NiCr Surface Heating Element With Controlled Oxide for High-Temperature Use
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Solution Overview
Problem
Existing surface type heating elements for electric ranges face challenges such as material elution at high temperatures, low fracture toughness, high thermal expansion coefficients, and inadequate adhesion to substrates, leading to reliability and lifetime issues, and require lengthy high-temperature manufacturing processes that limit substrate material options and increase energy consumption.
Innovation Solution
A surface type heating element composed of a NiCr alloy with controlled oxygen content (1-3 wt%) and photonic sintering, which enhances fracture toughness, reduces thermal expansion, and ensures stable electrical resistivity and adhesive strength, eliminating the need for a reducing atmosphere and long-term high-temperature thermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal components with low melting point are used in heating elements, then ease of manufacture is improved, but operating temperature is limited to about 400°C and material elution occurs
Solution Approach 1:
The heating element uses a composite structure combining a metal powder layer (Ni, Cu, or their alloys) with a ceramic layer (alumina, zirconia, or magnesia). The metal layer provides electrical conductivity and ease of manufacturing, while the ceramic layer enables high-temperature operation (900°C or higher) and prevents material elution. This composite approach resolves the contradiction between ease of manufacture and high-temperature capability.
2Strength
If metal components are oxidized during thermal firing, then adhesive strength to substrate is improved, but electrical resistivity increases and output decreases
Solution Approach 1:
The patent controls the oxidation state of the metal powder layer by adjusting firing atmosphere parameters (oxidizing, neutral, or reducing atmosphere) and firing temperature (800-1000°C). By precisely controlling these parameters, the metal layer achieves optimal adhesive strength to the ceramic layer while maintaining electrical resistivity within the range of 10^-6 to 10^-4 Ω·cm, thus resolving the contradiction between adhesive strength and electrical output.
3Temperature
If thermal firing is used to manufacture heating elements with high melting point components, then high temperature resistance is improved, but manufacturing time increases and substrate material options are limited
Solution Approach 1:
The patent replaces traditional long-duration thermal firing with a optimized firing process that uses controlled atmosphere (oxidizing, neutral, or reducing) and specific temperature ranges (800-1000°C). This substitution reduces manufacturing time while achieving the same heat resistance效果, and the flexible atmosphere control allows various substrate materials to be used, resolving both the time consumption and substrate limitation issues.
4Reliability
If metal powder layer is applied to substrate, then electrical conductivity is improved, but adhesion to ceramic layer or substrate is insufficient
Solution Approach 1:
The patent controls the oxidation state of the metal powder layer by adjusting firing parameters (atmosphere and temperature). This creates an optimal interface between the metal layer and ceramic layer/substrate, achieving both good electrical conductivity and strong adhesion. The controlled oxidation forms a metallurgical bond that satisfies both requirements simultaneously.
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 NiCr alloy surface type heating element operates effectively at high temperatures (400°C or more) with improved reliability and lifetime, reduced thermal shock, and stable electrical output, while simplifying the manufacturing process and reducing energy consumption.
Implementation Method 1
A surface type heating element composed of a NiCr alloy with controlled oxygen content (1-3 wt%) and photonic sintering
Implementation Method 2
a surface type heating element which generates heat using electricity
Implementation Method 3
controlled oxide layer... ensures stable electrical resistivity
Data Source
AI summary
Discussed are a surface type heating element which generates heat using electricity and a method of manufacturing the surface type heating element. The surface type heating element 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 at least one of a substrate and an insulating layer, and controlled electrical resistivity.