High-Temperature Ceramic Pressure and Flow Sensors
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Solution Overview
Problem
Existing sensors fail to reliably measure properties like temperature, pressure, and fluid flow in very high temperatures and harsh conditions, such as those found in propulsion and power generation systems, due to material limitations.
Innovation Solution
Development of a sensor device with an electrically non-conductive ceramic core and electrically conductive ceramic or metal conductors, along with a transducer that can withstand temperatures up to 1800°C, using materials like alumina, zirconia, and refractory metals, and incorporating capacitive pressure sensing mechanisms and resistive elements that vary with temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional sensors are used in very high temperature environments, then they are easy to manufacture and operate under normal conditions, but they fail to operate reliably at temperatures up to 1800°C due to material limitations
Solution Approach 1:
The sensor employs a composite structure combining ceramic materials (alumina, zirconia) for structural components with refractory metal coatings (platinum, rhodium, iridium) for electrical conductivity and corrosion resistance. This composite approach enables the sensor to withstand temperatures up to 1800°C while maintaining both structural integrity and electrical functionality, resolving the contradiction between temperature resistance and reliability.
2Temperature
If standard electrical conductors are used, then the device is simple to construct, but the conductors cannot withstand very high temperatures and corrosive fluids
Solution Approach 1:
The electrical conductors transition from conventional metal wires to ceramic-based conductive paths with modified electrical parameters. The ceramic conductors exhibit temperature-dependent resistance characteristics that remain stable up to 1800°C, and the capacitive transducer parameters are adjusted to compensate for thermal effects, enabling high-temperature operation without excessive structural complexity.
3Object-affected harmful factors
If existing transducer materials are used, then manufacturing is straightforward, but the transducers cannot operate in corrosive, oxidizing, or reducing fluids
Solution Approach 1:
A protective ceramic coating layer acts as an intermediary barrier between the transducer components and the corrosive fluid environment. This ceramic coating provides chemical inertness against corrosive, oxidizing, and reducing fluids while allowing the underlying transducer structure to maintain its electrical and mechanical functions, thus protecting the sensor without requiring complete redesign of the manufacturing process.
4Temperature
If conventional sensor designs are used, then they are simple in structure, but they cannot maintain structural integrity at very high temperatures
Solution Approach 1:
The sensor is divided into functionally distinct segments: a ceramic body for structural stability, refractory metal coatings for electrical conductivity, and protective outer layers for corrosion resistance. Each segment is optimized for its specific function and can be manufactured separately using conventional ceramic and metallurgical processes, then assembled into the final composite structure, maintaining manufacturability while achieving high-temperature structural integrity.
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 sensor device provides reliable and long-term operation in extreme conditions, enabling accurate measurement of temperature, pressure, and fluid flow, even in corrosive and oxidizing environments, by utilizing high-temperature resistant materials and designs that maintain structural integrity and electrical conductivity.
Implementation Method 1
A capacitive pressure sensing transducer comprising a ceramic housing and a ceramic membrane that together enclose and hermetically seal a space, wherein the membrane is positioned a spaced distance apart from a first electrode and is resiliently deformable toward and away from the first electrode in response to pressure changes outside of the enclosed and hermetically sealed space. A second electrode on the membrane is movable with the membrane toward and away from the first electrode in a manner that forms a variable capacitor.
Implementation Method 2
Some embodiments of the transducer also comprise electrically conductive ceramic elements in which electrical resistance varies as a function of temperature.
Implementation Method 3
the membrane is positioned a spaced distance apart from a first electrode and is resiliently deformable toward and away from the first electrode in response to pressure changes outside of the enclosed and hermetically sealed space
Data Source
AI summary
Heat resistant sensors equipped with any of a variety of transducers for measuring any of a variety of properties of fluids are constructed with components comprising materials that can withstand very high temperatures. Some embodiments of the sensors include a first pressure sensitive element and a second pressure sensitive element with respective first and second membranes positioned in juxtaposed relation to each other to form a capacitor. Some embodiments include a pusher that extends from the membrane toward a first electrode. Some embodiments have a housing comprising a ceramic substrate with a sensor element mounted on an inside surface of the substrate. Other embodiments have direction sensing capabilities including a heater positioned in a core material and at least three temperature sensors located at or near the peripheral surface of the core material and spaced apart angularly in relation to each other.