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]

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

1999 ◽  
Vol 593 ◽  
Author(s):  
C.S. Bhatia ◽  
C.-Y. Chen ◽  
W. Fong ◽  
D.B. Bogy
Keyword(s):  
Thermal Desorption ◽  
High Vacuum ◽  
Catalytic Decomposition ◽  
Ultra High Vacuum ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Desorption Temperature ◽  
Carbon Coated ◽  
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 carbon-coated A1203-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 A1203/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

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.

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.

Effects of Backbone and Endgroup on the Decomposition Mechanisms of PFPE Lubricants and Their Tribological Performance at the Head-Disk Interface

2000 ◽  
Vol 123 (2) ◽  
pp. 364-367 ◽  
Author(s):  
Chao-Yuan Chen ◽  
David B. Bogy ◽  
C. Singh Bhatia
Keyword(s):  
Removal Rate ◽  
Catalytic Decomposition ◽  
Degradation Process ◽  
Catalytic Degradation ◽  
Carbon Surface ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Pfpe Lubricant ◽  
Carbon Coated ◽  
Chemical Studies

Tribo-chemical studies of the lubricant endgroup effect on the tribology of the head-disk interface were conducted using carbon disks coated with PFPE lubricant. The studies involved drag tests with uncoated and carbon-coated Al2O3-TiC sliders in an ultrahigh-vacuum (UHV) tribochamber. The UHV drag tests show that a good lubricant should have one active OH endgroup and one nonactive endgroup. The active one insures the lubricant is adsorbed very well onto the disk carbon surface, resulting in a lower removal rate of the lubricants during the contact sliding. The nonactive one prevents the catalytic decomposition of the lubricant in the presence of the Al2O3 surface of the uncoated slider. The studies also demonstrate that the catalytic degradation process of ZDOL in the presence of Lewis acid occurs most readily at the acetal units -O-CF2-O within the internal backbones (CF2O and CF2CF2O) instead of the endgroup functionals. Therefore, demnum, without any acetal units, experiences less catalytic degradation with the uncoated Al2O3/TiC sliders as compared to ZDOL.

Tribo-Chemical Wear of Amorphous Carbon Overcoats and TiC in Al2O3-TiC Sliders

2000 ◽  
Vol 123 (2) ◽  
pp. 324-329 ◽  
Author(s):  
Lihong Zhang
Keyword(s):  
Amorphous Carbon ◽  
Shear Force ◽  
Frictional Heating ◽  
Carbon Diffusion ◽  
Raman Analysis ◽  
Titanium Oxidation ◽  
Carbon Coated ◽  
Carbon Overcoats ◽  
Interface Materials ◽  
Crystalline Graphite

Ambient drag experiments were carried out using Al2O3-TiC sliders and carbon-coated aluminum/magnesium substrate disks. Worn carbon of disks resulted in sub-micron particles that transferred to smears under frictional heating and mechanical shear force. Raman analysis found graphitization for carbon debris and smears but not for carbon within wear tracks. The carbon of wear tracks was also considered graphitized but was very superficial. Decomposition of TiC in DLC-coated and uncoated sliders was also observed and caused by carbon diffusion and titanium oxidation. Diffused carbon could be poly-crystalline graphite and amorphous depending on the reactive environment of the interface. Discussions were made on tribo-chemical wear of the interface materials.

Selective Oxidation of Ammonia on Ruthenium to Form p(2 x 2) Nitrogen Layer

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Balgooyen ◽  
I. Waluyo
Keyword(s):  
Low Temperature ◽  
High Vacuum ◽  
Hydrogenation Reaction ◽  
Ultra High Vacuum ◽  
Surface Chemical ◽  
Low Energy Electron Diffraction ◽  
Chemical Studies ◽  
Low Energy Electron ◽  
Temperature Programmed ◽  
Oxidation Of Ammonia

Oxidation of ammonia was used to prepare a p(2 x 2) nitrogen layer on the Ru(0001) surface as verified by temperature-programmed desorption (TPD) and low energy electron diffraction (LEED). The process takes place in an ultra-high vacuum (UHV) chamber. The surface is precovered with oxygen and then exposed to ammonia at low temperature. Upon heating, the ammonia is oxidized to form water, which desorbs at low temperature to leave a nitrogencovered surface. The resulting layer can be used in a variety of surface chemical studies, including a hydrogenation reaction, which is an important part in the study of the Haber-Bosch process, in which ruthenium is used as a catalyst.

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