Temperature Sensor Coating Structure for Reducing Atmospheres
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Solution Overview
Problem
Existing temperature sensor elements face reduced temperature detection accuracy in strong reducing atmospheres due to gas intrusion and reduction reactions, with concerns about oxygen-supplying oxides being depleted over time.
Innovation Solution
A temperature sensor element design featuring a heat sensitive body, a first coating layer, lead-out wires penetrating through the first coating layer, a second coating layer made of a mixture of glass and specific oxides (such as chromium oxide, manganese oxide, ruthenium oxide, iridium oxide, and platinum oxide) covering the lead-out wires, and a third coating layer covering the first and second coating layers, enhancing wettability and reducing reduction reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a second coating layer containing oxygen-supplying oxide is provided to suppress reduction reaction, then temperature detection accuracy is improved, but the oxygen-supplying oxide may be depleted after long time usage in strong reducing atmosphere
Solution Approach 1:
The invention changes the chemical composition parameters of the second coating layer by incorporating specific metal oxides (Cr, Mn, Fe, Co, Ni, Ce, Pr) that can supply oxygen. This compositional modification enables the coating to actively counteract reduction reactions through chemical mechanisms, resolving the contradiction between maintaining detection accuracy and extending service life in reducing atmospheres.
Solution Approach 2:
The invention creates a composite coating layer combining multiple metal oxides with complementary properties. This composite structure provides both protective functions (preventing gas intrusion) and active chemical functions (oxygen supply to counteract reduction), thereby simultaneously improving measurement precision and extending the duration of reliable operation in reducing atmospheres.
2Reliability
If a coating layer is provided to prevent gas intrusion, then reduction reaction is suppressed, but interface gaps between coating layer and lead-out wire allow reducing gas to intrude
Solution Approach 1:
The invention applies different material compositions to different regions: the second coating layer contains oxygen-supplying metal oxides specifically at the interface region with lead-out wires to prevent gas intrusion and suppress reduction reactions locally, while other regions provide overall protective coverage. This localized material optimization resolves the contradiction between comprehensive protection and interface vulnerability.
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 enhanced wettability between the lead-out wire and the second coating layer effectively suppresses reduction reactions of the heat sensitive body, maintaining accurate temperature detection even after long-term use in strong reducing atmospheres.
Implementation Method 1
the second coating layer surrounding an extending portion of the lead-out wire on the outer surface of the first coating layer and being formed mainly containing an oxygen-supplying oxide
Implementation Method 2
a temperature sensor element that includes a heat sensitive body such as a thermistor, in which electrical characteristics change in response to a temperature change
Data Source
AI summary
An object is to provide a temperature sensor element that can suppress a reduction reaction of a heat sensitive body, even after a long time usage in a strong reducing atmosphere.A temperature sensor element 1 includes: a heat sensitive body 11 of which electric resistance changes according to a temperature; a first coating layer 20 that covers a periphery of the heat sensitive body 11; a pair of lead-out wires 15 and 15 that are connected to the heat sensitive body 11, and also are led out in penetration through the first coating layer 20, toward a rear end side; a second coating layer 25 that covers a periphery of the pair of lead-out wires 15 and 15 which are led out in penetration through the first coating layer 20; and a third coating layer 30 that covers peripheries of the first coating layer 20 and the second coating layer 25. The second coating layer 25 is formed of a mixture of glass and at least one of chromium oxide, manganese oxide, ruthenium oxide powder, iridium oxide powder and platinum oxide.