A method for preparing a uniform porous tungsten product

A technology of porous tungsten products, which is applied in metal processing equipment, transportation and packaging, etc., can solve the problems of loose packing and low tap density, large sintering shrinkage of the formed body, easy deformation and cracking, etc., and achieves the improvement of loose packing and vibration Density, improving product dimensional accuracy, and avoiding uneven distribution of pores

Active Publication Date: 2018-09-14
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Chinese patent (ZL200510011617.4) discloses a method for preparing high-density special-shaped tungsten products, using high-energy ball milling to improve the sintering activity of powder, and using powder injection molding to prepare complex-shaped tungsten products. The preparation of dense shaped tungsten products has high energy consumption, long process route, and a certain amount of impurities will be introduced, which has nothing to do with the preparation of porous tungsten materials
Chinese patent (ZL2011102134647) discloses a method for preparing a special-shaped porous cathode substrate by using powder injection molding technology. The method uses commercially available tungsten powder to directly inject and form a porous cathode substrate. The commercially available powder has a relatively irregular shape of tungsten powder. The packing and tapping density is small, the loading of the feed material is low (45-60%), and the sintering shrinkage of the formed green body is large, especially for large-scale cathode substrates (such as high-power, high-current-density cathodes such as thyratrons) Cathode, etc.) have the problems of large shrinkage during sintering, easy deformation and cracking, and poor dimensional accuracy of the product, and due to serious agglomeration of commercially available powders and wide particle size distribution, the prepared cathode substrate has uneven pore distribution

Method used

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  • A method for preparing a uniform porous tungsten product
  • A method for preparing a uniform porous tungsten product
  • A method for preparing a uniform porous tungsten product

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] 1. Raw material powder: the raw material powder is commercially available tungsten powder, the purity is greater than 99.9%, and the Fischer particle size is 3um;

[0033]2. Feed preparation: Mix and disperse the tungsten powder particles obtained by the first heat treatment with the organic binder evenly, and make granular feed. The volume fraction of powder particles in the feed is 54%;

[0034] 3. Injection molding: The feed material is formed into a tungsten body of the required shape and size on the injection molding machine. The injection parameters are: injection speed is 90%, injection pressure is 100Mpa, and injection temperature is 165°C;

[0035] 4. Degreasing: Remove the binder in the tungsten body by proper process. The degreasing process is: immerse in trichlorethylene for 12 hours. The thermal degreasing process system is to raise the temperature to 300°C at 1°C / min and keep it warm for 60min. , then raise the temperature to 420°C at 2°C / min, hold for 30 ...

Embodiment 2

[0038] 1. Raw material powder: the raw material powder is commercially available tungsten powder, the purity is greater than 99.9%, and the Fischer particle size is 3um;

[0039] 2. Jet mill disperses and removes fine powder: Clean the jet mill equipment, turn on the main control to preheat, fill in high-purity nitrogen with a purity higher than 99.9% as the working gas, reduce the oxygen content to 0.1%, open the grinding valve, and adjust the grinding The pressure is 0.70Mpa, add high-purity tungsten powder into the grinding chamber for grinding, so that the agglomerates are opened, start the sorting wheel, adjust the speed of the sorting wheel to 6000rpm, and collect the sorted ultrafine particle tungsten powder (<2um);

[0040] 3. Jet mill classification treatment: reduce the rotation speed of the sorting wheel to 6000rpm to 3000rpm four times, and collect tungsten powder in batches;

[0041] 4. Powder heat treatment: under the protection of high-purity hydrogen atmosphere...

Embodiment 3

[0047] 1. Raw material powder: The raw material powder is commercially available tungsten powder with a purity greater than 99.9% and a Fischer particle size of 5um;

[0048] 2. Feed preparation: Mix and disperse the tungsten powder particles obtained by the first heat treatment with the organic binder evenly, and make granular feed. The volume fraction of powder particles in the feed is 54%;

[0049] 3. Injection molding: The feed material is formed into a tungsten body of the required shape and size on the injection molding machine. The injection parameters are: injection speed is 90%, injection pressure is 100Mpa, and injection temperature is 165°C;

[0050] 4. Degreasing: Remove the binder in the tungsten body by proper process. The degreasing process is: immerse in trichlorethylene for 12 hours. The thermal degreasing process system is to raise the temperature to 300°C at 1°C / min and keep it warm for 60min. , then raise the temperature to 420°C at 2°C / min, hold for 30 min...

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Abstract

The invention provides a method for preparing a special-shaped porous tungsten product with uniform pores, and belongs to the technical field of porous high-temperature alloy preparation. After the high-purity tungsten powder is dispersed, the agglomerates of tungsten can be opened, and the ultrafine particles (<2um) in the original tungsten powder can be collected and removed. After classification, the tungsten powder with narrow particle size distribution can be obtained. After heat treatment , can purify tungsten powder and reduce the activity of tungsten powder, obtain a nearly spherical powder with narrow particle size distribution, improve the fluidity and tap density of the powder, correspondingly increase the loading capacity of the injection molding powder, and reduce the shrinkage of the product during the sintering process. A porous cathode substrate with high dimensional accuracy is obtained, and because the powder particle size distribution is narrow and there is no ultrafine powder, the cathode substrate pore distribution is uniform. Multiple treatments of jet mill combined with injection molding process can directly prepare porous tungsten products with complex shape and high dimensional accuracy.

Description

technical field [0001] The invention belongs to the technical field of porous high-temperature alloy preparation, and provides a method for preparing a special-shaped porous tungsten product with uniform pores. Background technique [0002] Porous materials have many excellent properties such as low density, high specific surface area, stability, etc., and their pores can accommodate a large number of guest molecules or large-sized guests, making porous materials useful in many technical fields such as catalysts, fillers, and composite materials. significant application. Porous tungsten is used as a porous body or as a porous matrix to prepare various components in power electronics, aerospace and other fields, such as porous cathode substrates for high current densities, filters for high-temperature fluids, and high-temperature heating of rocket nozzles. body etc. In the above applications, the porosity, pore size and uniformity of pore distribution of porous tungsten pro...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F3/11B22F3/22B22F1/00
CPCB22F3/1121B22F3/225B22F2998/10B22F1/142B22F1/10B22F2009/044
Inventor 秦明礼李睿章林陈鹏起鲁慧峰陈铮贾宝瑞赵尚节曲选辉
Owner UNIV OF SCI & TECH BEIJING
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