The stabilisation of carbon fibres studied by micro-thermal analysis Original Research Article

Micro-thermal analysis, or local thermal analysis, is a relatively new technique that combines the imaging capabilities of atomic force microscopy with the physical characterisation capabilities of thermal analysis. This paper reports the application of this technique in a study of the stabilisation process of pitch-based carbon fibres. The technique allowed the determination of softening temperature profiles across model large diameter fibres, as a function of the stabilisation degree. The changes in the softening temperatures promoted by the stabilisation were related to the local oxygen content of the fibre measured by electron probe micro-analysis (EPMA). The depth of the stabilised region was also determined. The results obtained indicate that the higher temperatures studied (180–200 °C) promoted a rapid oxidation of the outer region of the fibre, which acts as a surface diffusion barrier for oxygen, longer times being required for full-stabilisation of the fibres.