Is there a characteristic temperature for moisture, amorphous carbon and onset of burn-out of crystalline carbon?
Hi Kais,
Moisture is the weight decrease below 150 ºC.
The amorphous and graphitic peak occur at much higher temperature. For example, the paper of Utsumi et al. (DOI: 10.1021/jp0512661 ),in their Figure 7 show 820 K and 950 K respectively.
thank you for your reply. I can't have access to the paper. However, I have a reference (http://www.masontechnology.ie/x/Usercom_13.pdf) suggesting moisture persisting up to 320C. It seems that there is a debate how on to identify the range and type of carbon and moisture!
When I look am doing experiments that look for phase changes, I use a TGA-DTA combination in order to see weight loss and exo and endothermic reactions. Using this method you will be able to see that there are two water evaporation 100 C and 300 C, where 100 C is free water in the system and 300 C is molecular bonded water, both will show endothermic peaks for those two temperatures. You should see another exothermic peak up to the temperature/point that graphitic carbon is formed. At the formation of graphitic carbon you should see and exothermic peak. You can confirm the temperature that graphitic carbon is formed via powder X-Ray Diffraction, test the samples before the graphitic temperature and after the graphitic temperature to confirm that graphitic carbon was formed. This way you can pin point temperature for the phase change from amorphous carbon to graphitic carbon.
Hi Kais,
Here is the paper. Most should be clear by looking at the above-mentioned figure.
Regards,
- Badges
- Science topic