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. With our own inventory, our national network of mills, suppliers and processors, metalmen is able to respond to your most challenging requests. Small quantity and custom requests are welcomed.

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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. We don’t want customers who use us one time, we want to establish lifelong relationships with customers that last generations. Contact us for more info!

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Metal Associates $$$

Richardson, TX  |  800-442-4914

The Trident Company, with almost 40 years of metals sales and service experience, makes on-time shipments throughout the world. Nickel sheet, plate, rod, bar, tubing, pipe, standard structural shapes and wire. Also, Stainless, Carbon, Red metals, Aluminum and many exotic alloys. 11 US locations.

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The Trident Company $$$

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. $$$

Philadelphia, PA  |  800-523-3663

Producing parts from stainless steel & nickel alloy plate since 1952, we're a leader with the biggest & broadest inventory in North America. Our stainless & nickel alloy supply spans 34 grades & 34 thicknesses. With over 100 processing machines, we shape & configure nickel plate to virtually any requirement.

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Sandmeyer Steel Company $$$

Chicago, IL  |  312-292-5000

Ryerson distributes and processes of a variety of metals, including stainless, aluminum, carbon, nickel, brass, copper, alloy, and specialty metal building products. Semi-finished metals come as sheet, coil, plate, bars, structurals, tubing and pipe. We provide unparalleled service through service centers throughout the US & Canada, offering exceptional product range & fabrication capabilities.

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Ryerson Inc. $$$
placeholder image Metalmen Sales Inc. Metal Associates The Trident Company Ferralloy Inc. Sandmeyer Steel Company Ryerson Inc.

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