Alumina Ceramic Fiber and Textile Products ( Al2O3 ) from Zircar Zirconia

Topics Covered

Background
Product Overview
Properties
Application Information
Microstructure of Zircar Zirconia’s Alumina Ceramic Fiber

Background

Typical features of ZIRCAR Zirconia’s Type AL Alumina Ceramic Fibers and Textiles include:

  • 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’

Figure 1. Face of Alumina Knit Cloth Type ALK-15 at 6.

Product Overview

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. Zircar's 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. Zircar's 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.

Properties

Property

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, 1hr @ 950°C (1742°F), wt %

3.8

1.4

Outgassing

Nil

Nil

% Shrinkage 1hr at 1650°C (3002°F)

15

7

Application Information

  • 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).

Microstructure of Zircar Zirconia’s Alumina Ceramic Fiber

Zircar’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 in figure 2 shows the cut edge of Type ALK-15 and the individual filaments of the knit threads.

Figure 2. Micrograph of Alumina Cloth Type ALK-15

The SEM photomicrograph in figure 3 shows individual fibers arranged mostly parallel to each other in a thread. These filaments show the serrated nature of all “Zircar Process” fibers.

Figure 3. Micrograpgh showing the parallel nature of the alumina fibers.

The SEM photomicrograph to the in figure 4 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.

Figure 4. SEM photomicrograph showing the end of an individual fiber in Type ALK-15.

Date Added: Nov 7, 2005 | Updated: Jun 11, 2013
Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit