Thermal Stability Evaluation of Aluminium Oxide (Al?O?) for High-Temperature Applications

Abstract

Aluminium oxide (Al?O?) is a common ceramic material widely recognized for its thermal stability, chemical inertness, and mechanical strength, and is therefore ideally suited for high temperature uses. Its stable ?-phase allows it to resist extreme heating without changing structure, in turn supporting common applications in refractory linings, thermal barrier coatings, structural ceramics, electronic substrate applications, and catalytic supports. In this investigation, the thermal stability of aluminium oxide powder is evaluated using thermogravimetric (TG) and differential scanning calorimetry (DSC) techniques. The investigation shows that aluminium oxide remains structurally stable in high-temperature conditions (300-900 °C), and only experiences minor mass loss at low temperatures due to surface moisture and hydroxyl groups. These investigations demonstrate that aluminium oxide is suitable for challenging high-temperature and protective applications. Earlier investigations conducted by Toledo, Laboureur, Trunov, Vippola have pointed out alike thermal reliability thereby ensuring it functioned well in confirmation of thermal systems. Having elevated thermal resistance, mechanical hardness, and chemical non-reactivity, aluminium oxide is a flexible option of material for parts undergoing harsh thermal conditions.In summary, this study determines that aluminium oxide is a durable, thermally stable, and reliably performing material for high temperature systems, reinforcing its importance in ceramics, aerospace, electronics, and chemical industries where materials must perform and maintain their durabiity under extreme conditions.

Introduction

Aluminium oxide (Al?O?) is a widely used ceramic material known for its high thermal stability, chemical inertness, mechanical hardness, and corrosion resistance. These properties make it ideal for high-temperature applications such as refractory linings, thermal barrier coatings, structural ceramics, electronic substrates, and catalysts.

The α-phase of alumina is the most stable form and retains its structure even at extreme temperatures. This phase does not undergo phase transitions or decomposition under heat, making it suitable for long-term thermal exposure.

Experimental Findings (TG–DSC Analysis)

• TG (Thermogravimetric Analysis):
  Only a 2.2% weight loss up to 1000?°C, mostly below 150?°C due to surface moisture evaporation.

• DTG (Derivative TG):
  A single shallow peak below 120?°C confirms no major decomposition or phase change.

• DSC (Differential Scanning Calorimetry):
  An endothermic peak below 150?°C aligns with moisture loss. No thermal transitions observed up to 1000?°C, indicating stable α-alumina.

Key Insights

• The alumina used is already in the stable α-phase, verified by the absence of structural transitions.

• The material retains ~97.8% of its mass after heating, confirming excellent thermal resistance.

• These results are consistent with literature findings (Toledo, Laboureur, Trunov, Vippola).

Industrial Applications

• Refractory linings in furnaces and kilns.

• Thermal barrier coatings for turbine blades and aerospace parts.

• Electronic substrates due to thermal stability and electrical insulation.

• Structural ceramics and abrasives used in high-wear, high-heat environments.

Conclusion

The thermal characterization of aluminium oxide powder by TG, DTG, and DSC methods evidently shows its superior thermal stability and crystalline quality. The overall weight loss of a mere 2.2%, primarily below 150 °C, is associated with the evaporation of adsorbed water and surface hydroxyl groups. Beyond this point, the sample is thermally inert with no indication of decomposition or phase transformation up to 1000 °C, a proof of its presence in the stable ?-phase of Al?O?. The level TG, DTG, and DSC traces further attest its chemical inertness and high-temperature stability This stability renders aluminium oxide a suitable material for high-temperature coatings and thermal barrier coatings. Its melting point is high, with low thermal conductivity and high adhesion to metal substrates, which enables it to safeguard components against oxidation, corrosion, and thermal fatigue. In industrial environments—gas turbines, furnaces, and aerospace systems—aluminium oxide coatings serve as effective shields against heat, providing longer service life and reliability in performance. In total, the combined TG–DTG–DSC results affirm that the investigated aluminium oxide powder has the thermal stability, phase steadiness, and chemical strength required for sophisticated high-temperature engineering and protective coating usage.

References

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Copyright

Copyright © 2025 Brijendra Kumar, Abhishek Srivastava, Rohit Srivastava. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.