This KOVAR part has a linear expansion coefficient similar to that of hard glass within the range of 20 to 450℃, and can be effectively sealed and matched with the corresponding hard glass. It also has a high Curie point and good low-temperature microstructure stability. The oxide film of the alloy is dense, easy to weld and fuse, and has good plasticity and can be machined. Kovar alloy is widely used in the production of electro-vacuum components, emitter tubes, picture tubes, switch tubes, transistors, as well as sealed plugs and relay housings, etc. Due to the cobalt content, the products are relatively wear-resistant.
The performance test samples for the coefficient of expansion and low-temperature microstructure stability as stipulated in the standard are heated to 900℃±20℃ in a hydrogen atmosphere, held for 1 hour, then heated to 1100℃±20℃, held for 15 minutes, and cooled to below 200℃ at a rate not exceeding 5℃/min before being taken out of the furnace.

Kovar alloy is a typical Fe-Ni-Co hard glass sealing alloy commonly used internationally. After long-term use in aviation factories, its performance is stable. It is mainly used for glass sealing of electronic vacuum components such as emitter tubes, oscillation tubes, ignition tubes, magnetrons, transistors, sealed plugs, relays, lead wires of integrated circuits, chassis, shells, brackets, etc.

In application, the selected glass should be matched with the coefficient of expansion of the alloy. Strictly test its low-temperature microstructure stability according to the usage temperature. Appropriate heat treatment should be carried out during the processing to ensure that the material has good deep drawing and drawing performance. When using forged materials, their airtightness should be strictly inspected.

The structure and properties of the constituent phases in an alloy play a decisive role in its performance. Meanwhile, changes in the alloy's microstructure, namely the relative quantity of phases in the alloy, as well as variations in the grain size, shape and distribution of each phase, also have a significant impact on the alloy's performance.

Therefore, by combining various elements to form different alloy phases and then undergoing appropriate processing, it is possible to meet various performance requirements.

Hydrogen storage alloys are alloys composed of two specific metals. One of them can absorb a large amount of hydrogen to form stable hydrides, while the other metal, although having a low affinity for hydrogen, allows hydrogen to move easily within it. Mg, Ca, Ti, Zr, Y and La, etc. belong to the first type of metal, while Fe, Co, Ni, Cr, Cu and Zn, etc. belong to the second type of metal.

The former controls the amount of hydrogen stored, while the latter controls the reversibility of hydrogen release. By rationally formulating the two and adjusting the hydrogen absorption and release performance of the alloy, an ideal hydrogen storage material that can reversibly absorb and release hydrogen at room temperature is obtained.
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