Method for preparing high-density pure tungsten product through low-temperature sintering

A low-temperature sintering and densification technology, which is applied in the field of powder injection molding, can solve the problems of difficult powder agglomeration, higher than 2100 ° C, and easy introduction of impurities by ball milling, so as to achieve fine grain size, reduce shrinkage and deformation, and improve dimensional accuracy and surface quality effects

Active Publication Date: 2016-04-13
UNIV OF SCI & TECH BEIJING
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the high melting point, the densification of tungsten requires a very high temperature, and its sintering temperature is often as high as 70%-80% of the melting point (above 2300 ° C), otherwise it will lead to problems such as low density and poor strength.
[0003] In order to solve the problem of sintering densification, mechanical alloying or adding active elements such as Fe and Ni can be used to obtain high-density tungsten products at lower temperatures, but the introduction of impurity elements has a bad impact on its performance. (Below 2000℃) Densification of tungsten is a difficult problem
The Chinese patent (ZL200510011617.4) introduces that after 2-12 hours of high-energy ball milling, coarse tungsten powder is ground to obtain high-activity raw material tungsten powder, which is sintered at 2100-2400°C to obtain denser tungsten parts, but ball milling is easy. Impurities are introduced, the treatment time is long, and it is difficult to remove powder agglomeration. After treatment, the sintering temperature of tungsten products with a density higher than 93% needs to be higher than 2100 ° C; Chinese patent (CN101623760A) discloses a tungsten-based alloy product. Micro-injection molding technology, the patent adds alloy elements such as iron and nickel, mixes various powders uniformly through ball milling, and uses powder injection molding technology to prepare miniature tungsten alloy products with a mass of less than 0.5g. The focus of this patent is to use micro-injection molding to Solve the forming problem of micro parts, add iron-nickel alloy elements to form liquid phase sintering to solve the problem of sintering densification, which belongs to the densification of tungsten-based alloys, and has nothing to do with the preparation of high-density pure tungsten products

Method used

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  • Method for preparing high-density pure tungsten product through low-temperature sintering
  • Method for preparing high-density pure tungsten product through low-temperature sintering
  • Method for preparing high-density pure tungsten product through low-temperature sintering

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Experimental program
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Effect test

Embodiment 1

[0025] 1. Clean the jet mill equipment and fill it with high-purity nitrogen with a purity of more than 99.9% as the working atmosphere, reduce the oxygen content to 0.1%, and add commercially available tungsten powder with a purity of more than 99.9% and a particle size of 3um to the feeding chamber;

[0026] 2. Open the grinding valve, adjust the grinding gas pressure to 0.80Mpa, and send powder for grinding;

[0027] 3. Turn on the sorting wheel, adjust the rotating speed of the sorting wheel to 7500rpm, and collect the powder;

[0028] 4. Mix the treated tungsten powder and binder evenly to make granular feed, the mixing temperature is 160 degrees, the mixing time is 2 hours, and the volume fraction of tungsten powder in the feed after mixing is 65%;

[0029] 5. The feed material is formed into a green body of a certain shape on the injection molding machine, and the injection parameters are: the injection speed is 90%, the injection temperature is 165°C, and the injection...

Embodiment 2

[0038] 1. Clean the jet mill equipment and fill it with high-purity nitrogen with a purity of more than 99.9% as the working atmosphere, reduce the oxygen content to 0.1%, and add commercially available tungsten powder with a purity of more than 99.9% and a particle size of 1um to the feeding chamber;

[0039] 2. Open the grinding valve, adjust the grinding gas pressure to 1Mpa, and send powder for grinding;

[0040] 3. Turn on the sorting wheel, adjust the rotating speed of the sorting wheel to 8000rpm, and collect the powder;

[0041] 4. Collect the powder in step 3 for secondary treatment, the grinding pressure is 1Mpa, adjust the frequency of the sorting wheel to 9000rpm, and collect the powder;

[0042] 5. Mix the treated tungsten powder and binder evenly to make granular feed, the mixing temperature is 170 degrees, the mixing time is 3 hours, and the volume fraction of tungsten powder in the feed after mixing is 55%;

[0043]6. The feed material is formed into a green b...

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Abstract

The invention provides a method for preparing a high-density special-shaped pure tungsten product through low-temperature sintering, and belongs to the technical field of powder injection molding. The method comprises the technological processes that an air flow mill is adopted for carrying out dispersing and staging treatment on commercially available high-purity tungsten powder, the treated powder and a bonding agent are evenly mixed for mixing, and even feed is obtained; the feed is subjected to injection molding to form a blank in a certain shape; and the formed blank is subjected to solvent degreasing and hot degreasing and then is sintered, and the tungsten product is obtained. Powder is subjected to dispersing and staging treatment through the air flow mill under the protective atmosphere, the powder is driven by gas to collide with each other and can be treated on a large scale, and no impurity is introduced; the particle size distribution of the treated powder becomes narrow, and the shape of particles becomes regular and is similar to a spherical shape; and loose-fitting tap density is increased, the loading amount of the injection-molded powder is correspondingly improved to 55%-70%, and the density of the pure tungsten product manufactured after sintering of the hydrogen atmosphere of 1,900 DEG C is higher than 96%.

Description

technical field [0001] The invention belongs to the technical field of powder injection molding and provides a method for preparing high-density pure tungsten products by low-temperature sintering. Background technique [0002] Metal tungsten has a high melting point (3410°C), high density (19.3g / cm 3 ), high strength and low expansion coefficient, occupy an important position in engineering applications such as defense electronics industry. Tungsten products are widely used in the fields of aerospace, atomic energy and high temperature. Due to the high hardness, high brittleness, poor conductivity and difficulty in cutting and processing of metal tungsten, traditional powder metallurgy methods cannot prepare thin-walled and complex-shaped tungsten products, and produce complex-shaped tungsten products. Parts will increase the processing cost. Powder injection molding is a new type of near-net powder forming technology formed by introducing modern plastic injection molding...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F3/22B22F9/04
Inventor 秦明礼李睿章林陈鹏起赵尚节鲁慧峰陈铮贾宝瑞曲选辉
Owner UNIV OF SCI & TECH BEIJING
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