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Method for directly manufacturing heavy pressure blank strength tungsten powder with ammonium metatungstate

An ammonium metatungstate, high pressure technology, applied in the field of powder metallurgy, can solve the problems of poor formability and low green body strength, and achieve the effect of simple process, high sintering activity and high purity

Inactive Publication Date: 2008-12-10
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The invention overcomes the shortcomings of poor formability and low green body strength of traditional conventional tungsten powder, and uses ammonium metatungstate as raw material for direct reduction to prepare high-pressure green body strength tungsten powder

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] (1) placing the industrially pure ammonium metatungstate powder in a stainless steel material boat with a material layer thickness of 8 mm;

[0015] (2) Put the powder in the high temperature zone of the reduction furnace, raise the temperature to 800°C at a rate of 10°C / min, keep it warm for 2 hours, and the hydrogen dew point is -40°C;

[0016] (3) Pass the reduced powder through 100 sieves (screen out the agglomerated large particle powder) to obtain tungsten powder with an average particle size of 0.8 μm, and the compact strength of the powder reaches 4.0MMPa without adding any forming agent.

Embodiment 2

[0018] (1) placing the industrially pure ammonium metatungstate powder in a stainless steel boat with a layer thickness of 6mm;

[0019] (2) Put the powder in the high temperature zone of the reduction furnace, raise the temperature to 950°C at a rate of 7°C / min, keep it warm for 3 hours, and the hydrogen dew point is -45°C;

[0020] (3) Pass the reduced powder through 100 sieves (sieve out agglomerated large particle powder) to obtain tungsten powder with an average particle size of 1.9 μm. The compact strength of the powder reaches 4.0 MPa without adding any molding agent.

[0021] In the present invention, because the ammonium metatungstate is used for direct reduction treatment under hydrogen gas, the development of powder particles is not complete, and irregular particle morphology is formed. Partial bridging between particles forms a loose aggregate structure, which makes the powder mesh with each other during compaction, thus having high strength.

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PUM

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Abstract

The invention discloses a preparation method of high pressed compact strength tungsten powder by ammonium metatungstate (AMT) direct hydrogen reduction. The tungsten powder prepared by the invention is directly formed into high-intensity pressed compacts without adding any forming agents, and the transverse rupture strength of the pressed compacts reaches 2.5 to 4.0MPa. The tungsten powder prepared by the invention can be widely used for preparing large tungsten products and tungsten alloy products. In the method, ammonium metatungstate is used for direct reduction, and calcination and other intermediate processes are not necessary, thereby process is simple and energy consumption is low. The granularity of the tungsten powder prepared by the method is controlled to be homogeneous and the sintering activity is high, thereby being benefit for the preparation of high-performance tungsten products.

Description

Technical field: [0001] The invention relates to a preparation method of high billet strength tungsten powder in the field of powder metallurgy, in particular to a method for preparing high billet strength tungsten powder by direct hydrogen reduction of ammonium metatungstate (AMT). technical background: [0002] Tungsten has a high melting point (3417°C), high density (19.3g / cm 3 ), low thermal expansion coefficient and high hardness, so tungsten and alloys composed of tungsten and other alloying elements are widely used in aviation, weaponry and high-temperature structural parts and other fields. At present, the preparation of such tungsten products is made of tungsten powder by powder metallurgy method. The shape and particle size of tungsten powder directly affect the compactability and formability of the powder, which in turn affects the final performance of the product, especially for the preparation of large When tungsten products are used, the formability of the pow...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/20
Inventor 范景莲田家敏游峰刘涛
Owner CENT SOUTH UNIV
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