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Freeze drying preparing method for dispersion strengthening tungsten powder

A technology of dispersion strengthening and tungsten powder, which is applied in the field of materials, can solve the problems of long cycle time, poor economy and high energy consumption of dispersed tungsten powder, and achieve the effect of convenient tungsten powder preparation, wide applicability and uniform distribution

Active Publication Date: 2016-10-26
UNIV OF SCI & TECH BEIJING
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Problems solved by technology

For mechanical alloying, it needs to consume a lot of energy. During the mixing process, impurities are easily introduced due to the violent movement of the tank body and the grinding ball. Moreover, the preparation of dispersed tungsten powder by this method has a long cycle and poor economy.
The precipitation coating method can obtain doped tungsten powder with good dispersion and uniform quality, but because this method requires a large amount of acid and alkali to prepare and control the pH value of the solution for precipitation coating reaction, it is an environmentally unfriendly method

Method used

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  • Freeze drying preparing method for dispersion strengthening tungsten powder
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  • Freeze drying preparing method for dispersion strengthening tungsten powder

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preparation example Construction

[0033] Such as Figure 1-Figure 6 As shown, the present invention provides a freeze-drying preparation method of dispersion-strengthened tungsten powder. The preparation method utilizes polyvinylpyrrolidone as a joint dispersant, methacrylic acid as a nucleating agent, and liquid nitrogen as a refrigerant. Through vacuum drying technology and The staged calcination reduction process freezes, dries, and calcines the solution dispersed with nano-ceramic particles, rare earth nitrates or a combination of the two into dispersion-strengthened tungsten powder;

[0034] Described preparation method comprises:

[0035] S1: preparing a precursor solution; the S1 specifically includes:

[0036] S11: using ammonium metatungstate as a tungsten source, and using deionized water to prepare a solution, the mass ratio of tungsten in the ammonium metatungstate to deionized water is 1:5-1:10;

[0037] S12: Add PVP and MA respectively to the solution in S11, and stir to dissolve them evenly; ...

Embodiment 1

[0047] 1. Preparation of precursors doped with ceramic nanoparticles:

[0048]1) Ammonium metatungstate is used as the tungsten source, and deionized water is used to prepare a solution. The mass ratio of tungsten (converted from ammonium metatungstate) to deionized water is 1:5-1:10. Add 0.1%-3% PVP and MA in deionized water quality, stir to make them dissolve evenly.

[0049] 2) Add nano-ceramic powder (such as titanium carbide) that needs to be dispersed into the solution according to the designed mass percentage (0.1% to 2%), and fully stir evenly. Disperse in ultrasonic for 1h.

[0050] 2. Precursor freezing and drying:

[0051] The dispersed solution is sprayed into a container containing liquid nitrogen with a special nozzle. Due to the huge supercooling degree of liquid nitrogen, the sprayed solution is quickly frozen into small droplets and sinks into the container. These frozen The small droplets exist in the form of spheres, which are collected and placed in a va...

Embodiment 2

[0056] 1. Preparation of precursors for doping rare earth oxides:

[0057] 1) Ammonium metatungstate is used as the tungsten source, and deionized water is used to prepare a solution. The mass ratio of tungsten (converted from ammonium metatungstate) to deionized water is 1:5-1:10. Add PVP and MA with 0.1%-3% deionized water quality respectively into the solution, and stir to make them dissolve evenly.

[0058] 2) The required rare earth nitrate is added into the solution according to the designed mass percentage (0.1% to 2%), and fully stirred evenly.

[0059] 2. Precursor freezing and drying:

[0060] The dispersed solution is sprayed into a container containing liquid nitrogen with a special nozzle. Due to the huge supercooling degree of liquid nitrogen, the sprayed solution is quickly frozen into small droplets and sinks into the container. These frozen The small droplets exist in the form of spheres, which are collected and placed in a vacuum dryer for sublimation of wa...

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Abstract

The invention provides a freeze drying preparing method for dispersion strengthening tungsten powder. According to the preparing method, polyvinylpyrrolidone is utilized as a joint dispersing agent, methacrylic acid serves as a nucleating agent, liquid nitrogen serves as a refrigerant, a solution in which nano ceramic particles or rare earth nitrate or the combination of the nano ceramic particles and the rare earth nitrate is dispersed is frozen, dried and roasted into dispersion strengthening tungsten powder in a reduction manner through the vacuum drying technology and the segmented roasting reduction technology. According to the method, even distribution of a dispersion object in a tungsten base body can be achieved, and preparing of a large amount of tungsten powder in single batches can also be conveniently achieved.

Description

technical field [0001] The invention belongs to the field of materials, and in particular relates to a freeze-drying preparation method of dispersion-strengthened tungsten powder. Background technique [0002] The first wall tungsten material required by the nuclear fusion engineering tokmak device is an armor material that needs to withstand multi-field coupling effects such as high temperature, radiation and thermal shock. The existing tungsten materials are faced with a high ductile-brittle transition temperature. , Poor thermal shock resistance and other issues. Through the dispersion strengthening method, the second phase particles are dispersed into the tungsten matrix, which can effectively toughen the tungsten material and improve its thermal shock performance. Therefore, the preparation of dispersion strengthened tungsten powder is the first step to obtain tungsten material. Traditional methods mostly use mechanical alloying [1], that is, mixing dispersed particle...

Claims

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Application Information

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IPC IPC(8): B22F9/22
CPCB22F9/22
Inventor 燕青芝王一甲
Owner UNIV OF SCI & TECH BEIJING
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