Multi-Layer Thermistor Coating for Reducing Atmosphere Accuracy
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Solution Overview
Problem
Existing temperature sensor elements face a challenge in maintaining accurate temperature detection in strong reducing atmospheres, as the oxygen-supplying oxides used in previous solutions can be depleted over time, leading to reduced performance.
Innovation Solution
A temperature sensor element is designed with multiple coating layers, including a first, second, and third coating layer, where at least one of these layers is formed from a mixture of an oxygen-supplying oxide and glass. This configuration enhances oxygen supply and reduces the risk of reduction reactions in the heat-sensitive body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an oxygen-supplying oxide coating layer is used to suppress reduction reactions, then temperature detection accuracy is improved, but the coating layer becomes depleted over time in strong reducing atmospheres
Solution Approach 1:
The coating layer is divided into multiple functional layers: a first coating layer containing oxygen-supplying oxide for suppressing reduction reactions, a second coating layer for mechanical protection and sealing, and optionally a third coating layer for additional protection. This segmentation allows each layer to perform its specific function optimally while extending the overall service life.
Solution Approach 2:
The coating structure uses composite materials with different properties: the first coating layer uses oxygen-supplying oxide (such as CeO2, Pr6O11, or Mn3O4) to provide oxygen, while the second coating layer uses glass-based materials for sealing and mechanical strength. This composite structure combines the benefits of both materials to achieve both protection and durability.
2Reliability
If a thick coating layer is used to prevent reducing gas intrusion, then protection against reduction reactions is improved, but the response time of the temperature sensor increases
Solution Approach 1:
The coating layers are applied with different thicknesses and compositions at different locations: the first coating layer is applied where reduction protection is most needed (around the thermistor), while the second coating layer provides sealing at the lead-out wire interfaces where gas intrusion occurs. This localized quality approach provides maximum protection without unnecessarily increasing overall coating thickness.
Solution Approach 2:
The first coating layer containing oxygen-supplying oxide has a controlled porous structure that allows oxygen to diffuse through to the thermistor surface while still providing protection. The porosity enables oxygen transport necessary for maintaining thermistor stability without creating a thick barrier that would slow temperature response.
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 proposed solution effectively suppresses reduction reactions in the heat-sensitive body by maintaining a consistent oxygen supply, even after prolonged use in strong reducing atmospheres, thereby ensuring accurate temperature detection.
Implementation Method 1
at least one of the coating layers is formed from a mixture of an oxygen-supplying oxide and glass
Implementation Method 2
The oxygen-supplying oxide in the second coating layer can suppress a reduction reaction under exposure of the thermistor to a strong reducing atmosphere
Implementation Method 3
a heat sensitive body of which the electric resistance changes according to a temperature
Data Source
AI summary
[Solution] A temperature sensor element 1 according to the present invention includes: a heat sensitive body 11 of which electric resistance changes according to a temperature; a first coating layer 20 that covers a periphery of the heat sensitive body 11; a pair of lead-out wires 15 and 15 that are connected to the heat sensitive body 11 and also are led out in penetration through the first coating layer 20, toward a rear end side; a second coating layer 25 that covers a periphery of the pair of lead-out wires 15 and 15 which are led out in penetration through the first coating layer 20; and a third coating layer 30 that covers peripheries of the first coating layer 20 and the second coating layers 25 and 27. In the temperature sensor element 1, the second coating layer 25 is formed from a mixture of an oxygen-supplying oxide and glass.