Electrically Isolating Gasket Coatings for Thin High-Temperature Seals
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Solution Overview
Problem
Existing gaskets with electrically isolating properties face limitations such as inadequate dielectric strength, temperature limitations, structural complexity, and chemical resistance issues, leading to failures at elevated temperatures and pressures, and increased thickness due to the need for high-voltage resistance.
Innovation Solution
A gasket design featuring a core component coated with a dielectric material like polyimide, ceramic, or aluminum oxide on all surfaces, including grooves and protrusions, eliminating the need for glass reinforced epoxy and providing enhanced electrical isolation, temperature resistance, and chemical resistance without the use of adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass reinforced epoxy (GRE) is used to provide electrical isolation, then dielectric strength is improved, but temperature resistance deteriorates because GRE becomes soft above 250-350°F and loses strength
Solution Approach 1:
The patent uses a composite structure combining a metal core gasket component with a dielectric coating layer. The metal core provides mechanical strength and dimensional stability, while the dielectric coating (polyimide, ceramic, or aluminum oxide) provides electrical isolation and high-temperature resistance. This composite approach resolves the contradiction by separating the functions of structural support and electrical isolation into different materials optimized for each function.
Solution Approach 2:
The patent changes the material parameters by selecting dielectric coatings with glass transition temperatures above 500°F (such as polyimide, ceramic, or aluminum oxide), which maintains electrical isolation properties at temperatures where GRE would fail. This parameter change in material selection directly addresses the temperature resistance issue while preserving electrical isolation.
2Strength
If adhesive is used to adhere GRE to the gasket core, then bonding strength is improved, but reliability deteriorates at elevated temperatures and pressures due to adhesive failure and delamination
Solution Approach 1:
The patent eliminates the adhesive layer from the construction by using a metal core gasket component with a dielectric coating applied directly to it. This removes the weak link (adhesive) that fails at high temperatures, while the direct coating-to-metal bond provides reliable attachment throughout the operating temperature and pressure range.
3Reliability
If common isolation materials with dielectric strength of 400-800 volts/mil are used, then electrical isolation is provided, but gasket thickness increases which limits application versatility
Solution Approach 1:
The patent selects dielectric coating materials with exceptionally high dielectric strength values exceeding 1000 volts/mil, such as ceramic and aluminum oxide coatings. This parameter improvement in dielectric strength allows for thinner coating layers to achieve the same electrical isolation performance, resulting in thinner overall gasket profiles that are more versatile for various applications with limited space.
4Reliability
If GRE is used for electrical isolation, then dielectric properties are improved, but chemical resistance deteriorates
Solution Approach 1:
The patent employs a composite system where the metal core provides chemical inertness and resistance to degradation, while the dielectric coating (particularly ceramic or aluminum oxide) provides both electrical isolation and enhanced chemical resistance. This composite structure resolves the contradiction by combining materials that individually address different requirements, achieving both dielectric properties and chemical resistance simultaneously.
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 results in a thinner, more reliable, and dimensionally stable gasket with improved electrical isolation, expanded temperature and pressure capabilities, and simplified structure, suitable for various applications including steam and nuclear services, while reducing component complexity and external corrosion.
Implementation Method 1
the coating or film comprises polyimide, ceramic, or aluminum oxide
Data Source
AI summary
An electrically isolating gasket is disclosed wherein a coating layer is disposed on at least one conductive surface, and in some embodiments, on all surfaces or at least all of the conductive surfaces. The electrically isolating gasket includes a core gasket component, a ring seal component, and a non-conductive inner seal component. The coating layer can be, for example, polyimide, polyamide, ceramic, and aluminum oxide.