Single Crystal Preloader for High-Temperature Seal Resiliency
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Solution Overview
Problem
Conventional thermal barriers and seals lose resiliency at elevated temperatures, leading to open gaps and potential catastrophic heat ingestion in aerospace and industrial applications, particularly above 1200°F, where polycrystalline alloys lose strength and exhibit excessive creep.
Innovation Solution
Development of a high-temperature single crystal preloader using nickel base superalloys, fabricated through investment casting or machining, with processes involving rapid prototyping and precise orientation of single crystal materials to create resilient coil and wave spring configurations that maintain sealing contact up to 2000°F.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polycrystalline alloys are used for thermal barriers and seals, then manufacturing is easier and cost is lower, but resiliency is lost at temperatures above 1200°F leading to open gaps and heat ingestion
Solution Approach 1:
The patent changes the material parameter from polycrystalline structure to single crystal structure, which fundamentally alters the thermal and mechanical properties. Single crystal nickel base superalloys maintain resiliency at temperatures exceeding 1200°F where polycrystalline alloys fail, directly resolving the high-temperature reliability issue while accepting increased manufacturing complexity
Solution Approach 2:
The patent employs single crystal nickel base superalloys as a specialized composite material system. These alloys combine multiple elements (nickel, chromium, cobalt, tungsten, molybdenum, aluminum, titanium) in specific proportions to create a material with superior high-temperature strength and creep resistance, enabling seal resiliency at temperatures where conventional materials fail
2Temperature
If single crystal nickel base superalloys are used for high temperature applications up to 2000°F, then seal resiliency and strength are maintained, but new fabrication processes are required
Solution Approach 1:
The patent applies preliminary action by creating a sacrificial pattern (positive replica of the desired spring geometry) before casting. This pattern is embedded in a refractory material to form a mold cavity, ensuring the single crystal alloy solidifies into the precise complex spring geometry required. This preliminary patterning step enables the subsequent casting process to produce the intricate shapes that would otherwise be impossible to manufacture
Solution Approach 2:
The patent uses a refractory material as an intermediary to create the mold cavity. The sacrificial pattern is embedded in this refractory material, which then serves as the negative mold for casting the single crystal spring. This intermediary refractory layer enables the transfer of the complex pattern geometry into the final spring component while withstanding the high temperatures of the casting process
3Reliability
If single crystal materials are used to maintain over 80% resiliency up to 2000°F, then thermal integrity is ensured, but manufacturing precision and orientation control are required
Solution Approach 1:
The patent applies local quality by orienting the single crystal structure with specific crystallographic directions aligned with principal stress axes in different regions of the spring. The goniometer measures and controls the orientation of the <001> crystal direction relative to the spring geometry, ensuring that each region of the spring has the optimal crystal orientation for resisting the local stress state, thereby maximizing thermal integrity and resiliency
Data Source
AI summary
A process for forming a high temperature single crystal canted spring is provided. In one embodiment, the process includes fabricating configurations of a rapid prototype spring to fabricate a sacrificial mold pattern to create a ceramic mold and casting a canted coiled spring to form at least one canted coil spring configuration based on the ceramic mold. The high temperature single crystal canted spring is formed from a nickel-based alloy containing rhenium using the at least one coil spring configuration.