Matched Seal Feedthrough Partial Nickel Coating
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Solution Overview
Problem
Current matched seal feedthroughs in glass-to-metal applications face challenges with corrosion resistance and high production costs, particularly due to the use of nickel-iron or nickel-iron-cobalt alloys, which lack sufficient corrosion resistance and result in imperfections that lead to gas pockets and increased production costs when using bimetallic materials.
Innovation Solution
A matched seal feedthrough design where the functional element, such as a contact pin, is partially coated with a nickel or nickel alloy, ensuring a hermetic seal and corrosion resistance by applying the coating over at least 5% to 95% of the glazing length, allowing a chemical bond between the glass and metal while maintaining impermeability and simplicity in manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If nickel-iron or nickel-iron-cobalt alloys are used for the functional element, then the coefficient of thermal expansion matches the fixing material, but corrosion resistance is insufficient
Solution Approach 1:
The functional element is constructed as a composite structure combining nickel-iron or nickel-iron-cobalt alloy (for thermal expansion matching) with a corrosion-resistant coating layer (for protection). This composite approach allows both materials to contribute their respective advantages without compromising either thermal compatibility or corrosion resistance.
Solution Approach 2:
The corrosion-resistant coating is applied selectively to specific regions of the functional element where corrosion risk is highest, such as the transition area between the fixing material and the exposed portion. This localized protection strategy addresses corrosion vulnerability without requiring complete redesign of the entire component.
2Reliability
If a surface coating is applied to the functional element, then corrosion resistance is improved, but cracks occur in the transition area between fixing material and functional element
Solution Approach 1:
The coating is applied in advance to the functional element before insertion into the fixing material, or the coating process is optimized to ensure proper adhesion and flexibility. This preliminary preparation allows the coating to accommodate thermal expansion differences and mechanical stresses without cracking during subsequent assembly and operation.
Solution Approach 2:
The coating's physical and chemical parameters are adjusted to improve flexibility and adhesion properties. This includes modifying coating thickness, composition, and curing characteristics to enable the coating to withstand thermal cycling and mechanical stresses without developing cracks in the transition area.
3Reliability
If a bimetal functional element is used, then corrosion resistance is improved, but production costs increase and gas pockets form in the glazing
Solution Approach 1:
Instead of using a bimetal structure throughout the entire functional element, the corrosion-resistant coating is applied only to specific regions where corrosion protection is most critical, such as the transition area and exposed portions. This localized approach achieves necessary protection while maintaining manufacturing simplicity and avoiding the complexity and cost of bimetal fabrication.
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 partial coating achieves a leakage rate of less than 10^-8 mbar/l for gaseous helium, providing both high corrosion resistance and hermetic sealing without the need for bimetallic materials, thus reducing production costs and ensuring reliability in harsh environments.
Implementation Method 1
allowing a chemical bond between the glass and metal while maintaining impermeability
Implementation Method 2
providing both high corrosion resistance and hermetic sealing
Data Source
AI summary
A matched seal feedthrough comprising: a support body having at least one passage opening, wherein the support body has a first coefficient of thermal expansion α1; at least one functional element; and an electrical insulation fixing material consisting of a glass material, wherein the fixing material has a second coefficient of thermal expansion α2, and the second coefficient of thermal expansion α2 is substantially the same as the first coefficient of thermal expansion α1; wherein the at least one functional element has an outside circumferential surface and is held in the at least one passage opening by the fixing material, the outside circumferential surface includes at least partially a coating with at least one of nickel and nickel alloy resulting in a coated region and an uncoated region of the outside circumferential surface, and the fixing material covers the coated and uncoated region at least partially.