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Kovar

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Kovar was specifically formulated as a sealing alloy for glass and ceramic materials (specifically for compatibility with the thermal expansion characteristics of borosilicate glass). Read More…

Kovar Also known as Rodar, Kovar is a registered trademark that refers to a low expansion alloy that is composed of iron, nickel, cobalt and trace amounts of the elements manganese, silicone and carbon.
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Leading Manufacturers

Long Island City, NY  |  800-767-9494

We supply Nickel and its alloys for a broad range of applications. metalmen provides supply solutions – we respond with quick quotes and on-time deliveries.

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Metalmen Sales Inc. $$$

Pompton Plains, NJ  |  800-838-1978

Our company may have started small, but we quickly grew to handle the largest aluminum orders. Our metals are made from the highest quality materials, and we pledge to offer superior service to all our customers.

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Metal Associates $$$

Cleveland, OH  |  440-250-1900

For over 30 years, we have provided metal forged products for a wide variety of industries, including the aerospace, military, food service, medical, and automotive industries. Our customers know they can trust our forgings for quality and affordability. We will never try to make you pay more than you should for our products. Contact us by phone or email to find out more!

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Ferralloy Inc. $$$

Ronkonkoma, NY  |  631-981-2300

At Industrial Metals International, nickel is among our many product offerings. We offer nickel plate, nickel sheet, nickel strip, nickel bar, nickel tube, nickel rings, nickel forgings and nickel wire. We also can heat treat, metal test and provide precision cutting and drilling. We are ISO 9002 certified and an SSCI member.

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Industrial Metals International, Ltd. $$$

Plainview, NY  |  516-241-7214

Custom manufacturer & distributor of all types of raw materials: Titanium, Stainless, Aluminum, Steels, Copper, Brass, Nickel, High Temp Alloys — common & non-standard, hard-to-find alloys. Nickel alloys available in Bars, Plates, Sheets, Tubing, Forgings, Wire, and Coil. Daily shipments for domestic & international sales.

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Rockwell Industries International Corporation $$$
placeholder image Metalmen Sales Inc. Metal Associates Ferralloy Inc. Industrial Metals International, Ltd. Rockwell Industries International Corporation

The material is used by many industries, including electronics, medical, semiconductor and industrial manufacturing, to provide exceptional hermetic seals for applications such as power tubes, vacuum tubes, transistors, microwave tubes, diodes, integrated circuits, and x-ray tubes.

Most often used in applications requiring a glass to metal seal, Kovar is vacuum melted, meaning that it has undergone melting, refining, and casting under a vacuum. An additional property of Kovar is that at any temperature under that of the Curie point (435°C or 815ºF) it is magnetic. Kovar is very similar to another nickel alloy referred to as Invar.

Invar is a nickel steel alloy with specific thermal expansion properties; however, Invar is unique for its low thermal expansion qualities, while Kovar is for its low thermal expansion in terms of its compatibility to heat-resistant glass.

Kovar is specifically composed of 54% iron, 29% nickel, 17% cobalt, .2% silicon, .3% manganese and less than .01% carbon. This chemical composition has narrow limits that are very controlled in order to ensure optimal thermal expansion compatibility. Kovar can be fabricated into shapes and parts such as sheets, rods, plates, bars and tubing through a variety of heat treating processes including annealing and forging.

Although high temperatures are not critical when annealing Kovar, temperatures greater than 900°C (1652ºF) are not recommended because the high heat will promote grain growth. When it comes to forging Kovar, the biggest concern is that the Kovar must be heated quickly in order to avoid soaking within the furnace which can affect the surface appearance of the alloy.

In addition to manufacturing processes, there are many types of secondary services that are commonly used on Kovar including turning, drilling, tapping and reaming. When it comes to turning Kovar, it is necessary to pay attention to the angle of the cutting tools.

For drilling Kovar, it is the speed of the drill and the resulting feed that must be taken into consideration, and it is the same for reaming, but with different required proportions. Lastly, when it comes to tapping Kovar, the speed should be around 20 feet per minute (FPM) and it is recommended to use either nitrided or electrolyzed tools.

Kovar Informational Video