A preparation method of rare earth oxide dispersion strengthened fine grain tungsten materials

Patent metadata

Field	Value
Publication number	US-2017225234-A1
Application number	US-201414901780-A
Country	US
Kind code	A1
Filing date	Oct 20, 2014
Priority date	Oct 20, 2014
Publication date	Aug 10, 2017
Grant date	—

Abstract

This invention relates to a preparation method of rare earth oxide dispersion strengthened fee grain tungsten materials, the mass percent of the rare earth oxide is of 0.1 - 2 %, and the rest ingredient is W. Weigh soluble rare earth salt and tungstate, dissolve into water to made into 50 - 100 g/L of rare earth salt solution and 150 - 300 g/L of tungstate solution, respectively. Firstly, add trace alkali in rare earth salt solution to control pH in 7 - 8 , then add organic dispersant and stir to form evenly suspended R(OH) 3 particle colloid (R refers to rare earth element). Secondly pour the tungstate solution into the R(OH) 3 colloid, add trace acid to control pH in 6 - 7 , then add organic dispersant and stir to form tungstic acid micro particles, which wrap around the colloidal particles, forming coprecipitation coating particle colloid. Thirdly, the coprecipitation coating particle colloidal is spray-dried, forming tungsten and rare earth oxide compound precursor powder. Alter that, ultrafine or nanoscale tungsten powder with particle size of 50˜500 nm is obtained through a process of calcination subsequent with hydrogen thermal reduction. Finally, the tungsten powder is subjected to ordinary compression molding and then conventional high temperature sintering. The trace rare earth oxide dispersion strengthened high performance fine grain tungsten materials prepared by this invention, its density is close to full density ( 98.5 % or higher), its grain size is uniform and very fine (average in 5˜10 microns), and the rare earth oxides particles evenly distribute in tungsten intracrystalline or grain, boundary with particle size of 100˜500 nm.

First claim

1 . A preparation method for rare earth oxide dispersion strengthened fine grain tungsten material, its character is that includes the following steps:
(1) The mass percent of the rare earth oxide is of 0.1˜2%, and the rest ingredient is W. Weigh soluble rare earth salt and tungstate, dissolve into water to made into 50˜100 g/L of rare earth salt solution and 150˜300 g/L of tungstate solution, respectively. Firstly, add trace alkali in rare earth salt solution to control pH in 7˜8, then add organic dispersant and stir to form evenly suspended R(OH) 3 particle colloid (R refers to rare earth element). Secondly, pour the tungstate solution into the R(OH) 3 colloid, add trace acid to control pH in 6˜7, then add organic dispersant and stir to form tungstic acid micro particles, which wrap around the colloidal particles, forming coprecipitation coating particle colloid. Thirdly, the coprecipitation coating particle colloidal is spray-dried at 350˜450□, forming tungsten and rare earth oxide compound precursor powder, which is then calcined at 300˜600□ for 1˜4 h. After deaggregatlon and sieving, the calcined powder is hydrogen reduced at 600˜850° C. for 2˜6 h, ultrafine or nanoscale tungsten powder with particle size of 50˜500 nm is obtained. Rare earth oxides referred to any one or more of Y 2 O 3 , La 2 O 3 , or in CeO 2 ; (2) The ultrafine/nanoscale tungsten powder containing trace rare earth oxide prepared in step (1) is compression molded under 150˜300 MPa using mold pressing or cold isostatic pressing; (3) The pressing molded compaction is subjected to regular high temperature sintering in high temperature sintering furnace, sintering temperature is 1800˜2000□, holding time 1˜5 h, then dense high-performance rare earth oxide homogeneous dispersion strengthened fine grain tungsten materials are obtained.

2 . According to the preparation method of rare earth oxide dispersion strengthened fine grain tungsten materials in claim 1 , its character is: the described tungstate is ammonium metatungstate, ammonium paratungstate or ammonium tungstate.

3 . According to the preparation method of rare earth oxide dispersion strengthened fine grain tungsten materials in claim 1 , its character is: the described rare earth salts are nitrate, oxalate, carbonate, chloride or sulfate of Y, La or Ce.

4 . According to the. preparation method of rare earth oxide dispersion strengthened fine grain tungsten materials in claim 1 , its character is: the described stirring speed is 10001˜5000 revolutions per minute.

5 . According to the preparation method of rare earth oxide dispersion strengthened fine grain tungsten materials in claim 1 , its character is: the described spray drying nozzle rotating speed is 20000˜30000 revolutions per minute.

6 . According to the preparation method of rare earth oxide dispersion strengthened tine grain tungsten materials in claim 1 , its character is: the described reaction dispersant are stearic acid, polyethylene glycol (PEG), urea, N,N-dimethyl formamide, OP emulsifier, twain-20 or sodium dodecyl sulfate, the mass fraction of reaction dispersant is of 0.1˜1.5% of rare earth salt solution or tungstate solution.

7 . According to the preparation method of rare earth oxide dispersion strengthened fine grain tungsten materials in claim 1 , its character is: to control pH in step (1), the described acid is hydrochloric acid (HCl), nitric acid (HNO 3 ) or oxalic acid (H2C2O4), the described alkali is sodium hydroxide (NaOH), potassium hydroxide (KOH) or aqueous ammonia (NH 3 ·H 2 O).

Assignees

• Univ Central South

Inventors

• Fan Jinglian
• Han Yong

Classifications

• B22F1/00

  Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties · CPC title

• B22F1/054

  Nanosized particles · CPC title

• C22C32/0031

  Matrix based on refractory metals, W, Mo, Nb, Hf, Ta, Zr, Ti, V or alloys thereof · CPC title

• C22C1/1026

  starting from a solution or a suspension of (a) compound(s) of at least one of the alloy constituents · CPC title

• C22C27/04 Primary

  Alloys based on tungsten or molybdenum · CPC title