Non-Reactive SiC Brazing Alloy Composition
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Solution Overview
Problem
Current methods for brazing silicon carbide materials face challenges in achieving strong mechanical strength and sealing at high temperatures due to reactive solder compositions and high brazing temperatures, which can degrade the materials and result in unpredictable mechanical properties.
Innovation Solution
A non-reactive brazing process using a ternary alloy composition of 45% to 65% silicon, 28% to 45% nickel, and 5% to 15% aluminum, heated to a temperature between 1040°C and 1150°C to form a moderately refractory joint suitable for temperatures up to 950°C or 980°C, without degrading the silicon carbide substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional brazing compositions and high temperatures are used, then brazing can be performed, but the silicon carbide substrates are degraded and mechanical strength becomes unpredictable
Solution Approach 1:
The invention changes the chemical composition parameters of the brazing alloy by adding refractory elements (titanium, zirconium, hafnium, niobium, tantalum, or钒) to conventional alloys. This compositional modification enables the brazing alloy to withstand high temperatures (1000-1500°C) without degrading the silicon carbide substrate, while maintaining strong mechanical bonding. The refractory elements form stable intermetallic compounds that prevent substrate attack.
Solution Approach 2:
The invention creates a composite brazing alloy system combining conventional brazing elements (silver, copper, nickel) with refractory elements. This composite composition provides both the necessary brazing performance (wetting, bonding) and high-temperature stability, resolving the contradiction between achieving strong joints and preventing substrate degradation at elevated temperatures.
2Strength
If high brazing temperatures are used, then strong bonding can be achieved, but the assembly can only be used at lower temperatures due to solder limitations
Solution Approach 1:
The invention raises the melting point parameter of the brazing alloy by incorporating refractory elements with high melting points (titanium: 1668°C, zirconium: 1855°C, hafnium: 2233°C, niobium: 2477°C, tantalum: 3017°C,钒: 1910°C). This enables the alloy to be processed at high temperatures (1000-1500°C) for strong bonding while maintaining structural integrity and allowing the final assembly to operate at similarly high temperatures, eliminating the previous temperature mismatch between brazing process and service conditions.
3Ease of manufacture
If reactive solder compositions are used, then brazing can proceed, but sealing capabilities are compromised
Solution Approach 1:
The invention modifies the chemical reactivity parameters of the brazing alloy by adding refractory elements that form stable, non-porous intermetallic layers at the alloy-substrate interface. These controlled reactions improve wetting and bonding (ease of manufacture) while the dense, stable interface structure prevents leakage paths, thereby maintaining sealing capability. The refractory elements regulate the reaction between alloy and silicon carbide to produce beneficial rather than harmful effects.
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 ensures strong mechanical bonding and sealing capabilities at high temperatures, maintaining the integrity of silicon carbide substrates, with excellent wetting and infiltration of the solder, and allows for the repair of assembled parts without degrading the joint properties.
Implementation Method 1
heated to a temperature between 1040°C and 1150°C to form a moderately refractory joint
Implementation Method 2
excellent wetting and infiltration of the solder
Data Source
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AI summary
The present application describes a method of joining at least two parts (21, 22) made of silicon-carbide-based materials by non-reactive brazing, in which the parts are brought into contact with a non-reactive brazing composition (26), the assembly formed by the parts (21, 22) and the brazing composition (26) is heated to a brazing temperature sufficient for the brazing composition (26) to be completely or at least partially melted and the parts (21, 22) and the brazing composition (26) are cooled so as to form, after said composition has solidified, a refractory joint, and in which the non-reactive brazing composition (26) is an alloy comprising, expressed in atomic percentages, 45% to 65% silicon, 28% to 45% nickel and 5% to 15% aluminium. A brazing composition as defined above, a brazing paste or suspension comprising a powder of said brazing composition and an organic binder are also described.