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Method for preparing nm-class composite rare earth molybdenum material by sol-gal process

A nanocomposite and gel technology, which is applied in the field of preparing nanocomposite rare earth molybdenum materials and refractory metal materials by using sol-gel, can solve the problems of increasing material brittleness and reducing material processing performance, and achieves the effect of strong emission ability

Inactive Publication Date: 2005-01-26
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the tungsten-thorium oxide prepared by the ball milling method inevitably introduces iron impurities, which affects the further improvement of cathode emission performance, reduces the processing performance of the material, increases the brittleness of the material, and the low content of iron impurities also affects its use under vacuum.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Take by weighing 88.32 grams of ammonium heptamolybdate to make a concentration of 17.5% ammonium heptamolybdate aqueous solution, and take by weighing 88.32 grams of citric acid simultaneously, be dissolved in the ammonium heptamolybdate aqueous solution completely. Then weigh 1.28 g of lanthanum oxide and dissolve it completely in 7 ml of nitric acid to obtain a lanthanum nitrate solution, then pour the prepared lanthanum nitrate solution into an aqueous solution of ammonium heptamolybdate; add nitric acid to adjust the pH to 1.5. Heat to 90°C in a water-soluble pot, stir with an electric stirrer, evaporate to a sol, and cool to a gel at room temperature. Dry in an oven at 110°C. Put it into a muffle furnace and burn at 450°C. The calcined powder is reduced in a hydrogen furnace at 450°C and 850°C in two stages to obtain molybdenum / lanthanum oxide nanopowder. Then it is cold-pressed at 500MPa, and then hot-pressed and sintered at 1500°C and 45Mpa in a hydrogen furna...

Embodiment 2

[0016] Weigh 85.00 grams of ammonium dimolybdate to make a concentration of 18% ammonium dimolybdate aqueous solution, and weigh 85.00 grams of citric acid at the same time, completely dissolve in the ammonium dimolybdate aqueous solution. Weigh 1.36 g of lanthanum oxide and dissolve it completely in 8 ml of nitric acid to obtain a lanthanum nitrate solution, then pour the prepared lanthanum nitrate solution into an aqueous solution of ammonium dimolybdate; add nitric acid to adjust the pH to 1.2. Heat to 85°C in a water-soluble pot, stir with an electric stirrer, evaporate into a sol, and cool at room temperature to form a gel. Dry in an oven at 115°C. Put it into a muffle furnace and burn it at 420°C. The calcined powder is reduced in a hydrogen furnace at 420°C and 860°C in two stages to obtain molybdenum / lanthanum oxide nanopowder. Then it is cold-pressed at 480MPa, and then hot-pressed and sintered at 1450°C and 50MPa in a hydrogen furnace. After the breakdown experime...

Embodiment 3

[0018] Take by weighing 126.96 gram of ammonium dimolybdate, make concentration and be 18.6% ammonium dimolybdate aqueous solution, take by weighing 126.96 gram citric acid simultaneously, dissolve in the ammonium dimolybdate aqueous solution completely. Weigh 2.3 g of lanthanum oxide and dissolve it completely in 13 ml of nitric acid to obtain a lanthanum nitrate solution, then pour the prepared lanthanum nitrate solution into an aqueous solution of ammonium dimolybdate; add nitric acid to adjust the pH to 2. Heat to 83°C in a water-soluble pot, stir with an electric stirrer, evaporate into a sol, and cool at room temperature to form a gel. Dry in an oven at 115°C. Put it into a muffle furnace and burn it at 430°C. The calcined powder is reduced in a hydrogen furnace at 430°C and 870°C in two stages to obtain molybdenum / lanthanum oxide nanopowder. Then it is cold-pressed at 470MPa, and then hot-pressed and sintered at 1550°C and 55MPa in a hydrogen furnace. After the break...

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Abstract

The invention discloses an infusible metal material, belonging to compound nanometer material field. Especially relates to a method for using sol-gel method to produce nanometer compound rare earth molybdenum material. The method is, in ammonium molybdate solution, the lemon acid is poured in, and then the rare earth nitrate solution is added into the mixed solution. They are dried in the drying box, and form the dry gel. Then the dry gel is baked in furnace, forms compound of molybdenum trioxide and lanthana or lanthanum hydroxide. Finally, they are reduced for 1.5-2.5 hours under temperature of 400-450deg.C and 800-900deg.C in hydrogen furnace. The reduced compound rare earth lanthana is formed under pressure, and it is heated and baked into shape under high temperature and pressure in hydrogen furnace. The material particle is tiny, the density can reach to 95% of the ideal density, the rare earth oxide exists with nanometer particle, the emitting ability is strong, and it can be used as new negative material.

Description

technical field [0001] The invention relates to a refractory metal material, which belongs to the field of composite nanomaterials, in particular to a method for preparing a nanocomposite rare earth molybdenum material by using sol-gel. Background technique [0002] The traditional hot cathode material is tungsten-thorium oxide material. Its working characteristics: the working temperature is above 1800 ℃, and the thorium element is radioactive. The rare earth molybdenum material is doped with a certain amount of rare earth oxides in molybdenum, and can be processed by plastic processing to prepare excellent cathode materials. It has the characteristics of working temperature below 1500 ℃, environmental protection, high toughness, and strong emission ability. [0003] At present, the unit molybdenum lanthanum oxide materials are being studied at home and abroad. A Japanese patent (JP59-17954) mentions that the lanthanum-molybdenum material is both a structural material and...

Claims

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Application Information

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IPC IPC(8): B22F9/22C22C1/04C22C27/04
Inventor 王新刚王茂林宋华丁秉钧
Owner XI AN JIAOTONG UNIV
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