Working principle of tungsten contacts in automotive relay:
Automotive relay can be thought of as been made up of main circuit which tungsten contacts are working and the control circuit which the coil works. In the relay control circuit, it can only be controlled by tungsten contacts, in order to control its on-off, because the capacity of tungsten contacts  which is used for controlling switch are smaller, therefore, the operating current is small, and it can not be used to directly control the larger load on the power consumption.

Coupled with a certain current or voltage at both ends of the coil of electromagnetic relay, magnetic flux will generate by the coil through the magnetic circuit (its compositions are the armature, yoke, core, working air gap magnetic circuit).

Under the influence of a magnetic field, armature will be attracted to the pole face of the core, thus promoting the normally open tungsten contacts are closed, and normally closed tungsten contacts open;

When the voltage or current across the coil is less than a certain value, the electromagnetic attraction is less than mechanical counterforce, the armature will return to its initial state, normally open tungsten contacts will disconnect, and normally closed tungsten contacts will connect.


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Tungsten contacts can be applied in automotive relay. Automotive relay is a relay in automotive applications, which consist of contact system, magnetic system and restoring mechanism, and tungsten contacts are used in contact systems; magnetic system is consisting of the coil, the core, the armature, etc.; restoring mechanism is composed of tension spring.
Relay is a kind of automatic control devices, when the input reaches a certain condition, so that output can change by leaps and bounds.

The environmental condition of tungsten contacts in automotive relay is harsh:
Withstanding high load power;
Standing instable voltage;
With good anti-seismic performance and its impact resistance should be better;
With corrosion resistance, tungsten contacts should be able to withstand water, salt, oil, sand, and dust, and other abuse;
Ambient temperature range requirements is : 40 ℃ ~ 125 ℃, other locations ambient temperature range is between -40 ℃and 85 ℃.

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During the machining operation, it is known that the chatter could be occurred easily even when adopting tungsten carbide countersink cutters in the cutting processes. The recommended setup in the machining is shorter and more rigid. Since the tungsten carbide fluted countersink cutters often have more than one flutes at an irregular pitching, which will reduce the smooth action of cutting edge set up. In addition the surface speed of the cutting edges, material type and the feed rate will affect the surface ripple, which is hard to remove once started.

Since if the feed rate is too small the chatter risk is likely to be increased, so the most suggested way to deal with chatter is decreasing the speed, meanwhile, increasing the feed.


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Tungsten carbide back countersink cutter is referred to a two piece countersink applied on areas that  are difficult to approach. It is also known as inserted countersink cutter, since it comprises two components, a rod and cutter. The rod is inserted into the pre-drilling hole in the material while the cutter is connected to the rod, or extends out of it when it is in position.



Similar to other ‘back’ machine like back milling ,back boring, it operates on the area, which is far side of workpiece from the spindle face, without second operation set up. As it could eliminate the unnecessary repeat setting up processes, it makes effort in time saving and frustration reduction in terms of flipping over, cleaning, re-clamping , which ensures effortless high concentricity, parallelism.


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d) Oxidation of amines (primary amines to hydroxylamines and nitro derivates and secondary amines to nitrones)
Sodium tungstate dihydrate catalyzes the oxidation of primary amines to the corresponding N-monoalkylhydroxylamines, important biologically active compounds, in the presence of UHP (urea-hydrogen peroxide adduct). This method can be applied for several primary amines, including chiral benzylic amines, α-1,2-hydroxylamines and α-amino esters, yields ranging from 65% to 80%.


 

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Poly-tungsten is lead alternative material in medical devices following regulation in the use of lead and other hazardous substances in electronic and electrical equipment. The material alternative, poly-tungsten thermoplastic, can be machined and fabricated in a variety of configurations.

Poly-tungsten thermoplastic-based material has the density of traditional metals without the safety issues associated with lead. Poly-tungsten is more durable than other lead substitutes and offers equal or better radiation-shielding capabilities. Because it is malleable, poly-tungsten offers increased design flexibility and the opportunity to create molded parts in lieu of multi-part assemblies.

Most expense associated with hazardous materials – from material handling and manufacturing to employee safety and disposal – is eliminated with poly-tungsten. In addition, the malleable material gives designers freedom that they haven't enjoyed in the past. As a result, poly-tungsten to be a cost-effective and attractive alternative to lead.

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The same approach can be used for primary alcohols. However, in the case of primary benzylic alcohols, the amount of hydrogen peroxide used affects the final product. Noyori and co-workers reported that when a small amount of hydrogen peroxide (< 1.5 molar amount) is used to oxidize primary benzylic alcohols, the corresponding aldehydes can be obtained; if a higher amount of hydrogen peroxide (2.5 - 5 molar amount) is added, the corresponding benzoic acids can be produced. The efficiency is highly dependent on the electronic propertiesof substituents.


 

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For many decades, lead (Pb) was the best option for protecting against radiation. It was cheap and plentiful, but it was toxic and highly-hazardous. Manufacturing with lead is currently banned in Europe, and is on track to be banned in the U.S. Poly tungsten shields are effectively and safely shield against radiation, that alternative for lead shields.

Proprietary combination of tungsten and polymers called poly tungsten has been developed. Poly tungsten shields against radiation even better than lead does —but far more safely. Poly tungsten has the same density as lead, meaning it can shield radiation at the same level as lead. It retains its shape during use, and can be used in many applications. Poly tungsten is safe and reliable.

Injection-molded poly tungsten parts have been successfully used in:
CT scanners
X-ray machines
Radiation therapy
Nuclear medicine equipment.

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c) Oxidation of alcohols
Secondary alcohols can be converted into the corresponding ketones (83-96% yield) under biphasic conditions (organic/aqueous) using 30% hydrogen peroxide in the presence of sodium tungstate dihydrate as catalyst and an appropriate PTC such as [CH3-(n-C8H17)3N]HSO4. Noyori and co-workers studied several cases with alkyl or aryl groups, namely 2-octanol or 1-phenylethanol, under solvent-free conditions or using toluene as solvent.


 

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Recently, a catalytic system based on Na2WO4.2H2O/CH3CO2H/H2O2 was developed as an effective method to oxidize natural rubber (with a large number of carbon-carbon double bonds in its structure) into the corresponding epoxy derivatives. This catalytic system possesses much higher epoxidation efficiency than the traditional CH3CO2H/H2O2 system. The proposed method also induces further oxidation of the epoxides into the corresponding ketones and aldehydes, resulting from C-C cleavage.


 

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