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Industry Applications of Tungsten Polymer

Category: Tungsten Information
Published on 17 July 2015

tungsten polymer is composed of tungsten powder and one of a number of standard plastic base resins, which are selected according to the application. These base resin systems include polysulfones (PSU), co-polyamides, polyamides (PA), polymethylpentenes (PMP), polyurethanes (TPU), acryloynitrile butadiene styrene (ABS), polyethylenes (PE) and polyetheretherketones (PEEK). It has a high molecular polymer composited material having a density up to 11 g/cc (equivalent to lead). It is composed of the following components by weight ratio: a high molecular polymer 20-100, tungsten powder 950-1000, tungsten fiber 0-50, a coupling agent 0.5-5 and other aids 0.5-10.

Tungsten polymer has been found many applications in industries, including:

  • X-ray devices in manufacturing industries and medical x-ray machines;
  • Nuclear and medical industries, it is used as radiation shielding;
  • Radiation shielding and radiation-protective equipment;
  • Gamma ray shielding material and substitute for lead fiber mat in nuclear reactor piping systems;
  • It is also used in weight and balance applications as a counterweight for applications like motors, ballasts and more;
  • Used as a sound proofing material in aviation headphones;
  • Acts as a damper to reduce shock due to vibration in the automotive industry.

tungsten polymer

 

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Low-temperature Structural Properties of Calcium Tungstate and Calcium Molybdate-III

Category: Tungsten Information
Published on 16 July 2015
To address the problem of material characterisation we used computation techniques and recently it was demonstrated that quasi-harmonic lattice dynamics and the lattice energy minimisation technique are viable tools for the characterisation of lattice dynamics of calcium tungstate. The lattice dynamics simulations were performed using the software code GULP; the energy was constructed from empirical interaction potentials. The success of this approach stimulated our interest in the modelling of lattice dynamics of other materials, specifically CaMoO4. 
 
Thermodynamic properties and lattice dynamics of calcium molybdate have been investigated using self-consistent semi-classical simulations based on the quasiharmonic approximation and free energy minimisation. Comparing with the previously reported simulations of lattice dynamics in CaWO4 the model was improved by defining the intermolecular forces that are responsible for the interaction between complex anions MoO4 −2 . The validity of the models and simulations undertaken was verified where possible by comparing the number of calculated parameters of the crystal under investigation with those measured in experiments at HASYLAB and it was shown that there is reasonable agreement between them. Based on the improved model of interactions the thermal dependencies of isothermal bulk and shear elastic modules, heat capacity, entropy S, thermal expansion and Grüneisen parameter, as well as phonon density of states were calculated and analysed.


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Defect Types of Tungsten Contacts- I

Category: Tungsten Information
Published on 16 July 2015

Defect types of tungsten contacts described as follows:

1. Porous holes, pores
This defect type is common in powder metallurgy to prepare tungsten contacts. This may be because:
Uneven particle size of tungsten powder;
The gas content of tungsten powder is relatively large;
Insufficient pressure when mixing powder;
Insufficient infiltration, when you are sintering the porous tungsten skeleton.

2. Unevenly distributed organization
Reason: Because of the existence of added element, it makes the added element or poor oxide in grain boundaries aggregated.

3. Inclusions
Under normal circumstances, the presence of inclusions in the tungsten contacts may be due to: non-metallic inclusions mixed in them and other foreign metal inclusions mixed with.

4. Bubbles
Because there are small holes in tungsten ingot itself, and the phenomenon of inner oxide will appear when pressing, crushed holes will expand to form bubbles.

5. Delaminating cracks
Because tungsten ingot itself has already gathered micro cracks, during the oxidation process, because stress makes delaminating of the cracks.

 

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Low-temperature Structural Properties of Calcium Tungstate and Calcium Molybdate-II

Category: Tungsten Information
Published on 16 July 2015
At room temperature CaWO4 and CaMoO4 echibit scheelite structure, having a complex layer structure with the layers being perpendicular to the c-axis. Each layer has a two-dimensional CsCl type arrangement of a Ca cation and complex anion WO4 –2 or MoO4 –2, which are surrounded by eight ions of opposite charge. Our studies reveal a scheelite type of structure in the whole temperature region investigated (5 – 300 K for CaWO4 and 12 – 300 K for CaMoO4). No structural anomalies have been observed. 
 
The lattice parameters increase nonlinearly with temperature (see Figs. 1 and 2). There is a pronounced anisotropy of thermal expansion in CaWO4 and CaMoO4: the thermal expansion in the [100] direction is about 50 % of that in the [001] direction of the tetragonal cell. Thermal dependences of the lattice parameters obtained using synchrotron radiation agree well with the respective ones from elastic neutron scattering and links fairly well to the high-temperature data.




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Low-temperature Structural Properties of Calcium Tungstate and Calcium Molybdate-I

Category: Tungsten Information
Published on 16 July 2015
The use of a material as CPSD relies on the efficiency of the process of phonon transport through the crystal. Therefore, knowledge of lattice dynamics of the crystal is of great importance. So far there is lack of information on the above properties not only for the prospective materials, but even for well-known scintillation materials when low-temperature applications are considered. In order to resolve this problem this study turned our attention to modelling techniques and the precise determination of structural parameters at different temperatures.
 
