NDE of microstructured materials by x-ray diffraction and refraction topography
For the purpose of micro structural characterization X-ray topography reveals the spatially resolved scattering of materials and small components. It combines the advantages of radiographic imaging and the analytical information of wide and small angle X-ray scattering like phase distribution, texture, micro cracks, interfaces and pores. Scanning techniques at selected scattering conditions permit the topographic characterization of any crystalline or amorphous solid or liquid. Topographic methods and applications for the purposes of research, quality control and damage evaluation are presented.
Synchrotron radiation (hard) X-ray diffraction microscopy of carbon fibre reinforced plastic (CFRP)
Abstract A simple “straight through” (hard) synchrotron radiation (SR) X-ray diffraction microscope of spatial resolution ≈ 25 μm (for photon energies ≈ 8 keV) is described for the bulk examination of an advanced material, carbon fibre reinforced plastic (CFRP).
Carbon fibre compressive strength and its dependence on structure and morphology
The axial compressive strength of carbon fibres varies with the fibre tensile modulus and precursor material. While the development of tensile modulus and strength in carbon fibres has been the subject of numerous investigations, increasing attention is now being paid to the fibre and the composite compressive strength. In the present investigation, pitch- and PAN-based carbon fibres with wide-ranging moduli and compressive strengths were chosen for a study of fibre structure and morphology. A rayon-based carbon fibre was also included in this study. Structural parameters (Lc, La(0), La(90), orientation parameter Z, and the spacing between graphitic planes d(00, 2)) were determined from wide angle X-ray spectroscopy (WAXS). Fibre morphology was characterized using high-resolution scanning electron microscopy (HRSEM) of fractured fibre cross-sections. The mechanical properties of the fibres, including compressive strength, the structural parameters from WAXS, and the morphology determined from HRSEM are reported. The influence of structure and morphology on the fibre compressive strength is discussed. This study suggests that the width of the graphitic sheets, the crystallite size perpendicular to the fibre axis (Lc and La(0)), and crystal anisotropy play significant roles in accounting for the large differences in compressive strengths of various carbon fibres.