Ceramic Pressure Sensor Diffusion Weld for Corrosive Media Sealing
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Solution Overview
Problem
Ceramic pressure sensors face challenges with corrosion resistance when exposed to highly corrosive media due to soldered joints, and existing solutions like sapphire membranes are costly and prone to measurement inaccuracies due to surface roughness and thermomechanical stresses.
Innovation Solution
A pressure measuring device with a ceramic measuring membrane secured by a titanium or titanium alloy mounting element using a diffusion weld, which provides a diffusion-tight and corrosion-resistant seal without interposing joint materials, allowing for high pressure resistance and reduced thermomechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If soldered joints are used to connect the ceramic measuring membrane to the base body, then the pressure sensor can be manufactured with standard ceramic joining methods, but the corrosion resistance deteriorates when exposed to highly corrosive media
Solution Approach 1:
The patent removes the soldered joint from the system by using a diffusion-tight ceramic-to-ceramic connection instead. The measuring membrane is directly integrated with the base body through a diffusion bond, eliminating the intermediate solder joint that would corrode in harsh environments. This extraction of the problematic component (solder joint) resolves the contradiction between manufacturability and corrosion resistance.
Solution Approach 2:
The patent employs composite material construction where both the measuring membrane and base body are made of ceramic materials with compatible thermal expansion coefficients. This ceramic-ceramic composite structure enables direct diffusion bonding without requiring metallic solder joints, thereby achieving both manufacturability through standard ceramic processes and superior corrosion resistance in highly aggressive media.
2Reliability
If sapphire membranes are used to improve corrosion resistance, then the sensor can withstand highly corrosive media, but the cost increases and measurement inaccuracies occur due to surface roughness and thermomechanical stresses
Solution Approach 1:
The patent applies local quality by using polycrystalline ceramic with controlled grain structure and surface properties specifically optimized for the measuring membrane region. Instead of using expensive sapphire throughout, the solution employs a tailored polycrystalline ceramic material that provides sufficient corrosion resistance while maintaining better surface quality and lower thermomechanical stress, thus preserving measurement accuracy.
Solution Approach 2:
The patent changes the material parameters by selecting polycrystalline ceramic with specific grain size, pore structure, and surface roughness characteristics that optimize both corrosion resistance and measurement precision. By adjusting these material parameters, the solution achieves adequate corrosion protection without the measurement inaccuracies associated with sapphire's surface roughness and high thermomechanical stress.
3Ease of manufacture
If a clamping apparatus with sealing apparatus is used to secure the pressure sensor, then the sensor can be mounted in the sensor mounting, but the sealing materials age with time and are not diffusion tight
Solution Approach 1:
The patent merges the measuring membrane directly with the base body through diffusion bonding, eliminating the separate clamping apparatus and sealing apparatus. The measuring membrane is integrally connected to the base body, creating a unified structure where the ceramic-to-ceramic diffusion bond provides both mechanical securing and diffusion-tight sealing in one integrated connection, removing the need for separate sealing components that would age over time.
Solution Approach 2:
The patent extracts and removes the aging sealing materials (elastomers, thermoplastics) from the system by replacing them with a diffusion-tight ceramic-to-ceramic connection. The clamping apparatus and its sealing components are completely eliminated in favor of a direct diffusion bond between the measuring membrane and base body, ensuring long-term sealing performance without material degradation.
4Adaptability or versatility
If ceramic pressure sensors are used to avoid diaphragm seals, then the sensor can be directly exposed to the medium, but the soldered joints become vulnerable to corrosion attacks
Solution Approach 1:
The patent employs a ceramic-ceramic composite structure where both the measuring membrane and base body are made of corrosion-resistant ceramic materials. This composite construction allows the entire pressure sensor to be directly exposed to aggressive media without vulnerable soldered joints, as the ceramic-ceramic diffusion bond maintains corrosion resistance throughout the structure, enabling full adaptability for direct medium contact.
Solution Approach 2:
The patent extracts and eliminates the soldered joint from the pressure sensor structure, replacing it with a diffusion-tight ceramic-to-ceramic connection. This removal of the vulnerable metallic joint allows the pressure sensor to be fully exposed to highly corrosive media without the risk of joint corrosion, maintaining both adaptability for direct contact and reliability in corrosive environments.
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 diffusion weld ensures a highly corrosion-resistant and pressure-resistant connection, enabling the use of ceramic pressure sensors in corrosive environments without degrading measurement characteristics, and allowing for the use of polycrystalline ceramic membranes with rough surfaces, reducing production costs and maintaining measurement accuracy.
Implementation Method 1
the membrane edge of the measuring membrane is connected directly with the mounting element of the sensor mounting by means of a diffusion weld, wherein the diffusion weld is a diffusion weld produced by means of a diffusion welding method
Data Source
AI summary
A pressure measuring device includes a ceramic pressure sensor including a ceramic measuring membrane and a sensor mounting configured to secure the pressure sensor such that a membrane region of the measuring membrane surrounded by a membrane edge is contactable with a medium having a pressure to be measured. The sensor mounting includes a titanium or titanium alloy mounting element including an opening through which the membrane region is contactable with the medium. The membrane edge is connected directly with the mounting element by a diffusion weld produced by a diffusion welding method.