Crystalline-Phase Glass Composition for HAMR Substrate Rigidity
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Solution Overview
Problem
Magnetic recording media require substrates with higher mechanical properties and heat resistance to support increased data density and heat-assisted magnetic recording (HAMR) technologies.
Innovation Solution
A glass containing a crystalline phase, comprising specific compositions and properties such as cristobalite, lithium disilicate, and petalite, with a Young's modulus to specific gravity ratio (E/ρ) of 35 or more and a glass transition point of 680°C or higher, providing enhanced rigidity, heat resistance, and reduced vibration during high-speed rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional glass substrates are used, then manufacturing is easier, but mechanical properties and heat resistance are insufficient for HAMR technology
Solution Approach 1:
The patent employs composite glass-ceramic materials containing specific crystalline phases (cristobalite, lithium disilicate, and/or petalite) embedded in a glass matrix. This composite structure provides superior mechanical properties and heat resistance compared to conventional glass, while the crystalline phases are formed through controlled heat treatment of the glass composition, making the manufacturing process feasible through standard ceramic processing techniques.
Solution Approach 2:
The patent specifies precise compositional parameters (SiO2: 65-85 wt%, Al2O3: 1.5-10 wt%, Li2O: 0-13 wt%, with specific ratios) and thermal processing parameters (glass transition temperature ≥680°C, heat treatment temperatures) to transform ordinary glass into high-performance glass-ceramic substrates. These parameter controls enable the formation of desired crystalline phases that provide enhanced mechanical and thermal properties.
2Strength
If glass substrate with high rigidity is used, then deflection during high-speed rotation is reduced, but weight increases
Solution Approach 1:
The glass-ceramic composite material provides high rigidity through the crystalline phase network structure while maintaining relatively low density. The specific crystalline phases (cristobalite, lithium disilicate, petalite) form a rigid framework that resists deflection during high-speed rotation, yet the overall material density is controlled through the glass matrix composition, achieving an optimal strength-to-weight ratio for rotating substrates.
3Temperature
If glass transition point is increased to 680°C or higher, then heat resistance is improved for HAMR, but manufacturing process becomes more difficult
Solution Approach 1:
The patent achieves high glass transition temperature (≥680°C) by controlling the chemical composition parameters, specifically the ratios of SiO2, Al2O3, and Li2O, along with the presence of specific crystalline phases. These compositional parameters directly determine the thermal properties of the glass matrix, enabling high heat resistance while maintaining manufacturability through controlled cooling rates and heat treatment schedules that facilitate crystalline phase formation.
Data Source
AI summary
Provided is a glass containing a crystalline phase, the glass including at least one crystalline phase selected from the group consisting of cristobalite, lithium disilicate, and petalite, in which a value of E/ρ, which is a ratio of Young's modulus E to specific gravity ρ, is 35 or more, and a glass transition point is 680° C. or higher.