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A method for preparing uniform chromium-doped ammonium paratungstate

A technology of chromium ammonium paratungstate and ammonium tungstate 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 inhibit abnormal growth of WC grains. , the effect of uniform particle size distribution

Active Publication Date: 2016-01-20
CHONGYI ZHANGYUAN TUNGSTEN +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In order to overcome the shortcomings of the 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 method for preparing uniform chromium-doped ammonium paratungstate, which can promote the distribution of grain growth inhibitors more Uniform, achieve molecular level mixing, effectively inhibit the abnormal growth of WC grains in the liquid phase sintering process, which is beneficial to improve Properties of Ultrafine Cemented Carbide

Method used

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  • A method for preparing uniform chromium-doped ammonium paratungstate
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  • A method for preparing uniform chromium-doped ammonium paratungstate

Examples

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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 =276g / L, NH 4 OH=4.3mol / L, add corresponding WO respectively 3 React with ammonia water in a reactor at 100°C for 1 hour;

[0029] (2) put 2m 3 Add the ammonium tungstate solution into the titanium-lined crystallization pot, stir at 70r / min, slowly add 15.4Kg of chromium acetate while stirring, open the steam valve to adjust the steam to 0.10-0.30MPa; control the temperature at 90-100°C, heat evaporative 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 30r / min and keep the steam pressure at 0.05-0.10MPa;

[0032] (5) When the solution density reaches 1.1g / cm 3 , control stirring 70r / min, kee...

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 prepared through calcination, hydrogen reduction, carbonization, molding, liquid phase sintering and other processes to prepare WC-Co cemented carbide. 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 =150g / L, NH 4 OH=1.8mol / L, add corresponding WO respectively 3 React with ammonia water in a reactor at 100°C for 1 hour;

[0041] (2) will 3m 3 Add the ammonium tungstate solution into the titanium-lined crystallization pot with a stirring speed of 70r / min, slowly add 18.3Kg of chromium acetate while stirring, open the steam valve to adjust the steam to 0.10-0.30MPa; control the temperature at 90-100°C, heat evaporative 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 30r / min and keep the steam pressure at 0.05-0.10MPa;

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

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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 uniform chromium-doped APT (ammonium paratungstate). The invention discloses a method for preparing uniform chromium-doped ammonium paratungstate. The steps are as follows: (1) dissolving WO3 in ammonia; (2) adding soluble trivalent chromium salt, heating, evaporating and crystallizing. (3) After the liquid level in the crystallization pot boils completely, keep stirring and turn off the steam. (4) When crystal nuclei appear in the crystallization pot, adjust the speed to maintain the steam pressure. (5) When the solution density reaches 1.1g / cm3, control the stirring speed and maintain the steam pressure; (6) When the solution pH=6.7-7.0, stop heating, cool down, and discharge. The beneficial effects of the present invention are: ① The present invention can prepare ammonium paratungstate powder with uniform chromium distribution, and chromium is evenly distributed at each ammonium paratungstate grain boundary, realizing molecular-level mixing. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ②The prepared chromium-doped ammonium paratungstate can effectively inhibit the abnormal growth of WC grains during liquid phase sintering, and greatly improve the performance of cemented carbide.

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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Patent Type & Authority Patents(China)
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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