Magnetic Recording Medium Surface Friction Stability
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Solution Overview
Problem
Magnetic recording media experience an increase in coefficient of friction during repeated sliding with a magnetic head, leading to deterioration in running stability, despite initial low friction achieved by controlling the surface shape of the magnetic layer.
Innovation Solution
A magnetic recording medium with a magnetic layer comprising ferromagnetic powder and a binding agent on a non-magnetic support, where the difference in spacing measured under different pressures is controlled to be equal to or smaller than 3.0 nm, preventing significant change in the surface projection height and thus maintaining low friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the surface shape of the magnetic layer is controlled to reduce the coefficient of friction initially, then the coefficient of friction decreases, but the coefficient of friction increases during repeated sliding
Solution Approach 1:
The invention controls the change in surface projection height by adjusting the difference in spacing under different pressures to be 3.0 nm or less. This parameter control prevents the surface shape from changing significantly during repeated sliding, thereby maintaining low coefficient of friction and stable running characteristics throughout the medium's service life
Solution Approach 2:
Instead of trying to maintain a perfectly flat surface (which would give high friction), the invention accepts and controls a specific type of surface unevenness (projections of 5-50 nm height) that initially reduces friction. The key is controlling how this surface shape changes under pressure during repeated sliding, rather than eliminating the surface features themselves
2Object-affected harmful factors
If projections are formed on the magnetic layer surface to reduce friction, then the coefficient of friction decreases, but the surface shape changes under pressing force
Solution Approach 1:
The invention quantifies and controls the change in surface projection height by measuring the difference in spacing under 0.5 atm and 13.5 atm pressures. By ensuring this difference is 3.0 nm or less, the invention maintains surface shape stability while preserving the friction-reducing projections
Solution Approach 2:
The invention allows different local regions of the magnetic layer surface to have different properties - some areas have projections (5-50 nm height) that reduce friction, while other areas maintain the base surface characteristics. This local variation is controlled to ensure overall shape stability under pressure
Data Source
AI summary
The magnetic recording medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which a difference (S0.5−S13.5) between a spacing S0.5 measured by optical interferometry regarding a surface of the magnetic layer under a pressing force of 0.5 atm after n-hexane cleaning and a spacing S13.5 measured by optical interferometry regarding the surface of the magnetic layer under a pressing force of 13.5 atm after n-hexane cleaning is equal to or smaller than 3.0 nm, and a magnetic recording and reproducing device including this magnetic recording medium.