Zirconia Toughened Alumina - ZTA
Components manufactured from Zirconia Toughened Alumina (ZTA)
show considerable improvement in strength and toughness over
alumina engineering ceramics.
The increase in strength and toughness in ZTA is attributable
to the stress induced transformation toughening mechanism which
is introduced with the addition of optimized amounts of fine
zirconia particles dispersed thoughout the alumina body.
Typical zirconia content is between 10% and 20%. As a crack
grows through the ceramic, the crystal structure of the zirconia
particles in the region of the crack changes from the metastable
tetragonal phase to the stable monoclinic phase.
The change increases the volume of the particles by about 3-4%
and produces compressive stresses in the alumina matrix. These
stresses in turn close the crack and act as an energy barrier
to further crack growth. The addition of zirconia to the alumina
matrix increases fracture toughness by two times and can be
improved by as high as four times, while strength is more than
doubled.
Key Properties
- Excellent mechanical properties
- Wear resistance
- High temperature stability
- Corrosion resistance
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Applications
ZTA components are more expensive than those in alpha alumina.
However, increased component life and performance result in cost
effective solutions for demanding environments.
Applications include:
- Bearing components (balls, rollers and raceways)
- Bushings
- Die and cutting tool inserts (replacing carbide and
metal tool inserts)
- Valve seats
- Pump components
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