Vacuum Brazing

Brazing Education
Vacuum Brazing Furnace (PVT) Altair USA

Vacuum brazing is particularly well suited for joining complex geometries, precision assemblies and materials like aluminum or titanium free of contamination. It is also sometimes favored over hydrogen brazing when processing very large parts because of the ability to purge occluded, close-fitting areas. The process deoxidizes the metals being joined and more importantly, eliminates undesirable reactions that would have occurred in hydrogen or other inert gases. The extremely low-pressure environment promotes the wetting of surfaces when the heating systems achieve brazing temperature and the brazing alloy (filler or die-cut pre-form) melts while also facilitating flow into the joints via capillary action. Lastly, the process is also used in the metallization of ceramic surfaces for joining ceramics to other metals by a process called Vacuum Active Metal Brazing.

Key Advantages & Benefits

Our vacuum brazing services offer a clean process that removes nasty oxides and prevents undesirable reactions that yield high-quality braze-joints. It is a process highly sought after by the semiconductor, medical, aerospace industries because it can hold tight tolerances, extremely clean, and provide time and cost savings. Bright, clean and beautiful parts are produced without the need for post-processing such as machining and there is virtually no limit on wall thickness when joining complex geometries or assemblies compared to welding processes.

Vacuum Brazing Applications

The most common applications are leveraging the thermal flow capabilities of aluminum and the deoxidizing nature of the process to join thermal components that makeup heating and cooling heat exchangers, cold plates, micro-channel heat exchangers, plate heat exchangers, aircraft components, intricate assemblies, sensors, medical devices, structural components, and other thermal devices. We are ITAR registered and ISO 9001 certified, hence we understand and serve the requirements for the defense and aerospace industries with ease.

Parts and Equipment for Defense & AerospaceParts and Equipment for Medical
Heat sink and Electronics CoolingPressure vessels
Liquid Cold PlatesEV Battery Enclosures (ESS)
Flat Tube Heat ExchangersAluminum Fin Heat Exchangers
Heat Pipes & Heater TablesPressure Vessels
Vacuum Chambers (Semiconductor)Instrumentation & Sensors
Electro-Static ChucksHigh Vacuum Components
Electric Vehicle (EV) ComponentsThermodynamic Engines
Hydraulic flow boxesStructural Components

Materials

With regards to material applications, for all the reasons explained above, our vacuum brazing services focus on the joining of:

  • Exotic base metals such as Aluminum, Titanium, Zirconium, Niobium, Molybdenum, and Tantalum
  • Nickel and Iron-based alloys containing aluminum and/or titanium
  • Refractory metals
  • Reactive metals
  • Ceramics & metal to ceramics
  • Beryllium brazing
What Are Refractory Metals

Refractory metals are the classification of metals with common properties and demonstrate very high melting temperatures, up to 3410° for Tungsten, which is more than double of Titanium. They all share high corrosion and abrasion/wear resistance and excellent thermal and mechanical strength properties. Although there are twelve in this class of metals, only five are widely used: Tungsten, Molybdenum, Niobium, Tantalum, and Rhenium. [1]

Vacuum Brazing Process and Firing

Instead of using a protective and deoxidizing inert gas such as the common hydrogen brazing process, it is fluxless and is performed at high temperatures and in a high vacuum atmosphere with pressures typically in the x 10-5 – 10-6 range. This clean process also deoxidizes the metals being brazed, but more importantly eliminates undesirable reactions that would have occurred in hydrogen and helps to vaporize or remove high vapor pressure materials that are seen as contaminants common to defense, aerospace and medical applications.

Even vacuum firing can be used to remove hydrogen gas from materials like stainless steel, which were previously brazed in hydrogen. Many of the same filler metals or alloys used with Hydrogen are also used and we also vacuum-braze common materials like silver, copper and stainless steel.

Vacuum brazing aluminum is a hefty sector of our business and if you would like to learn more about our approach specifically to joining aluminum to itself and other metals along with specific design guidelines for excellent braze-joint quality, please check out these two articles:

Precision Vacuum Furnaces

Our high efficiency furnaces are cold-walled retorts having either a graphite or Moly hot zone. Most furnaces use ultra-clean cryopumps, while a few use also very clean turbopumps to achieve a high-vacuum. We have furnaces of all sizes and our largest furnace has a 48” diameter hot zone.

  • High Vacuum 10-5 & 10-6
  • 48” x 28” x 28” Hot Zone
  • Temperature Profile Recording
Engineer operating a vacuum brazing Furnace at Altair Technologies
Precise Furnace Control

[1] https://www.pickpm.com/wp-content/uploads/2016/08/What-Are-Refractory-Metals.pdf