Topics Covered Background
How the Toughening Mechanism Works in ZTA
Key Properties
Applications Background 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.
How the Toughening Mechanism Works in ZTATypical 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
ApplicationsZTA 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