We were conducting TGA tests for a Mg Alloy system. The Y Axis that determined TG% starts its value from 100 and the curve that i got increased upto a value nearing 165-170 in Y Axis and then became constant. I don't know how to calculate the mass gain percentage. And also y does the Y Axis TG% value starts from 100???. Please help me in this regard
Normally, it should not start at 100 if initialization is carried out to make it ZERO. Even if the TG value started at 100 you can take it as base (ZERO) and can calculate the mass gain as proposed by Joachim.
1. You could calculate both i) weight gain and ii) weight loss by TGA. Pl take your starting point after initial buoyancy effect in the TGA axis and check the total weight gain in this specific case and find out the percentage. Looks like it is already in percentage scale and hence it is easy to find out the percentage. Moreover the analysis software would provide this.
2. Another point to mention, alloys could gain weight, when heated in air or oxygen atmosphere that could form corresponding oxides. Was the purpose of TGA run to calculate the oxidized weight of the alloy ? If not, you could perhaps take another TGA run in inert gas atmosphere, like nitrogen or helium atmosphere...and record the change (if the present TGA is not been carried under nitrogen atmosphere) and check the actual loss, if any in an inert atmosphere.
Sukumar Roy...
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