The Method of Making Tungsten Coil with Thorium Tungsten Wire

The tungsten coil used in the cathode of the magnetron is made of the thorium tungsten wire in a spiral shape. It has the ability to emit electrons by heating the current through the current to the specified temperature. The cathode has the advantages of short heating time and strong anti electronic bombardment.

When tungsten wire is made with thorium tungsten wire, a molybdenum core or iron core with a specified diameter is usually used to form a tungsten coil, and the core is finalized by heat treatment in a hydrogen furnace. Finally, the core is completely dissolved or semi dissolved. The main manufacturing process is as follows:

A certain amount of thorium nitrate solution is added to tungsten oxide in a certain amount. The specified amount is the amount of thorium nitrate solution required between the mass content of two thorium oxide in the final thorium tungsten wire from 0.7 to 1.1%, and then dried to make the doped tungsten oxide powder.

The doped tungsten oxide powder was reduced by hydrogen under heating conditions to obtain thorium tungsten powder with uniform fine particle dispersion.

The obtained thorium tungsten powder was sintered by powder metallurgy method, and the thorium tungsten wire with the required diameter was prepared by pressure processing, and it was wound by wire coil.

At last, the thorium tungsten wire wound with a wire disk is heated and straightened to increase the tensile force. When the thorium tungsten wire is passed through the die hole, the spindle is rotated at the speed of 2800 rotation per minute, making the surface of the material restricted by the mold. And straighten the bar and straighten the bar's shape and size and performance.

On the premise of guaranteeing the emitrate, the quality of thorium in thorium tungsten wire is controlled between 0.7% and 1.1%, the thorium tungsten wire is straightened to make the internal stress evenly distributed, to improve its winding performance and to restrain the splitting and brittle fracture of the tungsten coil. The rate of finished products optimizes the performance of the tungsten coil and saves the cost.

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