Pt Alloy Sensor Electrode Suppressing Volatilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Pt electrodes used in particulate matter detection sensors are prone to oxidation and volatilization at high temperatures, leading to decreased detection accuracy due to the loss of Pt from the detection face and increased electrode resistance, which is not effectively addressed by adding glass materials that also increase resistance.
Innovation Solution
The use of a Pt alloy with metals like Rh, Ru, Ir, or Os, combined with granular voids dispersed within the alloy, where the metal content is 40 mass % or less and the voids are between 3/100 μm3 to 50/100 μm3 per unit volume, to suppress Pt volatilization and resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Pt electrode is used for detection, then detection capability is provided, but Pt volatilizes and is lost at high temperatures leading to deterioration in detection accuracy
Solution Approach 1:
The invention changes the chemical composition parameters of the electrode by forming a Pt alloy with specific metals (Rh, Ru, Ir, Os, or Pd) at controlled ratios (1:99 to 4:96 by mass). This parameter change modifies the electrode's thermal stability and resistance to oxidation, preventing Pt volatilization at high temperatures while maintaining detection accuracy.
Solution Approach 2:
The invention creates a composite electrode material by combining Pt with other metals to form an alloy. This composite structure leverages the high detection capability of Pt while incorporating the thermal stability and oxidation resistance of the alloying metals, thereby preventing Pt loss during high-temperature operation.
2Loss of substance
If glass material is added to suppress Pt volatilization, then Pt loss is reduced, but electrode resistance increases
Solution Approach 1:
Instead of adding glass material, the invention changes the electrode composition by forming a Pt alloy with specific metals at controlled ratios. This approach suppresses Pt volatilization through the alloying effect while maintaining low electrical resistance, as the alloying metals are chosen to be conductive and compatible with Pt's electrical properties.
Solution Approach 2:
The invention replaces the glass material approach with a metal alloy approach that provides equivalent or superior protection against Pt volatilization without the side effect of increased resistance. The alloying metals (Rh, Ru, Ir, Os, Pd) serve as effective substitutes that maintain electrode performance.
3Loss of substance
If Pt alloy is used to suppress volatilization, then Pt loss is reduced, but metal segregation occurs leading to resistance increase
Solution Approach 1:
The invention optimizes the alloy composition parameters by selecting specific Pt-to-metal ratios (1:99 to 4:96 by mass) and choosing metals with similar atomic sizes and crystal structures. These parameter changes prevent excessive segregation during high-temperature operation, maintaining both low Pt loss and stable electrical resistance.
Solution Approach 2:
The invention ensures uniform distribution of the alloying metal throughout the Pt matrix, creating a homogeneous local composition. This uniform distribution prevents localized segregation that would lead to resistance increases, while still providing effective suppression of Pt volatilization throughout the electrode 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
This configuration maintains low electrode resistance and improves detection accuracy by preventing Pt loss and segregation of metals, ensuring consistent performance at high temperatures.
Implementation Method 1
volatilization due to oxidation of Pt tends to occur under high temperature conditions (for example, 850° C. or higher). Therefore, when the Pt electrode is applied to a particulate matter detection sensor, there is a risk that Pt is oxidized to PtO2
Implementation Method 2
there is a risk that Pt is oxidized to PtO2, which has a low vapor pressure, and evaporates from the detection face and is lost
Implementation Method 3
An electrostatic field is formed by applying a voltage between these electrodes. As a result, the charged particulate matter is attracted to the electrostatic field and trapped on the detection face, thereby causing the electrodes to conduct
Data Source
AI summary
An electrode for a sensor element 1 that detects a specific substance in a gas to be measured, wherein the electrode is embedded in an insulating substrate having a detection face to which the specific substance adheres, the electrode being embedded in such a manner that a part of the electrode is exposed at the detection face, the electrode comprises an alloy of Pt and at least one metal selected from the group consisting of Rh, Ru, Ir, Os, and Pd, and granular voids dispersed among the alloy, and the content of the metal in the alloy is 40 mass % or less, and the number of the granular voids per unit volume of the electrode for a sensor element is 3/100 μm3 to 50/100 μm3.