Because the blanks need to be processed and meshed to grid, there are special requirements for pyrolytic graphite grid blanks: small residual stress, no stratification, no obvious rumen, good processing and meshing performance.
Pyrolytic graphite grid can effectively reduce the volume of the electron tube, improve the reliability of the emission tube, and extend the service life, especially for the development of large power emission tube and UHF electron tube.
It can withstand higher power: the grid made of aluminum wire or molybdenum sheet can withstand 7-14 watts per cubic centimeter, and the grid made of two pyrolytic graphite can withstand 60 watts per square centimeter. Such a large dissipative power is helpful to reduce the volume and the weight, increase the power of the electron tube;
It has good high temperature mechanical properties: the strength of graphite will increase with the increase of temperature, and the electronic grid has high temperature stability.
Long service life: the service life of pyrolytic graphite grid has exceeded the specified limit of molybdenum grid, which can reach 4000-5000 hours, and the higher has reached 10000 hours.
The thermal emission is small: under the same load, the pyrolytic graphite grid is only about 1 / 50 of the zirconium molybdenum grid.
The second electron emission coefficient is low: the electron emission coefficient of pyrolytic graphite is low, when it is processed into a whole grid, and the surface of pyrolytic graphite blank does not need to spray any material;
Good thermal stability: pyrolytic graphite is a kind of anisotropic material. When it is made as a whole, its transverse axial thermal conductivity is high, which is conducive to reducing the grid temperature, and also has a smaller thermal expansion coefficient, which is conducive to making the electrode size of the electronic tube more precise, reducing the electrode spacing, improving the working frequency, and improving the reliability and service life of the electronic tube.