The thermal behaviour of structure was studied using the high-resolution powder diffraction technique and synchrotron radiation. The experiments were carried out at the beamline B2 on high resolution powder diffractometer equipped with a closed-cycle helium cryostat. All measurements were performed in DebyeScherer geometry (0.3 mm capillaries) using the Image Plate detector OBI and X-ray wavelength of 0.4996 Å. The measurements were carried out in the temperature range 12 – 300 K. First, the sample was cooled from room temperature to 12 K and a set of diffraction patterns (37 for CaMoO4 and 16 for CaWO4) in the 2θ region 2 – 40o was collected during cooling. The temperature was then stabilised at 12 K and another set of powder diffraction patterns was collected in the temperature range 20 - 300 K with temperature increments of 20 K. The measured XRD data where analysed using the full profile Rietveld method implemented in the WinCSD program package. Additionally, neutron scattering experiments were performed at the D2b instrument (ILL) for calcium tungstate.


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History of Professional Darts CorporationⅡ

Category: Tungsten Information
Published on 16 July 2015

2007 saw the Professional Darts Corporation (also known as PDC) introduce the ground-breaking Grand Slam of Darts competition, which features 32 players who have reached the finals of major PDC and BDO tournaments competing in Wolverhampton.

The PDC also introduced the innovative internet-streamed Championship League Darts in 2008, while the PDC World Cup - a Pairs tournament featuring 24 countries - season-ending Players Championship Finals and The Masters events have also been added to the circuit of major televised events.

The PDC continues to go from strength to strength with its central aim to ensure the sport receives the recognition and respect professional darts deserves, with both the Qualifying School - where players can win Tour Cards to compete on the PDC circuit full-time - and the introduction of the PDC Unicorn Development Tour and World Youth Championship guaranteeing a pathway to the top for aspiring stars.

The PDC also work with affiliated organizations for a number of region circuits worldwide, notably the DPA in Australia, SDC in Scandinavia, and in North America, where each region stages a series of ranking events each year which produces qualifiers for the World Championship.

The expansion of the PDC across Europe led to the introduction in 2012 of the European Tour series of events, which has expanded to nine tournaments in 2015 being held in the UK, Germany, Austria, Gibraltar and the Netherlands which give leading professionals and emerging talents from across the Continent the chance to compete at the top level.

2013 saw the introduction of the World Series of Darts, which began with the Dubai Duty Free Darts Masters and Sydney Darts Masters and see the world's top eight players spreading the professional game worldwide, with events in 2015 being also staged in Yokohama, Perth and Auckland.
As for professional game of dart, we recommend tungsten dart, tungsten is an extremely dense metal. It is also very durable, so a high-density tungsten dart resists wear and the knurling will last much longer.

tungsten dart

 

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Ammonium Paratungstate Preparing Submicron Spherical Tungsten Powder Process

Category: Tungsten Information
Published on 16 July 2015

Ammonium paratungstate preparing submicron spherical tungsten powder process: Violet tungsten oxide is prepared with pure ammonium paratungstate in argon gas. Tungsten powder is obtained from violet tungsten oxide through deoxidation in hydrogen gas (rate of purity:99.99%, dew point: -40℃), and tungsten powder is oxidized in the air. Tungsten oxide is reduced to tungsten powder in hydrogen gas. The samples are characterized with the laser particle size distribution measuring instrument and the electron probe scan instrument.

The results show that submicron tungsten powder can be obtained through circulatory oxidation twice and reduction three times. The percentage of the particle size distribution of submicron spherical tungsten powder is 95.73% between 0.1um and 1.0um, and its BET is 1.082 m2/g.




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Scheelite and the Synthetics

Category: Tungsten Information
Published on 16 July 2015
Although it is now uncommon as a diamond imitation—much more convincing products, like cubic zirconia and moissanite have long since superseded it—synthetic scheelite is occasionally offered as natural scheelite, and collectors may thus be fooled into paying high prices for them. Gemologists distinguish natural scheelite from synthetic material mainly by microscopic examination: Natural material is very seldom without internal growth features and inclusions (imperfections), while synthetic material is usually very clean. Distinctly artificial curved striae and clouds of minute gas bubbles may also be observed in synthetic scheelite.
 
The visible absorption spectrum of scheelite, as seen by a hand-held (direct vision) spectroscope, may also be of use: Most natural stones show a number of faint absorption lines in the yellow region of the spectrum (~585 nm) due to praseodymium and neodymium trace impurities. Conversely, synthetic scheelite is often without such a spectrum. Some synthetics may however be doped with neodymium or other rare earth elements, but the spectrum produced is unlike that of natural stones.


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Phosphotungstic Acid Producing

Category: Tungsten Information
Published on 16 July 2015

There are many ways for producing phosphotungstic acid has, such as making sodium tungstate (NaWO4 • 2H2O) and phosphoric acid to react while adding hydrochloric acid during the reaction and then obtained by ether extraction.
The producing processes of phosphotungstic acid are as follows:
1. Making 1000g sodium tungstate and 16g of diammonium phosphate dissolved in boiling water 1500ml, with constant stirring, 800ml concentrated hydrochloric acid was added dropwise in it.
2.When adding half of concentrated hydrochloric acid there has some phosphotungstic acid began with isolated, wait until the solution was cooled, added without reducing agent ether about 600ml, shaking until it was divided into three layers.
3. Then through the dust-free air into ether layer, so that it can evaporation and crystallization.
4. After filter, let crystals spread evenly in the air, but never contact with dust, until they no longer have the smell of ether.

 

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How to Keep Score in Tungsten Dart Game

Category: Tungsten Information
Published on 16 July 2015

In the tungsten dart game, the scoreboard starts as a blank sheet of paper which is usually hung on the wall about 50 cm or 1.5 feet to the left of the dartboard and at about the same height as the dartboard itself. The sequence below shows how a game is scored and how the scorecard takes form. The score shown in red is the last score thrown.

tungsten dart score

tungsten dart score

 

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