Low-Lithium LAS Glass Ceramic for Low-Expansion Cooktops
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Solution Overview
Problem
Existing glass ceramics for cooking surfaces face challenges in achieving low thermal expansion, cost-effectiveness, and optimal optical transmittance while maintaining chemical and thermal resistance, often requiring high lithium content and expensive coloring oxides, which increase raw material costs and thermal expansion.
Innovation Solution
A transparent colored glass ceramic with a high-quartz solid solution as the main crystal phase, containing 3.0 to 3.6% lithium oxide and colored with 0.003 to 0.05% vanadium oxide or molybdenum oxide, optimized with magnesium oxide, zinc oxide, and barium oxide to achieve low thermal expansion and reduced raw material costs, while avoiding expensive coloring oxides and harmful refining agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high lithium content (4-5% by weight) is used to achieve low thermal expansion, then thermal expansion control is improved, but raw material costs increase
Solution Approach 1:
The patent reduces the lithium oxide content from the conventional 4-5% to 3.0-3.6%, thereby lowering raw material costs while maintaining the required thermal expansion properties through optimized crystal phase composition and additional oxide additions
2Illumination intensity
If expensive coloring oxides (CoO, NiO, Nd2O3, CuO) are used to achieve desired coloration, then optical properties are improved, but raw material costs increase
Solution Approach 1:
The patent replaces expensive coloring oxides (CoO, NiO, Nd2O3, CuO) with cheaper alternatives such as iron oxide and manganese oxide, achieving the required optical transmittance and coloration at lower raw material costs
Solution Approach 2:
The patent optimizes the concentration and combination of coloring oxides to achieve the desired optical properties with minimal amounts, reducing overall raw material costs while maintaining performance
3Productivity
If toxic refining agents (arsenic oxide, antimony oxide) are used to achieve proper glass refinement, then refining efficiency is improved, but environmental safety deteriorates
Solution Approach 1:
The patent replaces toxic refining agents (arsenic oxide, antimony oxide) with non-toxic alternatives such as tin oxide and silicon oxide, achieving adequate refining efficiency without environmental and occupational safety hazards
Solution Approach 2:
The patent uses the natural refining properties of tin oxide and silicon oxide to achieve proper glass refinement without the harmful effects of traditional toxic agents, turning a potential disadvantage into a beneficial environmental feature
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 solution provides a cost-effective glass ceramic with low thermal expansion, adequate chemical and thermal resistance, and adapted optical transmittance, suitable for cooking surfaces and display elements, ensuring efficient energy use and environmental safety.
Implementation Method 1
colored with 0.003 to 0.05% vanadium oxide or molybdenum oxide
Implementation Method 2
adapted optical transmittance
Implementation Method 3
exhibit very small thermal expansion in the range from room temperature to 700° C. and above, and this is achieved by a combination of crystal phases that exhibit negative thermal expansion with an amorphous residual glass phase exhibiting positive thermal expansion
Data Source
AI summary
A transparent colored glass ceramic, in particular an LAS glass ceramic, suitable for use as a cooking surface is provided. The transparent colored glass ceramic includes high-quartz solid solution (HQ s.s.) as a main crystal phase and exhibits thermal expansion of −1 to +1 ppm/Kin the range from 20° C. to 700° C. The glass ceramic has from 3.0 to 3.6 percent by weight of lithium oxide (Li2O) as constituents and either is colored with 0.003 to 0.05 percent by weight of vanadium oxide (V2O5) or is colored with 0.003 to 0.25 percent by weight of molybdenum oxide (MoO3).