JJay - 31-3-2016 at 21:25
I have some alumina boats that I bought for my tube furnace, and they are a fraction of a millimeter too big to fit into my quartz tube. I'd like to
grind them down so they will fit and have a little room to expand, and I'm not sure what could grind alumina other than a diamond grinding wheel. Is
that my only option, or are there other grinding wheels that can grind alumina?
NedsHead - 31-3-2016 at 23:25
Silicon carbide (green wheel) should be able to do it, I use one to grind tungsten carbide lathe tools, it's harder than an aluminium oxide wheel but
softer than diamond, I would guess it can cut through alumina
JJay - 1-4-2016 at 00:02
I wonder if I have any silicon carbide dremel wheels around here anywhere....
Sulaiman - 1-4-2016 at 02:09
I just did a quick calculation;
for 1000C temperature rise the difference in linear thermal expansion between quartz and alumina is 0.7%
i.e. for a 50mm int. dia tube an extra 0.35 mm grinding compared to a sliding fit 
I think that principle is correct, the calculations may not be, check.