Carbon Nanotubes: Evolution and future of nanomaterials Presented by Ivan Muhizi History & Discovery In 1991, a Japanese scientist, Sumio Iijima conducted a momentous experiment. An experiment that introduced a material so strong that it could revolutionize how engineers approached design. What are Carbon Nanotubes (CNTs)? In simple terms, CNTs are structures entirely made of carbon atoms bonded together in a hexagonal lattice. Geometry: Consider a graphene sheet-a single layer of carbon atoms-rolled into a seamless cylinder. These cylinders can be of different configurations depending on how the graphene sheet is rolled: Armchair: Highly conductive, perfect for electronic applications. Zigzag: Can be a semiconductor. Chiral: Properties between metallic and semiconducting. Types of CNTs Single-Walled CNTs (SWCNTs): 0.4 to 2 nanometers in diameter, unique electronic properties. Multi-Walled CNTs (MWCNTs): Multiple concentric nanotubes, diameter range of 2 to 50 nanometers, much better mechanical strength. Properties of Carbon Nanotubes Mechanical Strength: Tensile strength: Up to 100 GPa (gigapascals), over 100 times stronger than steel. Elastic modulus: Up to 1 TPa (tera pascals), making them incredibly stiff. This property is critical in applications requiring lightweight yet mechanically robust materials. Electrical Conductivity: Can be metallic or semiconducting depending on their structure. Conductivity can exceed that of copper and Thermal Conductivity: Up to 3000 W/mK (watts per meter-kelvin), much higher than copper (400 W/mK). Low Density: About 1.3–1.4 g/cm³, making them lightweight and thus useful for aerospace and automotive applications. Production of Carbon Nanotubes Methods: Chemical Vapor Deposition (CVD): Hydrocarbon gases, such as methane, are decomposed over a metal catalyst at high temperatures. The most common and scalable method. Arc Discharge: High voltage is applied between graphite electrodes in an inert gas atmosphere. Produces high-quality CNTs with limited scalability. Laser Ablation: A high temperature vaporizes graphite by using a laser. Synthesizes CNTs with very high purity but is a highly expensive process. Issues Production Control: Length, chirality, and purity control in producing CNTs. Cost control for large-scale industrial usage What are their applications? Embedded CNTs are integrated into the polymer matrix, metal, or ceramic material for fabricating lightweight and strength-enhanced composites. Their higher tensile strength, and higher durability improves fatigue, corrosion and wear resistance. Applications: Components used in aircraft such as fuselage and wings. Automobile components: Frames made of lightweight material and bumpers Sporting Equipment: Bicycle frames and Tennis Rackets. Energy Systems CNTs allow improving energy efficiency and performance for the use of batteries, supercapacitors, and fuel cells. Examples: Li-ion batteries with CNT-based improved electrodes to enhance energy density or higher charging speed. Supercapacitors based on CNTs for storage applications. Thermal Management Very High CNTs thermal conductivity applied in different heat dissipation methods is widely used in both mechanical and electronic systems. Heat Sink: Heat dissipation inside central processing units. Power Electronic Thermal Interface Materials: Some Engine applications. Structural Health Monitoring CNTs act as sensors that mechanically detect strain, pressure, or damage in structures. Due to mechanical deformation, electrical resistance is changed, hence providing real-time feedback. Applications: Structural health monitoring of bridges, aircraft, and pipelines. Sensors for detecting damage Additive Manufacturing Description: CNT-infused materials are used in 3D printing to create parts with superior mechanical and electrical properties. Applications: Aerospace components and Custom medical implants. Example: CNT-Enhanced Automotive Parts In the automotive industry, carbon nanotube composites are employed for the manufacture of lightweight impact-resistant parts like bumpers and side panels. For example, A bumper made with CNTs can weigh 30 percent less than a conventional one with 5–10 times more resistance to impact. These developments lead to improvements in fuel efficiency and safety. Limitations of Carbon Nanotubes Besides being valuable for several applications, CNTs possess a few limitations. Solvent inability of CNTs in most of the solvents and incompatibility in biological milieu restricts their use in medicinal science. It is just about impossible to produce structurally and chemically reproducible batches with lot-to-lot variation with almost identical characters, therefore, so batch to batch variation in properties may take place. Difficulty in maintaining high quality and purity standards. High cost of production. Conclusion Carbon nanotubes are revolutionizing mechanical engineering by making materials and systems lighter, stronger, and more efficient. Though the challenges persist, the potential of carbon nanotubes across industries, from aerospace to energy and electronics, is so great that they will certainly play a key role in the future of engineering and technology. Their potential stretches across multiple future applications in areas such as nano-robotics, space exploration, and next-generation electronics. References Anazawa, K., Shimotani, K., Manabe, C., Watanabe, H., & Shimizu, M. (2002). High-purity carbon nanotubes synthesis method by an arc discharging in magnetic field. 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Carbon Nanotube Review, Definition, Structure, Properties, Applications [Video]. YouTube. https://www.youtube.com/watch?v=mf5wPBpnRnQ Takakura, A., Beppu, K., Nishihara, T., Fukui, A., Kozeki, T., Namazu, T., Miyauchi, Y., & Itami, K. (2019). Strength of carbon nanotubes depends on their chemical structures. Nature Communications, 10(1). https://doi.org/10.1038/s41467-019-10959-7 Tim Harper. (2024, November 6). http://www.cientifica.com/ Wikipedia contributors. (2024, November 14). Carbon nanotube. Wikipedia. http://en.wikipedia.org/wiki/carbon_nanotube