TITANIUM DIOXIDE - TITANIA ( TIO2)
|Property||Units (S.I.)||Minimum Value (S.I.)||Maximum Value (S.I.)|
|Atomic Volume (average)||m3/kmol||0.0057||0.007|
|Modulus of Rupture||MPa||140||441.2|
|Maximum Service Temperature||K||1840||1910|
ZTA (Zirconia Toughened Alumina)
The main advantage of Zirconia Toughened Alumina (ZTA) is the additional strength and toughness over alumina with a lower cost than zirconia (YTZP, MSZ, CSZ).
The combination of aluminum oxide and 10-20% zirconium oxide provides a much higher strength, toughness, hardness and wear resistance than alumina alone.
The 20-30% increase in strength often provides the design criteria needed at a much lower cost than using zirconia.
A process called transformation toughening is the phenomenon that increases the fracture toughness of ZTA. When placed under stress, the zirconia particles change their crystal structure from a tetragonal to a monoclinic structure, causing a volume expansion that compresses the surrounding crack in the alumina matrix.
ZTA should be considered for any application where structural strength is needed that exceeds the standard alumina properties.
|Higher strength than alumina||Lower cost than zirconia|
|High corrosion resistance||High erosion resistance|
|High fracture toughness||Capable of a very fine surface finish|
|Standoffs||Pump piston sleeves|
|Probe bodies||Sensor bulbs|
|Pump components||Valve seals|
|Fluid delivery system components||Analytical instrument columns|
|ZTA does provide a higher strength than alumina but the temperature limitation of 1500 C (2732 F) must be observed. Above this temperature the strength contribution of the zirconia is reduced.||Use in moist environments at temperatures above 250C also must be carefully considered as the zirconia is subject to low temperature degradation.|