LAS Glass-Ceramic Cooktop for Neutral Color and High Transparency
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Solution Overview
Problem
Existing glass ceramics for cooking surfaces have issues with color neutrality, thermal load capacity, and optical temperature sensing due to the use of borosilicate glasses, which suffer from low transparency and color shifting, and require high contents of nucleating agents that lead to increased melting and shaping temperatures, affecting manufacturing efficiency.
Innovation Solution
A lithium aluminum silicate (LAS) glass ceramic plate with high quartz mixed crystals and TiO2 as a nucleating agent, optimized to maintain low color and high transparency by controlling brightness and chroma values, ensuring the underside coating is perceived unadulterated through the glass ceramic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TiO2 is used as a nucleating agent in glass ceramic, then the glass ceramic achieves transparency and structural stability, but the color complexes increase leading to reduced brightness and increased color perception
Solution Approach 1:
The patent applies parameter changes by precisely controlling the TiO2 content within 0.5-2.0 wt% and adjusting the ratio of other oxides (Al2O3: 15-25 wt%, SiO2: 65-75 wt%, Li2O: 2-5 wt%) to optimize the balance between structural stability and optical properties. This compositional parameter optimization reduces color complex formation while maintaining the nucleating effect of TiO2 for crystal formation.
Solution Approach 2:
The patent creates a composite glass ceramic system combining multiple oxide components that work synergistically. The combination of TiO2 (nucleating agent), Al2O3 (structural former), SiO2 (glass matrix), and Li2O (flux) forms a composite material where each component contributes specific properties, achieving both structural stability and reduced color perception through the collective effect of the composite composition.
2Illumination intensity
If higher contents of alternative nucleating agents ZrO2 and/or SnO2 are used to avoid TiO2 color complexes, then color perception is reduced, but melting and shaping temperatures increase and devitrification resistance decreases
Solution Approach 1:
The patent changes the parameter of nucleating agent selection from alternative agents (ZrO2, SnO2) back to TiO2, but optimizes its concentration parameter to 0.5-2.0 wt% rather than higher contents. This parameter optimization allows TiO2 to function effectively as a nucleating agent at lower concentrations that do not trigger excessive color complex formation, thereby maintaining ease of manufacture with standard melting and shaping temperatures.
Solution Approach 2:
The patent applies local quality by distributing TiO2 uniformly throughout the glass ceramic matrix at optimized concentrations, ensuring that the nucleating effect is achieved locally at crystal formation sites without creating concentrated color complexes. This uniform distribution strategy maintains both optical brightness and manufacturing feasibility.
3Temperature
If transparent glass ceramics with high quartz mixed crystals are used for cooking surfaces, then thermal load capacity is improved, but color neutrality deteriorates due to yellowish tones from existing glass ceramics
Solution Approach 1:
The patent creates a composite glass ceramic material combining high quartz mixed crystals (for thermal capacity) with an optimized oxide composition (TiO2: 0.5-2.0 wt%, Al2O3: 15-25 wt%, SiO2: 65-75 wt%, Li2O: 2-5 wt%) that acts as a color-correcting matrix. This composite structure allows the crystalline phase to provide thermal performance while the glass matrix composition compensates for color deviations, achieving both thermal load capacity and color neutrality.
Solution Approach 2:
The patent changes the compositional parameters of the glass matrix to specifically counteract the yellowish tones inherent in high quartz glass ceramics. By adjusting the ratios of Al2O3, SiO2, and Li2O alongside controlled TiO2 content, the optical parameters are optimized to achieve color neutrality (ΔE < 2.0) while maintaining the thermal properties provided by the high quartz crystal structure.
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 LAS glass ceramic achieves high transparency and low color perception, maintaining manufacturing efficiency with reduced melting and shaping temperatures, allowing for clear display visibility and improved manufacturing processes.
Implementation Method 1
the glass ceramic plate contains TiO2 as a nucleating agent
Implementation Method 2
high transparency, which has a top surface and a bottom surface... Light transmission is > 88%... the glass ceramic plate has a brightness after the passage of light
Implementation Method 3
high quartz mixed crystals as the main crystal phase... Induction-heated cooking surfaces consisting of a transparent, colored glass ceramic plate
Implementation Method 4
Induction-heated cooking surfaces consisting of a transparent, colored glass ceramic plate... induction-heated cooking surfaces
Data Source
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AI summary
A cooktop made of a transparent lithium aluminum silicate glass-ceramic plate is described, which has a top surface and a bottom surface, wherein the bottom surface is at least partially provided with a bottom coating, wherein the glass-ceramic plate contains high-quartz mixed crystals as the main crystal phase, wherein the glass-ceramic plate contains TiO2 as a nucleating agent, wherein the glass-ceramic plate, after passing light of the standard illuminant D65 at a thickness of 4 mm, exhibits a brightness LT* and a chroma c* in the CIELAB color system, and wherein the brightness LT* satisfies the following relationship: LT*≥a⋅cT*+b with a = 0.765 with b ≥ 93.5 and with 0≤cT*≤3.