Jan 6 2004
Background
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 ( g.cm-3 ) |
3.05 |
| Refractive index |
1.62 |
| Thermal Properties |
| Coefficient of thermal expansion ( x10-6 K-1 ) |
5 @ 20-1000 °C |
| Specific heat ( J.K-1.kg-1 ) |
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 |
g.cm-3 |
3.05 |
| Modulus |
GPa |
180 |
| Tenacity |
GPa |
2.0 |
About Goodfellow
Goodfellow supplies metals, ceramics and other materials to meet the research, development and specialist production requirements of science and industry worldwide.
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