The ammonium metatungstate and heteropoly tungstic acid are mainly used as a catalyst in the petrochemical and organic synthesis. 

Sodium tungstate is used for the production of certain types of paints and pigments, in addition also be used for metal tungsten, tungstic acid and tungstate manufacture and dyes, pigments, inks, and electroplating. Tungstic acid is mordant dyes, in the textile industry, in the chemical industry is used as a catalyst for preparation of high-octane gasoline. Tungsten disulfide in organic synthesis, such as in the preparation of synthetic gasoline was used as a solid lubricant and a catalyst.

Based on the superiority of the tungsten and its compounds, tungsten occupies an important position in the field of national defense. In the military industry, the pressure – resistant and heating – resisting parts which would contact with gunpowder, like the guns, cannons, tanks and other weapons and equipments, are produced by tungsten steel. The aviation jet engine's combustion chamber, fuel nozzles, turbine guide vane, turbine rotor blades are all made of tungsten alloy; The skin materials of rockets, missiles and satellites are tungsten-containing high-temperature resistance alloy; penetrators heads made of high-density tungsten alloy, can improve the performance of the shells; gyroscopes are the heart of aircraft, naval vessels and rocket's navigation and control system, gyro inertial elements made of high-density tungsten alloy, can improve the stability and control precision of the instruments, such as the aircraft's ailerons, rudder and horizontal tail, etc. are required counterweight to balance. In some aircraft, hundreds of kilograms high density tungsten alloy is used for counterweight; tungsten alloy material has a very important significance to the development of modern aerospace, aviation and maritime industry.

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Tungsten is used as tungsten filament, tungsten band and various forging components form for vacuum tube production, radio electronics, and X-ray technology. Tungsten is the best material to manufacture the glower and spiral wire. High working temperature (2200 to 2500 ° C) can ensure a high luminous efficiency, and the small rate of evaporation can ensure the long life of the filaments. Tungsten can be used for manufacturing the directly heated cathode and the grid electrode in electronic shock tubes, the cathode of the high-voltage rectifier and the indirectly heated cathode heater in a variety of electronic equipments. Tungsten can be used for the manufacture of X-ray tubes and the cathode and anticathode of gas radiation tubes, and the radio device contacts and atomic hydrogen torch electrode. Tungsten and tungsten rod can be used as a high-temperature furnace (3000 ℃) heater. Tungsten heater should work in hydrogen atmosphere, inert atmosphere or vacuum.

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The tungsten materials use for preparation of tungsten-based alloy, are mainly metal tungsten powders and tungsten materials with certain purity, particle size and the grain shape, including tungsten metal plates, rods, wire rods, and mainly used for manufacturing the tubes, radio components, high temperature furnace heating elements and insulating element, and tungsten crucible. Tungsten-based alloys include tungsten-based contact alloy and high-density alloy. High density alloys is divided into the W-Ni-Fe series, and W-Cu series, which is characterized the high density reached 16.5 ~ 19.0g/cm³, equivalent to more than 2 times that of the steel; high strength, up to 800~1000 MPa; good plasticity, W-Ni-Fe series sintered state elongation rate of 10% to 15%; good oxidation resistance, in air above 500℃ have no obvious oxidation; good machining performance, which could be deal with lathing, milling, and planing processing. W-Ni-Cu can be used as gyro rotors and counterweight elements in aircraft navigation instruments, and the control accuracy is very high. In addition, the W-Ni-Fe, W-Ni-Cu high-density alloy has also been widely used for the manufacture of shielding materials in the medical industry, the vibrating elements of communications industry in the phone and BP machines, in the sports and entertainment industry used as the weight elements of the ball head part in Golf racket, in the electrical industry used as high-voltage contacts and the electrical heating elements. W-Cu (Mo-Cu) materials have good thermal conductivity and electrical conductivity, a small linear expansion coefficient, can be widely used as electrical contact materials, microelectronic packaging materials and the heat sink materials. This kind of alloy materials attached great importance to the countries in the world, has become one of the most active areas of research in the materials science community. W-Cu (10% ~ 40% Cu), and the W-Ag alloy combining the good electrical conductivity and thermal conductivity of copper and silver, and the wear resistance of tungsten, could be manufactured knife switch, circuit breaker, the contacts of switches in the working parts of spot welding electrodes and so on.

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The most infusible metal tungsten is often used as a component of many thermal strength alloy, for example, alloy make up with 3% to 15% tungsten, 25% to 35% chromium, 45% to 65% cobalt and 0.5% to 2.75% carbon mainly used for the manufacture of strong and wear-resistant parts, such as aviation engine valve, the working parts of the die eagerly knife, turbine impeller, mining equipment, ploughshares surface coating, as well as some other wear resistant parts. The alloy produced by tungsten and other refractory metals (tantalum, niobium, molybdenum, rhenium) is often used as heat resisting material.

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Tungsten is considered one of the most durable ring metals out there. It ranks a mere two points less than a diamond on the hardness scale. A tungsten ring is great for hard laborers and people whose rings suffer a lot of wear and tear because it requires so little maintenance. You can custom design your own tungsten ring online through any major jeweler.

