Why study ceramic materials?
– Very “traditional” (crude civil engineering material)
– BUTalso new high-tech ceramics and applications.
• Optical (transparency) opto-electronic.
• Electronic (piezoelectrics, sensors, superconductors)
• Thermo-mechanical (engine materials)
• Cutting tools
Introduction: Ceramic materials
• Carbon based materials
• Applications of ceramics
• Ceramic Processing
• Mechanical properties of Ceramics
Outline
Ceramics / Introduction
• keramikos - burnt stuff in Greek ? desirable properties of ceramics
are normally achieved through a high-temperature heat treatment
process (firing).
• Usually a compound between metallic and non-metallic elements.
• Always composed of more than one element (e.g.,Al2O3, NaCl,
SiC, SiO2)
• Bonds are partially or totally ionic, and can have …………….. of
ionic and covalent bonding
• Ceramics are typically characterized as possessing a high melting
temperature (i.e., “refractory”),
• Generally hard and brittle
• Generally electrical and thermal insulators (exceptions: graphite,
diamond, AlN… and others)
• Can be optically opaque, semi-transparent, or transparent
• Traditional ceramics – based on clay (china, bricks, tiles,
porcelain), glasses.
• New ceramics for electronic, computer, aerospace industries.
DIAMOND
diamond Zinc blende
same crystal structure as ZnS but
with carbon atoms exclusively
?? chemical bonding is purely covalent
?? highly symmetrical unit cell
?? extremely hard (………. known)
?? low electrical conductivity
?? high thermal conductivity (superior)
?? optically transparent
?? used as gemstones and industrial
Grinding, machining and cutting