Sensor Element Porosity Gradient Slip Layer Thermal Shock
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Solution Overview
Problem
Existing sensor elements for detecting gas properties, such as oxygen content in exhaust gases, face challenges in rapid operational readiness and robustness against thermal shock due to water condensation and thermal stresses, which can damage ceramic components.
Innovation Solution
A method for manufacturing sensor elements involving the application of a slip layer with a porosity gradient, followed by sintering, grinding, and impregnation with precious-metal-containing solutions, to enhance thermal shock resistance and operational readiness, using a cost-effective process that includes multiple coating and drying steps and thermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous ceramic protective layer is applied to the sensor element surface, then thermal shock resistance is improved, but device complexity and manufacturing complexity increase due to additional coating steps
Solution Approach 1:
The patent combines the protective layer formation with the sensor element manufacturing process itself. The protective layer is formed by sintering a porous ceramic material that is integrated into the sensor element structure during the initial sintering process, eliminating the need for separate coating and firing steps that would otherwise be required to create a thermal shock protective layer.
Solution Approach 2:
The sensor element structure is designed to serve multiple functions simultaneously. The porous ceramic layer acts both as a structural component of the sensor element and as a thermal shock protective layer, providing mechanical support while also protecting against thermal stress from water hammer effects during engine operation.
2Speed
If the sensor element is heated rapidly to operating temperature, then operational readiness is improved, but thermal stress increases causing potential damage to ceramic components
Solution Approach 1:
The porous ceramic protective layer is formed beforehand as an integral part of the sensor element structure. This layer acts as a cushioning layer that absorbs and distributes thermal stress during rapid heating, preventing thermal shock damage to the ceramic components while enabling fast heating to operating temperature.
3Object-affected harmful factors
If water droplets impact the heated ceramic sensor, then thermal shock damage occurs, but applying a protective layer increases manufacturing steps and cost
Solution Approach 1:
The protective function is merged into the sensor element manufacturing process itself. The porous ceramic material is applied and sintered as part of the sensor element fabrication, creating a protective layer that withstands water droplet impact during engine operation without requiring separate protective coating steps.
Solution Approach 2:
The sensor element structure provides its own protection against thermal shock. The porous ceramic protective layer is formed as an integral part of the sensor element, allowing the component to protect itself against water hammer effects during operation without requiring additional external protective systems.
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 method improves thermal shock resistance and operational readiness of sensor elements by creating a protective slip layer with a porosity gradient, ensuring the sensor elements can withstand thermal stresses and maintain accuracy in detecting gas properties effectively.
Implementation Method 1
sintering the slip layer on the functional element
Implementation Method 2
impregnating the slip layer
Implementation Method 3
thermally treating the impregnated slip layer
Data Source
AI summary
A method for manufacturing a sensor element for detecting (i) a gas component in a measuring gas or (ii) a temperature of the measuring gas includes: introducing at least one functional element into at least one slip at least once in such a way that a slip layer is applied to the functional element, the functional element including at least one solid electrolyte and at least one functional layer; sintering the slip layer on the functional element; grinding the slip layer at least in the area of the at least one functional layer; impregnating the slip layer; and thermally treating the impregnated slip layer.