Instructions

1
Search for "make your own tungsten ring" through a major search engine such as Google or Yahoo.

2
Choose a site.

3
Choose your custom settings. This will normally include shape, size, color and an inlay. You can also specify any engraving you want on the ring as well.

4
Click "Add to Cart" or send the specifications off to the website owner.

5
Use your credit card to pay for the ring, or wait for an email and payment information.

Tips & Warnings
Inlays can be gold, white gold, etc. The shapes to pick from are usually dome, concave or flat-top, and there are several different styles.

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Tungsten is a hardy and brilliantly shiny metal that is popular for a variety of ring styles, including wedding rings and wide designer bands. Tungsten is so hard that it has to be cut and polished with the same types of tools that are used to cut and polish diamonds. Ordinary tools will not even dent this beautiful metal. One of the best things about tungsten is that it is nearly maintenance free and holds its brilliance and shine with little or no help from you.

Instructions

1
Buff away fingerprints using a soft, dry cloth. Tungsten retains its polish forever, so you will just need to smooth away oily fingerprints periodically using a soft, dry cloth.

2
Brush away scratches. If your tungsten ring appears scratched, do not worry. It is not. Tungsten is too hard to be susceptible to daily wear-and-tear like scratches. Instead, these "scratches" are small pieces of material that have become attached to the tungsten. You can remove them with warm water and gentle scrubbing with a soft toothbrush.

3
Add mild detergent to your cleaning arsenal. For extremely contrary "scratches," you can add a few drops of a mild detergent to a small bowl of warm water and use the toothbrush to scrub the ring in this solution. This will remove any difficult marks and scratches completely.

4
Dry the tungsten ring with a dry, soft cloth. If you allow the ring to air dry, you will end up with spots on your otherwise unmarred ring.

Tips & Warnings
If your tungsten ring has silver inlays, they will need to be polished with silver polish periodically.

Do not leave a tungsten ring in an ultrasonic cleaner for more than one minute. While the metal is quite resilient, tungsten rings are originally made from powdered metal and too much time in an ultrasonic cleaner can cause them to deteriorate.

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Tungsten carbide is a very hard material made from tungsten and carbon. It is commonly used for the tips of tools, especially cutting tools. While this material is very hard, it does become worn over time and may require grinding or sharpening. Carbide tools and tips can be ground with a diamond grinding wheel, but grinding a tool evenly requires skill and practice.

Instructions

1
Attach the diamond wheel to your bench grinder. Refer to your manual to ensure that the wheel is properly attached and the grinder itself is appropriately mounted.

2
Hold your tungsten carbide tool against the rest beneath the wheel. Touch the tip to the wheel, but do not turn on the grinder yet. Adjust the rest as needed so that you achieve the necessary grinding angle for your particular tool. Many rests will allow you to adjust both the height and the angle of the rest.

3
Remove the tool from the rest, then turn on the grinder. Touch the tip of the tool to the moving wheel, just as you did before when determining the angle, and use the rest to guide the angle of the grinding. Carbide may emit short red sparks during grinding. These are normal. The carbide tool may also become very hot. Work in short intervals and do not burn yourself, overheat the tool or touch the tool immediately after grinding. Continue grinding until the tool is sharpened.

Tips & Warnings
If you have a grinder with a jig rest that allows you to angle the tool prior to grinding and holds it while the machine is operating, this is the best option because there will be no human error during the grinding process.

Wear eye protection and a mask. Tungsten carbide is hard, but somewhat brittle and it is possible for small piece to fly off.

Tungsten carbide is made largely from carbon and tungsten, but it may contain other materials that are hazardous when inhaled. Wash off any dust after grinding carbide tools.

Some carbide tools are very small. You may require another tool to hold the carbide tool to the grinding wheel so that your fingers are not in danger.

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What is Tungsten?
Tungsten is an elementary metal which has found many uses in industry and our daily lives over the years. It's typically found in natural ores such as wolframite in mines all over the world. Tungsten is extremely heat resistant, having the highest melting point of all non-alloy metals in the world. This makes it perfect for jobs in high energy or high electricity environments. The filament in incandescent light bulbs are most commonly made from tungsten thanks to their ability to hold shape at such high temperatures. Though about as tough as steel when pure, when combined in a compound such as tungsten carbide, it's nearly indestructible. As a result it's used for drill heads in major mining and oil drilling as well as other high-stress work.

What are Tungsten Rings?
Tungsten rings are a decorative affectation which are becoming more popular with men throughout much of the world. Such rings are taking the place of class rings and wedding bands thanks to their durability. They should not be mistaken for being made from pure tungsten, as they're really tungsten carbide. This compound, once shined, will never dull, scratch, rust, or discolor. It's also completely hypo-allergenic. The reason for their popularity is as much an issue of symbolism as practicality. Gold wedding bands have a tendency to deform over time. One made from tungsten-carbide will not, giving the impression that the marriage union which the ring represents will endure as well.

