SiC-Based Ceramic Heater Support Plate for High-Temperature Furnaces
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Solution Overview
Problem
Conventional support structures for electric heaters in continuous furnaces soften or deform at high temperatures when firing SiC-based materials containing alkaline or Si components, leading to reduced heater life due to component volatilization and erosion.
Innovation Solution
A two-layer support structure with an insulating ceramic plate laminated on an SiC-based ceramic plate, where the electric heater is mounted on the upper surface, using alumina or alumina-mullite ceramics for the insulating plate and recrystallized, sintered, or nitride-bonded SiC for the SiC-based plate, which provides high temperature resistance and corrosion resistance against volatile components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an alumina-based refractory support plate is used to support the electric heater at high temperatures, then the heater can be supported structurally, but the support plate softens or deforms due to temperature exceeding 1300°C, causing reduced heater life
Solution Approach 1:
The support plate is constructed as a composite structure with an SiC-based ceramic layer (90-99% purity) as the base material and an alumina-based refractory layer (90-99% purity) as the surface layer. This composite structure combines the high-temperature stability of SiC with the protective and insulating properties of alumina, preventing softening and deformation at temperatures above 1300°C while maintaining structural support for the electric heater.
2Productivity
If the support plate is exposed to volatile components from SiC-based materials during firing, then the firing process can proceed, but alkaline and Si components permeate and diffuse into the alumina-based support plate, causing enhanced softening and deformation
Solution Approach 1:
The SiC-based ceramic layer serves as an intermediary barrier between the volatile components and the alumina-based support plate. This base layer blocks the permeation and diffusion of alkaline and Si components into the alumina layer, preventing the enhanced softening and deformation that would otherwise occur during the firing process.
Solution Approach 2:
The dual-layer composite structure with SiC as the base material provides inherent resistance to volatilization from SiC-based materials being fired. The SiC layer acts as a protective barrier that prevents direct contact between volatile components and the alumina support plate, maintaining structural integrity during the firing process.
3Ease of manufacture
If a single-layer alumina-based support plate is used, then the structure is simple and easy to manufacture, but the plate softens and deforms at high temperatures, reducing heater lifespan
Solution Approach 1:
The support plate employs a composite structure where the SiC-based ceramic layer (90-99% purity) provides high-temperature stability and structural support, while the alumina-based refractory layer (90-99% purity) provides protective and insulating properties. This combination extends heater lifespan by preventing softening and deformation at temperatures above 1300°C.
Solution Approach 2:
Different regions of the support plate have different material properties optimized for their specific functions: the SiC-based base layer provides structural integrity and thermal stability, while the alumina-based surface layer provides protection and insulation. This local differentiation of material properties maximizes both manufacturing feasibility and operational durability.
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 significantly extends the durability of the electric heater support structure by preventing deformation and erosion, achieving a lifespan twice that of conventional structures, with the SiC-based ceramic plate effectively blocking alkaline and Si components and maintaining structural integrity at temperatures up to 1300°C or more.
Implementation Method 1
the SiC-based ceramic plate effectively blocking alkaline and Si components
Implementation Method 2
maintaining structural integrity at temperatures up to 1300°C or more
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3
AI summary
There is provided an electric heater support plate which is not likely to be softened or deformed during firing at a high temperature, even if a material to be fired contains an alkaline component or an Si component as a volatile component. A passage 2 for the material to be fired surrounded by a ceiling refractory 11, wall refractories 12 and a floor refractory 13 is provided with an electric heather 3 heating from above and an electric heater 5 heating from below. This electric heater 3 has at least its heating part 31 mounted and supported on a fire-resistant support plate 4, and this support plate 4 in this invention has a two-layer structure in which an insulating ceramic support plate 41 is laminated on an SiC-based ceramic plate 42. The two-layer structure support plates 4 are supported by refractories 14 installed in a furnace and are arranged in parallel in a plurality of rows in a longitudinal direction of the furnace, and the electric heater 3 mounted on the support plates is so constructed as to generate heat by an electric power supplied from an energizing terminal 32 exposed to the outside of a furnace wall.