Brazing vs. Diffusion Bonding
Metallurgical joining of high purity beryllium foil x-ray windows to dissimilar metal frames and housings has been an important technology for many years in the medical, analytical and scientific industries worldwide.
The typical method of accomplishing these high temperature joints is by liquidus brazing. This vacuum process consists of melting a silver-based braze alloy and then allowing it to resolidify, creating the beryllium-to-frame joint.
Using this method, windows are brazed one or two parts at a time, usually to a frame material of stainless steel, copper, Monel or nickel.
Unlike liquidus brazing which focuses solely on temperature, Materion Electrofusion’s diffusion bonding technique reflects innovative and leading-edge engineering processes.
We employ a combination of temperature and pressure to create the metallurgical joint. This specialized engineering process is known as diffusion bonding. Using both of these critical parameters – temperature and pressure – gives diffusion bonded windows important advantages over conventionally brazed windows.
Several applications that use diffusion bonded windows include:
- Industrial equipment
- X-ray source tube and detector manufacturing
- Synchrotron functioning and experimental uses
Advantages and Benefits of Diffusion Bonding
Materion Electrofusion provides customers with advantageous technology. Our specialized diffusion bonding technique is accomplished at temperatures below the melting point of the interstitial alloy, resulting in high temperature performance without compromising the strength of the beryllium, a principle weakness of conventionally brazed windows offered by other suppliers.
- Diffusion bonding also offers these advantages:
- Control over alloy flow; no high absorption alloy material in the clear line of sight of the window.
- Processing in one operation for many assemblies (lots of over 100 units have been diffusion bonded successfully), dramatically lowering the cost for larger quantities.
- Diffusion Bonding also works well with very thin beryllium foil. Beryllium foil of 0.001" (25µm) thickness has been consistently joined, and foils thinner than 0.001" are likewise successful with varying yields.
Materion Electrofusion is a collaborative partner throughout your project. Because the interstitial alloys used in diffusion bonding will diffuse at different rates into various frame materials, Materion Electrofusion can assist in designing the optimal joint configuration for your frame material or the material combination which best suits your needs. Our engineers will take in account considerations such as:
- Allowing sufficient area to join the beryllium to the frame, known as the "faying" surface.
- Designing the joint for survivability under operating conditions and during any subsequent manufacturing operations (such as welding or other joining processes).
- Choosing the best frame material for thermal and electrical conductivity as well as thermal expansion match to the tube or detector interface.
Materion Electrofusion customers gain an advantage through the use of our specialized technology and innovative products. Our windows can be baked to 450ºC, and are helium mass spectrometer leak tight to 1x10-9 atm-cm3/sec.
Contact Materion Electrofusion
To learn more about how diffusion bonded windows can help your business, contact Materion Electrofusion today.