Tribochemical Study of Hydrogenated Carbon Coatings With Different Hydrogen Content Levels in Ultra High Vacuum

1997 ◽  
Vol 119 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Xiaohan Yun ◽  
David B. Bogy ◽  
C. Singh Bhatia
Keyword(s):  
Hydrogen Content ◽  
High Vacuum ◽  
Carbon Films ◽  
Ultra High Vacuum ◽  
Carbon Overcoat ◽  
Carbon Coatings ◽  
Disk Interface ◽  
Atomic Structures ◽  
Chemical Factors ◽  
Friction Measurements

Hydrogenated carbon films (CHx) with different hydrogen content percentages have been examined. Drag tests on CHx coated disks, using 50 percent Al2O3/TiC sliders, with and without carbon coating on the slider air bearing surfaces (ABS), were conducted in an ultra high vacuum chamber equipped with a mass spectrometer. Mass fragments of lubricant released from the head disk interfaces were recorded in real time along with friction measurements. The results show that a higher hydrogen content in the carbon overcoat can improve wear durability by reducing the friction coefficient and affecting the chemical reactions between the sliders and the lubricant. A carbon overcoat on the slider ABS can protect Z-dol lubricant from catalytic reaction with the Al2O3 in the slider material. The wear durability at the head disk interface is controlled by combined mechanical and chemical factors, which are defined by the atomic structures of the contacting surfaces.

The Decomposition Mechanisms and Thermal Stability of ZDOL Lubricant on Hydrogenated Carbon Overcoats

1999 ◽  
Vol 122 (2) ◽  
pp. 458-464 ◽  
Author(s):  
Chao-Yuan Chen ◽  
Jianjun Wei ◽  
Walton Fong ◽  
David B. Bogy ◽  
C. Singh Bhatia
Keyword(s):  
Frictional Heating ◽  
High Vacuum ◽  
Catalytic Decomposition ◽  
Ultra High Vacuum ◽  
Carbon Overcoat ◽  
Disk Interface ◽  
Decomposition Mechanisms ◽  
Carbon Coated ◽  
Chemical Studies ◽  
Carbon Overcoats

Tribo-chemical studies of the head/disk interface (HDI) were conducted using hydrogenated CHx carbon disk samples coated with perfluoropolyether ZDOL lubricant. The studies involved drag tests with uncoated and carbon-coated Al2O3-TiC sliders and thermal desorption experiments in an ultra-high vacuum (UHV) tribochamber. The friction and catalytic decomposition mechanisms as well as the thermal behavior of ZDOL are described, and data demonstrating the chemical reactions of the lubricant and carbon overcoat are also presented. During the sliding at the carbon-coated slider/ZDOL lubricated CHx disk interface, frictional heating is the primary decomposition mechanism of ZDOL. [S0742-4787(00)01902-0]

Low-Temperature CVD Carbon Coatings on Glass Plates for Flat Panel Display Applications

2000 ◽  
Vol 621 ◽  
Author(s):  
Yonhua Tzeng ◽  
Chao Liu ◽  
Calvin Cutshaw ◽  
Zheng Chen
Keyword(s):  
Low Temperature ◽  
Electric Field ◽  
Electron Emission ◽  
High Vacuum ◽  
Carbon Films ◽  
Ultra High Vacuum ◽  
Flat Panel Display ◽  
Carbon Coatings ◽  
Coated Glass ◽  
Glass Plates

ABSTRACTLow-temperature chemical vapor deposition processes were studied for coating carbon films on metal-coated glass plates. Thermal CVD in hydrocarbon mixtures was used for carbon deposition at temperatures between 300°C and 550°C. Carbon deposited on metal coated glass plates were examined by SEM and analyzed using a pin to disk setup in an ultra high vacuum chamber for measuring the electron emission characteristics. Using a one-millimeter diameter tungsten rod with a hemispherical tip as the anode while the carbon coatings as the cathode, current-voltage characteristics of the carbon coatings were measured and used for calculating the electric field at which electron emission started as well as calculating the field enhancement factor of the carbon coatings. Field emission of electrons from carbon coatings starting from an electric field as low as 1.4 volts per micrometer has been achieved.

