Electron tube filament uses tungsten cobalt alloy wire, the composition range is wide. It is required that the filament with good sagging performance is generally doped W-3Re tungsten-cobalt alloy wire. The filament with good ductility at low temperature is required, and W-20Re and W-25Re tungsten-cobalt alloy wire is generally used. Wire winding and life tests were carried out on the tube filament made of tungsten-cobalt alloy wire. The results are shown in the table below. When annealing at 2000℃ and 2500℃, the ratio of wire winding radius increases with the increase of cobalt content, indicating that the plasticity of the alloy with high cobalt content decreases, the wire winding performance is poor, but the filament life is improved.
The electron tube is often affected by temperature change and strong vibration, the pitch of the screw wire is easy to change, and even collision and electrical short circuit. The bare wire is coated with a layer of aluminum oxide powder to improve the strength of the screw wire, reduce the embrittlement factor, and increase the insulation, so that the temperature fluctuations and mechanical vibration will not make the filament helix collision and short circuit.

Satellite tube, require long life, tens of thousands of hours, high reliability, vibration resistance. When launching an artificial Earth satellite, the electron tube is subjected to 5-8g of gravitational acceleration. Doped tungsten powder was prepared by H2 reduction using blue tungsten oxide as raw material and adding high content dopant and cobalt. After washing with hydrofluoric acid, it was mixed with ammonium cobaltate solution, and then reduced with H2 to produce pickling doped W-3Re alloy powder. After pressing and sintering, the doped W-3Re alloy wire is made by rotary forging and drawing. This kind of alloy wire can meet the requirements of satellite long - life surface electron tube filament.

The electron tube used by the ground receiving station of the artificial earth satellite requires high mechanical strength and will not break the electron tube filament when receiving the resonance of the same frequency; Bending 90° Angle is not brittle splitting, breaking and cracking; The low evaporation rate of the filament prevents the wall of the electron tube from becoming black. The tungsten-cobalt alloy wire with high cobalt content can meet this requirement.

The heating filament of the accelerator tube electron gun of medical treatment machine and industrial flaw detection machine uses tungsten and cobalt alloy wire, which can not only ensure the requirements of longevity noodles, but also ensure the requirements of other life.

The collapsible filament of the high voltage rectifier is made of tungsten-cobalt wire, which is not brittle. Split, break and crack, and the consistency of the electrical parameters of the rectifier tube is better.