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Materials & Flange Information

Materials commonly used to produce glass-to-metal seals include:

Kovar®-ASTM F15 Alloy

Kovar® is a nickel-cobalt-iron alloy used for producing vacuum tight seals with Borosilicate glasses. Corning type 7052 glass can be sealed directly to Kovar®. Corning type 7740 (PYREX®) and quartz can be sealed to Kovar® by using intermediate glasses. These are called "graded seals".

Stainless Steel - Type 304

Type 304 stainless steel is an 18% Cr, 10% Ni, low carbon, corrosion-resistant alloy used to manufacture stainless steel to Borosilicate glass seals. Type 304 is non-magnetic in an annealed condition and resists scaling up to 900°C. Quartz can be sealed to stainless steel by using a graded seal.

Type 316 and 321 stainless steel to glass seals are available by special order.

Copper - OFHC

Oxygen free, high-conductivity C10100 is used to produce copper to glass seals. OFHC copper is used in applications where non-porosity and ductility are required. In an annealed state at room temperature, OFHC copper has electrical conductivity of 100%.

Bellows - Type 321 Stainless Steel

The bellows offered in this catalog are "formed" bellows. They are used in glass systems to compensate for vibration, expansion, contraction and misalignment. Although the standard glass supplied with bellows is PYREX®, a variety of other Borosilicate glass types can also be sealed directly to them. Quartz can be sealed to bellows using a graded seal.

The end opposite the glass can be supplied with a thin wall cuff, a heavier tube end for welding or clamping, vacuum flanges, custom flanges, or other commercially available stainless steel fittings. Bellows are also available with glass on both ends.

Request a quote today, or contact Larson Electronic Glass if you need help finding the right glass-to-metal seals for your application.