Sol-Gel Scratch-Resistant Coating for Glass Ceramic Cooktops

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Solution Overview

Problem

Current scratch-resistant coatings for cooktops, particularly glass ceramic surfaces, face issues with high costs, low reproducibility, and unsuitability for transparent substrates due to expensive sputtering processes, batch-to-batch variation, and limited integration of fillers, which also affect their appearance and decorative design capabilities.

Innovation Solution

A sol-gel process-based method for applying a transparent scratch-resistant coating comprising metal nitrides like aluminum nitride and zirconium nitride, using a sol with a controlled molar ratio of nitrogen carrier to metal precursors, allowing for deposition without vacuum processes, enabling uniform, transparent, and patternable coatings with enhanced scratch resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If sputtering process is used to deposit hard material layer, then scratch resistance is improved, but manufacturing cost and complexity increase significantly

Engineering Contradiction:
Improvescratch resistanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical sputtering process with a chemical sol-gel deposition method. The sol-gel process uses chemical reactions in solution to form the hard material layer (containing aluminum nitride, zirconium nitride, and silicon oxide) on the glass ceramic surface, eliminating the need for complex vacuum sputtering equipment and processes while achieving comparable or superior scratch resistance.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the deposition parameters from physical vapor deposition (sputtering) to chemical solution deposition (sol-gel). This involves transforming the material delivery mechanism from sputtered atoms in vacuum to hydrolyzed metal alkoxides in liquid solution, fundamentally altering the manufacturing approach while maintaining the hardening effect through controlled chemical composition.

Inventive Principle:
Principle #35Parameter changes

2Strength

If sputtering process is used, then hard material layer properties are achieved, but batch-to-batch reproducibility decreases

Engineering Contradiction:
Improvehard material layer propertiesVSAvoidbatch to batch reproducibility
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The sol-gel process inherently provides homogeneous distribution of metal precursors (aluminum, zirconium, silicon) throughout the coating solution. This uniformity ensures consistent composition and properties across all coated batches, as the chemical reaction occurs uniformly throughout the solution and on the substrate surface, eliminating the variability associated with sputtering parameter adjustments between batches.

Inventive Principle:
Principle #33Homogeneity

3Strength

If sputtering is used for coating, then scratch resistance is improved, but ability to maintain transparency and apply decorative designs is reduced

Engineering Contradiction:
Improvescratch resistanceVSAvoidtransparency in visible range
Core Design Contradiction:
StrengthVSIllumination intensity

Solution Approach 1:

The patent creates a composite hard material layer containing aluminum nitride, zirconium nitride, and silicon oxide in specific proportions. This composite composition provides both the required hardness for scratch resistance and optical transparency in the visible range. The sol-gel process allows precise control of the composite composition to balance mechanical and optical properties, unlike sputtering which creates more uniform but less tunable compositions.

Inventive Principle:
Principle #40Composite materials

4Strength

If sputtering process is used, then hard coating is deposited, but integration of functional and aesthetic fillers is not possible

Engineering Contradiction:
Improvecoating hardnessVSAvoidintegration of fillers
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The sol-gel process uses the liquid sol solution as an intermediary medium that can dissolve and carry various filler particles (functional and aesthetic) along with the metal precursors. During the sol-gel transformation and subsequent drying/firing, these fillers are uniformly distributed and integrated into the hard material layer, enabling both mechanical reinforcement and aesthetic customization while maintaining coating adhesion and hardness.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 method provides a stable, transparent, and scratch-resistant coating with improved durability and aesthetic appeal, maintaining performance under high temperatures and reducing mechanical and chemical attacks from cooking items and cleaners, while being cost-effective and suitable for mass production.

Implementation Method 1

A sol-gel process-based method for applying a transparent scratch-resistant coating comprising metal nitrides like aluminum nitride and zirconium nitride

Methodology Applied
Scientific EffectSol-gel process: Sol

Implementation Method 2

solubilizing one or more metal precursors, preferably selected among metal chlorides, metal alkoxides or mixtures thereof, in a suitable solvent

Methodology Applied
Scientific EffectHydrolysis: Hydrolysis

Implementation Method 3

mixing the solubilized metal precursor(s) with a nitrogen carrier

Methodology Applied
Scientific EffectChemical reactions: Chemical Bonding

Data Source

PatentEP3995464A1Scratch-resistant coating for glass ceramic cooktop
Publication Date: 2022.05.11 WHIRLPOOL EMEA SPA
  • EP3995464A1 patent drawingFigure 1~2
  • EP3995464A1 patent drawingFigure 3~4
  • EP3995464A1 patent drawing

AI summary

The invention relates to scratch-resistant coatings, especially for cooktops, to substrates or products having said scratch-resistant coatings and to methods for the production thereof. More particularly the invention relates to scratch-resistant coatings obtained via sol-gel approach and coated substrates having thereon a hard material layer comprising metal nitride(s) and/or metal oxynitride complexes and to the manufacturing thereof.