Aqueous sols of tungsten oxide dihydrate (WO₃·2H₂O) were prepared from Na₂WO₄ by an ion-exchange method. An aqueous solution of Na₂WO₄ was let to flow through a glass column packed with protonated cation-exchange resin. The effluent, initially transparent, turned into an opaque viscous fluid (pale yellow) in a few hours, before yellow precipitate deposited to completion in three days. The precipitate was a mixture of a crystalline phase of WO₃·2H₂O and an amorphous phase, and the crystalline part could be separated from another by washing with deionized water and centrifuging. The gel of WO₃·2H₂O thus obtained consisted of platelike crystallite 25 nm thick and 42 nm wide as evaluated from the X-ray diffractometer (XRD) peaks, and could be dispersed well into deionized water to form a stable suspension of colloidal particles with a mean diameter of about 30 nm. The mean particle size as well as the crystallite size tended to increase gradually with the repetition of dispersion in water under ultrasonic wave agitation and gelling by centrifuging. On heating, the gel (WO₃·2H₂O) changed to the monohydrate (WO₃·H₂O) at 100 °C, which in turn changed to the anhydride (WO₃) at 240 °C. Remarkably XRD patterns showed conspicuous preferred orientation of WO₃·2H₂O crystallites in (0 1 0) plane after the sol was centrifuged for a long time (10 h) and, upon dehydration, it was inherited by the dehydrated phases, resulting in the conspicuous orientation of WO₃ crystallites in (0 0 1).


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Due to its high density, excellent absorption behaviour against radiation and environmental friendly characteristics, tungsten alloy can be widely used to produce Technetium 99( Tc99) tungsten radiation shielding. Tc99 tungsten radiation shielding usually be used in nuclear medicine, which as the radiation shielding and container for Technetium 99m.

One of the commonly used radioactive materials in nuclear medicine is technetium 99 (Tc99). This is produced in a tungsten Tc99 generator, which contains a radioactive core, loaded with molybdenum 99 which decays to produce Tc99. This is mixed with sodium chloride and other chemicals before being injected into patients. The tungsten provides protection to the clinical staff handling tungsten Tc99generator.

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Radiation is an effective tool within medicine for both diagnostics and treatment of patients. Techniques such as SPECT and PET utilize radioactive materials injected into the patient, which are then monitored by gamma cameras (SPECT) or scanners (PET) to detect the presence of tum ours in the body. Due to its high density, excellent absorption behaviour against radiation and environmental friendly characteristics, tungsten alloy can be widely used in SPECT and PET utilize radioactive materials injected as tungsten alloy syringe shield.

2 mm solid tungsten flange helps syringe shield the hand when withdrawing liquid from a vial. Flange is easily removed to allow transition from drawing dose to patient injection. 9 mm thick glass-5.2g/cc gives the greatest protection of any glass in any syringe shield and syringe shield is easily replaced. twist-turn and the syringe is held firmly.

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Packing: in iron drum with double inner plastic bag of 50kgs or 200kgs net  each.

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Installation method of tungsten points in automotive relay is shown as follows:
To fully play the properties of the automotive relay, the installing direction should be in accordance with the impact resistance direction of the automotive relay. That is to say, impact direction should be perpendicular to the direction of movement of the armature and tungsten points to effectively improve the anti-shock and impact resistance performance of the normally closed tungsten points in the non-energized state,.

In order to improve contacting reliability and to avoid the patter of tungsten points, tungsten carbide falling on the surface of tungsten points, the axial of tungsten points of automotive relay should be parallel to the ground when it is installed.

You should put the small load tungsten points on the top of the large load tungsten points when installing multiple sets of automotive relay.
You can choose housing installing method for preventing the damage of mounting feet in shock and vibration condition when install large volume of relays.

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i) Synthesis of 5-substituted 1-H-tetrazoles

The [2+3] cycloaddition reaction between nitriles and sodium azide, catalyzed by several tungstates, produced the corresponding 5-substituted 1-H-tetrazoles. Sodium tungstate dihydrate was used only for benzonitrile and 36% yield was obtained.


 

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h) Synthesis of β-arylvinyl bromides 

Roy and Bhar reported the synthesis of several β-arylvinyl bromides under environmentally friendly conditions (using water as solvent) through a bromodecarboxylation reaction of cinnamic acids with potassium bromide, using 30% hydrogen peroxide as oxidant and sodium tungstate dihydrate as catalyst, with moderate to good yields.


 

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The kinds of tungsten chloride have tungsten hexachloride, tungsten pentachloride, tungsten tetrachloride, tungsten dichloride, is an important raw material for new applications. It is based on tungsten carbene material which catalyzes paraffin 1- and 2- octene substitution reaction. Besides promote 1, 3-dithiolane and 1, 3-dithiane converted into chloride dihydro-1, 4-dithiins and dihydro-1, 4-dithiepines.

Tungsten chloride, also known as tungsten hexachloride, its physical properties are: formula WCI6, the molecular weight of 396.56 and a melting point 275 ℃, boiling point 347 ℃, the density of 3.52. Its chemical properties are: can decomposition in water and can be dissolved in CS2, soluble in chloroform, methanol, ether, acetone, pyridine, glycerol, petroleum ether, ethanol, carbon tetrachloride, phosphorus oxychloride, benzene, and it easily oxidized in air. Related system number of tungsten chloride is: CAS: 13283-01-7, MDL: MFCD00011463, SNILES: Cl [W] (Cl) (Cl) (Cl) (Cl) Cl, EINECS: 236-293-9. Tungsten chloride is sensitive to moisture so it should be sealed in a cool place. Tungsten chloride hydrogen reduction rationale: the characterized of tungsten chloride hydrogen reduction is there has a variety of low-cost chlorides which accompany series of decomposition reactions and disproportionation reactions.

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g) Halogenation of aromatic compounds

The regioselective halogenation of some aromatic substrates using KCl or KBr in the presence of sodium perborate (SPB) as oxidant and sodium tungstate dihydrate as catalyst, is an environmentally friendly catalytic halogenation procedure, which can provide good yields(up to 92%) under mild conditions.


 

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Technical requirements of tungsten points in interrupter as described below:
Brazing material purity should be higher than 99.9%;
The strength of weld seam must be higher than 78.45MPa;

Tungsten points, which are welded and manufactured in hydrogen and nitrogen gas condition, are consisting of tungsten sheet, sit nails and the solder;

Test of tungsten sheet should be according to regulations in JB / T9860.2 and its main technical parameters are as follows:
With purity of more than 99.95%;
With hardness of higher than 70HRA;
With crystals number: 7500-25000 points / mm²;

Sit nail material is low carbon steel with 0.15% -0.20% carbon content, you can also adopt other materials which have similar composition and properties and can easily caulk.


 

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