The problem with silicon is the oxide film (SiO2) that surrounds each particle. The finer the particles, the more oxide. During sintering in vacuum or inert gas, the oxide layer does not disappear, but is even thicker. For this reason, the products made of pure silicon can not be produced by means of sintering.

The problem with silicon is the oxide film (SiO2) that surrounds each particle. The finer the particles, the more oxide. During sintering in vacuum or inert gas, the oxide layer does not disappear, but is even thicker. For this reason, the products made of pure silicon can not be produced by means of sintering.

The attached 1997 paper looks helpful. According to it "The sintering behavior of silicon (Si) nanoparticles is still not very well understood [23]. Si is covalently bonded with sintering temperatures between 0.75 Tm (beginning of the densification) and 0.98 Tm (maximum density)." There is much more information in the paper on particle growth, structure and sintering.  

Dear Vadim and Daniels

Appreciate your comments

Regards

In my opinion, pure  Si can be sintering at about 1300-1350oC (mp: 1414 oC), we used to use Si as a infiltrator to dense the porous preform, the temperature  is about 1450oC,  the liquid Si can fluid into the porous preform.

As we know the temperature of sinteriring  is about 0.8  of melting point and the melting point of pure silicon about 1400 oC therefore the sinterireing  temperatur is about 1120oC

Dear Dr Raju,

I am totally agree with Dr Vadim, Dr Daniels and Dr Gao..

It's hard to control the presence of oxide layer on Si.. After all, as we all knew.. the stabilize structure of Si, are in the form of SiO2 (presence in nature as sand).. :-)

The best sintering temperature of Si, should be in the range of 1200 - 1450 degC. You should also try to verify the presence of oxide (with XRD and TEM)..

All the best then, Dr Raju.

By definition the sintering temperature is approximately  0.8 of melting point of material. The melting point of silicon is know and you can easy calculate the proper value for sintering temperature

I believe SI sintering by mean of conventional method alone is not possible due to the natural oxidation of silicon powders. You might be able to isolate the Si and oxygen by mean of hot press and other chemical means but then you will end up with contamination which mainly composed of oxygen precipitates. You can reduce the problem by using very high purity Si powder (says 99.9999% pure) but still, total elimination of oxygen precipitates  is not possible. So to overcome this hurdle, I think you need a secondary process to remove the oxygen contamination. It might involve recrystallization of the Si polycrystals by locally melting the Si. For details, you might want to check Mr. BELLANGER's work at Silicontile France.