I bought a 1kg tungsten cube
Top-quality paperweight.
Tungsten for radiation shielding use
41–50 of 65 posts
Re: Tungsten for radiation shielding use
#42Earlier quoted context omitted.
It's a timing thing - Australia used a "we built it ourselves" detector with shielding that rotated about the crystal pack to find that missing mining source that hit the news last month. The detector part (doped crystals + scintillation sensors) is fundamentally undirectional - those pesky gamma come in from any direction. One side has to be shielded to bias the reading (use Tungsten perhaps) .. and by rotating the…
>As alway, have a fiddle with a ground based setup first. now see, if we do that, then you're ruining the one chance I have of being the exact right person to go to space to fix the thing.
I feel obliged to mention coded apertures here too! https://en.m.wikipedia.org/wiki/Coded_aperture
Re: Tungsten for radiation shielding use
#43Tungsten has the highest melting point of any pure metal, I believe, as well as being close to the highest atomic number among the non-radioactive metals. It's also reasonably workable as a material, isn't terribly toxic, and has a reasonable availability and price. The other high-melting metals near it in the periodic table all fall down on one or more of those properties. Osmium, for instance, is rather expensive,…
I think it's worth highlighting just how horribly toxic osmium tetroxide is -- it's used as a stain for electron microscopy as it is dense and binds irreversibly to lipid membranes. Quoting from Wikipedia:
> In the staining of the plasma membrane, osmium(VIII) oxide binds phospholipid head regions, thus creating contrast with the neighbouring protoplasm (cytoplasm). Additionally, osmium(VIII) oxide is also used for fixing biological samples in conjunction with HgCl2. Its rapid killing abilities are used to quickly kill live specimens such as protozoa. OsO4 stabilizes many proteins by transforming them into gels without destroying structural features. Tissue proteins that are stabilized by OsO4 are not coagulated by alcohols during dehydration.
> OsO4 will irreversibly stain the human cornea, which can lead to blindness. The permissible exposure limit for osmium(VIII) oxide (8 hour time-weighted average) is 2 µg/m3. Osmium(VIII) oxide can penetrate plastics and food packaging, and therefore must be stored in glass under refrigeration.
Re: Tungsten for radiation shielding use
#44Tungsten has the highest melting point of any pure metal, I believe, as well as being close to the highest atomic number among the non-radioactive metals. It's also reasonably workable as a material, isn't terribly toxic, and has a reasonable availability and price. The other high-melting metals near it in the periodic table all fall down on one or more of those properties. Osmium, for instance, is rather expensive,…
I think it's worth highlighting just how horribly toxic osmium tetroxide is -- it's used as a stain for electron microscopy as it is dense and binds irreversibly to lipid membranes. Quoting from Wikipedia: > In the staining of the plasma membrane, osmium(VIII) oxide binds phospholipid head regions, thus creating contrast with the neighbouring protoplasm (cytoplasm). Additionally, osmium(VIII) oxide is also used for f…
Worse, osmium tetroxide is volatile and sublimes at room temperature. I was told by my lab instructor that it is said to smell sweet, but that if you ever inhale enough to be able to smell it, you will have already absorbed a lethal dose.
Re: Tungsten for radiation shielding use
#45Re: Tungsten for radiation shielding use
#46this sounds more entertaining for 3-d printing things that startle people by being staggeringly heavy rather than things that are actually useful it should be heavier than lead; lead is only 11.3 g/cc, tungsten is 19.3, 75% tungsten would be 14.5, but then the other 25% is petg with sp.gr. ≈ 1 so you should actually get a density of 14.7 but i struggle to imagine cases where using tungsten is a more cost-effective op…
If it's only 75% tungsten, I'm figuring it's a tungsten powder. I work with lead all the time but I would not fuck with lead dust. Lead sulfide would be much safer, although studies feeding it to rats did show elevated lead levels. That said, no metal dust is very nice. Solid lead might be safer than tungsten powder. Maybe you could make an iodinated polymer or use a barium cement.
my candidate list of high-density fillers from dernocua (sorry for markdown) is
- Osmium: [US$13000/kg][8], 22.65 g/cc, or possibly iridium at more than twice that price
- Tungsten: [US$30/kg][9], 19.3 g/cc
- Tungsten carbide? Not sure what it costs but its density is 15.6 g/cc.
