Embrittlement
Embrittlement is a loss of ductility of a material, making it brittle. Various materials have different mechanisms of embrittlement.
- Hydrogen embrittlement is the effect of hydrogen absorption on some metals and alloys.
- Sulfide stress cracking is the embrittlement caused by absorption of hydrogen sulfide.
- Liquid metal embrittlement (LME) is the embrittlement caused by liquid metals.
- Metal-induced embrittlement (MIE) is the embrittlement caused by diffusion of atoms of metal, either solid or liquid, into the material.
- Neutron radiation causes embrittlement of some materials, neutron-induced swelling, and buildup of Wigner energy. This is a process especially important for neutron moderators and nuclear reactor vessels (see ductility).
- The primary embrittlement mechanism of plastics is gradual loss of plasticizers, usually by overheating or aging.
- The primary embrittlement mechanism of asphalt is by oxidation, which is most severe in warmer climates. Asphalt pavement embrittlement can lead to various forms of cracking patterns, including longitudinal, transverse, and block (hexagonal). Asphalt oxidation is related to polymer degradation, as these materials bear similarities in their chemical composition.
Cryogenic embrittlement
Around cryogenic temperatures plastics and rubbers become brittle, which is known as the embrittlement temperature.
| Material | Temperature [°F] | Temperature [°C] |
|---|---|---|
| Plastics | ||
| ABS | −270 | −168 |
| Acteal? | −300 | −184.4 |
| Delrin | -275 to -300 | -171 to -184 |
| Nylon | -275 to -300 | -171 to -184 |
| Polytron | −300 | −184.4 |
| Polypropylene | -300 to -310 | -184 to -190 |
| Teflon | −275 | −171 |
| Rubbers | ||
| Buna-N | −225 | −143 |
| EPDM | -275 to -300 | -171 to -184 |
| Ethylene propylene | -275 to -300 | -171 to -184 |
| Hycar | -210 to -275 | -134 to -171 |
| Natural rubber | -225 to -275 | -143 to -171 |
| Neoprene | -225 to -300 | -143 to -184 |
| Nitrile | -275 to -310 | -171 to -190 |
| Nitrile-butadiene (ABS) | -250 to -270 | -157 to -168 |
| Silicone | −300 | −184.4 |
| Urethane | -275 to -300 | -171 to -184 |
| Viton | -275 to -300 | -171 to -184 |
| Metals | ||
| Zinc | −200 | −129 |
| Steel | −100 | −73 |
See also
References
- ↑ Gillespie, LaRoux K. (1999), Deburring and edge finishing handbook, SME, pp. 196–198, ISBN 978-0-87263-501-2.
This article is issued from Wikipedia - version of the Saturday, March 19, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.