C haptEr 9 design Environments and systems
300
has led to increases in fracture toughness, strength, and creep as
well as resistance to oxidation and thermal shock. Improvements of
around 50% in fracture toughness and 200% in strength have been
observed in alumina reinforced with SiC. Furthermore, enhancements in tensile creep by two or three orders of magnitude were
also measured for the same material. In most cases, the reinforcing phase is a ceramic material, such as nanoparticles of silicon
carbide, alumina, zirconia, and silicon nitrate, although metallic
reinforcements can be also used. Some examples include nanoparticles of iron (Fe), tungsten (W), molybdenum (Mo), nickel (Ni)
copper (Cu), and cobalt (Co). In general, metallic fillers are used
to improve magnetic, electrical, and optical properties. However,
in some cases, the addition of metallic reinforcements can affect
the mechanical properties because they create a connected network
with consequences for plastic deformation.
General applications include many types of hard coatings with
high temperature capabilities, a number of different applications
in electronics (such as semiconductor products), oral dentifrices,
and many others. Wear- and corrosion-resistant coating materials based on nanostructured ceramic composites promise to have
many applications in structures, vehicles, aircraft, and similar settings. Bioceramics are being explored for many medical implant
applications.
amorphous materials
In Section 7.3, amorphous materials were described as an extreme
class of nanostructured matter. As crystal sizes shrink atomic
dimensions, the material becomes completely disordered. Ordinary glass is amorphous and is known for its unique properties.
Other highly disordered materials with similar structures, such as
polymers or metallics, are possible as well and are often also called
glasses. Section 7.3 pointed out that these kinds of amorphous
materials can have remarkably high strength and stiffness properties. Indeed, amorphous materials can approach the fundamental
limit of strength.
Successful applications of this class of nanosolid in mechanical
environments have come about, including:
■ Tooling, particularly knife edges. The high hardness (a direct
consequence of the high strength) suggests use in precision
tooling. The lack of microstructure allows a blade to be sharpened to an exceptional edge because there is no length scale
above the atomic to limit it.
300
has led to increases in fracture toughness, strength, and creep as
well as resistance to oxidation and thermal shock. Improvements of
around 50% in fracture toughness and 200% in strength have been
observed in alumina reinforced with SiC. Furthermore, enhancements in tensile creep by two or three orders of magnitude were
also measured for the same material. In most cases, the reinforcing phase is a ceramic material, such as nanoparticles of silicon
carbide, alumina, zirconia, and silicon nitrate, although metallic
reinforcements can be also used. Some examples include nanoparticles of iron (Fe), tungsten (W), molybdenum (Mo), nickel (Ni)
copper (Cu), and cobalt (Co). In general, metallic fillers are used
to improve magnetic, electrical, and optical properties. However,
in some cases, the addition of metallic reinforcements can affect
the mechanical properties because they create a connected network
with consequences for plastic deformation.
General applications include many types of hard coatings with
high temperature capabilities, a number of different applications
in electronics (such as semiconductor products), oral dentifrices,
and many others. Wear- and corrosion-resistant coating materials based on nanostructured ceramic composites promise to have
many applications in structures, vehicles, aircraft, and similar settings. Bioceramics are being explored for many medical implant
applications.
amorphous materials
In Section 7.3, amorphous materials were described as an extreme
class of nanostructured matter. As crystal sizes shrink atomic
dimensions, the material becomes completely disordered. Ordinary glass is amorphous and is known for its unique properties.
Other highly disordered materials with similar structures, such as
polymers or metallics, are possible as well and are often also called
glasses. Section 7.3 pointed out that these kinds of amorphous
materials can have remarkably high strength and stiffness properties. Indeed, amorphous materials can approach the fundamental
limit of strength.
Successful applications of this class of nanosolid in mechanical
environments have come about, including:
■ Tooling, particularly knife edges. The high hardness (a direct
consequence of the high strength) suggests use in precision
tooling. The lack of microstructure allows a blade to be sharpened to an exceptional edge because there is no length scale
above the atomic to limit it.