Ceramic Heater Conductive Layers Grain Diameter Control
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Solution Overview
Problem
Ceramic heaters face reliability issues due to crack formation in feeder lines when used in high-temperature environments, leading to air infiltration and abnormal heat generation, which complicates long-term usage.
Innovation Solution
A heater design featuring a ceramic multilayer body with a belt-shaped heat-generating resistor and conductive layers, where the first conductive layer has a smaller average grain diameter than the second, reducing air infiltration and unnecessary heat generation while enhancing durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feeder lines are exposed at the surface of the ceramic structure, then electrical connection is achieved, but cracks form and air infiltration occurs leading to abnormal heat generation
Solution Approach 1:
The conductive layers are embedded within the ceramic multilayer body, nesting the electrical connection structure inside the ceramic housing. This prevents the conductive layers from being exposed at the surface, thereby eliminating the pathway for air infiltration while maintaining electrical connectivity from the heat-generating resistor to external terminals.
Solution Approach 2:
The ceramic multilayer body acts as a protective shell that encloses the conductive layers and heat-generating resistor. This shell structure provides mechanical protection and seals the internal components from the external environment, preventing air infiltration and crack formation that would otherwise lead to reliability issues.
2Reliability
If feeder lines are exposed at the surface, then electrical connection is established, but resistance changes due to reaction with outside air causing abnormal local heat generation
Solution Approach 1:
The conductive layers are nested within the ceramic multilayer body rather than being exposed on the surface. This nesting arrangement isolates the conductive layers from atmospheric reactions, preventing resistance changes and the subsequent abnormal heat generation that would compromise long-term reliability.
Solution Approach 2:
The ceramic multilayer body creates an inert environment around the conductive layers and heat-generating resistor, shielding them from reactive outside air. This inert barrier prevents oxidation and chemical reactions that would alter electrical resistance and cause abnormal heat generation during prolonged operation.
3Reliability
If the first conductive layer has smaller grain diameter, then air infiltration is reduced, but manufacturing complexity increases
Solution Approach 1:
The conductive layers exhibit local quality variations with smaller grain diameters in regions more susceptible to air infiltration. This localized control of grain structure provides enhanced durability where needed while maintaining manufacturability through targeted material processing techniques rather than requiring complex manufacturing procedures throughout the entire component.
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 design increases the long-term reliability of the heater by minimizing air infiltration and heat generation issues, ensuring stable performance in high-temperature environments.
Implementation Method 1
a heat-generating resistor (2) provided between the adjacent ceramic layers (11)
Implementation Method 2
each of the first conductive layer (31) and the second conductive layer (32) being formed of a plurality of grains, the grains of the first conductive layer (31) having an average grain diameter smaller than an average grain diameter of the grains of the second conductive layer (32)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A heater includes a ceramic multilayer body including a plurality of ceramic layers that are stacked together; a heat-generating resistor having a belt shape, the heat-generating resistor being disposed between the ceramic layers and arranged, and including both ends that are at a side surface of the ceramic multilayer body; and conductive layers having a belt shape, disposed between the ceramic layers and stacked on both end portions of the heat-generating resistor in such a manner that one end of each conductive layer is at the side surface. Each conductive layer includes a first conductive layer that extends to the side surface and a second conductive layer that is adjacent to the first conductive layer, each of the first conductive layer and the second conductive layer being formed of a plurality of grains, the grains of the first conductive layer having an average grain diameter smaller than an average grain diameter of the grains of the second conductive layer.