Gas Sensor Element Dense Conducting Section
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Solution Overview
Problem
Existing gas sensors face accuracy issues due to gases outside the sensor element potentially moving through the lead or gaps and reaching the inner electrode, which can deteriorate the detection of specific gas concentrations.
Innovation Solution
A sensor element with a conducting section comprising a dense segment made of noble metal, alumina, and silica, which increases both denseness and adhesiveness, reducing the likelihood of gases reaching the inner electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If alumina is added to the peripheral-face conducting section to increase adhesive strength, then adhesiveness improves, but porosity increases making it difficult to obtain a dense structure
Solution Approach 1:
The patent applies composite materials by combining noble metal powder, alumina powder, and silica powder in specific proportions (silica: 1-10 wt%, alumina: 5-50 wt%, noble metal: 40-80 wt%). This composite composition resolves the contradiction by using silica to fill pores and enhance denseness while alumina provides adhesive strength, and noble metal ensures electrical conductivity. The synergistic effect of these materials achieves both high adhesiveness and high denseness simultaneously.
Solution Approach 2:
The patent applies parameter changes by optimizing the compositional parameters and sintering conditions. Specifically, it controls the weight ratio of silica to alumina (0.05-2.0), adjusts sintering temperature (900-1500°C), and controls sintering atmosphere to achieve the desired balance between denseness and adhesiveness. These parameter optimizations allow the conducting section to achieve both high adhesive strength and high denseness.
2Measurement precision
If the peripheral-face conducting section is made dense to prevent gas leakage, then detection accuracy improves, but adhesive strength decreases
Solution Approach 1:
The patent uses composite materials with noble metal powder (40-80 wt%) providing electrical conductivity and adhesive bonding, alumina powder (5-50 wt%) enhancing adhesive strength, and silica powder (1-10 wt%) filling pores to achieve denseness. This composite formulation simultaneously achieves high detection accuracy through denseness and high adhesive strength, resolving the contradiction between these two requirements.
Solution Approach 2:
The patent applies local quality by creating a conducting section with specific localized properties: high noble metal content (40-80 wt%) in the conducting section ensures electrical conductivity and adhesive strength, while controlled silica content (1-10 wt%) provides pore-filling for denseness. This localized optimization of material composition achieves both high detection accuracy and high adhesive strength in the critical conducting section.
Data Source
AI summary
A sensor element configured to detect a concentration of a specific gas in a measurement-object gas, the sensor element includes an element body having a columnar shape elongate in a longitudinal direction, the element body having a front end and a rear end that are opposite ends in the longitudinal direction and further having a peripheral face that is a surface extending in the longitudinal direction, an inner electrode disposed inside the element body; and a conducting section including an inner conducting section and an outer conducting section, the outer conducting section being electrically continuous with the inner conducting section, wherein a part of the outer conducting section that covers the inner conducting section and/or at least a part of the inner conducting section is a dense segment that has a dense composition with precious metal, alumina, and silica.