Fluidized Bed Powder Treatment Preventing Sintering
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Solution Overview
Problem
Current methods for pre-treating powders in additive manufacturing, such as degassing and heat treating, are complex, costly, and prone to sintering or oxidation, necessitating a simpler and more reliable system.
Innovation Solution
A fluidized bed system comprising an outer and inner chamber within a furnace, where the powder is fluidized and heat-treated using an inert gas to prevent sintering and oxidation, allowing for efficient microstructure manipulation and coating without exposing the inner chamber to high furnace temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional high temperature heat treatment is applied to powder, then sintering is prevented, but the system becomes complex and costly to manufacture
Solution Approach 1:
The system divides the treatment process into two separate chambers: a first chamber for degassing at lower temperature and a second chamber for heat treatment at higher temperature. This segmentation allows each chamber to be optimized for its specific function, preventing sintering during heat treatment while keeping the overall system simpler and more cost-effective than traditional single-chamber designs.
Solution Approach 2:
An inert gas flows through both chambers, serving as an intermediary that protects the powder from oxidation during heat treatment. The gas acts as a mediator that enables high-temperature processing without direct contact between the powder and oxidizing atmosphere, thereby preventing sintering while maintaining system simplicity.
2Reliability
If vacuum heating is used for degassing, then water vapor is removed from powder particles, but maintaining very low pressure vacuum becomes complicated
Solution Approach 1:
The system changes the pressure parameter by operating the degassing chamber at a reduced but not extremely low vacuum pressure. This parameter adjustment allows effective water vapor removal through the inert gas flow while avoiding the complexity of maintaining very low pressure vacuum, thus removing water vapor without complicating the vacuum system.
3Reliability
If powder is exposed to oxidizing environment during heat treatment, then oxidation occurs on powder surfaces, but preventing oxidation requires complex protective measures
Solution Approach 1:
The system uses an inert gas atmosphere in both chambers to prevent oxidation. The inert gas flows through the first chamber during degassing and continues into the second chamber during heat treatment, creating a protective inert environment that prevents oxidation without requiring complex protective measures such as vacuum sealing or reactive gas generation.
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 approach enables cost-effective, reliable pre-treatment of powders, preventing sintering and oxidation, and facilitating better bonding and deformation in additive manufacturing processes, while allowing for the use of less expensive materials in the fluidized bed assembly.
Implementation Method 1
fluidizing the powder particles with the gas
Implementation Method 2
heat-treating the powder particles with the furnace
Data Source
AI summary
A system comprises a furnace, a fluidized bed assembly and a powder bed. The fluidized bed assembly is positioned in the furnace and comprises an outer chamber having an outer chamber inlet for receiving gas, an inner chamber positioned inside of the outer chamber. The inner chamber comprises an inner chamber inlet in fluid communication with the outer chamber, and an outlet through which the gas may exit the inner chamber and the outer chamber. The powder bed is disposed in the inner chamber.