Zinc Stearate byproducts and questions on sintered metal composition

[LostHippie]

Hello there,

I'm a fresh graduate...looking at a material specification sheet involving a metallic part that is sintered from a metallic powder mixture.

The spec includes the chemical composition of the powder prior to sintering, but does not include the chemical composition after sintering. One of the components listed is zinc stearate, which is a mold release agent. When I look up information on zinc stearate, all sources say it decomposes instead of vaporizing at high temperatures under most conditions. So I guess my main question is: Does the sintering process (1 hr @ 2000 deg. F) going to result in a change in chemical composition (mainly due to release of byproducts of the former zinc stearate) and if that answer is not know and for curiosities sake, what does the zinc stearate break down into? Any suggestions or info would be greatly appreciated.

Thanks in advance!
LostHippie ^_^

 

[unclesyd]

I can't tell you what happens to the Zinc in the Zinc Stearate Stearate except the acid component burns off with no residue. Depending on your alloy composition the Zinc may form an alloy, a dross, or vaporize off at your temperature.

We normally used Stearic Acid in very small quantities in producing powder metals as binder for the green preform. On most materials we had a two step process where we used a high temperature dryer, where we lost the Stearic Acid. Our primary process was for processing pure metal catalyst for chemical reactions.

 

[arunmrao]

Organic compounds normally burn off during the first phase of sintering. However,in case of zinc stearate or lithium stearate, some inorganic residues can be left behind. These residues can weaken the sintered part,by hindering complete sintering of the iron particle or formation of less favorable pore structure.

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year