Tungsten-CFC Joined Material With Gradient Sintered Interface
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Solution Overview
Problem
The challenge lies in effectively joining high-melting point metals like tungsten with carbon materials due to poor wettability and thermal expansion differences, leading to stress concentration and difficulty in forming thick layers, which affects the durability and heat conduction of the joined material.
Innovation Solution
A joined material is created by sintering a ceramic layer with a sintering aid agent on a carbon material layer, followed by a tungsten layer, ensuring a strong anchoring effect and high heat conduction, with the ceramic layer thickness ranging from 10 µm to 500 µm to balance strength and thermal stress, and using SiC or AlN as ceramics to enhance the bonding mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a high-melting point metal material is joined to a carbon material using a brazing material, then the joining process becomes feasible, but the metal has poor wettability with the metal making it difficult to join
Solution Approach 1:
The patent introduces a gradient intermediate layer between the carbon material and high-melting point metal. This intermediate layer has a composition that gradually transitions from carbon-rich near the carbon material to metal-rich near the high-melting point metal, improving wettability and bonding strength while eliminating the direct interface between incompatible materials.
Solution Approach 2:
The patent employs plasma treatment to modify the surface properties of the high-melting point metal before joining. By changing the surface parameters (surface energy, roughness, chemical composition) through plasma exposure, the metal achieves better wettability with the brazing material and improved bonding to the carbon material.
2Temperature
If a high-melting point metal material is joined to a carbon material, then the thermal expansion rate difference causes stress concentration, but the resulting material becomes easier to break
Solution Approach 1:
The patent creates a gradient intermediate layer with locally varying composition and properties. Near the carbon material, the layer has properties matching carbon (lower thermal expansion, higher thermal conductivity), while near the metal, it transitions to match metal properties. This local adaptation of material properties reduces stress concentration at the interface.
Solution Approach 2:
The patent uses a composite gradient structure combining carbon-containing compounds, metal compounds, and metal phases in varying proportions. This composite approach allows the intermediate layer to exhibit intermediate thermal expansion properties between carbon and metal, reducing thermal stress while maintaining structural integrity.
3Quantity of substance
If a tungsten layer is formed on a carbon material by CVD or PVD, then a metal layer is achieved, but the maximum thickness is limited to several hundred micrometers
Solution Approach 1:
The patent applies preliminary surface treatment and intermediate layer formation before depositing the tungsten layer. By preparing the surface with a gradient intermediate structure first, the subsequent tungsten deposition can proceed more effectively, allowing for thicker layers without compromising adhesion or quality.
Solution Approach 2:
The gradient intermediate layer serves as a mediator that enables thicker tungsten layer formation. The intermediate layer provides a progressive transition zone that supports the weight and stress of thicker metal deposits, allowing the tungsten layer to exceed the conventional several hundred micrometer limit while maintaining bonding integrity.
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 solution enables robust joining of tungsten and carbon fiber composite materials, improving flexural strength and heat conduction, while preventing peeling and cracking, and maintaining structural integrity under high temperatures, suitable for applications like nuclear fusion reactors.
Implementation Method 1
a joined material is created by sintering a ceramic layer with a sintering aid agent on a carbon material layer
Data Source
Figure 1(a)~3(b)
Figure 4(a)~4(b)
Figure 5
AI summary
A joined material and a method of manufacturing the joined material are provided which enable a metal layer and a carbon material layer to be easily joined to each other while making the thickness of the metal layer larger and which can inhibit failure. A joined material includes a CFC layer (3) and a tungsten layer (4) that are joined to each other. A sintered tungsten carbide layer (5), a mixed layer (6) of SiC and WC, and SiC and WC (7) that have been sintered while intruding into the CFC layer (3), are formed between the CFC layer (3) and the tungsten layer (4), and these layers (3, 4, 5, 6, and 7) are joined to each other by sintering.