Thermal oxidation of high-modulus carbon fibers impregnated with potassium nitrate
✍ Scribed by Nadeshda Popovska
- Publisher
- Elsevier Science
- Year
- 1985
- Tongue
- English
- Weight
- 461 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0008-6223
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✦ Synopsis
A~~ract-~e~~ oxidation of ultra-high-modulus Sigrafil UHM-3 carbon fibers (C-fibers) was performed by using potassium nitrate as an oxidizing agent. The imp~gnat~n~ solution consisted of OS-10 wt% KNQ in a water/methanol (3:i) mixture. Thermal treatment of the impregnated C-fibers was performed at 400 or 800°C in nitrogen or air, respectively. Furthermore, the influence of a subsequent treatment with 60% sulfuric acid was investigated. The thermal treatment of the impregnated C-fibers in nitrogen caused no change in their mechanical properties, whereas in the case of treatments in air, fiber damage was observed as indicated by a decrease in the tensile strength as well as by an increase of the BET surface area. Therefore, further investigations were carried out in a nitragen atmosphere. An increase of the C-fibers' interlaminar shear strength (ILSS) from 22 to 40 MN/m' without loss of mech~ical properties was achieved by impregnation with solutions of <5 wt% KNO,. Impregnating solutions with higher concentrations damaged the fibers, however. A further increase of the ILSS to 57 MN/m2 was obtained by subsequent treatment after the salt decomposition step with 60% sulfuric acid. Key WordsCarbon fibers, carbon oxidation, surface treatment, interlaminar shear strength.