nanoceramic

Nanoceramics are ceramics in which the crystalline grains and phases exist at nanometer dimensions, typically less than 100 nanometers. These materials may be produced as bulk nanocrystalline ceramics or as nanostructured composites in which nanoscale ceramic grains are embedded in a secondary phase. The nanoscale structure alters defect density, grain boundary characteristics, and phonon scattering, often delivering higher hardness and strength, improved wear resistance, and modified optical or dielectric properties compared with conventional ceramics. In some cases, extremely fine grains can impede certain deformation mechanisms, while in others they may promote grain-boundary sliding at high temperature.

Fabrication methods include mechanical milling to produce nanocrystalline powders, sol-gel, hydrothermal, and chemical precipitation routes to form nanoparticles, and various densification techniques such as spark plasma sintering, hot pressing, and microwave or field-assisted sintering to consolidate powders with limited grain growth.

Common nanoceramic systems include nanocrystalline alumina (Al2O3), zirconia (ZrO2), titania (TiO2), silicon carbide (SiC), and silicon nitride (Si3N4). Nanoparticles are also used as fillers in polymer matrices to create ceramic-reinforced nanocomposites.

Applications span cutting tools and wear-resistant coatings, dental and orthopedic ceramics, dielectric and optical components, and catalysis support. In biomedical contexts, nanoscale hydroxyapatite and related composites are explored for bone repair.

Challenges for nanoceramics include controlling agglomeration, achieving uniform densification without excessive grain growth, high production costs, and long-term reliability. Research continues to optimize processing, scale-up, and the relationship between grain size and properties for specific applications.