Alumina Textiles and Fibers, Type AL




  • Excellent Thermal Shock Resistance
  • 99% Pure Alumina
  • Trace Level of Silica (0.09 wt%)
  • Dimensional Stability in Hydrogen
  • Low Thermal Conductivity
  • No Outgassing
  • Six Different Product Formats Offered
  • Available ‘Off the Shelf’

Alumina (Al2O3) has excellent thermal shock resistance, high dimensional stability and
good chemical inertness, which makes our alumina fiber products ideal for fast firing cycles
up to 1700°C. Our alumina fibers and textiles are made by the same unique Zircar process
used for manufacturing yttria-stabilized zirconia cloths and felts. This process yields a high
purity alumina fiber with only trace amounts of silica, making it more stable in hydrogen environments than the more commonly found sol-gel alumina fibers that have 3% silica. Our
high purity alumina fiber and textiles are offered in six different standard product forms;
bulk fiber Type ALBF, two felts Types ALF-50 and ALF-100 and three types of knit cloth
Types ALK-15, ALW-15 and ALW-30.


  • Alumina fiber textiles are used as insulation for glass melting furnaces.
  • Alumina bulk fiber, Type ALBF, is used as bulk fill insulation.
  • Alumina fiber textiles are used as insulation for fiber optic furnaces.
  • Alumina fiber textiles are used in SOFC and PEM type fuel cells as gaskets.
  • Alumina fiber cloth is used as insulation in differential scanning calorimeters (DSC’s).

Alumina Cloth Type ALK-15 has the unique advantage of being a knit structure. This structure allows irregular shapes to be cut that do not unravel or fray. The SEM photomicrograph to the left shows the cut edge of Type ALK-15 and the individual filaments of the knit threads.
The SEM photomicrograph above shows individual fibers arranged mostly parallel to each other in a thread. These filaments show the serrated nature of all “Zircar Process” fibers.
The SEM photomicrograph to the left shows the end of an individual fiber in Type ALK-15. The individual submicron crystallites which make up the near theoretical density fiber can be seen clearly. Fiber diameter is approximately 6 microns


ALF-100 ALK-15
Nominal Composition, Wt%
Al2O3 99+ 99+
ZrO2 & HfO2 0.42 0.42
SiO2 0.09 0.09
CaO 0.06 0.06
Melting Point, °C (°F) 2015 (3630) 2015 (3630)
Bulk Porosity, % 97 88
Bulk Density, g/cc (pcf) 0.13 (8) 0.49 (31)
Tensile Strength, g/cm width (lb/inch width) 49 (0.28) 116 (0.65)
Loss on Ignition, 1 hr at 950°C (1742°F), Wt% 3.8 1.4
Outgassing Nil Nil
% Shrinkage, 1 hour at 1650°C (3002°F) 15 7


Type AL Fibers and Textiles are available in six standard product forms, which are listed in
the table below with their ordering item number. Please contact our Sales Department for
pricing and availability.

Standard Sizes Item Number
ALF-50, FELT, 12″X 12″X ~0.05″ E01A01
ALF-100, FELT, 12″X 12″X ~0.1″ E01B01
ALK-15, TRICOT KNIT CLOTH, 12″X 12″X ~0.015″ E01C01
ALW-15, SQUARE WEAVE CLOTH, 12″X 12″X ~0.015″ E01D01
ALW-30, SATIN WEAVE CLOTH, 12″X 12″X ~0.03″ E01E01
ALBF, BULK FIBER, 1 pound E01F01

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