Thermal barrier coatings (TBCs) play a critical role in mitigating the effects of extreme temperatures on structural materials, particularly in high-performance applications such as aerospace, automotive, and power generation industries. These coatings enhance the thermal resistance of airframes, turbines, and other components, ensuring their durability and operational efficiency under severe thermal conditions. The advent of environmentally sustainable technologies has further amplified the need for eco-friendly alternatives to traditional thermal coatings, prompting research into materials that offer optimal thermal performance without compromising environmental safety.

Steel, a widely used structural material, is prone to thermal degradation under prolonged exposure to high temperatures. In this context, the application of TBCs serves as an effective strategy to reduce surface temperatures, thereby improving the service life and reliability of steel-based systems. This research aims to compare the thermal performance of eco-friendly and non-eco-friendly TBCs applied to steel airframes under simulated high heat flux conditions.

In this study, transient thermal simulations were performed using ANSYS APDL to evaluate the temperature profile of steel airframes coated with ten different TBC materials. Five of these materials—Silicon Carbide (SiC), Titanium Nitride (TiN), Yttria-Stabilized Zirconia (YSZ), Zirconia (ZrO₂), and Alumina (Al₂O₃)—were selected for their environmental friendliness. The remaining five—Tantalum Carbide (TaC), Nickel-Chromium (NiCr), Chromium Carbide (Cr₃C₂), Tungsten Carbide (WC), and Molybdenum Disilicide (MoSi₂)—were chosen for their established thermal efficiency but lack of environmental sustainability.

This research adopts a structured approach to analyze and compare the temperature reductions achieved by each coating. The simulations involved subjecting the coated airframes to a constant heat flux of 10,000 W/m² over 300 seconds, with initial conditions set at 300 K. The study further quantifies the percentage reduction in surface temperatures achieved by the coatings compared to uncoated steel.

This paper is organized as follows: Section 2 describes the methodology and simulation parameters, including the geometry and material properties of the airframes and TBCs. Section 3 presents and discusses the results, including a detailed analysis of the temperature reduction and a comparison between environmentally friendly and non-environmentally friendly materials. Finally, Section 4 concludes with key insights and potential directions for future research in sustainable thermal coatings.

By addressing the balance between thermal efficiency and environmental impact, this study seeks to contribute to the development of advanced, sustainable materials for thermal management in critical applications.

Thermal barrier coatings (TBCs) have undergone significant advancements since their initial development. They are widely utilized in various engineering applications such as internal combustion engines, gas turbine blades, and pyrochemical reprocessing units. The development of new materials and deposition techniques is crucial for enhancing the life of the substrate by improving the performance of coatings. Current research focuses on understanding the mechanical properties, high-temperature behavior, residual stresses, failure mechanisms, and life prediction models of TBCs [1].

The primary objective of TBCs is to reduce the temperature of components in high-temperature environments, thereby improving their performance and efficiency. Ceramic materials are predominantly used for TBCs due to their low thermal conductivity, excellent resistance to oxidation, corrosion, and wear. The most commonly employed coating method is thermal spray coating. TBCs act as effective thermal insulators and protective barriers in aviation and power generation sectors [2].

Modern advancements in TBCs are driven by the need to enhance the performance of gas turbines and similar high-temperature systems. TBCs typically consist of two layers: the bond coat and the top coat. The top coat, often composed of yttria-stabilized zirconia (YSZ), is known for its low thermal conductivity. However, ongoing research is exploring alternative materials like pyrochlore rare-earth zirconates and hexaaluminates to overcome the limitations of YSZ. These novel materials exhibit excellent refractory properties and thermal stability, making them promising candidates for future TBC applications [3].

The use of TBCs extends to protecting aircraft turbine blades, power plants, and components in nuclear industries from high-temperature exposure. Advanced fabrication methods such as plasma spray deposition, electron-beam physical vapor deposition (EB-PVD), and electrophoretic deposition have enhanced the structural integrity and performance of TBCs. Current research also highlights the limitations of existing systems and provides recommendations for their application in harsh environments [4].

The competition to develop better TBC materials has led to the creation of various advanced materials and coating technologies. Techniques such as atmospheric plasma spray (APS) and EB-PVD have significantly improved the microstructure and lifespan of coatings. Studies on high-temperature behavior, residual stresses, and failure modes of TBCs continue to drive innovation in this field [5].

