Several studies have shown the importance of carbon fibres (CF) for different high technology markets. In recent years, different fibre types with improved properties have been developed for those markets. Polyacrylonitrile (PAN) copolymers are the basic raw material (precursor) for these fibres in the predominant case. Improvements of the mechanical fibre properties have mainly been achieved by defect reduction during the manufacturing process. Thus, commercial carbon fibres with tensile strengths up to approx. 7000 MPa are currently available. It can be shown that the strengths can be further increased (in the direction of graphene properties) when the relationship between process conditions and defects due to manufacturing of the fibres is better understood. In this context, novel processes like electron beam crosslinking or UV‐activation have proven to be very promising. The article gives an overview about the current situation in the field of carbon fibres development and particularly shows recent shortcomings with respect to novel applications.

No abstract

No abstract

No abstract

Freeze foaming is a method to manufacture cellular ceramic scaffolds with a hierarchical porous structure. These so-called freeze foams are predestined for the use as bone replacement material because of their internal bone-like structure and biocompatibility. On the one hand, they consist of macrostructural foam cells which are formed by the expansion of gas inside the starting suspension. On the other hand, a porous microstructure inside the foam struts is formed during freezing and subsequent freeze drying of the foamed suspension. The aim of this work is to investigate for the first time the formation of macrostructure and microstructure separately depending on the composition of the suspension and the pressure reduction rate, by means of appropriate characterization methods for the different pore size ranges. Moreover, the foaming behavior itself was characterized by in-situ radiographical and computed tomography (CT) evaluation. As a result, it could be shown that it is possible to tune the macro- and microstructure separately with porosities of 49–74% related to the foam cells and 10–37% inside the struts.