Glass-ceramic plate for fireplace insert and manufacturing process
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Solution Overview
Problem
Glass-ceramic coatings used in high-temperature applications, such as chimney inserts and fireplaces, degrade over time due to temperature variations, losing their reflective properties and posing challenges when applied to bent substrates, while maintaining mechanical strength and visual appeal.
Innovation Solution
A glass-ceramic plate with a stack of layers comprising a first metal nitride layer, an indium tin oxide (ITO) layer, and a second metal nitride layer, deposited in a specific order and under controlled conditions, to enhance infrared radiation reflection without degrading low-emissivity properties, even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional metal oxide coatings are applied on glass-ceramic parts, then infrared radiation reflection is improved and user comfort is increased, but the coatings degrade over time when subjected to high temperature variations and lose their reflective properties
Solution Approach 1:
The patent applies a composite coating structure consisting of multiple layers: a first metal nitride layer (5-50 nm), an indium tin oxide layer (<100 nm), and a second metal nitride layer (10-100 nm). This composite structure combines the advantages of metal nitrides (thermal stability) and ITO (infrared reflection) to achieve both high reflectivity and long-term durability at temperatures above 250°C.
Solution Approach 2:
The patent changes the material composition parameters by using metal nitrides instead of traditional metal oxides, and optimizes the thickness parameters of each layer to achieve the desired balance between infrared reflection and thermal stability. The specific thickness ranges (5-50 nm for first nitride, <100 nm for ITO, 10-100 nm for second nitride) are critical for maintaining performance under high temperature conditions.
2Ease of manufacture
If metal oxide coatings are applied before bending and ceramization, then the coating process is simplified, but the coatings are destroyed during ceramization
Solution Approach 1:
The patent applies the multi-layer coating after the glass-ceramic substrate has already undergone ceramization, rather than before. This preliminary action timing ensures that the coating is applied to a stable, fully-ceramized substrate that can withstand the coating process without degrading the coating during subsequent heat treatments.
Solution Approach 2:
The patent changes the material composition from traditional metal oxides to metal nitrides, which have higher thermal stability and resistance to degradation during high-temperature processes. This material parameter change allows the coating to survive the ceramization process and maintain its integrity at elevated temperatures.
3Reliability
If metal oxide coatings are applied after ceramization, then the coating integrity is maintained, but obtaining a homogeneous thickness becomes problematic
Solution Approach 1:
The patent uses a composite multi-layer structure where each layer serves a specific function. The metal nitride layers provide structural stability and adhesion, while the ITO layer provides infrared reflection. This composite approach allows for better control of thickness uniformity across the substrate surface compared to single-layer coatings.
Solution Approach 2:
The patent optimizes the thickness parameters of each individual layer within specific ranges (5-50 nm for first nitride, <100 nm for ITO, 10-100 nm for second nitride). By controlling each layer's thickness independently within these optimized ranges, the patent achieves both homogeneous overall thickness and maintains coating integrity after ceramization.
4Adaptability or versatility
If glass-ceramic plates are bent to fit appliance designs, then adaptability to different appliance configurations is improved, but the mechanical strength and structural integrity are reduced
Solution Approach 1:
The patent modifies the glass-ceramic substrate composition parameters to achieve optimal flexibility and strength balance. By adjusting the chemical composition and crystalline phase content of the glass-ceramic, the material can be bent to fit various appliance configurations while maintaining sufficient mechanical strength and structural integrity after bending.
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 solution effectively maintains low-emissivity properties over time, prevents degradation, and ensures the plate retains mechanical strength and visual appeal, making it suitable for high-temperature applications without maintenance or abrasion issues.
Implementation Method 1
these coatings typically having a thickness of a few hundred nanometers... adding such an infrared radiation-reflecting coating on said glass parts has multiple advantages such as reducing the temperature perceptible on and around said parts
Implementation Method 2
improving and optimizing combustion, reducing the number of fine particles in the air, reducing window soiling by pyrolytic effect
Data Source
AI summary
The present invention relates to a plate, intended to equip appliances of the chimney insert, stove, chimney, boiler, heating appliance, fireplace or equivalent type and/or to serve as a fire barrier, said plate being formed of at least one glass-ceramic substrate coated on at least one of its faces with the following stack of layers:1. a first metal nitride layer of thickness comprised in the range from 5 nm to 50 nm,2. an indium tin oxide layer of less than 100 nm thickness,3. a second metal nitride layer of thickness comprised in the range from 10 nm to 100 nm.The present invention also relates to a process for obtaining said plate, as well as a device incorporating said plate.