Ammonium paratungstate (or APT) is a white crystalline salt of ammonium and tungsten, with the chemical formula (NH₄)₁₀(H₂W₁₂O₄₂)·4H₂O. Its shape is like sheet or needle.  It is insoluble in water and alcohol. Ammonium metatungstate is very versatile and can be used as catalysts, capacitors, nuclear shielding, flame retardants, corrosion inhibitors raw materials, but also excellent raw materials in the preparation of ultra fine tungsten powder, tungsten heavy alloy powder, phosphotungstic acid, arsenic acid, silicon tungstate.

Ammonium paratungstate content is listed as below:

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Compared to the traditional preparing method, tungsten powder prepared by ammonium paratungstate hydrogen reduction has higher property and green strength. Tungsten powder prepared by this method has uneven particle size and incompletion of crystal. Because of these characters, tungsten powder has greater shaping property and green strength.

Traditional tungsten powder is formed without binder which has low formability. When the pressing pressure is low, the binding strength of powder is insufficient and it is very fragile. It will crack if the pressure rises and cause hierarchy. However tungsten powder prepared by hydrogen reduction under 300MPa, there is no hierarchy and green strength reaches above 2MPa.

Tungsten powder prepared by ammonium paratungstate hydrogen reduction is of irregular shape, during the pressing process, the corner of powder contacts with corner unlike traditional surface contact with surface. The formability thus increases.



Tungsten Manufacturer & Supplier: Chinatungsten Online -http://www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
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Ammonium paratungstate hydrogen reduction preparing tungsten powder combines the calcination of raw material powder and hydrogen reduction of tungsten oxide. It reduces the intermediate process and improves producing efficiency.

During the process of preparing tungsten powder by ammonium paratungstate hydrogen reduction, reduction temperature and time affects the producing or tungsten powder. Raising reduction temperature and extending reduction time will make the size of tungsten powder bigger and the completion of tungsten powder crystal. Extend the reduction time will make the gaseous phase transport more active. The fine tungsten oxide particles will deposit on the large tungsten powder particles. Thus enlarge the size of grain size.

Compared to the traditional preparing method, tungsten powder prepared by ammonium paratungstate hydrogen reduction has higher property and green strength. 



Tungsten Manufacturer & Supplier: Chinatungsten Online -http://www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
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Changing dynamics of four endogenous hormones in normal and aborted ovules of hazelnut（Corylus heterophylla Fisch）was analyzed during fruit development stage，and following ABA and its synthesis inhibitor sodium tungstate solution spraying treatments were carried out to study the effects of ABA on ovules filling process. The results showed that：（1）Content changing curves of IAA，GA₃ and ZR in normal filled ovules were approximately single peak shaped，and their peak value appeared on 80th，90th and 100th day after blooming，respectively. Compared during the same developing period，content of IAA and GA₃ in aborted ovules were lower than that in filled ovules in most cases，while higher ZR content was found to exist in aborted ovules. Eighty to 110 days after blooming was a key period for rapid growth of hazelnut ovule. During the stage，ABA content in developing ovules was significantly higher than that in abortive one.（2）20.0 and 50.0 mg · L^-1 ABA treatments promoted fresh weight of kernel，shell and nut to different degrees，while sodium tungstate had an opposite effects on the above indexes compared with ABA treatments. The results above indicated that ABA was involved in the regulation process of ovule filling in hazelnut.