Cerium Tungsten Alloy Wire Preparation Process

Cerium tungsten alloy wire is a promising electrode material. Compared with traditional thorium tungsten alloy wire, cerium tungsten wire has the advantages of low electron emission work, high emissivity, high luminous efficiency and low arc voltage. The most important thing is that there is no radioactive contamination. It is the general trend to replace thorium tungsten alloy wire.

Some scholars have proposed a preparation method of cerium tungsten wire, the process is as follows:

A square monoclinic ammonium parotungstate with a grain size of 30μm to 50μm is selected to produce blue tungsten oxide by mild reduction, doped with Al (NO₃)₃ solution, K₂SiO₃ solution, Co(NO₃)₂ solution. The elements of aluminum and cobalt can promote the potassium element into the tungsten matrix, which can obviously reduce the low temperature brittleness of tungsten wire and reduce the splitting of tungsten wire, so that the tungsten wire is made. It has good high temperature resistance of droop performance.

The one part from mixture is reduced directly, and the other part is reduced in two stages. The first stage reduction temperature is 550 to 660°C, the reduction temperature of the second stage is 610 to 810°C, and the ratio of the potassium and cobalt elements is uniformly dispersed in the tungsten powder body, which can improve the anti-seismic performance of tungsten wire at high temperature.

After two reduction of raw materials for 30-40 hours of acid washing and vacuum drying at the temperature of 80 to 120°C, the cerium nitrate solution is added to the raw material, and the cerium element is resistant to high heat. It has the characteristics of high emissivity, luminous efficiency, low arc voltage, no radioactive pollution and so on.

After sifting and sintering, the mixture was first reduced at 750 -800°C, and the second reduced at 900 C -950°C, after isostatic pressing and mechanical steel pressing, the blanks are pressed into blank bars and then pre-baked at a low temperature. The pre-sintering temperature is controlled at 1100°C-1250°C, and sintered in an intermediate frequency induction furnace or two time high-temperature vertical melting sintering to ensure the crystallization of the tungsten bars. The performance can also reduce the production cost, increase the density of the tungsten bar, make the grain size uniform, and the high temperature performance of the tungsten wire is good.

Multi-machine blanking and rotary forging method is adopted to increase production efficiency, save energy, and twice crystallization annealing and stress relief annealing; alternating with rotary swaging processing, it can be processed to Φ3.8mm; multiple annealing can eliminate the stress of tungsten wire surface in time. Reduce the production of tungsten cracks. The metal's plastic deformation ability is restored and the high temperature anti-sagging performance of the tungsten wire is improved.

By adding the dopant of cerium, potassium, cobalt and other elements, the distribution of elements in the tungsten alloy strips is more uniform, the properties of the wire winding are better, the anti-seismic performance of the tungsten wire is increased, the product rate is high, the service life is long, and it can be processed to 0.39mm. It can be widely used in space, aviation, optoelectronics and information technology, engineering, lighting and other fields.
 

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