Dear friends,
I want to sinter a pellet of NiMnSn alloy in vacuum furnace at 900 degree centigrade temperature under high vacuum for 8 hours. Since we do not have vacuum sintering furnace therefore there is high risk of oxidation of the sample during sintering. To avoid oxidation of sample during sintering, I am planning to wrap the pellet in a copper foil and then do sintering in normal furnace without vacuum. Will this wrapping prevent oxidation?
Kindly give your valuable suggestions. Other ideas are also welcomed.
You will probably have problems with diffusion of Cu to your pellet or Ni, Mn,Sn diffusion to Cu, which might lead to composition change and local melting.
Sinter in the presence of some inert gas like argon. Better than sintering in air.
Definitely you need high vacuum in this case. No inert gas will help you if you do not go to the high vacuum. First Tin will oxidize and you will end up with individual or mixed oxide phase rather than an alloy. At the end you will get some colored powder. So better not try and waste the samples and resources rather change the problem.
A suggestion; you can sinter in a mixture of hydrogen and argon or hydrogen and nitrogen.The mixtures with less than 3.9% are not dangerous. By this way you will prevent oxidation.
keep the sample in a quartz tube and vacuum seal it . that may solve the problem of oxidation.
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