How are Tungsten Rings Made?
Ground tungsten and carbon are poured into a metal die cube containing a ring mold. The mold is subjected to high pressure to push the powder together into a solid ring blank. The blank is then fired in an oxygen-powered furnace at temperatures exceeding 6,000 degrees Fahrenheit. Only at this obscenely high temperature will the blank's component elements intermingle and solidify as one. Once cooled, any burs or extra metal is removed with high-powered diamond edged saws. Diamond powdered files and sanders are then used to polish the ring until it shines. With this done the ring is ready to be worn. It should be noted that since such rings cannot be re-sized, each one must be constructed to order if it's to be a perfect fit.

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Nanoparticles of tungsten carbide and tungsten carbide cobalt can enter cultured mammalian cells. These are the findings of a study conducted by researchers from the University of Dresden, the Leipzig-based Helmholtz Centre for Environmental Research and the Fraunhofer Institute for Ceramic Technologies and Systems in Dresden.

The results further show that pure tungsten carbide nanoparticles do not have cytotoxic effects. Only when the nanoparticles are mixed with a toxic substance, metallic cobalt in this case, are cytotoxic effects observed. The in vitro study, which was published in the renowned journal Environmental Health Perspectives, examined the effect of tungsten carbide and tungsten carbide cobalt nanoparticles with an aggregate size of 150 nanometres on cell lines of human lung, skin and intestinal cells and of primary cultures of rat brain cells.

Tungsten carbide is used primarily in the heavy metal industry for the manufacture of tools. The addition of cobalt increases its toughness and strength. During the manufacture process workers may be exposured. But until now, no scientific findings on the effects of nano-sized particles of the material have been available. Before nano-grained materials are used on a large scale, the risks to humans and the environment need to be investigated and taken into account.

The chemical and physical studies confirmed that both tungsten carbide and tungsten carbide cobalt particles are stabilised by albumin or serum in nutrient solutions. Adding albumin to the nutrient solutions makes it possible to carry out research in conditions that are very close to those found in exposed organisms. Using electron microscope methods it was possible to detect uptake of the particles by the cells under investigation.

Subsequent biological tests showed that tungsten carbide nanoparticles alone are not acutely toxic, whereas combinations of these particles with cobalt did have toxic effects at high particle concentrations. The toxicity of the WC-Co mixture was higher than that of similar concentrations of cobalt ions. It is not yet entirely clear why the combination of tungsten carbide and cobalt is more toxic. It is possible that nanoparticles act as a Trojan horse, i.e. they increase the cell's uptake of toxic cobalt ions. Further research is needed to clarify the effect of particle size and combination effects in order to draw conclusions about possible consequences for health risk assessments.

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Background
Tungsten-filament bulbs, although the most widely used light source in the world, are inefficient, generating more heat than light. However, a new microscopic tungsten lattice developed at the Department of Energy’s Sandia National Laboratories has been shown to have the potential to redirect much of this wasted heat energy into visible light.

Increased Efficiency
This could raise the efficiency of an incandescent electric light bulb from 5% to greater than 60%. In doing so it would greatly reduce the world’s excess consumption of electrical power by inefficient lighting, and the accompanying environmental impact caused by CO2 emissions.

Fabrication of the New Lattices
The first step toward this goal, achieved at Sandia by Shawn Lin and Jim Fleming, was reported in Nature in May. The tungsten lattice device was built using an extension of well-known microelectro-mechanical systems technologies that themselves have been derived from mature semiconductor technologies. As a result, fabrication of such devices could be cheap and easy.

The tungsten structures, usually made out of silicon, consist of tiny bars fabricated to sit astride each other at regular pre-set distances and angles. Together, these form an artificial crystal. The spacing of the bars allows passage of only certain wavelengths of radiation they pass through but can also change direction as defects in the artificial crystal cause the light to follow the defect.

The Lattice’s Ability to Stop Other Frequencies
A further question considered by Lin and Fleming, with assistance from colleagues at Ames Laboratories in Iowa, was the tungsten lattice’s capability of ‘stopping’ other frequencies. If the crystals were built of tungsten, the metal could handle quite high temperatures and have a large and absolute photonic band gap in the visible range, where it is already known to emit light. But what would happen to the other, lower-wavelength radiation brought in by an electric current? Would the structure melt, or would the thermally excited tungsten atoms somehow prefer to reinforce emissions at higher wavelengths, such as in the visible frequency range?

Energy at the edge of the photonic band was observed to undergo an order-of-magnitude absorption increase energy was being preferentially absorbed into a selected frequency band. Meanwhile, periodic metal-air boundaries led to a large transmission enhancement. Experimental results show that a large photonic band gap for wavelengths from 8 to 20 microns proves ideally suited for suppressing broadband blackbody radiation in the infrared and has the potential to redirect thermal energy into the visible spectrum.

Results and Prospects
Lin and Fleming are delighted with the results, although the theory for the effect - re-partitioning energy between heat and visible light - remains unexplained. ‘It’s not theoretically predicted,’ says Fleming. ‘Possible explanations may involve variations in the speed of light as it propagates through such structures.’

Although the work was carried out with light in the mid-infrared range, no theoretical or practical difficulties are known to exist in downsizing the structure into the visible light range.

from www.azom.com

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