Nanophase ceramic
From Wikipedia, the free encyclopedia
Nanophase ceramics are ceramics that are nanophase materials (that is, materials that have grain sizes under 100 nanometers).[1][2] They have the potential for superplastic deformation.[1] Because of the small grain size and added grain boundaries properties such as ductility, hardness, and reactivity see drastic changes from ceramics with larger grains.
The structure of nanophase ceramics is not too different than that of ceramics. The main difference is the amount of surface area per mass. Particles of ceramics have small surface areas, but when those particles are shrunk to within a few nanometers, the surface area of the same amount of a mass of a ceramic greatly increases.[3] So in general, nanophase materials have greater surface areas than that of a similar mass material at a larger scale.[3] This is important because if the surface area is very large the particles can be in contact with more of their surroundings, which in turn increases the reactivity of the material.[3] The reactivity of a material changes the material's mechanical properties and chemical properties, among many other things.[3] This is especially true in nanophase ceramics.
Properties
Nanophase ceramics have unique properties than regular ceramics due to their improved reactivity.[3] Nanophase ceramics exhibit different mechanical properties than their counterpart such as higher hardness, higher fracture toughness, and high ductility.[4] These properties are far from ceramics which behave as brittle, low ductile materials.
Titanium dioxide
2.[5]
2.[5]
Titanium dioxide (TiO
2), has been shown to have increased hardness and ductility at the nanoscale. In an experiment, grains of titanium dioxide that had an average size of 12 nanometers were compressed at 1.4 GPa and sintered at 200 °C.[5] The result was a grain hardness of about 2.2 times greater than that of grains of titanium dioxide with an average size of 1.3 micrometers at the same temperature and pressure.[5] In the same experiment, the ductility of titanium dioxide was measured. The strain rate sensitivity of a 250 nanometer grain of titanium dioxide was about 0.0175, while a grain with size of about 20 nanometers had a strain rate sensitivity of approximately .037; a significant increase.[5]
