Low-CTE Enamelled Ceramic Composition for Large-Format Sheets
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Solution Overview
Problem
Existing ceramic materials with low thermal expansion coefficients require high-temperature heat treatments and have high frit content, leading to processing difficulties in conventional kilns and high pyroplasticity, and there is a lack of materials suitable for large format sheets without inosilicates.
Innovation Solution
A ceramic material composition in the SiO2—Al2O3—Li2O system with 65-85% frit and 15-35% inorganic raw materials, processed at 1150°C, which can be pressed and glazed, offering a low thermal expansion coefficient and suitable for large format sheets and slabs, with a decorative and protective glaze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high frit content (65-85%) is used to reduce thermal expansion coefficient, then low CTE is achieved, but pyroplasticity increases making processing difficult in conventional kilns
Solution Approach 1:
The invention changes the chemical composition parameters of the frit, specifically using a eutectic mixture in the SiO2-Al2O3-Li2O system with precise oxide ratios (45-70% SiO2, 20-40% Al2O3, 5-20% Li2O). This parameter optimization allows the frit to achieve low CTE while maintaining processability at lower temperatures (1150-1250°C) through controlled melting and crystallization behavior.
Solution Approach 2:
The invention creates a composite ceramic material combining the specialized low-CTE frit with traditional ceramic raw materials (kaolin, ball clay, flint) in optimized proportions. This composite approach allows the frit to provide thermal expansion control while the ceramic matrix maintains structural integrity and processability during kiln firing.
2Reliability
If high-temperature heat treatment (1180-1700°C for 1-40 hours) is applied to achieve low CTE, then thermal expansion is reduced, but processing time and energy consumption increase
Solution Approach 1:
The invention exploits phase transition phenomena during firing, specifically the eutectic melting and subsequent crystallization of the SiO2-Al2O3-Li2O frit system. The controlled phase transitions occur at lower temperatures (1150-1250°C) compared to conventional treatments, achieving the desired low CTE state through these transitions while significantly reducing processing time to typical kiln cycle durations.
3Strength
If inosilicates are included in the raw material composition, then ceramic material properties are improved, but thermal expansion coefficient increases
Solution Approach 1:
The invention extracts and removes inosilicate components from the raw material composition, replacing them with the specialized eutectic frit mixture. This extraction eliminates the source of high thermal expansion while maintaining ceramic strength and other desirable properties through the carefully formulated frit-ceramic composite system.
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 material achieves low thermal expansion, enabling processing in conventional kilns and providing a durable, decorative, and protective surface suitable for induction hobs and kitchen worktops without the need for additional heating elements.
Implementation Method 1
a ceramic material composition in the SiO2—Al2O3—Li2O system with 65-85% frit and 15-35% inorganic raw materials, processed at 1150°C, which can be pressed and glazed, offering a low thermal expansion coefficient
Implementation Method 2
processed at 1150°C, which can be pressed and glazed
Implementation Method 3
coated with a thin vitreous layer of glaze
Implementation Method 4
coated with a thin vitreous layer of glaze with a low coefficient of expansion, formulated with between 85% and 95% frit
Data Source
AI summary
Glazed ceramic material with a low coefficient of thermal expansion to be used as the main raw material (65% to 85%) in porcelain stoneware compositions to manufacture large format sheets (larger than 1.4 m) and also to be used as the main raw material in the manufacture of a glaze (85% to 95%) that will provide the large format sheet with a waterproof, protective and decorative surface. The frit will give the set (body with glaze) a very low coefficient of thermal expansion (hereinafter referred to as CTE). In addition, the resulting ceramic composition can be processed in a conventional ceramics kiln, as aspects such as melt viscosity or adhesion to the rollers have been taken into account during development. As it has a very low CTE, glazed ceramic material can be used as a substitute for glass ceramic material used in the manufacture of induction hobs. This glazed ceramic material can be coloured (both the body and the glaze) and decorated (the glaze), thus adding a new feature to the traditional induction hob.