the silicon substrate. The discontinuities in the load–displacement curves at low loads are attributed to plastic deformation of the silicon substrate, whereas at higher loads they are attributed to plastic deformation as well as phase transformation.

Effects of Interlayer on Mechanical Properties of Diamond-Like Carbon Coatings

2018 ◽  
Vol 883 ◽  
pp. 43-47 ◽  
Author(s):  
Sun Hui Yao ◽  
Yan Liang Su ◽  
Yu Chen Lai ◽  
Huang Ming Wu
Keyword(s):  
Mechanical Properties ◽  
Diamond Like Carbon ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Mechanical And Tribological Properties ◽  
Dlc Coating ◽  
Unbalanced Magnetron Sputtering ◽  
Unbalanced Magnetron ◽  
The One ◽  
Sputtering System

This paper reports comparative studies on effects of interlayer on mechanical properties of diamond-like carbon (DLC) coatings. Two interlayers, TiC/Ti and CrC/Cr, were deposited and studied. The DLC coatings were prepared by using an unbalanced magnetron sputtering system. The chemical composition, micro-structure, constituted phases, and fundamental mechanical and tribological properties were evaluated. The results showed that the two amorphous (a-) DLC coatings were obtained. The a-DLC coating with the TiC/Ti interlayer showed higher adhesion, hardness and wear resistance than the one with the CrC/Cr interlayer.

Morphology of Fibroblastic Cells Cultured on Diamond-Like Carbon Coatings Produced by Plasma Immersion Using AFM and SEM

2006 ◽  
Vol 309-311 ◽  
pp. 713-716 ◽  
Author(s):  
E.T. Uzumaki ◽  
C.S. Lambert ◽  
L.O. Bonugli ◽  
A.R. Santos ◽  
Cecília A.C. Zavaglia
Keyword(s):  
Biological Effects ◽  
Diamond Like Carbon ◽  
Electron Microscopic ◽  
Adhesion Properties ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Dlc Coating ◽  
Atomic Force ◽  
Fibroblastic Cells ◽  
Potential Use

For the potential use of diamond-like carbon (DLC) coating for biomedical applications, it would be important to evaluate the biological effects of these coatings. In this study, DLC coatings were deposited on glass coverslips using the plasma immersion process, which produces films with adhesion properties superior to those prepared with conventional techniques. Scanning electron microscopic and atomic force microscopic observations were used to study the morphology of fibroblasts growth on DLC coatings.

Comparative Analysis of Wear Rates of Microcrystalline Diamond and Diamond-Like Carbon Coatings Deposited on WС-Co Substrates

2016 ◽  
Vol 721 ◽  
pp. 436-440 ◽  
Author(s):  
Maxim Yashin ◽  
Andrei Bogatov ◽  
Vitali Podgursky
Keyword(s):  
Chemical Vapor ◽  
Diamond Like Carbon ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Wear Rates ◽  
Dlc Coating ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Wear Tests ◽  
Plate Type

The study investigates the wear of microcrystalline diamond (MCD) and diamond-like carbon (DLC) coatings. The MCD and DLC coatings were grown by plasma enhanced chemical vapor deposition (PECVD) method on WC-Co substrates. The sliding wear tests were performed on the ball-on-plate type of tribometer in reciprocating mode. The ball-cratering wear tests were carried out using Calo tester. The mechanical profilometer, optical and scanning electron microscopes (SEM) were used for investigation of the surface morphology of the wear scars. The wear of DLC coating is more intense in comparison to the MCD coating. In contrast to the MCD coating, no evidence of the DLC coating deflection was found.

scholarly journals Surface Reformation of Medical Devices with DLC Coating

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 376
Author(s):  
Mao Kaneko ◽  
Masanori Hiratsuka ◽  
Ali Alanazi ◽  
Hideki Nakamori ◽  
Kazushige Namiki ◽  
...  
Keyword(s):  
High Pressure ◽  
Medical Devices ◽  
Diamond Like Carbon ◽  
Steam Sterilization ◽  
Dlc Coatings ◽  
Chrome Plating ◽  
Living Body ◽  
Dlc Coating ◽  
Pressure Steam ◽  
Adhesion Friction

We evaluated the adhesion, friction characteristics, durability against bodily acids, sterilization, cleaning, and anti-reflection performance of diamond-like carbon (DLC) coatings formed as a surface treatment of intracorporeal medical devices. The major coefficients of friction during intubation in a living body in all environments were lower with DLC coatings than with black chrome plating. DLC demonstrated an adhesion of approximately 24 N, which is eight times stronger than that of black chrome plating. DLC-coated samples also showed significant stability without being damaged during acid immersion and high-pressure steam sterilization, as suggested by the results of durability tests. In addition, the coatings remained unpeeled in a usage environment, and there was no change in the anti-reflection performance of the DLC coatings. In summary, DLC coatings are useful for improving intracorporeal device surfaces and extending the lives of medical devices.

scholarly journals Amorphous Carbon Coatings for Total Knee Replacements—Part I: Deposition, Cytocompatibility, Chemical and Mechanical Properties

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1952
Author(s):  
Benedict Rothammer ◽  
Kevin Neusser ◽  
Max Marian ◽  
Marcel Bartz ◽  
Sebastian Krauß ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Amorphous Carbon ◽  
Detailed Characterization ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Total Knee Replacements ◽  
Knee Replacements ◽  
Total Knee ◽  
Amorphous Carbon Coatings

Diamond-like carbon (DLC) coatings have the potential to reduce implant wear and thus to contribute to avoiding premature failure and increase service life of total knee replacements (TKAs). This two-part study addresses the development of such coatings for ultrahigh molecular weight polyethylene (UHMWPE) tibial inlays as well as cobalt–chromium–molybdenum (CoCr) and titanium (Ti64) alloy femoral components. While a detailed characterization of the tribological behavior is the subject of part II, part I focusses on the deposition of pure (a‑C:H) and tungsten-doped hydrogen-containing amorphous carbon coatings (a‑C:H:W) and the detailed characterization of their chemical, cytological, mechanical and adhesion behavior. The coatings are fabricated by physical vapor deposition (PVD) and display typical DLC morphology and composition, as verified by focused ion beam scanning electron microscopy and Raman spectroscopy. Their roughness is higher than that of the plain substrates. Initial screening with contact angle and surface tension as well as in vitro testing by indirect and direct application indicate favorable cytocompatibility. The DLC coatings feature excellent mechanical properties with a substantial enhancement of indentation hardness and elastic modulus ratios. The adhesion of the coatings as determined in modified scratch tests can be considered as sufficient for the use in TKAs.

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