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Size-controllable high-purity alkali metal chromate crystal powder and preparation method thereof

A metal chromate and crystal powder technology, applied in the direction of chromate/dichromate, etc., can solve the problems of failure to form scale, disadvantages of high-purity alkali metal chromate, unsatisfactory product purity, etc., and achieve crystal grain The effect of uniform size distribution, avoiding nucleation and agglomeration, and shortening the crystallization induction period

Inactive Publication Date: 2020-07-28
GRIMAT ENG INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First of all, the research and development technology of alkali metal chromate in my country started later than that of foreign countries, and the early research basically served national defense and military industry, lacking high-purity material withdrawal and application development research, which led to insufficient research and development vitality in the market; in addition, the current domestic market There is no targeted detection method for impurity ions in the product, which further leads to unsatisfactory product purity; finally, the current preparation process is mainly based on small-scale experiments, and there are very few basic researches, so the basic data related to the preparation of high-purity chromate Most of them are quoted from foreign countries, and these basic data often restrict the research on the crystallization process of chromate, which in turn affects the purity of the final product
It has failed to form a scale itself, and the market lacks vitality. Various reasons lead to a clear disadvantage in the competition between domestic and foreign countries for high-purity alkali metal chromate
The vast majority of alkali metal chromate products on the market are far behind foreign products in terms of product purity and crystal form, which greatly limits their development and application
Taking cesium chromate as an example, in the existing main purification technology of cesium chromate, because its solubility at room temperature is as high as 74g / 100ml water, the extremely large saturated solution concentration leads to explosive nucleation during its evaporation and crystallization process, covering a large amount of Impurities in solution, so it is difficult to increase the purity above 99.99%

Method used

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  • Size-controllable high-purity alkali metal chromate crystal powder and preparation method thereof
  • Size-controllable high-purity alkali metal chromate crystal powder and preparation method thereof
  • Size-controllable high-purity alkali metal chromate crystal powder and preparation method thereof

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Experimental program
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Effect test

Embodiment 1

[0031] Selecting purity to be 99.9% cesium hydroxide monohydrate and 99% chromium trioxide as reactant, be dissolved in deionized water respectively and be configured into chromic acid and cesium hydroxide solution of 2M and 1M; The flow rate is added into the cesium hydroxide solution in equal proportions to prepare 10ml of cesium chromate solution with a concentration of 1M. Get 30ml ethanol, join in the above-mentioned solution drop by drop with the flow rate of 20ml / min and shake the solution, separate out a large amount of yellow cesium chromate crystals; After centrifugation, filtration, the powder after drying is tested by laser particle size analyzer, as figure 1 As shown, the cesium chromate crystal powder whose grain size D50 is 15.4±0.3 microns and D90 is 40.3±0.3 microns is finally obtained. The results show that the crystal particle size D50 obtained by alcohol elution is relatively small.

[0032] The cesium chromate crystal powder is sieved to a grain size of 1...

Embodiment 2

[0034] Selecting purity to be 99.9% cesium hydroxide monohydrate and 99% chromium trioxide as reactant, be dissolved in deionized water respectively and be configured into chromic acid and cesium hydroxide solution of 2M and 1M; The flow rate is added into the cesium hydroxide solution in equal proportions to prepare 10ml of cesium chromate solution with a concentration of 1M. Take 30ml of ethanol, add it dropwise to the above solution at a flow rate of 20ml / min and shake the solution, wash repeatedly, and a large amount of yellow cesium chromate crystals are precipitated; the centrifuged and filtered powder is added to high-purity water to form a saturated cesium chromate solution. Evaporate at a constant temperature at 60°C, supplemented by 200W ultrasonic treatment during the process, centrifuge, filter, and dry to obtain cesium chromate crystal powder. The final crystal powder is tested by a laser particle size analyzer, as shown in figure 2 As shown, the grain size D50 ...

Embodiment 3

[0037] Selecting purity to be 99.9% cesium hydroxide monohydrate and 99% chromium trioxide as reactant, be dissolved in deionized water respectively and be configured into chromic acid and cesium hydroxide solution of 2M and 1M; The flow rate is added into the cesium hydroxide solution in equal proportions to prepare 10ml of cesium chromate solution with a concentration of 1M. Take 30ml of ethanol, add it dropwise to the above solution at a flow rate of 20ml / min and shake the solution, wash repeatedly, and a large amount of yellow cesium chromate crystals are precipitated; the centrifuged and filtered powder is added to high-purity water to form a saturated cesium chromate solution. Evaporate at a constant temperature of 60°C, process ultrasonically at 400W, centrifuge, filter, and dry to obtain cesium chromate crystal powder. The final crystal powder is tested by a laser particle size analyzer, according to image 3 , the grain size D50 is 41.1±1 microns, and D90 is 74.6±0.3...

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Abstract

The invention discloses size-controllable high-purity alkali metal chromate crystal powder and a preparation method thereof, and belongs to the technical field of alkali source releasing agents for low-light level night vision devices. The purity of the chromate crystal powder reaches up to 99.99% or above, and the grain size is 1-350 microns. The chromate prepared by the method is relatively highin purity, controllable in particle size, uniform in product particle size distribution and complete in crystal form; meanwhile, by controlling the ultrasonic power and the evaporation rate of recrystallization, burst nucleation can be effectively prevented, the purity of a final product can be better improved, and the method can be effectively applied to preparation of an alkali metal releasingagent in a third-generation low-light level night vision device.

Description

technical field [0001] The invention belongs to the technical field of alkali source release agents for low-light night vision devices, and in particular relates to a size-controllable high-purity alkali metal chromate crystal powder and a preparation method. Background technique [0002] As an important industrial chemical product, alkali metal chromates are widely used in many industries such as military industry, aerospace, and medicine because of their diverse types and characteristics. Among them, it plays an important role in the manufacture of high-purity metals, photomultiplier tubes, photocathodes, microwave night vision technology and special electric light sources. The performance of such precision devices depends mainly on the characteristics of the raw materials. Taking the application of cesium chromate in the photocathode tube as an example, the photocathode has the characteristics of high spectral response bandwidth, high sensitivity, small induced current, ...

Claims

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Application Information

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IPC IPC(8): C01G37/14
CPCC01G37/14C01P2006/80C01P2004/61C01P2004/60
Inventor 杜昊瑾何学良张庆猛杨志民杨剑
Owner GRIMAT ENG INST CO LTD