Carbon-Silicon Carbide Heating Element for Plasma Suppression

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Solution Overview

Problem

Conventional carbon fiber heating elements in ovens suffer from dielectric breakdown, sparks, and plasma generation under high voltage, leading to reduced radiation efficiency and shortened lifespan due to local voltage concentration and plasma reactions.

Innovation Solution

A carbon heating element composed of carbon and silicon carbide (SiC) with specific thermal conductivity, resistance, and oxygen content, manufactured through a process involving mixing, thermal extrusion, stabilization, and carbonization treatments to prevent dielectric breakdown and plasma formation, while maintaining efficient heat dissipation and surface oxidation resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional carbon fiber is used as heating element, then radiation heating function is achieved, but dielectric breakdown and plasma generation occur under high voltage

Engineering Contradiction:
Improveheating powerVSAvoidelectrical stability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent uses a composite material consisting of carbon particles (90-99 wt%) and silicon carbide particles (1-10 wt%). The silicon carbide component has high electrical stability and resistance to dielectric breakdown, while the carbon component provides the necessary heating properties. This composite structure prevents plasma generation and electrical instability that occurs with pure carbon fiber, thus resolving the contradiction between heating power and electrical stability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the heating element by controlling the particle size distribution, oxygen content (0.1-5 wt%), and thermal conductivity (1.0-3.0 W/m·K) of the composite material. These parameter adjustments optimize the electrical stability and prevent dielectric breakdown while maintaining effective heating power.

Inventive Principle:
Principle #35Parameter changes

2Power

If carbon fiber with large surface area is used, then heating efficiency is improved, but surface oxidation and erosion increase at high temperature

Engineering Contradiction:
Improveheating efficiencyVSAvoidsurface durability
Core Design Contradiction:
PowerVSStrength

Solution Approach 1:

The silicon carbide particles in the composite material form a protective network that reduces surface oxidation and erosion at high temperatures. Silicon carbide has excellent thermal stability and resistance to chemical attack, which protects the carbon particles from oxidative damage while maintaining the heating efficiency provided by the carbon component's surface area.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent creates an environmentally stable composite material where silicon carbide acts as a protective barrier, effectively creating a chemically inert environment around the carbon particles. This prevents direct contact between oxygen and the carbon surface, thereby reducing oxidation and erosion while preserving the heating efficiency.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

3Reliability

If shield member is added to suppress plasma, then electrical stability is improved, but radiation efficiency is greatly lowered

Engineering Contradiction:
Improveplasma suppressionVSAvoidradiation efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

Instead of using a shield member to block plasma, the patent converts the harmful plasma-generation tendency into a beneficial property by selecting carbon and silicon carbide materials with appropriate electrical characteristics. The composite material inherently resists dielectric breakdown and plasma formation, eliminating the need for shielding while preserving full radiation efficiency for heating.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent extracts and eliminates the need for the shield member by using a composite material that inherently prevents plasma generation. This removes the harmful effect of radiation blocking while maintaining electrical stability, as the material composition itself provides plasma suppression without requiring additional shielding components.

Inventive Principle:
Principle #2Taking out (Extraction)

4Power

If carbon fiber with high aspect ratio is used, then heating function is achieved, but local voltage concentration occurs between filaments

Engineering Contradiction:
Improveheating functionVSAvoidvoltage concentration
Core Design Contradiction:
PowerVSStress or pressure

Solution Approach 1:

The patent changes the physical structure from fibrous to particulate, eliminating the high aspect ratio that causes voltage concentration. By using particles with controlled size distribution and arranging them in a matrix, the patent achieves uniform electrical field distribution while maintaining heating function, thus resolving the voltage concentration issue.

Inventive Principle:
Principle #35Parameter changes

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 prevents dielectric breakdown and plasma generation under high voltage, enhances radiation efficiency, and extends the lifespan of the heating element by ensuring uniform heat distribution and resistance to surface oxidation, allowing for efficient heat dissipation and improved electrical design flexibility.

Implementation Method 1

the heating element may have a thermal conductivity of 1.6 W/m·K or more

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

resistance to surface oxidation

Methodology Applied
Scientific EffectOxidation resistance: Oxidation

Data Source

PatentEP3425997B1Carbon heating element and manufacturing method for the same
Publication Date: 2022.09.21 LG ELECTRONICS INC
  • EP3425997B1 patent drawingFigure 1~2
  • EP3425997B1 patent drawingFigure 3~4
  • EP3425997B1 patent drawingFigure 5~6

AI summary

The present invention, which aims to efficiently dissipate heat and prevent disconnection or destruction of a heating element to prolong a lifespan thereof without generating a spark and plasma under a high voltage, relates to a heating including carbon (C) and silicon carbide (SiC), and the heating element characterized by having a thermal conductivity of 1.6 W/m·K or more.