Alumina / Silica / Boria - Al2O3 70/SiO2 28/B2O3 2 - Supplier Data by Goodfellow


Nextel® 440 and Nextel® 312 are two similar materials - compositions of ceramic specially developed for the production of continuous filament yarns which are sufficiently flexible to manufacture conventional textile articles such as fabrics and sewing threads whilst retaining much of the high temperature and chemical resistance typical of ceramics.

Nextel® 440 has somewhat better tensile properties and a higher upper working temperature but is less flexible than Nextel® 312 and is available from Goodfellow as a yarn.

The fibres are coated with finishes during manufacture which can be removed, if desired, by “heat cleaning” at about 550 °C. If the best possible properties are required, further heat treatment at about 1215 °C should be used. More details of recommended treatment methods are available on request.

Key Properties

The key properties of Nextel® 440 and Nextel® 312 are provided in Table 1.

Table 1. Key Properties

Chemical Resistance
Acids - concentrated Fair
Acids - dilute Good
Alkalis Poor-Fair
Electrical Properties
Dielectric constant 5.7 @ 9.4 GHz
Mechanical Properties
Tensile modulus ( GPa ) 185
Tensile strength ( MPa ) 2000
Physical Properties
Density ( ) 3.05
Refractive index 1.62
Thermal Properties
Coefficient of thermal expansion ( x10-6 K-1 ) 5 @ 20-1000 °C
Specific heat ( ) 1000 @ 500 °C
Sublimation point (°C ) 1800
Upper continuous use temperature (°C ) 1350-1650
Properties Alumina/Silica/Boria Fibre
Property Value
Coefficient of thermal expansion - Longitudinal x10-6 K-1 4.4
Density 3.05
Modulus GPa 180
Tenacity GPa 2.0

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Goodfellow supplies metals, ceramics and other materials to meet the research, development and specialist production requirements of science and industry worldwide.

Source: Goodfellow

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