In powder metallurgy stearates are added while mixing of powders in order to facilitate compaction. Further these stearates are removed during dewaxing.
If zinc stearate is added as a lubricant during mixing of iron powder or other metallic based composites, does zinc stearate evaporates during sintering or remains there in the compacts.
Zinc can be harmful to sintering if it does not evaporate to 100%. For this reason, it would be better to use metal-free waxes and paraffins instead of zinc stearate.
Dear Vadim,
Thanks for the reply.
In our case, we used zinc stearate as a lubricant mixed with the powders before compaction. Sintering was done in an Industry where dewaxing was done followed by sintering at 1120 degree Celcius.After sintering, we performed EDS analysis and there was no trace of Zinc found. Does it means that Zinc stearate evaporated completely. What is your opinion?
For the sintering of iron at 1120°C it is perhaps not a problem, but you have asked in general: "Does addition of zinc stearate to metallic powders of iron, copper, aluminium etc in Powder metallurgy brings in problems?". For sintering of copper and aluminum, zinc is always a problem.
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