Refractory Component Additive Manufacturing via Binder Jet and CVI
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Solution Overview
Problem
Existing methods struggle to produce complex components made from refractory materials, such as heat exchangers and turbines, which are essential for high-efficiency energy systems due to their inability to handle high temperatures.
Innovation Solution
An additive manufacturing process involving binder-jet printing of a green body followed by chemical vapor infiltration (CVI) is used to create objects with complex geometries from refractory materials like SiC, C, ZrC, Mo, and W, achieving high density and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional manufacturing methods are used to produce refractory components, then simple geometries (e.g., piping) can be manufactured, but complex components (e.g., heat exchangers, flanges, turbines) cannot be readily produced
Solution Approach 1:
The manufacturing process is segmented into distinct stages: (1) additive manufacturing of a green body with complex geometry using binder-jet printing, (2) removal of the binder, and (3) chemical vapor infiltration (CVI) to densify and produce the final refractory component. This segmentation allows each stage to be optimized independently, enabling complex geometries to be manufactured that would be impossible with conventional monolithic manufacturing methods.
Solution Approach 2:
A binder is used as an intermediary material during the additive manufacturing process to hold the refractory powder particles together in the green body. The binder is subsequently removed through combustion or oxidation, creating voids that are then filled through CVI. This intermediary approach enables the formation of complex geometries while maintaining structural integrity during manufacturing, and the binder removal creates space for the final densified refractory material.
2Temperature
If refractory materials are used to withstand high temperatures, then thermal efficiency of energy systems is improved, but the ability to manufacture complex components remains limited
Solution Approach 1:
The process separates the geometry formation stage (additive manufacturing at room temperature) from the heat treatment stage (CVI at elevated temperatures). This allows complex geometries to be created without thermal constraints during manufacturing, and then the same complex geometry can be densified and purified through CVI at high temperatures to achieve the required heat resistance.
Solution Approach 2:
The manufacturing process utilizes parameter changes in temperature and atmosphere: (1) Additive manufacturing occurs at room temperature in a controlled atmosphere, (2) Binder removal occurs through combustion or oxidation at elevated temperatures, and (3) CVI occurs at high temperatures in a controlled atmosphere to deposit refractory material. These parameter changes enable both complex geometry formation and high-temperature resistance to be achieved in the same component.
3Use of energy by stationary object
If CVI is performed at temperatures far below sintering temperatures, then energy consumption is reduced, but densification and binder removal must be achieved through alternative means
Solution Approach 1:
The binder is extracted or removed through combustion or oxidation reactions before or during the CVI process. This extraction creates voids and porosity that allow the CVI process to proceed at lower temperatures. The removal of the binder is a separate, controlled step that enables the CVI process to achieve densification without requiring the extremely high temperatures typically needed for sintering.
Solution Approach 2:
The binder removal process utilizes phase transitions and chemical reactions: (1) Combustion of organic binders, (2) Oxidation of metal binders, or (3) Thermal decomposition of binder materials. These phase transitions occur at relatively low temperatures compared to sintering, creating the necessary porosity for CVI to proceed efficiently at reduced temperatures while still achieving the required densification and binder removal.
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 method enables the production of high-density, heat-resistant components with complex geometries, such as heat exchangers and turbines, exceeding conventional methods in thermal efficiency and packing density, particularly in nuclear fuel assemblies.
Implementation Method 1
additive manufacture of a green body from a powder-based refractory matrix material
Implementation Method 2
densification via CVI
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method for the manufacture of a three-dimensional object using a refractory matrix material is provided. The method includes the additive manufacture of a green body from a powder-based refractory matrix material followed by densification via chemical vapor infiltration (CVI). The refractory matrix material can be a refractory ceramic or a refractory metal. In one embodiment, the matrix material is deposited according to a binder-jet printing process to produce a green body having a complex geometry. The CVI process increases its density, provides a hermetic seal, and yields an object with mechanical integrity. The residual binder content dissociates and is removed from the green body prior to the start of the CVI process as temperatures increase in the CVI reactor. The CVI process selective deposits a fully dense coating on all internal and external surfaces of the finished object.