The process
A process developed by Aalberts Surface Technologies Eindhoven B.V. in the field of high temperature / vacuum brazing.
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HD Brazing® has been developed by Aalberts Surface Technologies Eindhoven B.V. as a further development of vacuum brazing. The connections made with this joining technique are reproducible and of a high quality.
What is vacuum brazing?
Vacuum brazing is a high-quality, reproducible joining process in which joints are formed in a vacuum furnace at temperatures between 800°C and 1200°C. Because the process takes place in a vacuum, oxygen and contaminants are absent, so no oxidation occurs and no flux is needed.
Due to capillary action (through the precisely small solder gaps), the solder material (often based on silver, copper, nickel, and/or gold) flows between the parts, resulting in an extremely strong and clean (metallically bright) joint. It is suitable for all metals such as stainless steel & titanium, copper and nickel alloys with a melting point above approximately 800°C. Various non-metals such as graphite, hard metal, diamond, and ceramics can also be vacuum brazed.
The Process
- Preparation: Thorough cleaning of parts and application of solder material (foil, paste, or wire).
- Heating: The parts are heated in a vacuum furnace with a controlled temperature profile to above the melting temperature of the solder and then cooled in a controlled manner (with nitrogen/argon). Brazing under hydrogen is also possible.
- Joining: The liquid solder wets the surfaces.
- Cooling: Controlled cooling ensures a uniform microstructure and minimal distortion.
- Inspection: Visual inspection and testing for density and strength.
Key Advantages
- High Quality: Very strong (often equal to the strength of the base material), leak-tight, and corrosion/heat-resistant joints. Also, very clean, hygienic, gap-free joints (no flux required). Important for the food or medical industry.
- High Design Freedom: Thick/thin is possible, large surfaces can be joined.
- Multiple Joints: More than one joint can be made in a single process. The production of complex products is possible.
- Versatile: Possibility to join dissimilar materials, such as ceramics to steel.
- Efficient: Brazing and hardening (for example, of dies) can often be combined in a single process step.
- Dimensional Stability: Minimal distortion, ideal for complex and precise products.
Application Areas
Due to its high reliability and the ability to produce precision components, vacuum brazing is widely used in:
- Aerospace: For temperature-resistant components.
- Medical Industry: For hygienic and gap-free joints.
- Mechanical Engineering: For joining stainless steel, hard metals, diamond, and tool steel.
- Automotive: For hydraulic systems and heat exchangers.
- Energy Technology: Fuel cells and heat exchangers.