Zirconia Toughened Alumina (ZTA)

Zirconia Toughened Alumina, (ZTA) is often used in wear applications as an intermediate solution between alumina and zirconia

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> Zirconia Increases Strength

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.

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Prime Features
Higher strength than aluminaLower cost than zirconia
High corrosion resistanceHigh erosion resistance
High fracture toughnessCapable of a very fine surface finish
Typical Applications
StandoffsPump piston sleeves
InsulatorsInstrument
Probe bodiesSensor bulbs
Pump componentsValve seals
BushingsImpellers
Fluid delivery system componentsAnalytical instrument columns
Application Limitations
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.
Materials Property Chart
 Zirconias
 PropertyASTM MethodUnitsZTA-02 US Patent 8679995ZTA-14ZTA-20
GeneralCrystal Size (Average)Thin SectionMicrons<263
Color----Off WhiteWhiteWhite
Gas Permeability--atms-cc/secgas tight <10-10gas tight <10-10gas tight <10-10
Water AbsorptionC 20-97%000
MechanicalDensityC 20-97g/cc3.964.174.30
HardnessVickers 500gmGPa (kg/mm2)14 (1440)14.5 (1478)14.4 (1470)
Hardness--R45N818282
Fracture ToughnessNotched BeamMPam1/2566
Flexural Strength (MOR)
(3 point) @ RT
F417-87MPa (psi x 103448 (65)586 (85)620 (90)
Tensile Strength @ RT--MPa (psi x 103)259 (38)344 (50)350 (51)
Compressive Strength @ RT--MPa (psi x 103)2413 (350)2758 (400)2758 (400)
Elastic ModulusC848GPa (psi x 106)358 (52)338 (49)338 (49)
Poisson's RatioC848--0.230.230.23
ThermalC.T.E. 25 - 100° CC 372-96x 10-6/C6.76.06.0
C.T.E. 25 - 300° CC 372-96x 10-6/C8.17.07.0
C.T.E. 25 - 600° CC 372-96x 10-6/C8.37.17.1
Thermal Conductivity @ RTC 408W/m K272424
Max Use Temp--Farenheit (°F)273227302730
--Celsius (°C)150015001500
ElectricalDielectric Strength (.125" Thick)D 149-97AV/mil230250250
Dielectric Constant @ 1 MHzD 150-98--10.512.512.5
Dielectric ConstantD 2520-95------12.4
@ GigahertzD 2520-95------9.4
Dielectric Loss @ 1 MHzD 150-98--0.00030.00060.0006
Dielectric LossD 2520-95----0.00050.0005
@ GigahertzD 2520-95----9.49.4
Volume Resistivity, 25°CD 257ohms-cm> 1 x 1014> 1 x 1014> 1 x 1014
Volume Resistivity, 300°CD 1829ohms-cm3 x 10121 x 10101 x 1010
Volume Resistivity, 500°CD 1829ohms-cm6 x 10102 x 1092 x 109
Volume Resistivity, 700°CD 1829ohms-cm6 x 1092 x 1084 x 108
Note: The information in this data sheet is for design guidance only. STC does not warrant this data as absolute values. Forming methods and specific geometry could affect properties. Slight adjustments can be made to some of the properties to accommodate specific customer requirements. Most of the dense materials in the table are resistant to mechanical erosion and chemical attack. STC has performed ASTM testing qualification for certain compositions, in accordance with ASTM D2442. Please consult our technical staff for appropriate material and specific test results.