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.

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 $$$

Commerce, CA  |  800-800-1150

Since 1952, the Welding Warehouse has been manufacturing and distributing a variety of stainless steel products as well as titanium, aluminum, nickel, low alloy steel, magnesium, silver alloy and copper base alloy products. We also offer precision wire processing. In addition, we meet aerospace material specifications.

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The Welding Warehouse $$$

Ronkonkoma, NY  |  800-900-9209

Alloys International specializes in performance metal solutions within the Aerospace, Petro-chemical, Nuclear, Electrical Power, Medical industries. Alloys International sources the best high-tech specialty metal mills throughout the world for your needs in nickel and other exotic & high temperature alloys. We provide the difficult alloys, sizes and specifications that others can’t in nickel, cobalt, titanium and most other specialty alloys.

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Alloys International $$$

Cleveland, OH  |  440-250-1900

Ferralloy is a manufacturer of raw metals and alloys including nickel, nickel aluminide, and Waspaloy. We offer various forms such as bars, tubes, and wire. Capabilities include casting customization, forging, fabrication, and machining.

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Ferralloy Inc. $$$

Anaheim, CA  |  877-932-7832

Count on Weartech's more than 150 years of combined experience for superior nickel & cobalt based hardfacing & wear resistant alloys. Weartech supplies the most versatile cobalt & nickel alloys for the harsh environments of automobile to aerospace. Rods, electrodes, wires, powders and engineered components. Weartech produces its products to the ISO 9001 system and is a certified ISO 9001 company.

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Weartech International Inc. $$$

Hamilton, OH  |  888-282-3292

The diversity of our selection of high-performance metal items is unsurpassed. Our team works hard to make our products suitable for various industries, and save you money in the long run. We are determined to supply the best stainless steel products around. Your satisfaction is guaranteed when you select United Performance Metals as your supplier. Please give us a call today to learn more information!

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United Performance Metals $$$
placeholder image Metalmen Sales Inc. Metal Associates The Welding Warehouse Alloys International Ferralloy Inc. Weartech International Inc. United Performance Metals

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