Nbc12Ni cermet mixed in ethanol for 24hr uniaxially pressed to 3ton then cip pressed to 300mpa.sintered in a tube furnace with flowing ar atmosphere to1430c with a heating rate of 10c/min and 1hour dwell time and slowly cooled. The pellet deformed with some greenishbrown layer(i think its NiO the nickel oxidized?) on the exposed surface. Placed on an alumina holder in alumina tube. Pictures attached for reference. Would be kind if you can shed somelight on where it went wrong or how can i improve final sintered pellet to near net shape.
Should i increase argon flow rate? And slowdown heating rate to 5c/min after 1200 till 1430.?Sample inside the dish is unsintered pressed compact.
lamination of the pellet at its exposure surface could be due to the oxidation. I recommend you wholly wrapping your sample at the furnace. Another factor affecting the lamination of the pellet is the compaction pressure which loose its effects at final stages of compaction because of the work hardening and/or oxidation of the particles near the surface area. You might also do the compaction process in a glove box under a neutral gas. Good luck
@Thomas breuer Sir for ferrites open atmosphere calcination is the preffered way but for carbide binded with LPS atm reactions are to be avoided. I mixed the powders in ethanol in ball mill them vaccum dried the powders @45celcius for 4 hours. I vaccumed the tubefurnace chamber for 10mins and purged the chamber with high flowing argon for 10 mins and sintered the pellet in flowing argon medium and sintered another pellet the results are attached. The surface is still scarred/burned idk why. You can see the scratched surface aswell.
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