World's Strongest Material | NOVA | Science Documentary
Δημοσιεύτηκε στις 25 Οκτ 2016
World's Strongest Material | NOVA | Science Documentary
A
superhard material is a material with a hardness value exceeding 40
gigapascals (GPa) when measured by the Vickers hardness test. They are
highly incompressible solids with high electron density and high bond
covalency. As a result of their unique properties, these materials are
of great interest in many industrial areas including, but not limited
to, abrasives, polishing and cutting tools and wear-resistant and
protective coatings.
Diamond is the hardest known material to
date, with a Vickers hardness in the range of 70–150 GPa. Diamond
demonstrates both high thermal conductivity and electrically insulating
properties and much attention has been put into finding practical
applications of this material. However, diamond has several limitations
for mass industrial application, including its high cost and oxidation
at temperatures above 800 °C. In addition, diamond dissolves in iron and
forms iron carbides at high temperatures and therefore is inefficient
in cutting ferrous materials including steel. Therefore, recent research
of superhard materials has been focusing on compounds which would be
thermally and chemically more stable than pure diamond.
Superhard
materials can be generally classified into two categories: intrinsic
compounds and extrinsic compounds. The intrinsic group includes diamond,
cubic boron nitride (c-BN), carbon nitrides and ternary compounds such
as B-N-C, which possess an innate hardness. Conversely, extrinsic
materials are those that have superhardness and other mechanical
properties that are determined by their microstructure rather than
composition. An example of extrinsic superhard material is
nanocrystalline diamond known as aggregated diamond nanorods.
Read More about “World's Strongest Material | NOVA | Science Documentary”: https://en.wikipedia.org/wiki/Superha...
You may also subscribe to
SCIENCE DOCUMENTARY Channel for more updated videos:
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Thank you for watching “World's Strongest Material | NOVA | Science Documentary”.
A
superhard material is a material with a hardness value exceeding 40
gigapascals (GPa) when measured by the Vickers hardness test. They are
highly incompressible solids with high electron density and high bond
covalency. As a result of their unique properties, these materials are
of great interest in many industrial areas including, but not limited
to, abrasives, polishing and cutting tools and wear-resistant and
protective coatings.
Diamond is the hardest known material to
date, with a Vickers hardness in the range of 70–150 GPa. Diamond
demonstrates both high thermal conductivity and electrically insulating
properties and much attention has been put into finding practical
applications of this material. However, diamond has several limitations
for mass industrial application, including its high cost and oxidation
at temperatures above 800 °C. In addition, diamond dissolves in iron and
forms iron carbides at high temperatures and therefore is inefficient
in cutting ferrous materials including steel. Therefore, recent research
of superhard materials has been focusing on compounds which would be
thermally and chemically more stable than pure diamond.
Superhard
materials can be generally classified into two categories: intrinsic
compounds and extrinsic compounds. The intrinsic group includes diamond,
cubic boron nitride (c-BN), carbon nitrides and ternary compounds such
as B-N-C, which possess an innate hardness. Conversely, extrinsic
materials are those that have superhardness and other mechanical
properties that are determined by their microstructure rather than
composition. An example of extrinsic superhard material is
nanocrystalline diamond known as aggregated diamond nanorods.
Read More about “World's Strongest Material | NOVA | Science Documentary”: https://en.wikipedia.org/wiki/Superha...
You may also subscribe to
SCIENCE DOCUMENTARY Channel for more updated videos:
https://www.youtube.com/channel/UCnzO...
Thank you for watching “World's Strongest Material | NOVA | Science Documentary”.
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