Sol–Gel Transition in Nanodiamond Aqueous Dispersions by Small-Angle Scattering

This paper reports the results of the comparative structural characterization of detonation nanodiamond particles and their aggregates in hydrosols and hydrogels by small-angle scattering (SAS) techniques. The data from different neutron and X-ray (synchrotron radiation) diffractometers cover a wide range of momentum transfer and show multilevel structure organizations at the size scale from 1 to 1000 nm and higher. For this purpose, in addition to the conventional SAS techniques the methods of very small-angle and ultrasmall-angle neutron scattering were applied. The fraction of nanodiamond particles in the aggregates is determined. A complex two-step mechanism of nanodiamond cluster association into a network during the sol–gel transition is revealed. It is assumed that a reason for the reversibility of this process is a different compactness of the corresponding structural levels defined by different fractal organizations

Neutron investigation of Nitinol stents and massive samples before and after PIRAC coating

Nitinol, a thermoelastic Ni-Ti Shape Memory Alloy (SMA) with approximately 50 at. % Ti, is adopted in a wide range of medical equipment and devices used in interventional radiology, orthopaedics, neurology and cardiology, in particular as a smart material for stents. In this work, NiTi real stents and massive samples before and after different Powder Immersion Reaction Assisted Coating (PIRAC) treatments have been investigated by using two neutron techniques: (1) Small and Ultra-Small Angle Neutron Scattering (SANS, USANS) for nano- and micro-scale characterization, obtaining information on structure and the effects due to the coating treatment; and (2) High-Resolution Neutron Diffraction (HRND), evaluating the macrostrain components resulting from angular shifts of diffraction peaks and the micro-strains in the plastically deformation region by means of profile-broadening analysis. The obtained results contribute: improving knowledge of defects and other key features of the materials complementary to those achieved by using traditional examination techniques; helping to better understand the functional characteristics of Nitinol parts and predict the material’s mechanical behaviour.peer-reviewe