Ceramic Diaphragm Vacuum Cell Corrosion Protection
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Solution Overview
Problem
Existing ceramic vacuum measuring cells with diaphragms are not suitable for high-resolution measurements in low-pressure vacuum applications due to corrosion issues, especially in chemically aggressive environments, as the joining regions between the diaphragm and housing are vulnerable to chemical reactions and difficult to protect effectively.
Innovation Solution
A capacitive vacuum measuring cell entirely made of ceramic, such as Al2O3 or sapphire, with a diaphragm sealed in the margin region, using gold-coated surfaces for electrodes and an ALD (Atomic Layer Deposition) method to apply a corrosion-resistant metal oxide coating on the inner walls, including the joining regions, to enhance corrosion resistance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon sensors are used for pressure measurement, then cost-effectiveness and ease of manufacture are improved, but corrosion resistance and reliability in aggressive vacuum environments deteriorate
Solution Approach 1:
The patent applies composite materials by combining ceramic diaphragm (Al2O3) with metal components (stainless steel or nickel alloy) in a hybrid construction. The ceramic provides corrosion resistance while the metal components provide mechanical strength and ease of manufacture, resolving the contradiction between ease of manufacture and corrosion resistance.
2Reliability
If protective coatings are applied to silicon sensors, then corrosion resistance is improved, but manufacturing complexity and difficulty of application increase
Solution Approach 1:
The patent uses homogeneous ceramic material (Al2O3) for the diaphragm and housing, eliminating the need for protective coatings on silicon surfaces. The ceramic material inherently provides corrosion resistance without requiring additional coating layers, thus reducing manufacturing complexity while maintaining reliability.
3Reliability
If ceramic materials are used for vacuum measuring cells, then corrosion resistance is improved, but manufacturing precision and joining reliability deteriorate due to difficulty in joining ceramic components
Solution Approach 1:
The patent introduces glass sealant as an intermediary material between ceramic diaphragm and housing components. This glass sealant facilitates reliable joining of ceramic parts while maintaining the corrosion-resistant properties, resolving the contradiction between corrosion resistance and joining reliability.
4Measurement precision
If thin ceramic diaphragms are used for high-resolution low-pressure measurement, then measurement precision is improved, but mechanical strength and durability deteriorate
Solution Approach 1:
The patent employs composite material construction where the thin ceramic diaphragm (Al2O3) is supported by a robust ceramic housing and sealed with glass sealant. This composite structure enables the use of thin diaphragms for high-resolution measurement while the overall composite construction maintains mechanical strength and durability.
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 provides high corrosion resistance and extended service life by effectively protecting the sensitive joining sites and less corrosion-resistant materials, allowing the measuring cell to operate reliably in aggressive vacuum processes while maintaining measurement accuracy.
Implementation Method 1
an ALD (Atomic Layer Deposition) method to apply a corrosion-resistant metal oxide coating on the inner walls, including the joining regions
Implementation Method 2
The capacitor is implemented by disposing the thin flexible diaphragm surface at a short distance opposite a further surface and coating both opposing surfaces with an electrically conducting coating
Data Source
AI summary
Introduced is a method for the production of a diaphragm vacuum measuring cell, wherein on the one side of the diaphragm (2) at a spacing a first housing plate (1) is disposed sealing in the margin region with a joining means (3), and that on the other side of the diaphragm (2) at a spacing a second housing plate (4) is disposed sealing in the margin region with a joining means (3), and that the second housing plate (4) has an opening at which a connection means (5) is disposed sealing with joining means (3) for the connection of the measuring cell (8) with the medium to be measured, wherein the diaphragm (2) and the two housing plates (1, 4) are comprised of a metal oxide. Using an ALD method, the measuring cell is coated in a vacuum chamber (64), in particular through the opening of the measuring cell, such that the inner wall of the measuring vacuum chamber (9) and the opening with the connection means (5) is covered with a protective layer (13) such that at least the joining means (3) for the diaphragm (2) is protectively covered against corrosion.