Glass ceramic with reduced lithium content
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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.
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 using vanadium oxide or molybdenum oxide, which reduces raw material costs and thermal expansion, while optimizing thermal and chemical resistance and optical properties.
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 cost increases
Solution Approach 1:
The patent reduces the lithium oxide content from the conventional 4-5% by weight to 3.0-3.6% by weight, changing the chemical composition parameter to lower costs while maintaining the required thermal expansion properties through optimized crystal phase formation
Solution Approach 2:
The patent uses a composite approach by combining lithium aluminosilicate glass ceramic with specific crystal phases (high-quartz solid solution, keatite solid solution, and/or forsterite solid solution) to achieve the desired thermal expansion characteristics with reduced lithium content
2Illumination intensity
If expensive coloring oxides (CoO, NiO, Nd2O3, CuO) are used to achieve desired coloration, then optical properties are improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive coloring oxides (CoO, NiO, Nd2O3, CuO) with cheaper alternatives such as Fe2O3, MnO, and Cr2O3, using cost-effective materials to achieve the required optical properties without sacrificing performance
Solution Approach 2:
The patent optimizes the concentrations of coloring oxides (Fe2O3: 0.01-0.5%, MnO: 0.01-0.1%, Cr2O3: 0.01-0.1%) to achieve desired optical transmittance and coloration while minimizing raw material costs
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 (SnO2), using environmentally safe materials to achieve proper glass refinement without compromising refining efficiency
Solution Approach 2:
The patent converts the potential harm of toxic refining agents into a benefit by using non-toxic tin oxide that provides effective refining while improving environmental safety and occupational health conditions
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 resistance, and adapted optical transmittance, suitable for cooking surfaces, ensuring efficient energy use and environmental safety.
Implementation Method 1
The characteristic of these materials that is crucial for use as a cooking surface is to 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.
Implementation Method 2
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 using vanadium oxide or molybdenum oxide, which reduces raw material costs and thermal expansion, while optimizing thermal and chemical resistance and optical properties.
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/K in 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).