High-Temperature Sensor Coating to Block Foreign Atom Diffusion
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Solution Overview
Problem
Existing high-temperature temperature sensors experience drift and poisoning due to diffusion of foreign atoms, such as chrome, nickel, iron, and silicon, from corrosive exhaust gas flows in internal combustion engines.
Innovation Solution
A high-temperature temperature sensor with a substrate containing zirconium oxide or zirconium oxide ceramic, coated with an insulation layer and featuring strategically placed openings to prevent foreign atom diffusion, along with a ceramic intermediate layer and a protective glass ceramic layer for passivation and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous insulating layer is used to protect the resistance structure, then the resistance structure is protected from corrosive gases, but foreign atoms can diffuse through the porous metal oxide insulation layer and poison the platinum resistor structure
Solution Approach 1:
The insulating layer is segmented by creating openings that divide it into separate segments. This segmentation prevents continuous diffusion paths for foreign atoms while maintaining the insulating function in the segmented regions. The openings are filled with protective layer material to create barrier walls that further block diffusion paths.
Solution Approach 2:
The protective layer material acts as an intermediary substance that fills the openings and creates diffusion barrier walls. This intermediary material blocks the path of foreign atoms (chromium, nickel, iron, silicon) from reaching the resistance structure, while allowing the insulating layer to maintain its electrical insulation function.
2Adaptability or versatility
If the insulation layer is made porous to allow gas flow, then exhaust gas can reach the sensor, but the porosity promotes diffusion of foreign atoms into the resistance structure
Solution Approach 1:
Different regions of the sensor have different properties: the insulating layer is porous in general to allow gas flow, but the openings filled with protective layer material create localized barrier regions. The resistance structure is located in a central segment surrounded by these barrier regions, creating a local quality difference that allows gas access while blocking foreign atom diffusion to the critical resistance area.
3Reliability
If openings are formed in the insulating layer to create diffusion barriers, then foreign atom diffusion is reduced, but the insulating layer structure becomes more complex
Solution Approach 1:
The protective layer material is applied to cover both the openings and the resistance structure simultaneously. This merging of functions - filling openings to create barriers while also protecting the resistance structure - simplifies the overall process compared to creating separate barrier structures. The protective layer serves multiple functions: filling openings, creating diffusion barriers, and protecting the resistance structure.
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 significantly reduces sensor drift and prevents poisoning by creating a diffusion barrier that shields the resistance structure from foreign atoms, ensuring stable and accurate temperature measurements even in harsh environments.
Implementation Method 1
the resistor structure and the free areas of the insulating layer on which no resistor structure is arranged are coated at least partially with a ceramic intermediate layer for passivation
Implementation Method 2
creating a diffusion barrier that shields the resistance structure from foreign atoms
Data Source
Figure 1
Figure 2a~2d
Figure 3a~3b
AI summary
The invention relates to a temperature sensor, in particular a high-temperature sensor, comprising a coated substrate, wherein the substrate contains a zirconium oxide or a zirconium oxide ceramic, at least one resistance structure and at least two connection contacts, wherein the connection contacts electrically contact the resistance structure, wherein the substrate is coated with an insulation layer, wherein the insulation layer contains a metal oxide layer, the resistance structure and the free regions of the insulation layer, on which no resistance structure is arranged, are coated at least in regions with a ceramic intermediate layer, and a protective layer and/or a cover is arranged on the ceramic intermediate layer, wherein at least one opening is formed in the insulation layer, which exposes at least sections of a surface of the substrate.