4J29 alloy is also known as Kovar alloy. The alloy has a linear expansion coefficient similar to that of borosilicate hard glass at 20-450°C, a higher Curie point, and good low-temperature microstructure stability.
The alloy has a linear expansion coefficient similar to that of borosilicate hard glass at 20-450°C, a higher Curie point, and good low-temperature microstructure stability. The oxide film of the alloy is dense and can be well wetted by glass. It does not interact with mercury, and is suitable for use in instruments containing mercury discharge. It is the main sealing structural material of electric vacuum devices.
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29HК Kovar Nilo K KV-1 Dilver P0 Vacon 12
29HК-BИ Rodar KV-2
Techallony Glasseal 29-17 Telcaseal KV-3 Dilver P1 Silvar 48
Technical standard
YB/T 5231-1993 "Fe-Ni-Co glass sealing alloy 4J29 and 4J44 technical conditions".
Chemical composition
C≤0.03%
Mn≤0.50%
Si≤0.30%
P≤0.020%
S≤0.020%
Cu≤0.20%
Cr≤0.20%
Mo≤0.20%
Ni=28.5~29.5%
Co=16.8~17.8%
Fe=surplus
Under the condition that the average linear expansion coefficient reaches the standard, the content of nickel and cobalt is allowed to deviate from the range specified in Table 1-2. The content of aluminum, magnesium, zirconium and titanium should not exceed 0.10% each, and the total amount should not exceed 0.20%.
Heat treatment system
The performance test samples for the expansion coefficient and low temperature microstructure stability specified in the standard are heated to 900ºC±20ºC in a hydrogen atmosphere, kept for 1h, then heated to 1100ºC±20ºC, and kept for 15min, at a temperature of not more than 5ºC/min The speed is cooled to below 200 ºC.
Application overview
The alloy is a typical Fe-Ni-Co hard glass sealing alloy commonly used in the world. It has been used for a long time in the aviation factory with stable performance. It is mainly used for glass sealing of electric vacuum components such as launch tubes, oscillator tubes, ignition tubes, magnetrons, transistors, sealed plugs, relays, integrated circuit lead wires, chassis, shells, brackets, etc. In the application, the selected glass should be matched with the expansion coefficient of the alloy. Strictly test its low temperature tissue stability according to the use temperature. Appropriate heat treatment should be carried out during processing to ensure that the material has good deep drawing properties. When using forgings, their air tightness should be strictly checked.
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