Large Area Surface Treatment by Ion Beam Technology

1996 ◽  
Vol 438 ◽  
Author(s):  
R. L. C. Wu ◽  
W. Lanter
Keyword(s):  
Ion Beam ◽  
High Vacuum ◽  
Polycrystalline Diamond ◽  
Carbon Films ◽  
Ultra High Vacuum ◽  
Diamond Like Carbon ◽  
Chemical Compositions ◽  
Rf Power ◽  
Large Area ◽  
Ion Energy

AbstractAn ultra high vacuum ion beam system, consisting of a 20 cm diameter Rf excilted (13.56 MHz) ion gun and a four-axis substrate scanner, has been used to modify large surfaces (up to 1000 cm2) of various materials, including; infrared windows, silicon nitride, polycrystalline diamond, 304 and 316 stainless steels, 440C and M50 steels, aluminum alloys, and polycarbonates; by depositing different chemical compositions of diamond-like carbon films. The influences of ion energy, Rf power, gas composition (H2/CH4 , Ar/CH4 and O2/CH4/H2), on the diamond-like carbon characteristics has been studied. Particular attention was focused on adhesion, environmental effects, IR(3–12 μm) transmission, coefficient of friction, and wear factors under spacelike environments of diamond-like carbon films on various substrates. A quadrupole mass spectrometer was utilized to monitor the ion beam composition for quality control and process optimization.

Tribochemistry of ZDOL Decomposition on Carbon Overcoats in Ultra-High Vacuum (UHV)

1999 ◽  
Vol 594 ◽  
Author(s):  
C. S. Bhatia ◽  
C.-Y. Chen ◽  
W. Fong ◽  
D. B. Bogy
Keyword(s):  
Thermal Desorption ◽  
Wear Track ◽  
High Vacuum ◽  
Catalytic Decomposition ◽  
Ultra High Vacuum ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Desorption Temperature ◽  
Two Distinct Temperatures ◽  
Carbon Overcoats

AbstractTribochemical studies of the effect of lubricant bonding on the tribology of the head/disk interface (HDI) were conducted using hydrogenated (CHx) carbon disk samples coated with perfluoropolyether ZDOL lubricant. The studies involved drag tests with uncoated and carboncoated Al2O3-TiC sliders and also thermal desorption experiments in an ultra-high vacuum (UHV) tribochamber. We observed that a larger mobile lubricant portion significantly enhances the wear durability of the (head/disk interface) HDI by providing a reservoir to constantly replenish the lubricant displaced in the wear track during drag tests. In the thermal desorption tests we observed two distinct temperatures of desorption. The mobile ZDOL layer is desorbed at the lower thermal desorption temperature and the residual bonded ZDOL layer is desorbed at the higher thermal desorption temperature. We also observed that the hydrogen evolution from CHx overcoats initiates lubricant catalytic decomposition with uncoated Al2O3/TiC sliders, forming CF3 (69) and C2F5 (119). The generation of Hydroflouric acid (HF) during thermal desorption experiments provides the formation mechanism of Lewis acid, which is the necessary component for catalytic reaction causing Z-DOL lube degradation.

