What is Tungsten: Definition and 52 Discussions

Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include tungsten, scheelite, and wolframite, the last lending the element its alternate name.
The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements discovered, melting at 3,422 °C (6,192 °F; 3,695 K) (carbon sublimes rather than melts at atmospheric pressure). It also has the highest boiling point, at 5,930 °C (10,710 °F; 6,200 K). Its density is 19.25 grams per cubic centimetre, comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw.Tungsten occurs in many alloys, which have numerous applications, including incandescent light bulb filaments, X-ray tubes, electrodes in gas tungsten arc welding, superalloys, and radiation shielding. Tungsten's hardness and high density make it suitable for military applications in penetrating projectiles. Tungsten compounds are often used as industrial catalysts.
Tungsten is the only metal in the third transition series that is known to occur in biomolecules, being found in a few species of bacteria and archaea. However, tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to most forms of animal life.

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  1. I

    I Doubling Ionization of Tungsten: Effects on Energy?

    Lets say that i have i mole of tungsten atoms. They are all ionized, only one electron is removed from each atom. If i accelerate this mole of tungsten atoms through one electron volt, i would get 96.48 kj. If the mole of tungsten was doubly ionized, two electrons removed from each atom, and...
  2. Slimy0233

    I Heating a tungsten filament to find out the maximum brightness emitted

    I was taking notes from a lecture on Quantum Physics and during the introduction, they gave an example of what led to the discovery of Quantum Physics: The electric bulb example where the brightness and colour of light depended on the temperature of the filament(see...
  3. Skyland

    Tungsten Battery Anode: Charge & Experiments

    Does anyone know if a tungsten-/copper+ saltwater battery have any significant charge if any? Willing to experiment myself, but don't want to waste money without asking first
  4. Mackenzie Cobb

    Why isn't tungsten used in nuclear reactors?

    Me again, with another potentially ignorant nuclear science question: Why isn't tungsten used to prevent meltdown in nuclear reactors? If tungsten has a higher melting point of tungsten is almost 6200 degrees Fahrenheit, and nuclear meltdown happens when the uranium fuel is some 5200 degrees...
  5. Y

    I Effective electron mass of tungsten

    Hello! Please tell me what Effective electron mass of tungsten and Effective hole mass of tungsten?
  6. ephphatha16

    Resistance of a tungsten filament bulb at 20 C

    I was looking for any credible sources who could reveal the resistance of a normal tungsten filament bulb at room temp 20 C? I heard its cold resistance is about 9.5ohms. Is that the resistance at rtp? Thanks a lot in advance!
  7. S

    I Is there no stable isotope of Tungsten?

    I was looking at this neat graph of all the isotopes and which ones are stable and how they decay: https://upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Table_isotopes_en.svg/715px-Table_isotopes_en.svg.png The black squares represent stable isotopes, and columns that have no such black...
  8. S

    I Structural differences between W, WC, and W2C?

    In my research group, I'm tasked with determining the purity of a tungsten sample sent from a supplier. Using FIB, we cut a 20 by 20 by 20 micron well into the sample and tested a wall of the well about 10 microns down from the surface. After taking a spectrogram, there seemed to be a large...
  9. K

    Tungsten Permittivity: Properties & Values

    Good evening, So... I am looking for the Tungsten permettivity and i don't find this feature... I have searched on Wikipedia, some material data but i don't find... Do you know what is the Tungsten permettivity? Thanks.
  10. T

    What is the Rate of Tungsten Evaporation in a Light Bulb?

    Homework Statement Ina light bulb, billions of electrons flow through the tungsten wire bumping around, causing the filament to glow hot. Hot tungsten evaporates slowly, so its initial thickness profile r(x, t=0) can change over time. Consider a volume V of tungsten, with N bonds total, each...
  11. marcophys

    HT 'low current' resistance fundamentals in Tungsten Welder - event horizon

    Does anybody understand the fundamentals of what is happening in this circuit? Tungsten welding info is all about high current... but this is a low current scenario. AC input, CDI Coil generated 20Kv (estimated) suffers voltage drop over 100mm of tungsten rod. The larger the diameter... the...
  12. S

    Tungsten x-ray target replaced by molybdenum.

