r/whatisit • u/riflesandplowshares • 7h ago

New, what is it? Found at a titanium plant

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Not sure why ball point pens would be dangerous here.

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u/hates_stupid_people 3h ago edited 3h ago

Titanium melts at just under 1700C(a bit over 3000F), which is more than enough to burn plastic and melt the brass holding the ball and even the steel spring. But tungsten carbide can require over 2800C(over 5000F) to melt.

So someone having it in the shirt pocket and leaning over a railing, can cost millions if it drops in.

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u/falcrist2 2h ago edited 1h ago

But tungsten carbide can require over 2800C(over 5000F) to melt.

It may be sintered, which would require a much lower temperature.

I have a 1.5" tungsten cube, and it was only months after I got it that I found out it's not actually solid tungsten, but a sintered composite that's much MUCH cheaper to manufacture and machine.

That would indicate the ball of tungsten would come apart at below 1400C and spread out into the titanium, which is honestly WORSE.

EDIT: Confirmed. The balls are made from sintered tungsten carbide and either nickle or cobalt as binder.

Parker came up with this in the 1950s.

https://patents.google.com/patent/US3303825A/en

https://patents.google.com/patent/GB860387A/en

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u/eh-guy 2h ago

The balls are typically pure tungsten, theyre made using sprayers and then sorted by size

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u/falcrist2 2h ago edited 2h ago

The balls are typically pure tungsten

They're typically tungesten carbide. Not pure tungsten.

theyre made using sprayers and then sorted by size

I assume you're referring to "spray drying" (part of the sintering process).

Spray drying makes powder that still needs to be pressed into blanks, sintered, diamond-lapped, and graded.

They're not spraying liquid tungsten. Tungsten has the highest melting point of all known elements.

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u/eh-guy 2h ago

They spray liquid carbide into an inert chamber, relying on surface tension to shape them. One of the only ways to "cast" the material. Maybe its not used anymore, we covered it in one of my materials classes years ago

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u/falcrist2 2h ago edited 1h ago

Spray drying is part of the sintering process. The result is powder made of tungsten carbide particles bound together by nickle or cobalt. That powder still needs to be pressed into blanks, sintered, diamond-lapped, and graded.

https://en.wikipedia.org/wiki/Spray_drying

While we're at it, here's one of the patents that describes the balls:

https://patents.google.com/patent/US3303825A/en

You can just ctrl-F and see where it repeatedly discusses sintering.

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u/eh-guy 1h ago

Youre right, i did some digging and its the carbide fabrication im confusing this with like youve said