Partially Degradable Separation Interface for Pressure-Assisted Sintering

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Solution Overview

Problem

Advanced pressure-assisted sintering techniques face challenges in generating complex shapes due to difficulties in creating internal separation interfaces, leading to post-processing porosity and limitations in shape complexity.

Innovation Solution

A method involving 3D printing of a polymer shell model surrounded by sintering powder, where the polymer decomposes into a graphite interface layer, allowing for full densification and easy release of complex shape parts using a simple tooling geometry and internal separation interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional pressure assisted sintering techniques are used to fabricate complex shapes, then high pressure and temperature enable consolidation of powders with controlled microstructure, but post-processing porosity remains and shape complexity is limited due to complex tooling requirements

Engineering Contradiction:

Improvemicrostructure controlVSAvoidtooling complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The tooling system is segmented into a simple external container and an internal polymer shell model. The polymer shell model is divided into functional zones (support structure, separation interface, cavity definition) that can be independently designed and printed. This segmentation allows complex internal geometries to be achieved through additive manufacturing of the polymer model, while the external sintering tooling remains simple and standardized.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A polymer shell model serves as an intermediary between the simple external tooling and the final sintered powder part. This polymer model acts as a temporary sacrificial structure that defines the complex internal geometry, provides separation interfaces, and supports the powder assembly during sintering. After sintering, the polymer model is removed by decomposition or melting, leaving the desired complex shape without requiring complex permanent tooling.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Shape

If complex shape fabrication is attempted using traditional methods, then some level of post-processing porosity remains, but full densification cannot be achieved

Engineering Contradiction:

Improveshape complexityVSAvoiddensification uniformity

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The polymer shell model is designed with locally optimized properties: thicker walls in regions requiring structural support, thinner walls where separation interfaces are needed, and strategic placement of ventilation channels. The powder is selectively placed in different regions (inside the polymer model, outside the polymer model, and in ventilation channels) to achieve uniform densification throughout the final part while maintaining complex geometry.

Inventive Principle:

Principle #3Local quality

3Productivity

If simple tooling geometry is used with internal separation interface, then complex shapes can be generated, but the generation of internal separation interface by traditional approaches such as imprint in powder bed or graphite foil container is difficult

Engineering Contradiction:

Improvecomplex shape generation capabilityVSAvoidinternal interface fabrication

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Traditional mechanical methods for creating internal separation interfaces (imprinting in powder bed, using graphite foil containers) are replaced with additive manufacturing of polymer shell models. The 3D printing process automatically creates complex internal geometries, separation interfaces, and support structures without manual intervention, significantly reducing fabrication difficulty and enabling shapes that would be impossible to create with traditional mechanical methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables the generation of fully dense, high-complexity shapes with increased productivity by combining 3D printing and pressure-assisted sintering techniques, facilitating the simultaneous sintering of multiple parts and overcoming traditional limitations in shape complexity and densification gradients.

Implementation Method 1

heating of the powder-encased polymer shell model to decompose the polymer shell model and generate an in bed graphite interface

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

sintering of the powder assembly

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS11926091B2In situ partially degradable separation interface for fabrication of complex near net shape objects by pressure assisted sintering

Publication Date: 2024.03.12 SAN DIEGO STATE UNIV RES FOUND

AI summary

The invention relates to a process for fabricating complex mechanical shapes, and in particular to fabricating complex mechanical shapes using a pressure-assisted sintering technique to address problems relating to variations in specimen thickness and tooling, or densification gradients, by 3-D printing of a polymer model that is surrounded by and filled with sintering powder material, wherein the 3-D polymer model decomposed into a graphite interface layer and facilitates release of the cast, e.g. metal, metal-alloy, ceramic, etc., manufactured item.