Article ID Journal Published Year Pages File Type
1415541 Carbon 2012 10 Pages PDF
Abstract

Alumina and titania coatings were deposited by atomic layer deposition onto carbon fibers at temperatures of 200 °C or below and reduced pressure. The coatings were smooth, uniform and conformed to the fiber surface. Thermogravimetric analysis (TGA) revealed that the coatings improved the oxidation resistance of the carbon fibers: the oxidation onset temperature of uncoated fibers and fibers coated with 66 nm of alumina was 630 °C. For fibers coated with 20 nm of titania it was 550 °C. Double layer coatings by 50 nm of alumina followed by 13 nm of titania yielded an oxidation onset temperature of 660 °C, while changing the order of the layers, i.e., coating fibers first with 20 nm of titania followed by 30 nm of alumina yielded an oxidation onset temperature of 750 °C. These TGA results were confirmed by a set of additional oxidation experiments conducted at a fixed temperature of 550 °C using a tube furnace in air. In this latter set of additional experiments, the times needed for a complete oxidation of the above mentioned samples were 8 h, 12 h, 10 h, 13 h, and 30 h, respectively.

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