Braze Powder Prewetting for Diffusion Bonding Discontinuous Surfaces
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Solution Overview
Problem
Diffusion bonding of components with complex or discontinuous surfaces is challenging due to ineffective use of braze foils and contamination from traditional binders, leading to inconsistent bonding and unwanted material modifications.
Innovation Solution
A method involving the controlled application of a binder material to form a self-supporting layer on discontinuous surfaces, followed by the deposition of braze powder, which is then sintered to create a prewet surface, allowing for uniform and consistent diffusion bonding without melting or reducing the braze material, thereby forming a strong, defect-free bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If braze foils are used for diffusion bonding, then bonding capability is improved, but effectiveness is reduced on irregular or discontinuous surfaces
Solution Approach 1:
The invention changes the physical state and application method of the braze material from foil form to powder form, allowing it to be deposited as a slurry or suspension that can conform to irregular and discontinuous surfaces. This parameter change enables the braze material to adapt to complex geometries while maintaining bonding capability.
Solution Approach 2:
The invention introduces a binder as an intermediary substance that carries the braze powder particles and enables their deposition onto the surface. The binder acts as a mediator between the braze powder and the substrate, allowing for uniform distribution and adherence to complex surface geometries before being removed during processing.
2Area of stationary object
If braze powder is deposited on complex surfaces, then coverage is improved, but consistency is reduced due to difficulty in uniform deposition
Solution Approach 1:
The invention employs fluid dynamics principles by suspending braze powder particles in a liquid carrier or slurry that can be sprayed or flowed onto the surface. This hydraulic approach allows the braze material to be distributed uniformly across complex geometries, with the fluid carrier ensuring consistent coverage and penetration into recesses and irregularities.
3Ease of manufacture
If traditional binders are used for braze powder, then deposition is facilitated, but contamination of the bonded joint occurs
Solution Approach 1:
The invention extracts and removes the binder substance from the final bonded joint through thermal decomposition or volatilization during the diffusion bonding process. The binder serves its temporary function of carrying and depositing the braze powder, then is completely eliminated, leaving no contaminating residues in the final joint.
Solution Approach 2:
The invention employs an inert or controlled atmosphere during the diffusion bonding process to prevent oxidation and contamination of the braze powder and bonded joint. This inert environment protects the sensitive materials from reacting with atmospheric gases, ensuring joint purity while still allowing the binder to perform its deposition function.
4Quantity of substance
If other deposition methods are used for elemental or ionic materials, then deposition capability is improved, but unwanted modifications of adjacent surfaces occur
Solution Approach 1:
The invention replaces mechanical or physical vapor deposition methods with a liquid-phase slurry deposition approach. This substitution allows for controlled material delivery without the high energies or reactive conditions that cause unwanted surface modifications, achieving clean deposition that preserves the integrity of adjacent surfaces.
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 method enables effective diffusion bonding of complex surfaces with reduced contamination and defects, resulting in a monolithic component with a homogeneous interface suitable for high-temperature applications like gas turbine engines.
Implementation Method 1
the binder material has a sufficient viscosity to be deposited as a self-supporting layer without flowing into the gaps
Implementation Method 2
The discontinuous surface is heated to remove the binder material and adhere the braze powder to the discontinuous surface
Implementation Method 3
followed by the deposition of braze powder, which is then sintered to create a prewet surface, allowing for uniform and consistent diffusion bonding without melting or reducing the braze material
Implementation Method 4
Diffusion bonding is a solid-state bonding method, where elevated temperatures and typically high pressures are employed to obtain diffusion of atoms between mating components
Data Source
AI summary
A method of preparing a surface for diffusion bonding comprises contacting a binder material with a discontinuous surface comprising surface regions separated by gaps. The binder material is selectively deposited onto the surface regions and has a sufficient viscosity to form a self-supporting layer without flowing into the gaps. The self-supporting layer of binder material comprises a mass density in a range from about 0.001 g/in2 to about 0.050 g/in2. A braze powder is distributed over the self-supporting layer of binder material, and a predetermined amount of the braze powder is attached to the binder material. The discontinuous surface is then heated to remove the binder material and adhere the braze powder to the discontinuous surface. Thus, a prewet surface with a braze deposit thereon is formed.