Multi-component composite rare earth electron emission material and preparation method thereof

Abstract

The invention discloses a multi-element composite rare earth electron emission material and a preparation method thereof, and belongs to the field of powder metallurgy. The material is a composite powder material made by adding rare earth oxide into tungsten metal matrix powder. The preparation method of the metrical takes the tungsten metal matrix powder, the rare earth oxide and nitrate as raw materials. The preparation method of mixed powder includes the steps: adding deionized water into the tungsten metal matrix powder to prepare turbid liquid; configuring the rare earth oxide and the nitrate into rare earth nitrate composite solution; adding the rare earth nitrate composite solution into the turbid liquid, uniformly stirring the turbid liquid, and heating and drying the turbid liquid to obtain the mixed powder. The mixed powder is subjected to two-step hydrogen reduction to prepare the composite powder material. The multi-element composite rare earth electron emission material prepared by the method is free from radioactive pollution, low in oxygen content and impurity content and uniform in rare earth element distribution and can be used for preparing plasma spraying and argon arc welding tungsten electrodes with low burning loss and long service life.

Description

technical field [0001] The invention relates to the technical field of powder metallurgy, in particular to a multi-component composite rare earth electron emission material and a preparation method thereof. Background technique [0002] Plasma spraying has the advantages of a wide range of spraying materials, strong adaptability, and strong coating adhesion. It plays an important role in wear resistance, thermal barrier, corrosion resistance, insulation, radiation resistance, and catalysis. [0003] Plasma spraying is to generate a DC arc between the cathode and the anode (nozzle). The arc heats and ionizes the introduced working gas into high-temperature plasma, which is ejected from the nozzle to form a plasma flame. The temperature of the plasma flame is very high, and its center temperature It can reach 32000K, and the temperature at the outlet of the nozzle can reach 16000~20000K. The flame velocity can reach 1000-2000m / s at the outlet of the nozzle, and the plasma spr...

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Problems solved by technology

Because of this high-temperature, high-speed flame flow, and high-current operating environment, the service life of existing tungsten electrodes is only 40-50h

Moreover, the plasma tungsten electrode is large in size and complex in shape, so it is difficult to process and has high requirements for materials.

[0004] At this stage, due to the strict requirements on working conditions and material size, cerium tungsten or thoriated tungsten are still used as materials for plasma torch tungsten electrodes at home and abroad. The currently used plasma torch tungsten electrodes have the following defects: (1) thoriated tungsten contains radioactive elements , causing harm to the environment and human body during processing and use

(2) The service life of cerium tungsten electrodes is low

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