    In an Xray tube containing tungsten target , 50kV voltage is applied. Calculate the minimum wavelength of xray emitted. If the target is replaced by molybdenum will the min. wavelength change. Justify your answer? I used λ min= hc/eV= 2.481×10^ (-11) m for the 1st part. For the 2nd part I am...
  13. A

    Glass crack on Aluminum and Copper tungsten

    Homework Statement Here is the issue I met.Could you refer to attached file? 1.We glued one piece aluminum block and one piece copper tungsten block on substrate. The aluminum and copper tungsten block have different height.The glue thickness underneath them is different...
  14. J

    High pressure tungsten incandescent light bulbs?

    With increased pressure tungsten has a higher melting point. (source below page 30) 45kBar increases melting point from 3422oC to 3700oC. http://www.nist.gov/data/PDFfiles/jpcrd55.pdf An ideal 5800 K black-body, truncated would be 37% efficient...
  15. M

    Tungsten Wire Resistance Test | 12Vdc | Fluke Clamp Meter

    Hi guys I have been playing around with a piece of tungsten wire by supplying it with 12Vdc and measuring the current draw to see how much the resistance changes when the wire is glowing hot. while doing this i am not getting any change in the resistance, the wire has the same resistance when...
  16. J

    Electroplating from tungsten via phosphate salt?

    At the bottom of page 54 of Tungsten: Properties, Chemistry, Technology of the Elements, Alloys, and Chemical Compounds by Lassner and Schubert: I'm presuming the reaction goes something like 2H_{3}PO_{4} + 2W → 3H_{2} + 2WPO_{4} Since I'm pretty sure copper phosphate works just fine for...
  17. A

    Young's modulus value of Ferrous Tungsten

    How can I get Young's modulus value of Ferrous Tungsten? Is it possible to get it from Young's modulus value of Ferrous and Young's modulus value of Tungsten?
  18. A

    Finding Young's Modulus of Ferrous Tungsten

    Homework Statement I want to know the Young's Modulus of Ferrous Tungsten. Homework Equations Is it possible to get the Young's modulus of ferrous Tungsten from Young's modulus of ferrous and Young's modulus of Tungsten? The Attempt at a Solution
  19. S

    Emissivity of Tungsten Carbide

    Hi, For the purpose of my FYP I am carrying out temperature analysis on a single point cutting tool while machining on a lathe. I am using a handheld infrared camera to determine this. In order to carry this out accurately the emissivity of the material must be inputted to the device as a...
  20. D

    How to find emissivity of tungsten from ln graph?

    Homework Statement I'm doing a lab where I'm trying to find the emissivity of a tungsten filament. I measured voltage and current of a bulb with a tungsten filament and found the power. Then I plotted Power vs Temperature^4 and used the slope along with surface area and Boltzman's constant...
  21. K

    Improving the density of tungsten

    hey all. i am making a sample of bulk tungsten. but i am getting only about 84% denstiy... can anyone suggest a mathod of improving it? i do not want to change my sintering process so the method should be after i get the bulk... so... anyone can suggest a process to go from 84% bulk...
  22. E

    Tungsten vs Lead for Gamma Radiation Protection

    Hey guys, I'm quite a noob in physics. Okay, here's my idea: We use lead to protect us from gamma radiation because it's dense enough to somewhat absorb the tiny wavelenght. As I take it, tungsten is more dense than lead, right? Wouldn't it be safer to use tungsten instead of lead? (Looking...
  23. P

    Spectrum of 6V 15W Tungsten Microscope Lamp

    Dear All I am trying to measure the spectrum of an incandesant 6V 15W tungsten microscope lamp. I have a reasonably old scanning monochromator (diffraction grating based) coupled to a fibre optic cable and it has given me the spectrum...
  24. K

    What are the chemical reaction happen indise lamp in tungsten

    Also the chemical involve in the W and iodine. Thx
  25. V

    What is the Diameter of a Tungsten Wire with a Weight of 1.72 mg?

