Has anyone tried to use Metal clay (artclay or pmc) with niobium?
I wantedto use the anodized niobium with the metal clay but wasn't
sure it the silver would fuse with the niobium.
It won't fuse, as the oxide layer on the niobium prevents metal to
metal contact, and thus fusion. You can join parts, though, by
shaping the niobium in such a way that the art clay is mechanically
locked to the niobium. For example, if you put a couple holes in the
niobium, and the art clay goes through those holes so it's on both
sides of the niobium, after firing, the two are essentially riveted
together.
Your bigger problem is that the heat of firing the art clay will
give you a very thick oxide layer on the niobium, such that any color
you'd put on the niobium would be destroyed. If you wanted a dark
grey to black niobium surface, this might be OK. If you don't then
you'd have to remove that oxide layer from the niobium, perhaps by
grinding, or with HF acid (very very dangerous to use, so not
recommended at all) I'm not sure whether Reactive Metals "Multi
etch" would be able to get through that type of thick oxide layer.
Sand blasting (with an abrasive harder than sand) might also work
fine. Anyway, once you're back to clean niobium with it's normal thin
oxide layer, you could then anodize it for color. But here too, there
are problems. The silver is highly conductive, and you'd have to
totally insulate the silver from the anodizing solution or the silver
will take current flow away from the niobium, preventing the niobium
from coloring properly, especially in the area right next to the
silver. You can get around this fairly easily by brush painting for
anodizing, rather than immersion anodizing, but even then, the
sections right adjacent to the silver may be difficult.
