Electromagnetic Flow Meter Electrode Ceramic Base Peeling
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Solution Overview
Problem
Electromagnetic flow meters with precious metal-covered electrodes face issues of peeling due to abrasive substances and impacts, leading to electrochemical noise, and existing insulating material-based solutions suffer from reliability problems due to contract stress and reduced conductor thickness at corners.
Innovation Solution
An electropotential detection electrode with a ceramic base material covered by a conductive material, featuring a cylindrical main body portion with a disc-shaped large diameter portion and a terminal portion with an annular recessed portion that accommodates a gasket, where the outer peripheral wall of the annular groove is not part of the conduction path, reducing peeling and increasing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precious metal material is used to cover the electrode, then corrosive resistance is improved, but the material may be peeled off due to low strength and abrasive substances
Solution Approach 1:
The patent uses a composite structure combining a ceramic base material (insulating) with a metal conductor layer (conductive). This composite approach allows the ceramic to provide mechanical strength and structural integrity while the metal layer provides electrical conductivity and corrosive resistance, resolving the contradiction between strength and corrosive resistance.
2Reliability
If precious metal material covering the electrode is used, then corrosive resistance is improved, but electrochemical noise is generated when peeling occurs
Solution Approach 1:
The patent extracts the problematic interface between base metal and precious metal coating by introducing a ceramic insulating layer. This eliminates the galvanic couple that causes electrochemical noise, while the metal conductor layer still provides corrosive resistance. The ceramic layer acts as an electrical isolator, preventing noise generation even if the metal layer peels.
3Adaptability or versatility
If annular groove is formed in the large diameter portion, then gasket accommodation is enabled, but conductor thickness is reduced at corners
Solution Approach 1:
The patent applies local quality by providing different structural characteristics in different regions. The annular groove is provided only in the large diameter portion (disc-shaped part) of the electrode, while the small diameter portion (cylindrical part) maintains uniform conductor coverage without grooves. This localized approach enables gasket accommodation where needed while preserving conductor thickness uniformity where conductivity is critical.
4Reliability
If metal paste sintering is used to cover the conductor, then corrosive resistance is improved, but contract stress causes peeling at outer peripheral wall
Solution Approach 1:
The patent changes the material parameter of the base material from conductive metal to insulating ceramic. This parameter change fundamentally alters the thermal expansion characteristics during sintering, reducing the linear expansion coefficient difference between base material and metal paste. Consequently, contract stress during cooling is minimized, preventing peeling at the outer peripheral wall while still achieving corrosive resistance.
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 enhances the reliability of conduction by minimizing peeling and corner-related issues, maintaining conductivity while reducing manufacturing costs through a cost-effective conductor configuration.
Implementation Method 1
a main body portion (21) having a liquid-contact portion (25) and being formed by covering a base material (41) with an electrically conductive material (42)
Implementation Method 2
Some electromagnetic flow meters of the related art are configured to extract an electromotive force generated in a fluid flowing in a measurement tube by using an electropotential detection electrode
Data Source
AI summary
An electropotential detection electrode includes a main body portion including a liquid-contact portion exposed into a measurement tube and formed by covering a base material with a conductor and a terminal portion electrically connected to the conductor. The main body portion includes a small diameter portion having a cylindrical shape and a large diameter portion having a disc shape extending outward from the small diameter portion in a radial direction. The terminal portion includes an electrically conductive body having a cylindrical body that accommodates the large diameter portion fitted therein and a shaft portion extending from the electrically conductive body in a direction opposite from the main body portion. The large diameter portion is provided on an outer peripheral portion thereof with an annular recessed portion that defines an annular groove between the large diameter portion and the cylindrical body.