Behavior of Chemical Reaction Between Siloxane Compounds and Surface on Carbon Materials

2017 ◽  
Author(s):  
Tsuyoshi Shimizu ◽  
Hiroshi Tani
Keyword(s):  
Carbon Materials ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Surface ◽  
Normal Operation ◽  
Disk Drives ◽  
Organic Vapor ◽  
Siloxane Oligomers ◽  
Acidic Catalysts ◽  
Pfpe Lubricants

Among many organic vapor contaminations released from structural components of hard disk drives, organic sioloxanes are particularly ominous, as they can be released in a relatively large quantity. Adherence of organic pollutants to the disk surface is a factor that hinders the normal operation of the head and the disk surface. It is known that volatile siloxane oligomers such as D4 (octamethyl cycletetrasiloxane) often form cyclic polydimethylsiloxane polymers in the presence of acidic catalysts. We investigated the reaction between D4 and some carbon materials such as diamond-like carbon in hard disk and graphite. The effect of the protection of carbon materials by Perfluoropolyether (PFPE) lubricants was observed.

Flying Height Control for a 2-DOF Tripad Slider in Hard Disk Drives With Switched Regulator

2005 ◽  
Author(s):  
Zhizheng Wu ◽  
Foued Ben Amara
Keyword(s):  
Control Method ◽  
Hard Disk Drives ◽  
Surface Profile ◽  
Hard Disk ◽  
Disk Surface ◽  
Switched System ◽  
Flying Height ◽  
Disk Drives ◽  
The Stability ◽  
Adaptive Regulator

Maintaining a constant small flying height of the read/write head is an important target in the design of the ultra high storage density hard disk drives. One effective way to achieve this goal is to use a feedback regulator to suppress the flying height variations. For low flying heights, the read/write head enters into intermittent contact with the disk surface, which results in a switched system regulation problem. In this paper a new control method is proposed to maintain the flying height at its desired value based on the switched system models, despite the unknown microwaviness in the disk surface profile and the unpredictability in the switching times. First, a switched system model is constructed. Then, a Q parameterized set of switched regulators is constructed and the stability of the resulting switched closed loop system is analyzed. Online adaptive regulator tuning is then performed by adjusting the Q parameter in the controller to achieve regulation. Simulation results are presented to illustrate the effectiveness of the proposed method.

Reduction of Head Wear on Thin-Film Magnetic Disks

2002 ◽  
Author(s):  
Youich Kawakubo ◽  
Shunichi Miyazawa ◽  
Kenjirou Nagata ◽  
Shinichi Kobatake
Keyword(s):  
Thin Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Surface ◽  
Disk Drives ◽  
Magnetic Disks ◽  
Surface Flattening ◽  
Magnetic Disk ◽  
Pin On Disk ◽  
Wear Tests

It is necessary to reduce head wear to develop future hard disk drives. For this purpose, we have been studying transparent pin-on-disk wear tests on thin-film magnetic disks. We reported that pin wear on thin-film magnetic disk showed running-in effects. The reason of the running-in was considered to be a result of disk surface flattening. This means that if we could introduce an efficient burnishing technique, we could reduce head wear in operation. We then introduced a burnishing technique using a hemispherical diamond slider and compared pin wear on disk surfaces with and without burnishing. The results showed that the pin wear was reduced by the introduction of the burnishing technique. We consider that burnishing with hard round slider is another way of reducing head wear on future disk surfaces.

A Method to Detect Head Media Spacing Change in a Hard Disk Drive Using an Embedded Contact Sensor

2019 ◽  
Author(s):  
Rahul Rai ◽  
Puneet Bhargava ◽  
Bernhard Knigge ◽  
Aravind N. Murthy
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Disk Surface ◽  
Physical Change ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Frequency Components ◽  
Contact Sensor

Abstract Growth in the demand for higher capacity hard disk drives (HDD) has pushed the requirement for head-media spacing (HMS) to sub-nanometer levels. The drop in operational clearance makes a head-disk interface (HDI) more susceptible to potential head-wear and contamination related issues. Such degradation processes are often accompanied by a noticeable shift in the head-disk clearance. Hence monitoring an interface for a spacing change can be helpful in early detection of its imminent failure. In this paper, we present a method to detect the change in head-disk spacing using an embedded contact sensor (ECS). This technique involves the analysis of ECS dynamic response for an interface that is subjected to heater induced spacing modulations. As the head moves closer to the disk surface, the magnitude of the ECS frequency components can be used to determine the ‘characteristic spacing’ which can be used as a metric to detect any physical change for a given interface.

scholarly journals Low Molecular Weight Z-Tetraol Boundary Lubricant Films in Hard Disk Drives

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
R. J. Waltman ◽  
H. Deng
Keyword(s):  
Molecular Weight ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Disk Surface ◽  
Polar Component ◽  
Disk Drives ◽  
Disk Interface ◽  
Boundary Lubricant ◽  
Evaporative Loss

Lower molecular weight Z-Tetraol films exhibit increased mechanical spacing in the slider-disk interface due to a lower z-profile. An increased resistance to lubricant disturbance on the disk surface (e.g., lube moguls) with decreasing film thickness is attributed to an increasing contribution from the polar component of the disjoining pressure. Evaporative loss at temperatures typically encountered in a hard-disk drive also increases with decreasing molecular weight but is strongly dependent on the initial bonded fraction.

scholarly journals Examining the feasibility of the urban mining of hard disk drives

2020 ◽  
Vol 248 ◽  
pp. 119216
Author(s):  
Laura Talens Peiró ◽  
Alejandra Castro Girón ◽  
Xavier Gabarrell i Durany
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Urban Mining

scholarly journals Evaluation of Vibration Characteristics of Suspensions for Hard Disk Drives and Reducing the Vibration by Using Viscoelastic Dampers.

2002 ◽  
Vol 68 (667) ◽  
pp. 720-727 ◽  
Author(s):  
Hiromitsu MASUDA ◽  
Toshihiko SHIMIZU ◽  
Mikio TOKUYAMA ◽  
Haruhide TAKAHASHI ◽  
Kousaku WAKATSUKI ◽  
...  
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Vibration Characteristics ◽  
Disk Drives ◽  
Viscoelastic Dampers
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