Alumina ceramics

Dr. Dmitri Kopeliovich

Alumina (aluminum oxide) is the most important, widely used and cost effective oxide ceramic material.

The technical alumina ceramics contain at least 80% of aluminum oxide (AL₂O₃).

Small amounts of silica (SiO₂), magnesia (MgO) and zirconia (ZrO₂) may be added to alumina ceramics.

Addition of zirconia to alumina ceramic results in considerable increase of the material fracture toughness.

Alumina possesses strong ionic bonding, which determines the material properties:

• High mechanical strength (flexural strength) and hardness;

• High wear resistance;

• High resistance to chemical attacks of strong acids and alkali even at high temperatures;

• High stiffness;

• Excellent insulating properties;

• Low coefficient of thermal expansion;

• Good fracture toughness;

• Good thermal conductivity;

• Good biocompatibility.

Aluminum ceramics parts are manufactured by the following technologies: uniaxial (die) pressing, isostatic pressing, injection molding, extrusion and slip casting. The parts may be machined in "green" condition before sintering (firing).

Aluminum ceramics are widely used in electronics and electrical engineering, metallurgical processes, chemical technologies, medical technologies, mechanical engineering, military equipment.

Aluminum ceramics are used for manufacturing insulators, capacitors, resistors, furnace tubes, sealing refractory parts, foundry shapes, wear pads, thermocouple protection tubes, cutting tools and polishing/grinding powders, ballistic armor, laboratory equipment, bio-ceramic parts for orthopedic and dental surgery, bearings.

(Materials Data)

• Alumina ceramic (94% alumina)
• Alumina ceramic (97.5% alumina)
• Alumina ceramic (99.8% alumina)
• Alumina aerogel monolith

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• Magnesia ceramics
• Zirconia ceramics
• Aluminum titanate ceramics
• Synthetic sapphire
• Wear resistant alumina coatings
• Bayer process
• Materials for joint prostheses
• Sol-Gel process

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