Glass Substrate Composition for High-Temperature Magnetic Recording
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Solution Overview
Problem
The challenge is to produce a glass substrate suitable for forming a magnetic recording layer at high temperatures while ensuring thermal stability and impact resistance, as silicon substrates are weak and conventional glass substrates are prone to cracking.
Innovation Solution
A method for producing a glass substrate with specific compositions, including SiO2, Al2O3, B2O3, and alkaline earth metal oxides, that can withstand high temperatures and minimize cracking, comprising steps such as lapping, polishing, and cleaning, with an annealing point of at least 650°C to support high-temperature magnetic recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicon substrate is used for thermal assist magnetic recording, then the substrate can withstand high temperatures, but the substrate strength is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the glass substrate by controlling the content of specific oxides (SiO2: 62-74%, Al2O3: 6-18%, B2O3: 2-15%, and alkaline earth metal oxides: 8-21%). This compositional adjustment raises the annealing point to at least 650°C while maintaining adequate mechanical strength, resolving the contradiction between heat resistance and strength.
2Strength
If conventional glass substrate is used, then the substrate strength is sufficient, but the substrate is prone to cracking at high temperatures
Solution Approach 1:
The patent modifies the glass composition parameters by incorporating specific ranges of Al2O3 (6-18%) and B2O3 (2-15%) along with alkaline earth metal oxides. These compositional changes increase the annealing point to at least 650°C and optimize the thermal expansion characteristics, thereby improving cracking resistance at high temperatures while preserving mechanical strength.
Solution Approach 2:
The patent creates a composite glass material system combining multiple oxide components (SiO2, Al2O3, B2O3, and alkaline earth metal oxides) in specific proportions. This composite composition achieves synergistic effects where each component contributes to different properties: SiO2 provides structural framework, Al2O3 enhances strength and heat resistance, B2O3 improves chemical stability, and alkaline earth metal oxides adjust thermal expansion. The composite structure resolves the contradiction between strength and cracking resistance.
3Temperature
If glass substrate composition is optimized for high temperature, then the annealing point increases, but the impact resistance may decrease
Solution Approach 1:
The patent optimizes the compositional parameters within specific ranges rather than maximizing single components. The alkaline earth metal oxides (MgO, CaO, SrO, BaO) are controlled at 8-21% total content, providing sufficient flexibility to adjust both annealing point and impact resistance. This balanced parameter optimization within defined ranges resolves the contradiction between high annealing point and impact resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables the formation of a magnetic recording layer at high temperatures with improved impact resistance and reduced cracking rates, making the glass substrate suitable for high-density magnetic recording.
Implementation Method 1
forming a magnetic recording layer on a glass substrate having a temperature of at least 550° C.
Implementation Method 2
a glass substrate for an information recording medium, which comprises... an annealing point of at least 650°C to support high-temperature magnetic recording
Data Source
AI summary
To provide a method for producing a magnetic disk, whereby a magnetic recording layer is formed at a high temperature. A method for producing a magnetic disk, which comprises a step of forming a magnetic recording layer on a glass substrate having a temperature of at least 550° C., wherein the glass substrate comprises, as represented by mol percentage, from 62 to 74% of SiO2, from 6 to 18% of Al2O3, from 2 to 15% of B2O3 and from 8 to 21%, in total, of at least one component selected from MgO, CaO, SrO and BaO, provided that the total content of the above seven components is at least 95%, and further contains less than 1%, in total, of at least one component selected from Li2O, Na2O and K2O, or contains none of these three components.