Everything You Need to Know About Kovar
Kovar – The History & Uses of Kovar
Originally patented in 1936, Kovar has been used for many decades and is something you will find in everyday life, but many people have never heard of it. Kovar is a controlled expansion alloy made up of Iron, Nickel and Cobalt and can be fabricated into a variety of parts such as: plates, round bars, sheets, coils, wires and tubes. Its chemical composition is closely controlled within narrow limits in order to ensure accurate and precise uniform thermal expansion characteristics.
Low Coefficient of Thermal Expansion
The coefficient of thermal expansion (CTE) is the most significant property of Kovar and what it is best known for. It is carefully formulated to produce a low CTE below the Curie point (435°C or 815ºF) which is remarkably similar to hard / borosilicate glass or ceramic. This means that it will expand and contract at a similar rate to these materials, with increasing temperature and very little change in dimension, making it perfect for hermetic sealing across a wide temperature range and glass-to-metal bonded assemblies.
Applications and Uses of Kovar
Hermetic sealing refers specifically to the bonding of glass or ceramic and metal; an oxide layer is created in between both substrates, keeping pollutants out and protecting each part. Kovar is one of the most popular choices for applications that require a hermetic seal.
The electronics industry utilises Kovar in its production of many different devices and components that many people would recognise. From everyday products like lightbulb ends and microwave tubes, to more complex and extensive applications like x-ray tubes and hybrid or integrated electronic circuit packages, Kovar is heavily relied on. Electronics require low expansion with temperature change, as well as longevity and durability, which Kovar can consistently provide.
The aerospace industry also uses Kovar for its hermetic sealing properties, but also for its high resistance to thermal shock. Because of the rapid change between extreme temperatures that aerospace components withstand, they require an alloy that will not deform or weaken in structure – Kovar is the perfect choice for this. Radar systems and satellites are just some of the devices that utilise Kovar and its reliable qualities, ensuring that the technology will never be compromised due to changing structures.
Other applications and uses include:
- Transistors and diodes
- Scientific vacuum systems and instruments
- Concentrated solar power
At City Special Metals, we are an industry leader in supplying a wide range of high performance, specialist alloys for a variety of markets across the world. Kovar is one of our featured products and, with over 20 years’ experience, we understand every aspect of this low expansion alloy and what it can do for our clients. To learn more about its mechanical and physical properties, as well as our stock range, visit the Kovar page. If you would prefer to talk to an expert engineer about what Kovar can bring to your application, contact us today to start your journey.