Please do you know in your opinion, which SPS machine allows sintering at the highest pressure. The one I know so far can sinter at 400 or 500 MPa. I believe that when people start to answer eventually we will discover the SPS with that capability.
HI Ismaila,
From my knowledge this is not a question of the machine itself but of the mold design and mold materials. Conventionally if the pressing force is sufficient (or the sample diameter is small enough) you can press at up to 80-100 MPa with graphite molds (must be excellent graphite, I do not dare to go higher than 60 MPa). By designing multiple mold- in - the- mold systems you can multiply the pressing force but you cannot use graphite for the inner molds anymore but you must use silicon carbide or cemented carbide materials. in case of WC-Co the applicable temperature is however drastically reduced.
The question is for which purpose you need such high pressures, in a talk given some years ago Anselmi-Tamburini has shown that in e.g. ultra high pressure SPS of titania at low temperature you do not really sinter the material but mainly deform the grains.
@Frank.Thanks a lot for your answer. Yes, you are right that the die has to be something other than graphite. In the example I mentioned in my question, it was a specialized die made of one of the materials you mentioned. They were able to reach 400/500 MPa. So I was wondering if there can be something higher than that.
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