Ultra High Vacuum Scanning Tunneling Microscopy Observation of Multilayer Step Structure on GaAs and AlAs Vicinal Surface Grown by Metalorganic Vapor Phase Epitaxy

1996 ◽  
Vol 448 ◽  
Author(s):  
Jun-Ya Ishizaki ◽  
Yasuhiko Ishizaki ◽  
Takashi Fukui
Keyword(s):  
Scanning Tunneling Microscopy ◽  
High Vacuum ◽  
Gaas Layer ◽  
Layer Growth ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Vicinal Surface ◽  
Microscopy Observation ◽  
Tunneling Microscopy ◽  
Atomic Structures

AbstractWe observe the atomic structures at the multilayer step region on MOVPE-grown GaAs (001) vicinal surface using ultra high vacuum scanning tunneling microscopy (UHV-STM), and clarify that (4×2) or (4×3) like reconstruction units are dominant. Oxide free AlAs surfaces grown on GaAs vicinal surface are also successfully observed by UHV-STM. The reconstruction units at the multilayer step region on AlAs surface have the same units on GaAs vicinal surface. GaAs surface has the lack of dimmer rows on the terrace region just below the multilayer step region, while AlAs surface has dimmer rows even on the terrace just below the multilayer step region. GaAs layer growth leads tothe step bunching phenomenon and AlAs surface leads to the step debunching phenomenon.

Delamination of Ultra-Thin Diamond-Like Carbon Coatings on Magnetic Recording Heads Under Normal Loading

2013 ◽  
Author(s):  
Michael Price ◽  
Andrey Ovcharenko ◽  
Raj Thangaraj ◽  
Bart Raeymaekers
Keyword(s):  
Amorphous Carbon ◽  
Normal Load ◽  
Substrate Material ◽  
Adhesion Layer ◽  
Carbon Overcoat ◽  
Normal Loading ◽  
Carbon Coatings ◽  
Disk Interface ◽  
Recording Heads ◽  
Magnetic Recording Heads

Delamination between an ultra-thin amorphous carbon overcoat, a silicon adhesion layer, and permalloy substrate material of a hard drive recording head is studied during normal loading/unloading of the head disk interface. The effect of normal load and thickness of the silicon adhesion layer on delamination of the Si-permalloy and amorphous carbon-Si interfaces is quantified using a molecular dynamics model. No permanent delamination is found for contact pressures up to 100 MPa, except for the case where a silicon adhesion layer is absent.

Controlling the formation process and atomic structures of single pyrazine molecular junction by tuning the strength of the metal–molecule interaction

2017 ◽  
Vol 19 (15) ◽  
pp. 9843-9848 ◽  
Author(s):  
Satoshi Kaneko ◽  
Ryoji Takahashi ◽  
Shintaro Fujii ◽  
Tomoaki Nishino ◽  
Manabu Kiguchi
Keyword(s):  
Formation Process ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Molecular Junction ◽  
Break Junction ◽  
Atomic Structures ◽  
Molecule Interaction

Fabrication of single pyrazine molecular junction with Au, Ag and Cu electrodes using mechanically controllable break junction technique in ultra-high vacuum.

Hrem Investigation of the Structure of the Σ5(210)/[001] Symmetric Tilt Grain Boundaries in Nb.

1991 ◽  
Vol 229 ◽  
Author(s):  
G. H. Campbell ◽  
S. M. Foiles ◽  
Wayne E. King ◽  
M. Rühle ◽  
W. Wien
Keyword(s):  
High Vacuum ◽  
High Resolution Electron Microscopy ◽  
Ultra High Vacuum ◽  
Experimental Result ◽  
Energy Structure ◽  
Interatomic Potentials ◽  
Pseudopotential Theory ◽  
Atomic Structures ◽  
Embedded Atom ◽  
Symmetric Tilt

AbstractWe have simulated the atomic structures of the Σ 5 (210)/[001 ] symmetric tilt grain boundary using interatomic potentials for Nb developed employing the embedded atom method (EAM) and the model generalized pseudopotential theory (MGPT). These potentials do not predict the same lowest energy structure for the Σ 5 (210)/[001]. Using the ultra high vacuum diffusion bonding process, we have fabricated Σ 5 (210)/[001] bicrystals. The samples have been observed using high resolution electron microscopy and the observed images have been compared with those simulated based on the structures predicted theoretically. The experimental result for the Σ 5 (210)/[001] is in close agreement with the structure predicted using the EAM.

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