Sciencemadness Discussion Board

casting strontium metal dendritic form?

beergod - 14-5-2011 at 00:39

So there are some pretty good deals on strontium metal online. Im interested in using it to generate hydrogen in a kipps type generator of my own design. I want to melt it down and cast it into specific shapes (I know how dangerous it is - no published autoignition temp tho?). The thing is the cheap stuff comes in a "dendretic form", if I were to melt it down and cool it quickly in the mold it should form a pretty homogeneous solid right? Because from what I understand calcium metal often comes in the dendritic form as well as a clean solid. Or is this due to the different processes used to isolate the element (electrolytic vs distilling workup)?

[Edited on 14-5-2011 by beergod]

watson.fawkes - 14-5-2011 at 05:43

Quote: Originally posted by beergod  
if I were to melt it down and cool it quickly in the mold it should form a pretty homogeneous solid right?
To get homogeneity in cast metals, you want to cool slowly. This is in no way specific to strontium.

beergod - 14-5-2011 at 13:24

That seems to be counterintuitive if the metal "crystalizes" into the stringy dendritic form. In my experience the longer something takes to cool while crystalizing the bigger the crystal lattice... The form im talking about is here:



Im assuming at this point that this form comes from an industrial process that ends with subliming/distilling, which is why it looks stringy. If it was made electrolytically or recasted it should assume a solid homogeneous form.


a_bab - 16-5-2011 at 21:02

Beergood is right; industrial grade Sr you can find on the Net in the dendritic form comes from the distilation of Sr oxide with Mg or Al.

Melting it to a button should be really easy, but a closed heat resistant vesel is needed. I'd use a cast iron pipe, with a screw cap, and I'd add some flux too (andhydrous Sr chloride maybe?)