Zirconia Toughened Alumina (ZTA)

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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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Property Charts & Safety Data Sheets
Property Charts	Zirconia Toughened Alumina (ZTA)
Master Ceramics Property Chart	Full Color Printer Friendly - Color Printer Friendly - B&W
Safety Data Sheets	Dense Zirconia Toughened Alumina (ZTA) Zirconia Toughened Alumina Powder (RTP)

Prime Features
Higher strength than alumina	Lower cost than zirconia
High corrosion resistance	High erosion resistance
High fracture toughness	Capable of a very fine surface finish

Typical Applications
Standoffs	Pump piston sleeves
Insulators	Instrument
Probe bodies	Sensor bulbs
Pump components	Valve seals
Bushings	Impellers
Fluid delivery system components	Analytical 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
	Property	ASTM Method	Units	ZTA-02 US Patent 8679995	ZTA-14	ZTA-20
General	Crystal Size (Average)	Thin Section	Microns	<2	6	3
	Color	--	--	Off White	White	White
	Gas Permeability	--	atms-cc/sec	gas tight <10^-10	gas tight <10^-10	gas tight <10^-10
	Water Absorption	C 20-97	%	0	0	0
Mechanical	Density	C 20-97	g/cc	3.96	4.17	4.30
	Hardness	Vickers 500gm	GPa (kg/mm²)	14 (1440)	14.5 (1478)	14.4 (1470)
	Hardness	--	R45N	81	82	82
	Fracture Toughness	Notched Beam	MPam^1/2	5	6	6
	Flexural Strength (MOR) (3 point) @ RT	F417-87	MPa (psi x 10³	448 (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 Modulus	C848	GPa (psi x 10⁶)	358 (52)	338 (49)	338 (49)
	Poisson's Ratio	C848	--	0.23	0.23	0.23
Thermal	C.T.E. 25 - 100° C	C 372-96	x 10^-6/C	6.7	6.0	6.0
	C.T.E. 25 - 300° C	C 372-96	x 10^-6/C	8.1	7.0	7.0
	C.T.E. 25 - 600° C	C 372-96	x 10^-6/C	8.3	7.1	7.1
	Thermal Conductivity @ RT	C 408	W/m K	27	24	24
	Max Use Temp	--	Fahrenheit (°F)	2732	2730	2730
	Max Use Temp	--	Celsius (°C)	1500	1500	1500
Electrical	Dielectric Strength (.125" Thick)	D 149-97A	V/mil	230	250	250
	Dielectric Constant @ 1 MHz	D 150-98	--	10.5	12.5	12.5
	Dielectric Constant	D 2520-95	--	--	--	12.4
	@ Gigahertz	D 2520-95	--	--	--	9.4
	Dielectric Loss @ 1 MHz	D 150-98	--	0.0003	0.0006	0.0006
	Dielectric Loss	D 2520-95	--	--	0.0005	0.0005
	@ Gigahertz	D 2520-95	--	--	9.4	9.4
	Volume Resistivity, 25°C	D 257	ohms-cm	> 1 x 10¹⁴	> 1 x 10¹⁴	> 1 x 10¹⁴
	Volume Resistivity, 300°C	D 1829	ohms-cm	3 x 10¹²	1 x 10¹⁰	1 x 10¹⁰
	Volume Resistivity, 500°C	D 1829	ohms-cm	6 x 10¹⁰	2 x 10⁹	2 x 10⁹
	Volume Resistivity, 700°C	D 1829	ohms-cm	6 x 10⁹	2 x 10⁸	4 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.

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