Invar 36 and Kovar 29 are two different alloys, each with unique properties and application areas.
Invar 36, also known as FeNi36, is an iron-nickel alloy characterized by a very low coefficient of thermal expansion over a narrow temperature range. This alloy has good corrosion resistance in dry air at room temperature, but may corrode in humid air. The chemical composition of Invar 36 mainly consists of 35-37% nickel and a residual amount of iron, along with small amounts of other elements such as carbon, manganese and silicon.
Its coefficient of thermal expansion is very low between -250 ° C and 200 ° C, which makes it ideal for applications that require dimensional stability, such as the production, storage and transportation of liquefied gas, as well as temperature regulation devices.
Kovar 29, also known as 4J29, is an iron-nickel-cobalt alloy with a coefficient of thermal expansion similar to that of hard glass, which makes it ideal for use in electronic components that are sealed with glass. The chemical composition of Kovar 29 mainly consists of 28.5%-29.5% nickel, 16.8%-17.8% cobalt and a residual amount of iron, as well as small amounts of other elements. This alloy has good plasticity, machinability, and is easy to weld and weld.
Kovar 29 is widely used in electric vacuum components such as transmitter tubes, picture tubes, switching tubes, transistors, as well as sealed plugs and relay housings.
The Invar 36 and Kovar 29 have different applications in the aerospace field, the specific differences are as follows:
Invar 36: This alloy is known for its extremely low coefficient of thermal expansion, which gives it excellent stability and accuracy at high temperatures. In the aerospace sector, Invar 36 is used to manufacture orbital control and orientation systems for spacecraft, as well as components for engines and turbines. In addition, Invar 36 maintains good strength and toughness at low temperatures, making it suitable for applications such as cryogenic engineering and laser assemblies.
Kovar 29: Kovar 29, also known as 4J29, is an iron-nickel-cobalt alloy that is widely used in the electronic component packaging and aerospace industries for its excellent thermal expansion coefficient matching and high strength properties. In the aerospace sector, Kovar 29 is used to manufacture high-temperature components, such as turbine blades and combustion chambers, due to its high temperature and corrosion resistance in extreme environments. In addition, Kovar 29’s coefficient of thermal expansion is similar to that of hard glass, which makes it ideal for use as a packaging material for electronic components that are sealed with glass, such as integrated circuits.
The application difference between these two alloys in the aerospace field is mainly reflected in their different requirements for thermal stability and thermal expansion coefficient. Invar 36’s low coefficient of thermal expansion makes it more suitable for applications where precise size and shape need to be maintained, while Kovar 29’s high temperature and corrosion resistance and thermal expansion coefficient matched to glass make it more suitable for high-temperature components and sealing applications.
The challenges facing Invar 36 and Kovar 29 in aerospace applications include:
Invar 36: One of the challenges in the application of Invar 36 alloy in the aerospace sector is the difficulty of its processing. Due to the extremely low coefficient of thermal expansion of Invar 36, it has excellent stability and accuracy in high temperature environments, but it also brings some problems during the processing, such as the need to control the temperature and strain rate during the manufacturing process to ensure the quality and performance of the material.
In addition, Invar 36 alloys in additive manufacturing processes, such as selective laser melting (SLM), require precise control of process parameters to avoid lack of fusion or small hole defects due to improper laser energy density.
Kovar 29: A major challenge in the application of Kovar 29 alloy in the aerospace field is the complexity of its heat treatment process. The heat treatment of Kovar 29 alloy has an important effect on its final properties, and it is necessary to strictly control the steps of solution treatment, aging treatment and stress relief treatment to ensure the mechanical properties and dimensional stability of the alloy.
In addition, although the coefficient of thermal expansion of Kovar 29 alloy is low, it is still necessary to consider the control of the coefficient of thermal expansion when achieving accurate matching with glass and ceramic materials to reduce thermal stress and deformation.
