FFF Vacuum Insulator Structure Without Melting or Trapped Powder

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Solution Overview

Problem

Additive manufacturing of vacuum insulators faces challenges with high-melt temperature alloys, which can crack due to localized melting and thermal gradients, and residual powder residue in internal passages, making it difficult to achieve precise microstructure control and thermal insulation.

Innovation Solution

The use of fused filament fabrication (FFF) with a sacrificial binder and metal or alloy powder, where the binder is removed and the powder is sintered to form vacuum insulators with internal support structures, creating a vacuum environment that reduces heat transfer and avoids melting, allowing for precise control of microstructure and reduced crack propensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If localized melting is used to form vacuum insulators, then manufacturing capability is improved, but crack formation occurs due to thermal gradients

Engineering Contradiction:

Improvemanufacturing capabilityVSAvoidcrack formation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the thermal processing parameter from melting to sintering. Instead of locally melting the material which creates severe thermal gradients, the process uses sintering at lower temperatures to bond particles together, thereby avoiding crack formation while maintaining manufacturing capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the phase transition of binder removal (devolatilization) followed by sintering to achieve consolidation without melting. The binder is removed first, then the remaining powder is sintered to form the final structure, avoiding the harmful effects of melting and thermal gradients

Inventive Principle:

Principle #36Phase transitions

2Ease of manufacture

If powder bed fusion is used, then manufacturing capability is improved, but residual powder residue remains in internal passages

Engineering Contradiction:

Improvemanufacturing capabilityVSAvoidresidual powder residue

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent segments the manufacturing process into distinct stages: binder removal and sintering. This segmentation allows for complete removal of volatile binder materials from internal passages before sintering, preventing residual powder residue that would otherwise remain trapped in complex geometries

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a sacrificial binder as an intermediary material that facilitates the manufacturing process. The binder acts as a temporary matrix holding the powder together during printing, then is completely removed through devolatilization, leaving no residual powder in internal passages

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If high-melt temperature alloys are used, then material performance is improved, but microstructure control becomes difficult

Engineering Contradiction:

Improvematerial performanceVSAvoidmicrostructure control

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the processing temperature parameter from high-melt temperatures to lower sintering temperatures. This parameter change enables precise control of microstructure development during sintering while maintaining the use of high-performance alloys, thereby achieving both material performance and microstructure control

Inventive Principle:

Principle #35Parameter changes

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

This method enables the production of vacuum insulators with reduced residual powder and crack risk, allowing for effective thermal insulation by maintaining a vacuum environment and controlling microstructure, thus improving the thermal performance and structural integrity of additively manufactured components.

Implementation Method 1

removing substantially all the binder

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

sintering the article to form the vacuum insulator

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 3

the vacuum insulator defines a substantially vacuum environment in the cavity

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11707788B2Fused filament fabrication of vacuum insulator

Publication Date: 2023.07.25 ROLLS ROYCE CORP

AI summary

In some examples, an additive manufacturing technique for forming a vacuum insulator. For example, a method including forming an article including a first layer, a second layer, and at least one support member extending between the first and second layer by depositing a filament via a filament delivery device, wherein the filament includes a sacrificial binder and a powder, and wherein the first layer, second layer, and at least one support member define an open cavity within the article; removing the binder; and sintering the article to form the vacuum insulator, wherein the vacuum insulator defines a vacuum environment in the cavity.