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Method for preparing uniformly chromium-doped APT (ammonium paratungstate)

A technology of chromium ammonium paratungstate and ammonium tungstate, which is applied in the field of preparing uniform chromium-doped APT (ammonium paratungstate), which can solve the problems of abnormal growth and uneven distribution of inhibitors, so as to reduce costs and suppress abnormal growth of WC grains , reduce the effect of investment

Active Publication Date: 2015-01-21
CHONGYI ZHANGYUAN TUNGSTEN +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In order to overcome the disadvantages of uneven distribution of inhibitors and the abnormal growth of "WC grains", the technical problem to be solved by the present invention is to provide a preparation The method of evenly doping ammonium paratungstate with chromium promotes a more uniform distribution of grain growth inhibitors, achieves molecular level mixing, and effectively inhibits the abnormal growth of WC grains during liquid phase sintering, which is conducive to improving The performance of ultrafine cemented carbide

Method used

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Embodiment 1

[0027] A method for preparing uniform chromium-doped ammonium paratungstate, the steps are as follows:

[0028] (1) Pre-dissolve WO with ammonia water 3 Preparation of ammonium tungstate solution in which WO 3 =276 g / L, NH 4 OH=4.3 mol / L, add corresponding WO 3 React with ammonia water in a reactor at 100 °C for 1 h;

[0029] (2) will be 2 m 3 Add the ammonium tungstate solution into the titanium-lined crystallization pot with a stirring speed of 70 r / min, slowly add 15.4 Kg of chromium acetate while stirring, open the steam valve and adjust the steam to 0.10-0.30MPa; the temperature is controlled at 90-100 °C, heating evaporation crystallization;

[0030] (3) After the liquid level in the crystallization pot boils completely, keep stirring and turn off the steam;

[0031] (4) When crystal nuclei appear in the crystallization pot, adjust the speed to 30 r / min and keep the steam pressure at 0.05-0.10 MPa;

[0032] (5) When the solution density reaches 1.1 g / cm 3 , cont...

example 1

[0034] Example 1 The physical properties of the chromium-doped APT powder are shown in Table 1.

[0035]

[0036] See the SEM and EDS results of this example figure 2 , image 3 , Figure 4 , XRD results see Figure 5 .

[0037] Chromium-doped APT powder is processed into WC-Co cemented carbide through calcination, hydrogen reduction, carbonization, molding, liquid phase sintering and other processes. The metallographic results are shown in Figure 6 .

Embodiment 2

[0039] A method for preparing uniform chromium-doped ammonium paratungstate, the steps are as follows:

[0040] (1) Pre-dissolve WO with ammonia water 3 Preparation of ammonium tungstate solution in which WO 3 =150 g / L, NH 4 OH=1.8 mol / L, add the corresponding WO 3 React with ammonia water in a reactor at 100 °C for 1 h;

[0041] (2) will be 3 m 3 Add the ammonium tungstate solution into the titanium-lined crystallization pot with a stirring speed of 70 r / min, slowly add 18.3 Kg of chromium acetate while stirring, open the steam valve and adjust the steam to 0.10-0.30MPa; the temperature is controlled at 90-100 °C, heating evaporation crystallization;

[0042] (3) After the liquid level in the crystallization pot boils completely, keep stirring and turn off the steam;

[0043] (4) When crystal nuclei appear in the crystallization pot, adjust the speed to 30 r / min and keep the steam pressure at 0.05-0.10 MPa;

[0044] (5) When the solution density reaches 1.1 g / cm 3 , ...

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Abstract

The invention belongs to the technical field of tungsten smelting and production and in particular relates to a method for preparing uniformly chromium-doped APT (ammonium paratungstate). The method for preparing the uniformly chromium doped APT comprises the following steps: (1) dissolving WO3 with ammonia; (2) adding soluble chromic salt, heating, and carrying out evaporation crystallization; (3) after liquid in a crystallizing pan is completely boiled, stopping steam introduction while stirring continuously; (4) when crystal nucleuses appear in the crystallizing pan, regulating a rotating speed, and maintaining a steam pressure; (5) when density of a solution reaches 1.1g / cm<3>, controlling a stirring speed, and maintaining the steam pressure; and (6) when the pH of the solution is 6.7-7.0, stopping heating, cooling and emptying. The method for preparing the uniformly chromium doped APT has the beneficial effects that APT powder with chromium uniformly distributed can be prepared, chromium is uniformly distributed at each APT crystal boundary, and molecular scale mixing is realized; and the prepared chromium doped APT can be used for effectively inhibiting abnormal growth of WC crystal grains in a liquid phase sintering process, so that properties of a hard alloy are greatly improved.

Description

technical field [0001] The invention belongs to the technical field of tungsten smelting and production, and in particular relates to a method for preparing uniform chromium-doped APT (ammonium paratungstate). Background technique [0002] Cemented carbide is widely used in modern tool materials, wear-resistant materials, high-temperature-resistant and corrosion-resistant materials due to its high melting point, high hardness and high strength and a series of excellent properties. of which ultra-fine grained Cemented carbide has become the development direction of cemented carbide because of its "double high" performance of high hardness and high strength. The rapid growth of liquid phase sintered WC grains is a major bottleneck restricting the development of ultrafine cemented carbide. Studies have shown that transition metal carbides (Cr 3 C 2 ) can effectively inhibit the growth of WC grains during liquid phase sintering. Therefore, the current preparation of sub-mi...

Claims

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Application Information

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IPC IPC(8): C01G41/00
CPCC01G41/00
Inventor 赵立夫黄海万林生潘明然
Owner CHONGYI ZHANGYUAN TUNGSTEN
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