Fused Silica Body Vitrified Inner Layer Moisture Barrier

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Solution Overview

Problem

Fused silica bodies, used in applications like radomes and pharmaceutical mixing, are prone to moisture penetration due to their porosity, which can lead to contamination and damage of sensitive components or chemicals, and existing coatings have varying success and may degrade the dielectric performance.

Innovation Solution

A thin, uniform vitrified silica layer is autogenically generated on the inner surface of fused silica bodies through focused heat treatment, creating a durable and fully integrated moisture barrier that maintains the dielectric properties of the silica.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If fused silica bodies are used in radome and pharmaceutical applications, then strength, light weight, and temperature resistance are improved, but porosity causes moisture penetration that compromises component protection and chemical purity

Engineering Contradiction:
ImprovestrengthVSAvoidmoisture penetration
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies a vitrified silica coating specifically to the inner surface of the fused silica body, creating a localized dense barrier layer while maintaining the overall porous structure of the bulk material. This local quality change prevents moisture penetration at the critical inner surface without altering the beneficial bulk properties of the fused silica.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure consisting of a porous fused silica bulk material combined with a dense vitrified silica coating layer. This composite approach combines the advantages of the porous structure (strength, light weight, temperature resistance) with the advantages of the dense coating (moisture barrier) to resolve the contradiction.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If organic or inorganic coatings are applied to radome exteriors as moisture barriers, then moisture penetration is reduced, but dielectric performance is degraded and coating durability is compromised

Engineering Contradiction:
Improvemoisture barrierVSAvoiddielectric performance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent uses vitrified silica, which is chemically and structurally homogeneous with the underlying fused silica substrate. This material compatibility ensures that the coating maintains the dielectric properties of the base material while providing moisture protection, avoiding the dielectric performance degradation associated with organic or inorganic coatings.

Inventive Principle:
Principle #33Homogeneity

Solution Approach 2:

The vitrified silica coating is applied through a process that utilizes the material's own properties - heating the fused silica body to transform its surface into a dense vitreous layer. This self-service approach creates a durable, integrated coating that enhances rather than compromises the material's inherent dielectric performance.

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If thin coatings are applied to radome exteriors, then moisture barrier function is achieved, but coating thickness is insufficient for durability against handling and wear

Engineering Contradiction:
Improvemoisture barrierVSAvoidcoating durability
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The vitrified silica coating is formed by heating the fused silica body itself, causing the surface material to transform into a dense vitreous layer. This self-service process creates a coating that is chemically bonded to the substrate, providing superior adhesion and durability compared to externally applied thin coatings that are susceptible to delamination from handling and wear.

Inventive Principle:
Principle #25Self-service

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 autogenic vitrified silica layer effectively prevents moisture penetration while maintaining the dielectric integrity of the fused silica, enhancing durability and resistance to wear and tear, and can be tailored for specific applications by adjusting the layer thickness and processing techniques.

Implementation Method 1

heating at least a portion of an inner surface of the silica body to the point of vitrification by passing over at least a portion of the inner surface a focused heat source

Methodology Applied
Scientific EffectVitrification: Vitrification

Implementation Method 2

passing over at least a portion of the inner surface a focused heat source configured to heat at one time an area of the inner surface

Methodology Applied
Scientific EffectFocused heating: Heating

Data Source

PatentEP2505565B1Fused silica body with vitreous silica inner layer, and method for making same
Publication Date: 2016.08.24 RAYTHEON CO
  • EP2505565B1 patent drawingFigure 1A~1B
  • EP2505565B1 patent drawingFigure 2A
  • EP2505565B1 patent drawingFigure 2B

AI summary

A fused silica body comprising a layer of vitreous silica adjacent at least a portion of an inner surface is described in embodiments herein. In other embodiments, a method of making a fused silica body with a layer of vitreous silica adjacent at least a portion of an inner surface is described herein, comprising heating at least a portion of the inner surface to the point of vitrification. In certain embodiments, the method involves passing a linear local heat source over the inner surface in a particular manner, such as a helical fashion transverse to the linear shape, and may involve creating on the inner surface of the body overlapping swaths of temporarily melted silica material.