Piezoelectric Sensor Metallic Insulator Coating
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Solution Overview
Problem
Piezoelectric sensor devices face noise signal interference due to thermal transients caused by differing thermal expansion coefficients between piezoelectric elements and metallic components, leading to parasitic signals that hinder accurate monitoring and detection of mechanical effects.
Innovation Solution
A metallic layer, preferably composed of precious metals like silver, gold, or platinum, is deposited on the surface of the insulator to create a metal-metal interface, reducing stick-slip sliding and allowing smooth movement, thus minimizing noise signals. This layer can be applied using screen printing or other deposition techniques, ensuring stability up to high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric element is arranged between electrical insulators and metallic parts, then the electrical charge can be measured as voltage, but thermal transients cause parasitic signals due to CTE mismatch between crystalline parts and metallic parts
Solution Approach 1:
A metallic layer is deposited on the surface of the insulator to create an intermediate interface between the crystalline insulator and the metallic carrier body. This metallic layer acts as a mediator that eliminates stick-slip sliding by providing a metal-metal contact interface, thereby suppressing parasitic signals generated during thermal transients while maintaining the electrical insulation function.
Solution Approach 2:
The interface material composition is changed from a direct ceramic-metal contact to a metal-coated ceramic-metal contact. By altering the surface properties of the insulator through metallic coating, the friction characteristics and thermal expansion compatibility are improved, reducing stick-slip behavior and parasitic signal generation during temperature changes.
2Adaptability or versatility
If materials with different CTE values are used for piezoelectric elements and metallic parts, then functional requirements are met, but stick-slip sliding occurs at interfaces during thermal transients
Solution Approach 1:
The metallic layer on the insulator surface serves as an intermediary that modifies the interface characteristics between materials with different CTE values. This intermediate layer prevents direct ceramic-metal contact, eliminating the stick-slip mechanism while allowing the bulk materials to maintain their different thermal expansion properties necessary for functional operation.
Solution Approach 2:
The solution applies a metallic coating only at the specific interface region where stick-slip sliding occurs, rather than changing the material properties of the entire insulator or carrier body. This localized modification preserves the overall material selection for functional requirements while eliminating the harmful sliding effect at the critical contact interface.
3Object-affected harmful factors
If transition elements are inserted to compensate for thermal dilation, then thermal expansion effects are reduced, but the design becomes more complex and measurement may be impeded
Solution Approach 1:
Instead of inserting a separate transition element that could complicate the design and impede measurement, the solution uses a thin metallic layer deposited on the insulator surface as the intermediary. This approach achieves thermal expansion compensation and stick-slip elimination with a simpler structure that does not interfere with the measurement function.
Solution Approach 2:
The solution replaces the mechanical transition element approach with a surface coating approach. By depositing a metallic layer on the insulator surface, the thermal and mechanical interface problems are solved through material surface modification rather than through additional mechanical components, thereby reducing design complexity.
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 effectively suppresses parasitic signals across various temperature and frequency conditions, providing reliable measurements without altering the existing sensor design or manufacturing processes, even in sensitive domains like aeronautics and power generation.
Implementation Method 1
The occurrence of stick-slip type sliding is related to the level of CTE mismatch, contact area dimension and friction coefficients at the interface
Implementation Method 2
the piezoelectric element and the insulators have differing CTEs (coefficient of thermal expansion) values and undergo differing thermal expansion when the operating temperature changes
Implementation Method 3
Sensor devices comprising a piezoelectric element are well known in the art. They serve to determine forces, f. i. pressure and forces exerted on constructional elements
Data Source
AI summary
A piezoelectric sensor device comprising a piezoelectric element and at least one metallic body, with an insulating body arranged between each metallic body and the piezoelectric element. The insulating body substantially consists of a crystalline material or ceramics. At least one surface of the insulating body in contact with the metallic body is covered by a metallic layer in order to suppress noise signals due to a stick-slip effect and differing thermal expansion coefficients