Alumina

ALUMINA

Almath Crucibles offer a variety of alumina products, including Crucibles, tubes and plates. We are also able to produce alumina furnaceware. Our Alumina products have a maximum operating temperature of 1750°C, making them ideal for high temperature applications.

Our high purity (Al₂O₃ content > 99%) ceramics are purpose built to perform across a wide range of high temperature applications. We use recrystallized alumina in the production of our crucibles as the material offers impressive thermal shock resistance, this is due to the larger grain size (up to 200µm (microns) is advantageous).

Our high purity alumina shows considerable resistance to chemical attack due to the lack of glassy phases that tend to determine corrosion resistance.

For more information on Alumina (Aluminium Oxide) material, check out its wiki page.

The electrical and dielectrical properties of the material generally improve with increased purity. Electrical resistance is greatest and dielectrical loss factor is lowest in materials of highest alumina content.

High purity Alumina produces a dense and essentially single-phase ceramic on sintering. Grain growth during sintering can be controlled by small additions of MgO up to 0.05%. Our product usually contains a small amount of closed porosity but this can be kept below 0.5% using modern firing techniques.

View the material safety datasheet by clicking the button below.

VIEW MSDS

Material Properties

Please note that the information set forth herein is offered for comparison only, and is not to be construed as absolute engineering data or constituting a warranty or representation for which we assume legal responsibility.

Property	Unit	Test	Alumina 99.5%	Alumina 99.6%	Alumina 99.8%
Density	g.cc-1	ASTM C20	3.8	3.9	3.9
Colour	**	**	WHITE	IVORY	IVORY
Elastic Modulus	GPa	ASTM C848	350	370	350
Flexural Strength	MPa	ASTM F417	375	379	360
Compressive Strength	MPa	ASTM C773	2500	2600	2400
Fracture Toughness Range	Mpa	NOTCHED BEAM	4-5	4-5	4-5
Hardness	GPa	ROCKWELL 45N	82	83	83
Thermal Conductivity	W/mK	ASTM C408	27.5	30	30
CTE 25-1000	10(-6)/0C	ASTM C372	8.2	8.2	8.2
Thermal Shock	delta Tc	NOTE3	200	200	200
Dielectric Strength	ac-kv/mm (6.25mm)	ASTM D116	8.7	8.7	8.7
Dielectric Loss	250C@1MHz	ASTM D2520	0.0002	0.0001	0.001
Volume Resistivity	1000C ohm-cm	ASTM D1829	2×10^6	2×10^6	5×10^7

DATA MEASUREMENTS – All data measurements are typical and made at room temperature unless otherwise noted.
THERMAL SHOCK RESISTANCE – Tests are run by quenching samples into water from various elevated temperatures. The change in temperature where a sharp decrease in flexural strength is observed is listed as ‘delta Tc’.
CHEMICAL RESISTANCE – Although all alumina and zirconia ceramics are highly resistant to chemical attack, it is recommended that specific applications are discussed with Almath Crucibles to ensure optimum ceramic selection.