I am observing an unexpected mass increase (about 16 %) in TG of my compound (a mix of Vanadium, Aluminum and Graphite) at temperatures between 450 and 1200 C. The atmosphere is highly pure argon and the rate of heating is 5 Celsius degree/min.
Do you have any idea about the reason?
Check the trace amounts of oxygen, nitrogen and moisture in your UHP Ar stream. Check for any leakage. When air is drawn inside by improper sealing, it will cause oxidation and nitriding. Analyze your tested samples for reaction products. All reactions are subject to mass and energy balance.
Please check if the TGA instrument was recently calibrated for analogous experimental conditions; namely in terms of heating rate (or thermal schedule), type of pans, selected gas, and its flow rate.
Hi
Please verfy the crucible material.... May i know what crucible material you used..... If it is a ceramic one no issue.... The air leakage may give unusuall mass change.
Best
Krishnan Raja , Carlos Araújo Queiroz thanks for your answers. The atmosphere has 5N purity and there is no leakage from instrument.
V R Arun Prakash the crucible is densed high alumina.
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