Standard Alumina (74%, 95%, 96%, 98%)

Aluminum Oxide, or alumina, is the most common technical ceramic material used today. The versatility of alumina stems from its broadly impressive material properties, ease of manufacture, wide availability, and budget-friendly cost. STC produces a range of alumina purity from 74% alumina to 99.96% alumina - these bodies are the industry work-horse materials for applications that require electrical isolation, wear resistance, high temperature resistance, and good mechanical strength.

Alumina sees application from aerospace to medical, from bearings to analytical instrumentation, from electrical standoffs to semiconductor processing. In addition, these materials lend themselves well to be hermetically sealed to metals through metallizing and brazing methods.

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Property Charts & Safety Data Sheets
Property Charts	Alumina (Standard)
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
Performs well in corrosive environments

Typical Applications
Structural ceramic parts	Aerospace
Medical	Bearings
Analytical instrumentation

Materials Property Chart

		Aluminas
	Property	ASTM Method	Units	AL74 74%	AL95 95%	AL96 96%	AL98 98%
General	Crystal Size (Average)	Thin Section	Microns	13	11	8	7
	Color	--	--	White	Ivory	White Or Purple	White
	Gas Permeability	--	atms-cc/sec	gas tight <10^-10	gas tight <10^-10	gas tight <10^-10	gas tight <10^-10
	Water Absorption	C 20-97	%	0	0	0	0
	Mechanical	Density	C 20-97	g/cc	3.03	3.65	3.71	3.78
Hardness		Vickers 500gm	GPa (kg/mm²)	10.5 (1075)	11.5 (1175)	12.7 (1300)	12.7 (1300)
Hardness		--	R45N	78	79	81	81
Fracture Toughness		Notched Beam	MPam^1/2	2 - 5	3 - 4	4 - 5	4 - 5
Flexural Strength (MOR) (3 point) @ RT		F417-87	MPa (psi x 10³	241 (35)	310 (45)	358 (52)	393 (57)
Tensile Strength @ RT		--	MPa (psi x 10³)	117 (17)	151 (22)	200 (29)	221 (32)
Compressive Strength @ RT		--	MPa (psi x 10³)	1378 (200)	1827 (265)	2068 (300)	2241 (325)
Elastic Modulus		C848	GPa (psi x 10⁶)	172 (25)	303 (44)	310 (45)	345 (50)
Poisson's Ratio		C848	--	0.22	0.22	0.22	0.23
Thermal	C.T.E. 25 - 100° C	C 372-96	x 10^-6/C	5.5	6.1	6.0	6.2
	C.T.E. 25 - 300° C	C 372-96	x 10^-6/C	5.8	7.0	6.8	6.8
	C.T.E. 25 - 600° C	C 372-96	x 10^-6/C	6.3	7.7	7.5	7.6
	Thermal Conductivity @ RT	C 408	W/m K	4	19	23	29
	Max Use Temp	--	Fahrenheit (°F)	2800	3000	3100	3100
	Max Use Temp	--	Celsius (°C)	1540	1650	1700	1700
Electrical	Dielectric Strength (.125" Thick)	D 149-97A	V/mil	225	250	250	260
	Dielectric Constant @ 1 MHz	D 150-98	--	7.0	9.0	9.1	9.5
	Dielectric Constant	D 2520-95	--	--	9.2	9.1	9.4
	@ Gigahertz	D 2520-95	--	--	11.0	10.9	9.8
	Dielectric Loss @ 1 MHz	D 150-98	--	0.0012	0.0006	0.0004	0.0006
	Dielectric Loss	D 2520-95	--	--	0.0009	0.0007	0.0005
	@ Gigahertz	D 2520-95	--	--	12.5	10.9	9.8
	Volume Resistivity, 25°C	D 257	ohms-cm	< 1 x 10¹³	> 1 x 10¹⁴	> 1 x 10¹⁴	> 1 x 10¹⁴
	Volume Resistivity, 300°C	D 1829	ohms-cm	4 x 10¹⁰	5 x 10¹²	3 x 10¹²	8 x 10¹¹
	Volume Resistivity, 500°C	D 1829	ohms-cm	3 x 10⁷	3 x 10⁹	7 x 10⁹	2 x 10⁹
	Volume Resistivity, 700°C	D 1829	ohms-cm	2 x 10⁶	3 x 10⁸	4 x 10⁸	2 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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