LAS Glass-Ceramic Cooktop Composition for Low-Color Transparency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing glass-ceramics used in cooking surfaces suffer from issues such as high coloration, low thermal stability, and poor optical properties, making them unsuitable for use in induction-heated cooktops, particularly due to the formation of Fe/Ti and Sn/Ti color complexes, which affect the perception of underside coatings and hinder the use of optical temperature sensors.
Innovation Solution
A lithium aluminum silicate (LAS) glass ceramic plate with specific compositions and manufacturing conditions, including TiO2 as a nucleating agent, is developed to achieve high transparency and low color perception, ensuring that the underside coating's color is perceived authentically through the glass ceramic plate by maintaining optimal brightness and chroma values within defined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional glass-ceramics with Fe/Ti and Sn/Ti color complexes are used, then manufacturing is easier, but color perception is poor and transparency is reduced
Solution Approach 1:
The patent changes the chemical composition parameters by strictly limiting Fe2O3 to ≤0.02 wt.% and SnO2 to ≤0.05 wt.%, and by optimizing TiO2 content to 1.6-2.8 wt.%. These parameter changes eliminate the harmful Fe/Ti and Sn/Ti color complexes while maintaining manufacturability through controlled raw material selection and processing.
Solution Approach 2:
The patent applies local quality by creating a specific compositional regime where TiO2 is present in optimal amounts (1.6-2.8 wt.%) to serve as a beneficial nucleating agent, while Fe and Sn are restricted to trace amounts only. This localized optimization of element distribution and concentration achieves both transparency and manufacturability.
2Illumination intensity
If transparent glass-ceramics with low color are developed, then color perception improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges: Fe2O3 ≤0.02 wt.%, SnO2 ≤0.05 wt.%, TiO2 = 1.6-2.8 wt.%, Li2O = 3.2-4.5 wt.%, Al2O3 = 19-24 wt.%, SiO2 = 62-68 wt.%. These defined parameters provide clear manufacturing targets that balance optical performance with production feasibility.
Solution Approach 2:
The patent creates a composite glass-ceramic system where multiple components work together: TiO2 provides nucleation for high-quartz crystals, Li2O-Al2O3-SiO2 forms the glass matrix, and trace Fe/Sn are controlled to minimum levels. This composite approach achieves superior optical properties while maintaining manufacturing control.
3Ease of manufacture
If high MgO content is added to reduce melting temperature, then ease of manufacture improves, but color perception deteriorates
Solution Approach 1:
The patent deliberately limits MgO to ≤0.5 wt.% despite its melting temperature reduction benefits, because higher MgO content promotes Fe/Ti and Sn/Ti color complexes. This parameter restriction prioritizes optical quality over processing ease, accepting higher melting temperatures to maintain color neutrality.
Solution Approach 2:
The patent converts the potential harm of high melting temperatures into a benefit by using the elevated processing conditions to ensure complete dissolution of raw materials and formation of a homogeneous glass matrix, which then crystallizes to produce the desired optical properties without color complexes.
4Illumination intensity
If TiO2 is used as nucleating agent, then transparency improves, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes TiO2 content to 1.6-2.8 wt.%, which provides sufficient nucleation for high-quartz crystal formation while avoiding excessive TiO2 that would create color complexes. This parameter optimization achieves transparency without requiring complex additional processing steps.
Solution Approach 2:
TiO2 serves multiple functions in the patent: it acts as a nucleating agent for high-quartz crystal formation, provides some coloring control, and contributes to the overall glass-ceramic structure. This multi-functionality reduces the need for separate additives and simplifies the overall formulation.
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 plate achieves high transparency and low color perception, allowing the underside coating's color to be seen authentically, while minimizing scattering and manufacturing disadvantages, thus enhancing the visibility of displays and improving the overall cooking surface's performance.
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... allowing the underside coating's color to be seen authentically through the glass ceramic plate
Data Source
Figure 1
Figure 2
Figure 3
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∗+bConditionB1 with a = 0.765 with b ≥ 93.5 and with 0≤cT∗≤3.