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Materion Electrofusion has been a trusted source for beryllium and beryllium processing since 1972. Our standard diffusion bonded windows can be baked to 450ºC, and are measured with a He mass spectrometer as leak tight to 1x10-9 atm-cm3/sec.  For applications that require higher temperature endurance, we offer other joining techniques including liquidus brazing, electron beam welding and TIG welding.


Customers can choose both, and Materion Electrofusion can provide responsive solutions to both options. We stock an on-hand supply of standard size CF flanges with the largest functional aperture size already machined, keeping order processing and delivery times of a finished assembly to a minimum. For these Catalog CF Flanges, customers can specify the grade and thickness of beryllium foil.

Materion Electrofusion offers best-cost solutions. Depending upon the application requirement, choosing a thicker foil will lower the cost and increase the amount of differential pressure the window can withstand. To assist with your decision, the table below lists the aperture size and the thinnest possible foil to withstand one atmosphere of differential pressure with a safety factor. After referring to the below table, you can request a quote by specifying Order Number, Beryllium Foil Grade, and Foil Thickness.

Order Number
Flange Outside Diameter
Minimum Foil
DB275153 ø70mm (ø2.75") ø39mm (ø1.53") 0.13mm (0.005")
DB338200 ø86mm (ø3.38") ø51mm (ø2.00") 0.18mm (0.007")
DB450277 ø114mm (ø4.50") ø70mm (ø2.77") 0.25mm (0.010")
DB600427 ø152mm (ø6.00") ø108mm (ø4.27") 0.38mm (0.015")
DB800560 ø203mm (ø8.00") ø142mm (ø5.60") 0.50mm (0.020")

In order to meet quick turnaround times, we stock some pre-built assembly configurations which are available for immediate shipment.  Please check our inventory page for a list of available CF Flange assemblies.

We can also meet the demands of your customized application.  Our Engineering staff can develop a completely custom CF Flange assembly to your specifications.


Materion Electrofusion specializes in diffusion bonded windows. This joining method differs from the brazed beryllium windows offered by other suppliers in several critical areas.

Typical high temperature liquidus brazing induces structurally weakening grain growth in the beryllium window material. Since diffusion bonding is accomplished at temperatures below the melting point of the braze alloy, it results in high temperature performance without compromising the strength of the beryllium.

By controlling the pressure in the process, diffusion bonding also offers control over braze alloy flow, meaning no high absorption alloy material in the active area of the window. In other words, a beryllium window best suited to your application.


Catalog CF Flange assemblies are typically available within six weeks of your order.  All products produced and sold by Materion Electrofusion carry an industry-leading lifetime warranty covering any defects in material and workmanship. (Normal wear and tear and corrosion from operational use is excluded from this warranty.)

Contact Materion Electrofusion

Find out more about the various CF flange assemblies we offer, contact Materion Electrofusion today.