For example, alumina Al 2 O 3 , is a compound made up of aluminum atoms and oxygen atoms. The atoms in ceramic materials are held together by a chemical bond. The two most common chemical bonds for ceramic materials are covalent and ionic.
For metals, the chemical bond is called the metallic bond. The bonding of atoms together is much stronger in covalent and ionic bonding than in metallic.
Piezoelectric ceramics have polycrystalline structure. An example of piezoelectric material is lead zirconate titanate PTZ in short. Specific gravity This chart displays specific gravity of materials, which is the density of a material relative to the density of water.
Comparative specific gravity graph. Hardnes This graph displays the hardness of various materials measured by Vickers hardness. Comparative hardness graph.
Fracture toughness Fracture toughness can be defined as resistance to crack growth. Comparative fracture toughness graph. Comparative graph of maximum use temperature. Thermal shock resistance Temperature range in which a material can withstand rapid changes in temperature. Comparative thermal shock resistance graph. Thermal conductivity This graph displays how well the heat is transfered through different materials. Thermal conductivity comparison graph. Coefficient of thermal expansion Rate of material expansion in response to a change of temperature.
Comparative graph for thermal expansion coefficient. Electrical resistivity Electrical resistivity, also known as volume resistivity, is the property which explains how difficult it is for electricity to pass through a material.
Electrical resistivity graph. Relative permittivity Permittivity describes how much dielectric polarization in a material occurs, if applying an electric field on it. Corrosion resistance Corrosion resistance describes how well a material can withstand chemical or biological effects without degradation of its properties or structure. Electric conductivity In general, advanced ceramics are insulation materials that do not conduct electricity. The hardness of alumina ceramics is nearly three times that of stainless steel; silicon carbide is more than four times harder than stainless steel.
Ceramic materials are brittle, hard, strong in compression, and weak in shearing and tension. They withstand chemical erosion that occurs in other materials subjected to acidic or caustic environments. In theory, ceramic is stronger than glass.
Glass is actually a type of ceramic, but to be specific, glass has no ordered molecular structure.
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