- Lead scrap: 95¢/kg, 11.3 g/cc
- Steel scrap: [21¢/kg][10], 7.9 g/cc
- Magnetite: [10¢/kg][11] [or so][12], 5.2 g/cc
- Quartz (as construction sand): 3¢/kg, 2.6 g/cc
- Water: [.06¢/kg][22] or so, 1 g/cc
[8]: https://www.metalary.com/osmium-price/ [9]: https://www.metalary.com/tungsten-price/ [10]: https://www.usgs.gov/centers/nmic/iron-and-steel-scrap-stati... [11]: https://www.usgs.gov/centers/nmic/iron-ore-statistics-and-in... [12]: https://stockhead.com.au/resources/barry-fitzgerald-why-magn... [22]: http://www.scientificamerican.com/article/israel-proves-the-...
this is my approximation of the pareto frontier; that is, each of the items on the list is conjectured to be cheaper than everything that's denser than it is, and denser than everything that's cheaper. corrections are welcome
i was thinking baryta (46¢/kg, 4.48 g/cc), mercury, litharge, minium, cinnabar, cupric oxide (US$3.90/kg, 6.315 g/cc), zinc oxide (US$29/kg, 5.6 g/cc), and manganese dioxide (5.026 g/cc) might be interesting in this context too
i hadn't thought of your suggestion of galena (just cinnabar) and generally i'm skeptical of metal sulfides because of their tendency to produce hydrogen sulfide; i don't think that's an issue with those two. litharge, minium, and mercury are a lot more worrisome toxicologically
i don't have solid pricing information for mercury, litharge, minium, cinnabar, or galena, and i'd be interested
tungsten is probably more chemically inert for medical purposes than a lot of these
Re: Tungsten for radiation shielding use
#47Earlier quoted context omitted.
lead isn't a hard material, and if you need a hard material, this filament isn't what you're looking for either; it will be almost as fragile as pure petg
I didn't say it was hard. I said machining tungsten is hard. Machining lead is also difficult and weird and the end result can be barely usable for anything, especially in hot environments or with any load. It's just not good. If you need complex parts, this could be an excellent choice. Idk what the confusion here is. Maybe you are unfamiliar with machining?
well i'm certainly no master machinist, heh
you seemed to be saying that this filament might be a better alternative to lead sometimes, but i couldn't tell when that might be. pure tungsten is clearly a better choice sometimes, for example because it shields better than lead, is harder, is denser, and is more refractory, but none of those seems to be true of this filament
from your other comment at https://news.ycombinator.com/item?id=35206874 it looks like you're saying that, although this composite is inferior to lead in those ways, it's easier to print
Re: Tungsten for radiation shielding use
#48Earlier quoted context omitted.
I think it's worth highlighting just how horribly toxic osmium tetroxide is -- it's used as a stain for electron microscopy as it is dense and binds irreversibly to lipid membranes. Quoting from Wikipedia: > In the staining of the plasma membrane, osmium(VIII) oxide binds phospholipid head regions, thus creating contrast with the neighbouring protoplasm (cytoplasm). Additionally, osmium(VIII) oxide is also used for f…
Worse, osmium tetroxide is volatile and sublimes at room temperature. I was told by my lab instructor that it is said to smell sweet, but that if you ever inhale enough to be able to smell it, you will have already absorbed a lethal dose.
lots of historical chemists smelled osmium and survived; that's how it got its name
Re: Tungsten for radiation shielding use
#49Interesting! I'm designing the flight computer/electronics of a 2U cubesat for academia, and something like this might work really well for our application. We were considering borated polyethylene but the cost for that is prohibitive. This is perhaps not as efficient in terms of mass-to-protection ratio, but we have plenty more room in our mass budget instead of actual budget. I also like the idea that we may be abl…
for a cubesat saving a few bucks on machining probably isn't a good tradeoff
Re: Tungsten for radiation shielding use
#50This material has radiation shielding properties far worse than just lead - lead which is cheaper and easier to manufacture Pure tungsten on the other hand is very good and can even shield beta particles
Yeah but it's lead! Lead isn't a very friendly thing to just have around.
paint it, sheesh