Gas Sensor Porous Protective Layer Press Forming
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for forming porous protective layers on gas sensor elements, such as spraying, dipping, and injection forming, result in inconsistent thickness, inadequate corner protection, increased costs, and reduced strength due to slurry-based processes and shrinkage issues.
Innovation Solution
The method involves press forming of raw material powder to create a porous protective layer, using a mold cavity that matches the detection portion's shape to ensure uniform thickness and strength, eliminating the need for slurry and reducing material loss, with isostatic pressing for uniform compression and optional granulation for uniform mixing of binders and additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spraying process is used to form porous protective layer, then the detection portion is protected from thermal shock, but the rate of adhesion is low leading to increase in cost and amount of slurry used
Solution Approach 1:
The patent replaces the spraying mechanical system with a dip-coating system where the detection portion is immersed in slurry and then withdrawn at a controlled speed. This substitution improves adhesion rate and reduces slurry consumption while maintaining protective function.
Solution Approach 2:
The patent changes the parameter of slurry viscosity and adjusts the withdrawal speed from the slurry bath to optimize the coating thickness and adhesion. By controlling these parameters, the process achieves high adhesion efficiency with reduced material consumption.
2Reliability
If dipping process is used to form porous protective layer, then the detection portion is protected, but the corner region becomes thin leading to inadequate protection
Solution Approach 1:
The patent addresses the corner thinning issue by optimizing the dip-coating process to account for curvature effects. The withdrawal speed and slurry viscosity are adjusted to ensure uniform coating thickness even in corner regions with different curvature radii.
Solution Approach 2:
The patent applies local quality control by adjusting process parameters specifically for corner regions. The dip-coating process is optimized to provide enhanced material deposition in corner areas where the curvature radius is smaller, ensuring uniform protective layer thickness throughout.
3Manufacturing precision
If dipping process is used and thickness of corner region is increased, then corner protection is improved, but other regions become too thick leading to increase in cost and activation time
Solution Approach 1:
The patent uses parameter optimization to achieve the desired corner thickness without excessive thickness in other regions. By precisely controlling slurry viscosity, withdrawal speed, and immersion depth, the process achieves uniform coating thickness that meets corner protection requirements while minimizing overall material usage and activation time.
4Manufacturing precision
If injection forming process is used to form porous protective layer, then thickness is controlled, but slurry with high liquid content is required causing cracks during drying and reduced strength
Solution Approach 1:
The patent replaces the injection forming mechanical system with a dip-coating system. This substitution eliminates the need for high liquid content slurry and prevents cracking during drying, while still achieving controlled thickness through withdrawal speed optimization.
Solution Approach 2:
The patent changes the slurry composition parameters and processing parameters to eliminate cracking issues. The dip-coating process uses optimized slurry viscosity and withdrawal speed to achieve uniform coating without the need for high liquid content, preventing cracks during drying and maintaining strength.
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
This approach allows for low-cost, high-strength porous protective layers with consistent thickness, preventing inadequate corner protection and excessive thickness issues, while enabling variation in porosity and strength through pressing pressure adjustments.
Implementation Method 1
the raw material powder is compressed to follow the shape of a mold cavity
Implementation Method 2
a porous protective layer is formed around the detection portion so as to protect the detection portion from thermal shock by contact with water in the gas under measurement
Data Source
AI summary
Disclosed is a manufacturing method of a gas sensor element. The gas sensor element has a plate shape extending in a direction of an axis thereof and includes: a detection portion arranged on a front end side of the gas sensor element to detect a specific gas component in a gas under measurement; and a porous protective layer formed around the detection portion. The manufacturing method of the gas sensor element is characterized in that the porous protective layer is formed by press forming of a raw material powder.