The core of a thermogravimetric analyzer is to analyze the quality loss/gain of a sample during temperature changes through "programmed temperature control+real-time quality monitoring". The steps are simplified as "sample preparation → instrument debugging → parameter setting → experimental operation → data processing", as follows:
Sample preparation:
Take 5-20mg of sample (preferably powder/small particles to avoid uneven heat transfer of large samples) and place it in a dedicated crucible (made of alumina or platinum material, selected according to the characteristics of the sample to avoid reaction);
If the sample is prone to oxidation and moisture absorption, it should be quickly loaded under inert gas (nitrogen, argon) protection to avoid sample deterioration.
Instrument debugging and calibration:
Accurately weigh the total mass of the crucible and sample using an analytical balance, and record the data (for subsequent calculation of mass change rate);
Turn on the instrument and preheat for 30 minutes to ensure the stability of the temperature control system and balance system;
Place an empty crucible for 'blank correction' to eliminate the influence of quality drift in the crucible itself;
If precise quantification is required, standard samples (such as calcium carbonate) can be used for calibration to verify the accuracy of temperature and quality detection.
Experimental parameter settings:
Temperature parameters: Set the starting temperature (usually room temperature or sample stability temperature), ending temperature (based on the sample thermal decomposition range, such as room temperature~1000 ℃), and heating rate (5-20 ℃/min, the faster the rate, the higher the efficiency, and the slightly lower the accuracy);
Atmosphere setting: Select air (oxidizing atmosphere), nitrogen/argon (inert atmosphere, used to avoid sample oxidation) or hydrogen (reducing atmosphere, special scenario), set gas flow rate (20-50mL/min, ensure stable atmosphere);
Other parameters: Check "Automatic recording of quality change rate" and set the data collection interval (such as recording the quality once every 1 ℃).
Experimental operation:
Place the sample crucible into the instrument sample stage, close the furnace door, and wait for the atmosphere inside the furnace to stabilize (about 5-10 minutes);
Start the experimental program, the instrument will heat up at the set rate, monitor the changes in sample quality in real time, and automatically generate thermogravimetric (TG) and differential thermogravimetric (DTG) curves;
During the experiment, avoid touching the instrument and observe whether the curve is normal (without sudden jumps or abnormal noise). If any abnormalities occur, pause the experiment for troubleshooting.
Experiment completion and data processing:
After the temperature reaches the set endpoint, the instrument automatically cools down. When the furnace temperature drops below 100 ℃, open the furnace door and remove the crucible;
The software automatically calculates the quality loss rate (%) and characteristic temperature (such as initial decomposition temperature and maximum decomposition rate temperature);
Export TG/DTG curves, analyze them in conjunction with experimental objectives (such as decomposition temperature, thermal stability, component content, etc.), and save the data report.
Key precautions:
The sample amount should not be too large to avoid uneven heat conduction leading to peak shape deviation;
Samples with high corrosiveness and volatility should be selected in corrosion-resistant crucibles, and the furnace chamber should be cleaned promptly after the experiment;
After the experiment, it is necessary to cool down with inert gas to protect the internal components of the instrument and extend its service life.