    Homework Statement If we know, that 200 mm of tungsten wire weight`s 1.72 mg, then what is the diameter of this wire Homework Equations The Attempt at a Solution I by my self came to the conclusion, that the answer is 0.13 mm. But if I take in accordance, that my Algebra and...
  26. J

    Tungsten coated molybdenum powder

    Hello Everybody, I would greatly appreciated your help. I have been working this problems for the past couple hours and can't seem to find the answer. I tried Google, and opening up my old textbooks but to no avail. I could really use some help. I have sample of tungsten coated...
  27. A

    Control Of Joule Heating Effect In Tungsten Wire.

    How can I accurately control the Joule Heating effect of a length of Tungsten wire to certain temperature ranges? The tolerance would have to be no more than a maximum of +/- 2°C. Would I require alternating or direct current and/or any other associated instrumentation? I have little or...
  28. A

    How do I find the pressure capacity of a tungsten tube?

    I am looking to find the maximum psi or atm capacity of a tungsten tube of 99.9% tungsten. How would I do this?
  29. A

    What is the maximum pressure that a %99.9 pure tungsten tube can withstand?

    I have been looking all over the web and can find nothing...How do I calculate this? Please help if you can..thankyou
  30. S

    Positive & Negative charge of Tungsten

    Homework Statement How much positive and negative charge are in a 50g Tungsten ring? Homework Equations Standard atomic weight 183.84 The Attempt at a Solution
  31. T

    A K shell electron is ejected from a tungsten atom

    Homework Statement A K shell electron is ejected from a tungsten atom. The result of this is the emission of a characteristic x-ray proton. (The binding energy of the K shell in tungsten is 69.5keV. The binding energy of the L shell in a tungsten atoms is 10.5 keV). a) If the vacancy in the K...
  32. R

    Heat conduction coefficient in tungsten

    Homework Statement Hello! I am supposed to explain the behaviour of the thermal conductivity of tungsten. I have plotted the relation http://img340.imageshack.us/img340/9776/heatcond.jpg is also experimental data Temp[0 10 50 100 300 500 1000 2000 3400] and thermal conductivity...
  33. B

    What happens if tungsten is used in domestic wiring?

    Hi ! Small doubts which need to be clarified. 1)What happens if tungsten is used in domestic wiring? 2)Fan has a regulator that is used to control and vary its rotational speed. Would it be possible to minimize the consumption of electricity by setting the regulator to the lowest speed?
  34. N

    Finding Length and Area of Tungsten Wire Resistor

    Homework Statement the actual question is the resitivity of tungsten metal is 4.9x10to the power of -6 Ωcm. choose appropriate values for length and cross-sectional area for a home made wire resistor of resitstance 20Ω Homework Equations r=pl/a r-resistance a-cross sectional area in...
  35. P

    Tungsten Filament bending and production

    Tungsten Filament bending and production! my machine produces filaments for a UV lightbulb, the filaments are basically tungsten coiled tightly around a tungsten shank, and the machine used to do this perfectly! however it was switched off for a about a year during development. but now when...
  36. I

    Plotting a Suitable Graph to find Emissivity of Tungsten Filament

    Plotting a suitable graph to find emissivity of tungsten It is given that: Q = pσ2πal(T^4 - t^4) Where Q is the Energy Loss Rate, p is Emissivity and T,t are the wire and room temperature. Other symbols are constant. I have data for Q and (T^4- t^4), which for simplification purposes...
  37. C

    Using DC Power to Create Electron Flow in a Tungsten Filament Light Bulb

    If i have a light bulb , and it has a tungsten filament and when i turn it on its gets hot , If i hook a lead to the filament and then put the anode away from the filament can i get electrons to flow through the vacuum , assuming this is done with DC current. If we used 2 different...
  38. E

    Diamond Coating of Tungsten Carbide

    Does anyone have any expertise in the coating of WC tools? Are these tools coated by a deposition process (ex. CVD)?
  39. D