In gas turbine engines, which operate under extreme temperatures and stresses, TBCs play a critical role in improving durability and efficiency. By forming a combination of oxidation-resistant metallic and insulating ceramic layers, TBCs enhance the performance of turbine components. Understanding the materials' failure mechanisms is essential for exploiting the full potential of TBC systems [6].

The evolution of TBCs has been closely tied to advancements in gas turbine technology. Between 1940 and 1970, improvements in superalloys and engine designs allowed for substantial gains in efficiency, durability, and performance. This period of innovation underscores the importance of material advancements in achieving higher operational temperatures and reliability in gas turbines [7].

The data obtained from the simulations is summarized in the table below:

The results demonstrate that the addition of TBC significantly reduces the surface temperature of the airframe. Materials such as Alumina (Al₂O₃) and Molybdenum Disilicide (MoSi₂) exhibited the highest reductions in surface temperature. Environmentally friendly materials achieved up to 31.75% reduction, while non-environmentally friendly materials performed better, achieving up to 41.98%.

Explanation of Graphs

1. Graph 1: Environmentally Friendly Thermal Coatings vs. Temperature

The first graph compares the thermal performance of environmentally friendly materials: Silicon Carbide (SiC), Titanium Nitride (TiN), Yttria-Stabilized Zirconia (YSZ), Zirconia (ZrO₂), and Alumina (Al₂O₃). The graph shows a steady improvement in temperature reduction across these materials, with Alumina achieving the maximum reduction of 31.75%.

This indicates that environmentally friendly materials can provide substantial thermal protection while adhering to sustainable material standards.

2. Graph 2: Non-Environmentally Friendly Thermal Coatings vs. Temperature

The second graph illustrates the thermal performance of non-environmentally friendly materials: Tantalum Carbide (TaC), Nickel-Chromium (NiCr), Chromium Carbide (Cr₃C₂), Tungsten Carbide (WC), and Molybdenum Disilicide (MoSi₂). Non-environmentally friendly coatings consistently outperformed eco-friendly alternatives, with Molybdenum Disilicide achieving the highest reduction of 41.98%.

These results reflect the trade-off between environmental impact and thermal performance, as non-environmentally friendly materials often utilize advanced compounds with superior thermal properties.

By comparing these graphs, the study highlights the potential for eco-friendly coatings to approach the performance of their non-environmentally friendly counterparts, underscoring the importance of material innovation for sustainable thermal management.

This study provides a comprehensive evaluation of the thermal performance of environmentally friendly and non-environmentally friendly thermal barrier coatings (TBCs) applied to steel airframes subjected to high heat flux conditions. The simulations, conducted using ANSYS APDL, demonstrated that the application of TBCs significantly reduces the surface temperature of steel substrates, thereby improving their thermal resistance and operational longevity. Key conclusions drawn from this research are as follows:

1. Thermal Performance of TBCs:

Non-environmentally friendly materials outperformed environmentally friendly ones in terms of temperature reduction, with Molybdenum Disilicide (MoSi₂) achieving the highest reduction of 41.98%. Among environmentally friendly coatings, Alumina (Al₂O₃) exhibited the best performance, reducing surface temperatures by 31.75%.

2. Sustainability vs. Performance Trade-off:

While non-environmentally friendly coatings demonstrated superior thermal efficiency, environmentally friendly coatings showed competitive performance, achieving an average temperature reduction of 29.64%. This highlights the potential for sustainable materials to meet industrial demands with further optimization.

3. Material Selection for Specific Applications:

Non-environmentally friendly materials are better suited for applications requiring maximum thermal protection, whereas environmentally friendly coatings are ideal for industries prioritizing sustainability without significant sacrifices in performance.

4. Future Scope:

The findings emphasize the need for innovative material development to enhance the thermal properties of environmentally friendly coatings. Advances in material science, such as nanotechnology or hybrid composites, could bridge the performance gap and promote widespread adoption of sustainable solutions.

In conclusion, this research underscores the importance of balancing environmental sustainability and thermal efficiency in the selection of TBCs. While non-environmentally friendly coatings remain the gold standard for high-performance applications, environmentally friendly alternatives show promising potential for sustainable engineering practices. Further research should focus on optimizing eco-friendly coatings to achieve performance parity with conventional materials, contributing to greener and more efficient thermal management systems in aerospace, automotive, and related industries.