Two-Layer Glass-Ceramic Coating for Dishwasher-Safe Metal Surfaces
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Solution Overview
Problem
Current glass-like or ceramic-like protective layers on metallic surfaces lack adequate mechanical and chemical properties, such as resistance to acids, bases, and dishwasher safety, due to limitations in thickness, expansion coefficients, and the presence of alkali content, which restricts their durability and suitability for applications like cookware and household appliances.
Innovation Solution
A two-layer protective system is applied, comprising a base layer of alkali and/or alkaline earth silicate with incorporated pigments, followed by a top layer of oxidic silicon compounds free from alkali and alkaline earth metal ions, which is thermally compacted to enhance chemical resistance and non-stick properties, avoiding the use of PTFE (Teflon) and ensuring long-term stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass-like protective layers are applied via sol-gel processes with thickness limited to around 1 μm, then the layers can be applied easily, but they lack adequate mechanical and chemical properties such as resistance to acids, bases, and corrosion
Solution Approach 1:
The protective layer is divided into two distinct layers: a base layer applied via sol-gel process providing ease of application, and a top enamel layer providing chemical resistance. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
The invention creates a composite structure combining sol-gel derived glass layer with traditional enamel coating. The base layer uses sol-gel process for easy application while the top layer uses enamel formulation for chemical resistance, achieving properties neither layer could provide alone.
2Temperature
If glass compositions are used with high alkali content to enable easy melting at low temperatures, then the melting temperature is reduced to 750-800°C, but the chemical resistance deteriorates due to low durability against glass corrosion
Solution Approach 1:
The functional requirements are segmented between two layers: the base layer handles application ease through sol-gel process, while the top enamel layer provides chemical resistance without requiring high alkali content, thus maintaining durability against corrosion.
Solution Approach 2:
Different regions of the coating system have different compositions optimized for their specific functions. The base layer has composition optimized for easy application and adhesion, while the top layer has composition optimized for chemical resistance and durability.
3Reliability
If large layer thickness is used to achieve dense enamel layers, then chemical resistance is improved, but the expansion coefficients must be adapted well to metallic shaped bodies, severely restricting composition selection
Solution Approach 1:
The coating system is segmented into base layer and top layer, each with different thicknesses and compositions. The base layer can be optimized for adhesion and expansion coefficient matching, while the top layer can be optimized for chemical resistance without being constrained by expansion coefficient requirements.
4Reliability
If enamel is applied on aluminum or magnesium alloys, then protective properties are achieved, but the metal melts or deforms significantly at temperatures above 600°C
Solution Approach 1:
The two-layer system allows the base layer to provide thermal management and adhesion to the metal substrate, while the top enamel layer provides chemical protection. This segmentation enables better thermal compatibility with sensitive metals like aluminum and magnesium alloys.
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 two-layer system achieves improved chemical and hydrolytic stability, dishwasher resistance, and non-stick properties, significantly extending the service life of the protective layer while maintaining mechanical and thermal resistance, making it suitable for high-temperature and corrosive environments.
Implementation Method 1
the coating composition applied to the metallic surface is then subjected to thermal compaction
Implementation Method 2
Glass, glass-ceramic or ceramic-like layers are produced by a sol-gel process
Data Source
AI summary
The invention relates to items comprising a metal surface that is provided with a glass-, glass ceramic- or ceramic-type protective layer, characterized in that the protective layer has a base layer comprising a matrix made of an alkali and/or earth alkali silicate and an alkali metal- and alkaline earth metal-free cover layer comprising a matrix made of an oxidic silicon compound, and to a method for producing said items. The items comprising the protective layer exhibit high chemical resistance and improved non-stick properties. They are characterized in particular by high dishwashing resistance.