Abstract
Defects play a significant role in the material properties of carbon fibers (CF). Several defects result in the formation of sp3 bonds in an otherwise sp2-dominant graphitic structure. Understanding the distribution of these defects within CF provides insight into their properties and the effect of manufacturing conditions. Reports showed time-of-flight secondary ion mass spectrometry (ToF-SIMS) is capable of characterizing the spatial distribution of sp2 and sp3 content in carbon materials. Here, ToF-SIMS was utilized to investigate the spatial distribution of sp3 defects in T700, T1000, and M46 CF. M46 had the lowest sp3 content. Center-to-edge analysis revealed that T700 CF had a gradient of sp3 defects starting from the center and increasing to the edge, whereas M46 CF had a sudden increase in sp3 defects roughly 1 μm from the edge. Comparatively, T1000 CF had a relatively uniform radial distribution of sp3 defects, except for a newly identified sp2 rich region at 0.8 μm from the center. This is hypothesized to originate from a skin–core structure that forms during CF manufacturing. This work demonstrates the utility of ToF-SIMS for characterizing the spatial distribution of sp3 defects within CF, establishing new ways to understand CF formation.
