Surface type heating element having controlled oxide layer and manufacturing method thereof
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Solution Overview
Problem
Existing surface type heating elements for cooktops face challenges such as material elution at high temperatures, low operation temperatures due to low melting points, and issues with fracture toughness, coefficient of thermal expansion, and adhesive strength, which affect reliability and lifetime.
Innovation Solution
A surface type heating element using a NiCr alloy with controlled oxygen content (1-4 wt%) and a photonic sintering method, which improves fracture toughness, reduces thermal shock, and enhances adhesive strength and electrical resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal components with low melting points are used in heating elements, then ease of manufacture is improved, but operation temperature is limited to about 400°C and material elution occurs
Solution Approach 1:
The patent uses a composite structure consisting of a metal heating element layer (NiCr alloy) combined with a glass-ceramic layer. This composite material approach allows the metal to provide electrical conductivity and heating function while the glass-ceramic layer provides high-temperature stability and prevents material elution, enabling operation at temperatures of 800°C or higher.
Solution Approach 2:
The glass-ceramic layer acts as an intermediary between the metal heating element and the environment. It protects the metal component from direct exposure to high temperatures and corrosive atmospheres, preventing oxidation and material elution while allowing the metal to maintain its electrical and heating properties.
2Strength
If metal components are oxidized during thermal firing, then adhesive strength between heating element and substrate is improved, but electrical resistivity increases and output decreases
Solution Approach 1:
The patent precisely controls the oxygen content parameter during the thermal firing process, maintaining it within the range of 1-4 wt%. This parameter control creates a passivation oxide layer that provides adequate adhesion to the substrate while preventing excessive oxidation that would harm electrical conductivity, thus balancing adhesive strength and electrical output.
3Strength
If oxygen content in NiCr alloy is increased to improve adhesive strength, then adhesion to substrate is improved, but electrical resistivity increases and heating output decreases
Solution Approach 1:
The patent optimizes the oxygen content parameter to a specific range of 1-4 wt%, which creates a passivation oxide layer on the metal surface. This controlled oxide layer provides sufficient adhesion to the glass-ceramic substrate while maintaining the electrical conductivity of the NiCr alloy, thus achieving both strong adhesion and high heating output without excessive electrical resistivity.
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 allows for stable operation at high temperatures (400 °C or more), reduces material elution, and improves the reliability and lifetime of cooktops by ensuring high fracture toughness, low thermal expansion, and strong adhesion.
Implementation Method 1
a surface type heating element using a NiCr alloy with controlled oxygen content (1-4 wt%) and a photonic sintering method
Implementation Method 2
A surface type heating element using a NiCr alloy with controlled oxygen content (1-4 wt%)
Implementation Method 3
a surface type heating element which generates heat using electricity
Data Source
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AI summary
The present disclosure relates to a surface type heating element which generates heat using electricity and a method of manufacturing the surface type heating element. An embodiment of the present disclosure provides the surface type heating element which includes a NiCr alloy and has an oxygen content of 1 to 4 wt%, so that it can be used even at a high operating temperature of 400 °C or more, suppresses the elution of the material itself, has high fracture toughness, a low coefficient of thermal expansion, and heat resistance, and furthermore, ensures conductivity by having improved adhesive strength with respect to a substrate and/or an insulating layer and controlled electrical resistivity.