The principle of the differential thermal analyzer is: the sample to be tested and the reference substance (thermal inert substance) are placed in the furnace under the same conditions, and the temperature is heated or cooled at the same speed according to the given program. When the heated sample produces changes in physical and chemical properties at different temperatures (such as phase transformation, crystallization structure transformation, crystallization, boiling, sublimation, gasification, melting, dehydration, decomposition, oxidation, reduction… And other reactions), accompanied by heat absorption or heat release, the temperature of the sample itself is lower than or higher than the temperature of the reference substance, that is, the temperature difference between the two. The magnitude of the temperature difference (the temperature difference between the two before and after the reaction is zero) and the polarity are detected by the thermocouple, and converted into electrical energy, amplified by the amplifier and input to the recorder, and the recorded curve is the differential heat curve.
The use of differential thermal analyzer tips together to understand the next
Differential heat analyzer use tips:
1. Special attention: the laboratory temperature is controlled at 15-20℃, and the test results and repeatability are high when the temperature is relatively constant. Turn on the air conditioner when the high temperature is high.
2, in order to ensure the accuracy of the test results, the use of the instrument first empty burning about 25 minutes. The instrument is not used for a long time, and when it is used again, it is burned (without any sample and reference substance) two to three times. You can set the temperature to 600℃, the rate to 5℃ / min, and the constant temperature to 0min. Press the RUN key.
3, the sample dosage should not be too much, should not be too little, should be appropriate. Generally about 20mg, if the test dosage is otherwise required, according to the requirements to determine the dosage; The powder sample should be compacted.
4. The data line of the instrument connected to the computer is 232 serial port line with nine-hole plugs at both ends. The two ends of the plug are connected in a one-to-one manner, that is, the foot of one end is connected to the other end, the foot, the second foot of one end is connected to the second foot of the other end, and so on. If there is a replacement please pay attention!
The use of differential thermal analyzer tips together to understand the next
5, the heating rate is generally selected (10-21) ℃ / min. Too large will make the curve drift, reduce the resolution; Too small measurement time is long.
6, do not use hard objects to clean the sample holder and test area, so as not to cause damage to the instrument.
7, if there is dust or other powdered debris in the test area, you should use the ear ball to blow it clean, and be careful to blow it with your mouth.
8. When the experimental area is seriously polluted, the temperature can be set to 700℃, the rate to 20℃ / min, and the constant temperature to 30min. Press the RUN button.