    Tungsten Disulfide Deposition

    I'm looking into using Tungsten disulfide as a lubricant in the form of a thin metal coating. Now I've been made to understand that it can be applied by various methods i.e burnishing, impingement and pulse laser deposited. From what I gather the method of applying this solid lubricant...
  40. S

    Why is a Tungsten filament used in incandescent bulbs? (Factual Question)

    Homework Statement Why is a tungsten filament used in incandescent bulbs? I earlier thought that it was due to the high resistivity of tungsten , but i was wrong , the resistivity of tungsten is low at 5.2 * 10^-8 Is it due to its high melting point?? I can't figure out as...
  41. M

    The science of flying molten tungsten

    Hi, a friend of mine - a college physics professor, and me, have had a discussion about an experience he had in his early school days, and we haven't been able to prove or dissprove what he thinks he saw. During an incandescent light burn-out (12V bulb on 220V =), he thinks he might have...
  42. S

    0.5V across 1.5m tungsten wire w/cross-sect. area 0.6 mm^2 - Find wire current

    Homework Statement 0.5 volts is maintained across a 1.5 meter tungsten wire that has a cross-sectional area of 0.6 mm2. What is the current in the wire? Homework Equations Resistivity of tungsten: 5.6E-8 ohm meters. Current Density: J = \sigma \cdot \frac{V}{l}, J = \frac{I}{A}...
  43. R

    Resistivity of tungsten filament

    ]1. A 1.3 cm length of tungsten filament in a small lightbulb has a resistance of 0.032 ohms. Find its diameter. Given: Length= 1.3 cm= .013m R= 0.032 ohms resistivity= 5.6e-8 ohms*meter [b]2. A= pi (r^2) R= resistivity (Length/ Area) The Attempt at a Solution R= resistivity...
  44. R

    Resistivity of tungsten filament

    [b]1. A 1.3 cm length of tungsten filament in a small lightbulb has a resistance of 0.032 ohms. Find its diameter. Given: Length= 1.3 cm= .013m R= 0.032 ohms resistivity= 5.6e-8 ohms*meter [b]2. A= pi (r^2) R= resistivity (Length/ Area) The Attempt at a Solution R=...
  45. T

    What is Tungsten Zirconium Nitrate and its Potential Applications?

    Does anyone know of a combination type metal called tungsten zirconium nitrate or how to make it or the formula or msds thanks- The000agent
  46. S

    Tungsten Filament Emissivity Assistance requested

    Hello, I have a Tungsten filament radiance source that has been calibrated in the UV region and would like to extrapolate the radiance to longer wavelengths. By calibrated, I mean, a NIST plot of spectral radiance v. wavelength at a certain set of operating conditions. I'm new to this...
  47. L

    Tungsten filament-finding length of coil

    Homework Statement Tungsten wire has an emissivity of 0.35. A tungsten filament in a light bulb can be considered to emit light only from the sides of the filament (consider it a cylinder... they are usually wire "cylinders" wrapped into coils.). If the operating temperature of the filament...
  48. M

    Calculating Energy Difference for K Characteristic X-Ray Line of Tungsten

    Homework Statement The K characteristic X-ray line for tungsten has a wavelength of 1.94 10-11 m. What is the difference in energy between the two energy levels that give rise to this line? Express this in each of the following units. (a) joules J (b) electron volts eV Homework...
  49. T

    Depleted Uranium vs tungsten

    So one of the big advantages to using depleted uranium (DU) rather than tungsten in anti-tank rounds is because a DU projectile will self sharpen upon impact whereas a tungsten projectile will flatten or "pancake". http://deploymentlink.osd.mil/du_library/how.shtml What is it about DU that...
  50. M

    Solving a Tungsten Filament Temperature Problem

    Hello everyone I'm stuck on this problem it says: A common flashlight bulb is rated at 0.30 A and 2.9 V (the values of the current and voltage under operating conditions). If the resistance of the bulb filament at room temperature (20°C) is 1.4 , what is the temperature of the filament when the...
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