Everlasting/General techniques of Thermal Analysis in Materials Testing

Introduction to the ‘theme’The five techniques of T.A.

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Summary

Mechanical is a vast Science with plenty of sub streams being thermal, fluid dynamics, kinematics, applied mechanics, astronomy, seismic, geology, marine, avionics, astronomy ……. to catalog a few!

Every field of science has various techniques of analysis of materials or matter. Thermal Engineering involves a number of scientific hypothesis, numerical equations, measurement / exp apparatus, processes, units and hundreds of formulae.

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The term ‘Thermal’ is derived from the ancient Latin word ‘Thermos’ which means heat i.e. study of everything relevant to transfer of heat.

Now - I present you with simple yet popular techniques involved in thermal analysis of materials.

Thermo gravimetric analysis

This analysis is used to measure the change in weight of a substance during heating or cooling. This mass difference can be measured as a function of temperature or function of time (at constant temperature).

Sample can be liquid or solid. The graph of - difference in mass versus temperature is initially plotted.

Study of material properties and decomposition pattern of substances.Study degradation mechanism in chemical reactions and kinetics.Determination of organic content in a sample.Determination of inorganic content in a sample.

Applications

Differential thermal analysis

DTA involves heating or cooling a test sample and an inert reference under identical conditions, while recording any temperature difference between the sample and reference.

This differential temperature is then plotted against time, or against temperature. Changes in the sample which lead to the absorption or evolution of heat can be detected relative to the inert reference.

DTA can be used to study thermal properties and phase changes which do not lead to a change in enthalpy.

Applications

Helps to differentiate between exothermal and endothermic reactions.

Helps in the study of reaction and decomposition stages, melting, crystallization, change in crystal structure, glass transition.

Differential scanning calorimetric

Differential scanning calorimeter or DSC is a thermo analytical technique. A technique in which the difference in the amount of heat required to increase the temperature of a sample and reference are measured as a function of temperature.

Applications

To observe fusion and crystallization events as well as glass transition.

As the temperature increases, an amorphous solid will become less viscous. At some point the molecules may obtain enough freedom of motion to spontaneously arrange themselves into a crystalline form. This is known as the crystallization temperature.

As the temperature increases the sample eventually reaches its melting temperature. The melting process results in an endothermic peak.

The ability to determine transition temperatures and enthalpies makes DSC an invaluable tool in producing phase diagrams for various chemical systems.

Dynamic mechanical analysis

DMA is the measurement of mechanical properties of materials under oscillatory load as a function of temperature. Examples of the material properties to be determined are -

Applications

Determination of glass transition temperature (sensitive method).Determine upper use temperature of structural composite

(research in construction materials).Selection of proper materials for specialized application (acoustic,

automobile etc.)Study of phase homogeneity of blends.

This is the technique of measure change in dimensions during heating or cooling.

Also involves measurement of dimensional changes under constant load as a function of temperature. The probe of TMA can be changed for different information just like universal testing machine.

Thermo mechanical analysis

Applications

Determination of linear expansion coefficient.Evaluation of material anisotropy.Determination of phase transition.Determination of melting point.

The final Conclusion

These techniques might seem rather effortless, but are practically complicated to analyze.

Now you might be knowing that thermal is an innovative & lucrative stream in itself.

These five methods of analysis that listeners come across - show how vast this vivid & flamboyant stream can be.

The acquired knowledge in the field of Thermodynamics is expanding from time to time.

But trust me – these are the ABC’s of this field, and so are going to last fore ever. Irrespective of any developments.

Suggestions 4 improvement are always welcome! Feel candid. You can our contact college at: www.sjec.ac.in

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