High Purity Alumina (99.5%, 99.8%, 99.96%)

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> High Purity (99.96%) Alumina Ceramics

Alumina (Al2 O3) is a common workhorse material in the world of technical ceramics and is utilized in an extensive variety of industries and applications. Alumina’s material properties offer electrical isolation, wear resistance, high temperature resistance, and good mechanical strength. STC’s fully dense, 99.5%, 99.8% and 99.96% alumina bodies offer improved performance over lower purity alumina ceramics in demanding operating conditions.

Our High purity aluminas make for improved corrosion resistance due to lower impurity/silica content. Higher hardness, increased dielectric strength, and in some cases, superior flexural strength. Finer grain sizes also allow for smooth surface finishes. The grade of alumina is selected to best fit the application.

Of our high purity aluminas our 99.96% material exhibits superior flexural strength and dielectric strengths making them excellent candidates for thin walled parts in high-voltage applications.

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Property Charts & Safety Data Sheets
Property Charts	Alumina (High Purity)
Master Ceramics Property Chart	Full Color Printer Friendly - Color Printer Friendly - B&W
Safety Data Sheets	Alumina AL-33R Bisque Alumina Ceramic Dense Alumina Ceramic Spray Dried Alumina Powder (RTP) Unfired Alumina Powder

Prime Features
High Mechanical Strength	High Temperature Resistance
High Wear Resistance	Excellent Corrosion Resistance
Excellent Dielectric Strength	Suitable For food applications
low dielectric loss	bio-inert

Typical Applications
High Strength, Thin Walled Components	Mass Spec Components
End Effectors	Precision Valve Seats And Seals
bio compatible parts	pump pistons and sleeves
high voltage dielectric parts	food compatible parts
semiconductor components

Materials Property Chart

		High Purity Alumina
	Property	ASTM Method	Units	AL995 99.5%	AL9980 99.8%	AL9996 99.96%
General	Crystal Size (Average)	Thin Section	Microns	6	6	2
	Color	--	--	Ivory - White	Ivory	Off White/Blush
	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	3.88	3.91	3.93
Hardness		Vickers 500gm	GPa (kg/mm²)	14.3 (1459)	15 (1530)	19.6 (2000)
Hardness		--	R45N	82	86	90
Fracture Toughness		Notched Beam	MPam^1/2	4 - 5	3 - 4	5 - 6
Flexural Strength (MOR) (3 point) @ RT		F417-87	MPa (psi x 10³	338 (49)	379 (55)	455 (66)
Tensile Strength @ RT		--	MPa (psi x 10³)	172 (25)	200 (29)	275 (40)
Compressive Strength @ RT		--	MPa (psi x 10³)	2137 (310)	2240 (325)	2413 (350)
Elastic Modulus		C848	GPa (psi x 10⁶)	379 (55)	379 (55)	393 (57)
Poisson's Ratio		C848	--	0.23	0.23	0.23
Thermal	C.T.E. 25 - 100° C	C 372-96	x 10^-6/C	6.3	6.5	6.5
	C.T.E. 25 - 300° C	C 372-96	x 10^-6/C	6.9	7.9	7.9
	C.T.E. 25 - 600° C	C 372-96	x 10^-6/C	7.6	8.1	8.2
	Thermal Conductivity @ RT	C 408	W/m K	30	30	35
	Max Use Temp	--	Fahrenheit (°F)	3047	3047	3100
	Max Use Temp	--	Celsius (°C)	1675	1675	1700
Electrical	Dielectric Strength (.125" Thick)	D 149-97A	V/mil	270	290	422
	Dielectric Constant @ 1 MHz	D 150-98	--	9.8	9.8	9.9
	Dielectric Constant	D 2520-95	--	9.7	10	--
	@ Gigahertz	D 2520-95	--	9.8	9.6	--
	Dielectric Loss @ 1 MHz	D 150-98	--	0.0002	< .0001	< .0001
	Dielectric Loss	D 2520-95	--	< .0001	< .0001	--
	@ Gigahertz	D 2520-95	--	9.8	9.6	--
	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	1 x 10¹²	3 x 10¹²	1 x 10¹³
	Volume Resistivity, 500°C	D 1829	ohms-cm	5 x 10¹⁰	6 x 10¹⁰	5 x 10¹²
	Volume Resistivity, 700°C	D 1829	ohms-cm	2 x 10⁹	6 x 10⁹	1 x 10¹²

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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