Refractory Brazing of Carbon Bodies Using Silicon Carbide Joints
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Solution Overview
Problem
Current brazing techniques for carbonaceous parts in microelectronics and solar photovoltaics are inadequate due to the use of metallic elements in solders, which are not suitable for very pure silicon environments, and lack control over silicon infiltration during assembly.
Innovation Solution
A refractory brazing process using silicon as the braze material, where carbonaceous parts are assembled with a silicon element under pressure and heated to form a continuous silicon carbide joint, ensuring all silicon is transformed into SiC, eliminating residual silicon and achieving a pure SiC solder suitable for high-temperature applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic elements are used in solders for brazing carbonaceous parts, then the brazing process can be performed with conventional materials, but the solder purity is insufficient for very pure silicon environments such as microelectronics and solar photovoltaics
Solution Approach 1:
The invention changes the chemical composition parameter of the solder from metallic elements to silicon-based materials (silicon powder, silicon carbide powder, and/or silane). This parameter change enables the solder to be compatible with very pure silicon environments while maintaining brazing functionality through silicon carbide formation at the carbon-silicon interface.
Solution Approach 2:
The invention introduces silicon carbide as an intermediary reaction product between silicon and carbonaceous parts. This intermediary forms a compatible interface that bonds carbonaceous parts while being pure enough for microelectronics and solar photovoltaic applications, resolving the contradiction between conventional brazing ease and solder purity requirements.
2Ease of manufacture
If silicon infiltration is allowed to proceed without control, then the brazing process is simpler, but the infiltration depth is uncontrolled and may compromise part integrity
Solution Approach 1:
The invention applies preliminary action by pre-coating the carbonaceous parts with a specific composition (silicon powder, silicon carbide powder, and/or silane) before the brazing process. This preliminary coating controls the subsequent silicon infiltration depth, preventing excessive penetration while ensuring complete interface coverage, thus maintaining both process simplicity and manufacturing precision.
Solution Approach 2:
The invention utilizes porous silicon-based coatings on carbonaceous parts to control infiltration. The porous structure allows controlled silicon penetration to a desired depth while the coating composition and porosity can be adjusted to achieve precise infiltration control, balancing process simplicity with manufacturing precision.
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 process allows for precise control of silicon infiltration, forming a pure silicon carbide joint over the entire interface, compatible with temperatures up to 2000°C, and is devoid of residual silicon, making it suitable for severe environments in microelectronics and solar photovoltaics.
Implementation Method 1
when liquid silicon is brought into contact with a carbonaceous material, a layer of silicon carbide is formed by reaction at their interface
Implementation Method 2
the growth of which is limited by the diffusion of carbon in its thickness
Implementation Method 3
maintaining the cohesive assembly under the effect of a pressure and subjecting it to heating at a temperature varying from 1410°C to 1500°C
Implementation Method 4
to melt the silicon and form a seal containing at least one silicon carbide bridge
Data Source
Figure 1~3
AI summary
The present invention relates to a method of assembling carbon parts using a braze based on silicon carbide. The invention also relates to the parts assembled using such a method.