Jiangxi Zhongyu Mstar Technology Ltd said that iron is absolutely impossible, because NaOH will melt and exposed to the air it will be severe corrosion, because of its strong reducibility in NaOH molten iron rust, so once the melt will immediately see Fe2O3 yellow (here is the iron NaOH H reduction in it with the O2 reaction in the air (NaOH), will enter the part of O2) and Fe2O3 (NaFeO2) dissolved in NaOH lead to iron to rust, in fact even the Pt crucible is not exposed in the air can not resist NaOH strong corrosion (data writing), I also do the steel stainless steel utensils had been rusting in a complete mess;

Ceramic crucible will be better, its components are mainly A2lO3, MgO, SiO2, in fact is composed of a double salt and difficult with NaOH or KOH react. But it also has disadvantages due to the NaOH strong ionic interaction when the high temperature and baking time is too long will the crucible dissolved in NaOH and lead to melt a higher melting point, the most powerful even melt through (I do the experiment had).

In conclusion or ceramic crucible best just to controlling the reaction temperature and reaction time, compared with the cost of iron crucible is much larger, and is disposable is vulnerable to pollution of the reactants.