Hydrogen Flame Surface Reduction for Oxide-Free Metal Joining
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Solution Overview
Problem
Existing methods for reducing oxidized metal surfaces, such as those used in industrial applications like coating deposition and welding, often require aggressive chemicals or complex systems, posing environmental risks and inefficiencies.
Innovation Solution
A method utilizing a diffuse hydrogen flame, which is rich in reactive hydrogen atoms, is used to reduce metal surfaces by reacting with surface oxides, eliminating the need for flux and acid treatments, and can be performed under ambient conditions using a mixture of hydrogen and oxygen, with asymmetric or eccentric gas feeding to enhance effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aggressive chemicals or complex systems are used to reduce oxidized metal surfaces, then the surface reduction effect is achieved, but environmental risks and process complexity increase
Solution Approach 1:
The invention changes the chemical parameters by using a hydrogen-rich atmosphere (high hydrogen concentration, low oxygen concentration) instead of aggressive chemicals. The hydrogen potential is controlled by adjusting the hydrogen-to-oxygen ratio and flow rates, creating a reducing environment that effectively removes oxides without environmental harm.
Solution Approach 2:
The invention replaces chemical cleaning methods (aggressive chemicals, fluxes, acids) with a physical-chemical method using hydrogen flame and hydrogen-rich atmosphere. This substitution eliminates the need for harmful chemical substances while achieving the same surface reduction effect.
2Temperature
If stoichiometric hydrogen-oxygen flames are used, then high temperature is achieved, but the temperature is too high for safe and effective surface treatment
Solution Approach 1:
The invention changes the combustion parameters by using a hydrogen-rich, oxygen-lean mixture instead of stoichiometric proportions. By limiting oxygen supply and maintaining high hydrogen concentration, the flame temperature is controlled to be below 1000°C, providing effective surface treatment without overheating or safety risks.
Solution Approach 2:
The invention uses excessive hydrogen relative to oxygen (hydrogen-rich mixture), where hydrogen is supplied in excess of what would be needed for complete combustion. This partial combustion approach generates sufficient heat for surface treatment while keeping temperatures controlled and safe.
3Reliability
If conventional hydrogen flame methods are used, then surface reduction is achieved, but re-oxidation occurs and post-soldering cleaning is required
Solution Approach 1:
The invention performs preliminary surface reduction immediately before soldering in a single continuous process. The hydrogen-rich atmosphere is maintained throughout the soldering process, preventing re-oxidation of the reduced surface, thereby eliminating the need for post-soldering cleaning operations.
Solution Approach 2:
The invention creates a protective hydrogen-rich atmosphere that acts as an inert environment, preventing oxygen from re-oxidizing the reduced metal surface. This atmosphere is maintained during and after the reduction process, ensuring surface integrity without requiring additional cleaning steps.
4Device complexity
If symmetric or coaxial gas feeding is used, then simple device structure is maintained, but reduction effectiveness is insufficient
Solution Approach 1:
The invention uses asymmetric or eccentric gas feeding where the oxygen supply is positioned offset from the center of the hydrogen flow rather than coaxially. This asymmetric arrangement creates a controlled hydrogen-rich zone with optimized flow patterns, significantly improving reduction effectiveness while maintaining relatively simple device structure.
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 process efficiently removes surface oxides, increasing surface energy and enabling high-quality solder joints without post-soldering cleaning, suitable for both batch processing and production lines, while being environmentally friendly.
Implementation Method 1
The method utilizes the core of a diffuse hydrogen flame, which is still rich in reactive hydrogen atoms. The temperatures involved are far below those of stoichiometric hydrogen-oxygen flames. This non-oxygen-burning hydrogen can then remove surface oxides from the surfaces to be soldered by reacting with the oxide.
Implementation Method 2
A diffuse flame system is one in which the mixing rate is slow relative to the reaction rate of the fuel and oxidizer, with the mixture controlling the combustion rate. Most practical combustion systems are mixture-rate controlled and result in diffusion flames, in which the fuel and oxidizer combine in a reaction zone via molecular and turbulent diffusion.
Data Source
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AI summary
The invention relates to a method in which hydrogen is conducted to a surface through a line and burned, and the hydrogen flame is directed at the surface. The invention also relates to a device for reducing surfaces, comprising, in the flow direction, a line for conducting hydrogen and a protective shield having a passage, and to a use of the method or of the device.