Molybdenum Inner Grid

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Yoji Watanabe
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Molybdenum Inner Grid

Post by Yoji Watanabe »

It seems like the majority of inner grids are made of either Nichrome or Tungsten. Is there a reason fusioneers don't use Molybdenum?
It has a higher melting point than Nichrome and is more malleable than Tungsten, making it a much easier material to work with.
Molybdenum also seems quite easy to acquire, am I missing something?
Dan Knapp
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Re: Molybdenum Inner Grid

Post by Dan Knapp »

Molybdenum has been used extensively in published IEC work, particularly by groups in Japan. They tend to make the grids from rings cut from thin sheet material. Amateur fusor builders would generally not have the capability to cut such rings.
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Richard Hull
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Re: Molybdenum Inner Grid

Post by Richard Hull »

I and others have used, niobium, tantalum, tungsten, molybdenum, titanium and SS. Nichrome is rather rare to be used here. Most who have melted a grid or grids in the past just go for tungsten as their end game grid material.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Dan Knapp
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Re: Molybdenum Inner Grid

Post by Dan Knapp »

If you decide to go with molybdenum, a good source for small quantities of molybdenum wire is: http://electrontubestore.com/.
They also have stainless, tungsten, tungsten-rhenium, titanium, and tantalum wire in different sizes. Their tungsten wire is annealed, so it is easy to bend.
Another source for even smaller quantities (tubes of ten 10 cm. lengths; about $10/tube) of annealed tungsten wire is the needle cleaning wires from the Hamilton microliter syringe company. They are available in several diameters, and are sold on Amazon.com. These lengths are adequate for spheres up to about 3 cm diameter.
Last edited by Dan Knapp on Sun Nov 08, 2015 5:57 pm, edited 1 time in total.
Yoji Watanabe
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Re: Molybdenum Inner Grid

Post by Yoji Watanabe »

Dan Knapp wrote:Molybdenum has been used extensively in published IEC work, particularly by groups in Japan. They tend to make the grids from rings cut from thin sheet material. Amateur fusor builders would generally not have the capability to cut such rings.
Is there a reason that it is cut from Mo sheets instead of simply bending wire? Perhaps it has to do with malleability?

Richard, Tungsten is definitely what I am looking to use in the future. However, I am testing a solder-less design for the inner grid and would like to test it with other materials before dedicating the time to making a tungsten grid. Is there a reason why NiCr is rarely used? Thanks!
Dan Knapp
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Re: Molybdenum Inner Grid

Post by Dan Knapp »

They use thin sheet to maximize transparency (with radial edges) while maintaining structural strength.
Silviu Tamasdan
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Re: Molybdenum Inner Grid

Post by Silviu Tamasdan »

The least expensive source of tungsten and molybdenum I have found is www.tungsten.com, particularly their "orphan bin" http://www.tungsten.com/orphan-bin/
There _is_ madness to my method.
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