Gas Sensor Element Reinforcing Layer Warping Prevention
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Solution Overview
Problem
The existing gas sensor elements face issues with cracking due to warping of the solid electrolyte body during firing, which affects the measurement chamber's integrity.
Innovation Solution
A gas sensor element configuration that includes a reinforcing layer with a lower sintering start temperature than the porous body, interposed between the second electrode and the porous body, to alleviate warping and prevent cracking, along with a manufacturing method that forms this layer before firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the solid electrolyte body is fired at high temperature, then the ceramic structure is formed and densified, but the solid electrolyte body warps and cracks occur
Solution Approach 1:
The patent introduces a reinforcing layer with different thermal expansion characteristics and lower sintering temperature than the porous body. This layer is positioned at the measurement chamber side where warping occurs, creating a composite structure with differentiated thermal and mechanical properties that compensates for warping stresses during high-temperature firing
Solution Approach 2:
The patent creates a composite structure by combining the porous body (ceramic material) with a reinforcing layer (different ceramic material having lower sintering temperature). This composite configuration allows the reinforcing layer to constrain the porous body during firing, preventing warping and crack formation while maintaining the functional properties of both materials
2Reliability
If a reinforcing layer with lower sintering temperature is added, then warping and cracking are suppressed, but the device structure becomes more complex
Solution Approach 1:
The reinforcing layer is not applied uniformly across the entire sensor element but is specifically positioned only at the measurement chamber side where warping and cracking occur. This localized application provides targeted reinforcement while minimizing the increase in overall structural complexity
Solution Approach 2:
The reinforcing layer is incorporated into the green sheet structure before firing, allowing it to pre-positioned at the critical measurement chamber side. This preliminary placement ensures the reinforcing layer is already in position to prevent warping during the firing process, eliminating the need for additional post-processing steps
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 effectively suppresses the occurrence of cracks around the measurement chamber, ensuring the gas sensor's reliability and accuracy.
Implementation Method 1
a reinforcing layer which is porous and contains, as a main component, a component having a lower sintering start temperature than a main component of the porous body
Data Source
AI summary
A gas sensor element includes: a second ceramic layer including a pump cell in which a first electrode and a second electrode are provided on a surface of a first solid electrolyte body; a first ceramic layer including a measurement chamber which is faced by the first electrode and into which a gas to be measured flows; a porous body covering the second electrode; and a dense layer having a void and not allowing the gas to be measured to pass therethrough. The second electrode and the void are connected through the porous body. A reinforcing layer which is porous and contains, as a main component, a component having a lower firing start temperature than a main component of the porous body is interposed between the second electrode and the porous body at a position overlapping the void in a thickness direction of the porous body.