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Modulated Protective Overcoat

IP.com Disclosure Number: IPCOM000035777D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brusic, VA: AUTHOR [+4]

Abstract

Thin film magnetic recording disks generally utilize Co-based alloys as the recording media and usually require a thin film of carbon to enhance flyability, lubrication retention and reduce atmospheric corrosion in files which are not hermetically sealed or protected by filters. The carbon is most often deposited by an RF or DC sputtering process and generally provides acceptable mechanical performance in terms of stiction, friction and wear. However, it has been found that these carbon overcoats do not provide corrosion protection. In fact, because the carbon is conductive and electrochemically more noble than the metallic underlayer, it can actually accelerate corrosion via galvanic attack.

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Modulated Protective Overcoat

Thin film magnetic recording disks generally utilize Co-based alloys as the recording media and usually require a thin film of carbon to enhance flyability, lubrication retention and reduce atmospheric corrosion in files which are not hermetically sealed or protected by filters. The carbon is most often deposited by an RF or DC sputtering process and generally provides acceptable mechanical performance in terms of stiction, friction and wear. However, it has been found that these carbon overcoats do not provide corrosion protection. In fact, because the carbon is conductive and electrochemically more noble than the metallic underlayer, it can actually accelerate corrosion via galvanic attack.

The carbon overcoat can be rendered much more protective by the introduction of hydrogen into the film to form amorphous C:H films.

The hydrogen may be introduced in a variety of ways, such as, but not limited to, plasma-enhanced CVD of an organic precursor, such as, acetylene, sputter deposition in the presence of hydrogen-containing plasmas, and reactive ion beam deposition. The table below shows the typical improvement afforded by the use of a-C:H films compared to C films where hydrogen has not been intentionally introduced. Corrosion Potential and Rate for C/CoP Samples

Sample Ecorr Icorr

V,nhe A/cm2

CoP -0.24 3x10-6

CoP/C(rf) -0.19 5x10-6

CoP/C:H(CVD) -0.26 7x10-9

While a-C:H films do significantly improve the corrosion resistance of CoP (and other Co-based alloys as well), they show poor adherence and erratic behavior on...