3. What Is Thermal Analysis?
• The process of measuring and recording physical parameters as they change
with temperature and time under heating.
• Physical properties include mass, temperature, enthalpy, dimension, dynamic
characteristics, and others, and depending on the physical properties to be
measured, the techniques of thermal analysis.
5. What is TGA?
• Thermogravimetric analysis (TGA) is a method for measuring the weight of
a sample while it is subjected to varying levels of heat.
• Throughout the process, the sample is held at different temperatures, and the
measurements are recorded.
• Typically, TGA is used to analyze inorganic materials, such as metal
ceramics and glasses.
• The parameters that are measured include temperature, mass, and time.
6. Types of TGA
There are three types of TGA (Thermogravimetric Analysis) that are used to
measure the properties of a substance as it undergoes changes in temperature.
They are:
• Static TGA: In this type of analysis, the parameters are measured without
change in temperature.
• Quasi-Static TGA: In this type of analysis, the sample is analyzed with
different temperature ranges.
• Dynamic TGA: In this type of analysis, the sample undergoes a linear
change in temperature while the analysis is being done.
7. Principle of TGA
• The weight of the sample is determined in relation to the temperature or
duration of heating.
• During the analysis, various processes may take place, including:
Desorption, adsorption, sublimation, vaporization, oxidation, reduction,
and decomposition. However, these processes cause a change in the
sample's mass.
But melting and crystallization will not affect the mass.
10. Microbalance
• The main purpose of a microbalance is to record the changes in mass.
• A microbalance should possess certain attributes such as:
• Precise recording of sample mass changes
• Prompt electronic signal response to mass alterations
• Immunity to vibrations.
11. Types Of Microbalance
• Deflection type
• Beam types
• Helical type
• Cantilevered beam type
• Torsion wire type
• Null-point type balances
13. Sample Holder
• A sample holder is used to contain the sample.
• Materials used for making sample holders include aluminum, platinum, and quartz.
• The sample holder needing to possess thermal stability at least 100°c higher than the
experimental temperature.
• The sample holder should efficiently and uniformly transfer heat to the sample.
• Therefore, it's essential to consider the thermal conductivity, shape, and thermal mass of
the sample holder before using it under predetermined experimental conditions.
14. Furnace
• When designing a Furnace, it is crucial to ensure a consistent linear heating
rate.
• The Furnace typically consists of a hot zone that accommodates both the
sample and sample holder.
• It is important to note that the temperature of the sample holder and sample
should match the temperature of the furnace.
• The internal atmosphere can be affected by the maintained temperature in
furnace.
• It is imperative to avoid any magnetic interaction between the sample and
heating coil, as it can significantly alter the sample's weight.
15. Factor Affecting TGA
The factors which are found to affect TGA are:
• The quantity and size of the sample utilized for analysis.
• The physical structure of the sample
• The design and composition of the sample holder.
• The environmental conditions during analysis, such as the atmospheric
composition.
• The pressure maintained within the sample chamber throughout the analysis.
• The rate at which heating and cooling occur.
16. Applications Of TGA
Applications of TGA include:
• Determination of thermal stability under modified atmosphere
• Prediction of thermal decomposition mechanism
• Determination of nanoparticle purity and amount of surface coatings
• Gas adsorption studies
• Determination of relative strength for catalysts
• Kinetic analysis
