THERMAL EXPANSION ALLOYS
Kovar® Rodar® Invar® Nilvar®
Supplier of Nickel Alloys and Specialist METALS
Expansion Alloys
Expansion alloys, often known as “low-expansion alloys” or “invar alloys,” are special types of materials designed to exhibit minimal expansion or contraction when exposed to changes in temperature. These alloys are engineered to have a very low coefficient of thermal expansion (CTE), which means they expand or contract to a minimal extent with temperature fluctuations. In other words, they maintain their dimensional stability over a wide range of temperatures.
Ordering Information
All orders are quoted individually and based in kg for specific dimensions. Contact Us to receive a rapid quote or sample for review. Stock items are available for immediate shipping.
Trade Names
Kovar, Rodar™, Telcoseal™, Sealvar™, Alloy 29-17™, Nilo K™, Dilver™, Pernifer, Alloy 29-18™, Nicosel, Nicoseal™, Therlo®
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Applications
F-15 Alloy / Kovar is classified as a controlled nickel-iron expansion alloy, as it contracts and expands and at a similar rate to glass and ceramics. It is therefore ideal in applications which require a hermetic seal between glass or ceramic materials. Thanks to its chemical composition it’s a very stable material that maintains its thermal expansion characteristics down to sub zero temperatures, almost minus 200 degrees C. There are a vast number of products where metal and glass or ceramic are joined together. Applications include x-ray tubes, lighting tubes, microwave tubes, transistors, vacuum tubes, diodes and power tubes and photography flash bulbs. This technique has also been used in integrated circuits, such as flat pack and dual-in-line packages and optoelectronic component cases and bases.
Standards
ASTM F15 AMS 7726 AMS 7727 AMS 7728 MIL I-23011 Class 1 UNS K94610
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Trade Names
Invar 36, Ametek 936™, Nilo 36™ and Pernifer 36™
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Applications
Classified as a nickel-iron controlled low expansion alloy Invar 36 has one of the lowest thermal expansion of all alloys and metals, a near zero coefficient of linear thermal expansion between the standard room temperature, 20 °C and 230 °C. Together with a near zero thermal expansion Alloy 36 provides a high retention of strength and toughness at cryogenic temperatures, making it ideal for a range of both low temperature and low expansion applications. The alloy is suited to applications where changes in temperature must not affect the materials dimensions, including tooling for aerospace composites, radio and electronic devices, and structural supports in precision equipment such as thermostats, measuring devices, lasers, and cryogenic instruments. It is a very workable material and easy to machine.
Standards
ASTM B388 DIN 1.3912 UNS K93600 MIL I-16598 MIL I-23011 Class 7 WS 1.3912
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Trade Names
Invar 36, Ametek 936™, Nilo 36™ and Pernifer 36™
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Applications
Super Invar Alloy 32-5 is a nickel-iron controlled ultra low expansion alloy which exhibits near zero thermal expansion at room temperature, the lowest of all the “low expansion alloys”, and one half of standard Invar Alloy at ambient temperature. Plus in the 67 to 203°F , -55 to 95°C temperature range its thermal expansion is less than that of standard Invar Alloy. It is designed to provide minimum thermal expansion at ambient temperatures. This property alone makes it valuable and even more expensive than regular invar. However, the useful range of Super Invar® is limited and valid only over a controlled temperature limit ( -32° to + 275°C ). The range of applications include various precision parts, optical instruments and electrical devices. Super Invar 32-5 machines similar to, but not as well as , Type 316 austenitic stainless steel
Standards
AMS I 23011 ASTM-F-1684 CHEM
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Ordering Information
Expansion Alloys are particularly useful in applications where precise dimensions must be maintained across temperature variations. Common applications for expansion alloys include:
- Precision instruments: Invar is used in various scientific and industrial instruments, such as optical and surveying equipment, where temperature stability is crucial for accurate measurements.
- Aerospace and aviation: Expansion alloys are used in aerospace components and systems where temperature changes can affect the performance and reliability of the equipment.
- Electronics: Invar and similar alloys find applications in electronic components and circuits where temperature-induced size variations can lead to electrical issues.
- High-precision engineering: Expansion alloys are used in applications such as semiconductor manufacturing, where exacting tolerances and stability are essential.
Ordering Information
Expansion alloys are typically composed of metals like iron, nickel, and cobalt, often with controlled amounts of other elements to achieve the desired thermal expansion properties. These materials are carefully designed to provide a predictable and stable response to changes in temperature, making them valuable in a wide range of technological and industrial applications.
