Pyrolysis-Resistant Sol-Gel Coating for Stain-Free Metal Surfaces
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Solution Overview
Problem
Existing coating systems for metal components in cooking appliances fail to provide adequate thermal stability, corrosion protection, and aesthetic appeal, often leading to tarnishing, porosity, and harmful emissions under high-temperature stress.
Innovation Solution
A sol-based coating solution composed of silane and polysiloxane, combined with alkali metal or alkaline earth metal oxides/hydroxides, which forms a dense, impermeable layer upon curing, preventing tarnishing and corrosion while maintaining mechanical stability and aesthetic appeal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a glass layer is applied wet-chemically using sol-gel process to protect stainless steel, then the tendency to flake off is minimized due to thin layer thickness, but the porosity of the layers leads to diffusion of food components during pyrolysis causing visible staining
Solution Approach 1:
The patent changes the chemical composition parameters of the coating system by combining organosilanes with specific metal oxides (Al2O3, SiO2, TiO2, ZrO2) and organic compounds. This composition modification transforms the coating from a porous structure to a dense, non-porous structure that prevents food component diffusion while maintaining thin layer thickness and good adhesion.
Solution Approach 2:
The patent creates a composite coating material combining organosilane base components with multiple metal oxides and organic compounds. This composite structure achieves both low porosity (preventing staining) and sufficient thickness for protection, resolving the contradiction between adhesion and stain resistance.
2Object-affected harmful factors
If enamel layers are used on metallic components, then protection from thermal and chemical stress is provided, but the enamel tends to flake off under shock/impact loads
Solution Approach 1:
The patent applies a thin film coating (1-10 μm) through sol-gel process that provides thermal and chemical protection without the brittleness of enamel. The flexible nature of this thin coating prevents flaking under impact loads while maintaining protective functions against thermal stress and chemical corrosion.
Solution Approach 2:
The patent modifies the coating thickness parameter from traditional thick enamel layers to thin sol-gel layers (1-10 μm). This parameter change maintains thermal and chemical protection while significantly improving impact resistance and preventing flaking.
3Quantity of substance
If inexpensive stainless steel types are used for oven components, then cost is reduced, but the steel tarnishes and corrode severely at high temperatures due to chloride salts
Solution Approach 1:
The patent applies a thin, cost-effective sol-gel coating that provides long-lasting protection against tarnishing and corrosion. While the coating itself is relatively inexpensive to apply, it extends the service life of the stainless steel component by protecting it from high-temperature degradation and chloride corrosion.
Solution Approach 2:
The sol-gel coating acts as an intermediary protective layer between the inexpensive stainless steel and the harsh oven environment (high temperature, chloride salts). This intermediate layer prevents direct contact between the steel and corrosive elements, eliminating tarnishing and corrosion while maintaining cost effectiveness.
4Object-affected harmful factors
If coating thickness is increased to prevent porosity and food component diffusion, then staining is prevented, but the coating becomes more prone to flaking and cracking
Solution Approach 1:
The patent changes the chemical composition parameters of the coating system by incorporating specific metal oxides and organic compounds that enable the formation of a dense, non-porous structure at very thin thickness (1-10 μm). This composition optimization achieves stain resistance without requiring increased thickness that would cause flaking or cracking.
Solution Approach 2:
The patent successfully applies a flexible thin film coating that is sufficiently thick to be non-porous and prevent food component diffusion, yet thin enough to maintain good adhesion and resist flaking and cracking under thermal and mechanical stress.
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 coating solution achieves high thermal resistance up to 500°C, prevents staining, and ensures mechanical stability without releasing harmful emissions, providing a durable and aesthetically pleasing surface on metal components.
Implementation Method 1
a sol composition based on a mixture of at least one silane and at least one polysiloxane curable by hydrolysis and condensation on a substrate to form a coating on the substrate
Implementation Method 2
a sol composition based on a mixture of at least one silane and at least one polysiloxane curable by hydrolysis and condensation on a substrate to form a coating on the substrate
Implementation Method 3
The coating solution achieves high thermal resistance up to 500°C
Data Source
AI summary
The invention relates to a coating solution made from a mixture of at least one silane and at least one polysiloxane which can be hardened on a substrate by hydrolysis and condensation to give a coating on the substrate, wherein the at least one silane is of general formula RxSi(OR')4-x and the at least one polysiloxane is of general formula [R2SiO]y or R3Si-(O-SiR2)Y-O-SiR3 , where R independently = alkyl, aryl, arylalkyl, alkylaryl or H, R' independently = H, methyl, ethyl, n- or i-propyl, n-, iso-, sec.- or tert.-butyl, x = 0 or 1 (for the first silane), x = 0, 1 , 2, 3 or 4 (for each further silane) and y = a whole number of at least 2 and which can be almost infinitely large, characterised in that the coating solution comprises in addition at least one alkali or earth alkali oxide or hydroxide.