Lately a great attention has been paid to the research of bonded hybrid composites with improved dynamic mechanical capacities capable of replacing bonded Nd-Fe-B magnetic materials, by using the cheaper (ferrite) materials instead of the Nd-Fe-B powder while retaining the satisfying values of the maximal magnetic energy. The objective of this study is to assess how different contents of Nd-Fe-B and/or barium ferrite particles can affect morphological, dynamic mechanical and magnetic properties of bonded composite materials. The interactions between employed magnetic powders and the interactions between magnetic powders and polymer binder are considered. For the examination of the magnetic behaviour, a vibrating sample magnetometer (VSM) is used. Different shapes and sizes of the obtained hysteresis loops are used for comparison and prediction of the polymer bonded materials properties. The homogeneous distribution of the magnetic particles in the polymer matrix is validated using the scanning electron microscope (SEM). The elastic and damping behaviour examined by the dynamic mechanical analysis (DMA) show improved properties for hybrid composite materials

A commercial Nd-rich Nd-Fe-B-based hard magnetic material was studied. The obtained results were compared before and after recording of the thermomagnetic curve up to 800 °C. The curve itself showed clearly besides Curie points of the Nd 2 Fe 14 B phase and α-Fe also another critical temperature. Mössbauer spectroscopic (MS) phase analysis and X-ray diffraction analysis (XRD) showed in addition to the commonly known phases Nd 2 Fe 14 B and NdFe 4 B 4 also some paramagnetic and ferromagnetic iron atoms (MS) and Fe 17 Nd 2 intermetallics (XRD). During the exerted thermal treatment, the content of the Nd 2 Fe 14 B and NdFe 4 B 4 phases remained almost unchanged, while iron atoms from remnant minor phases built a separate α-Fe phase. The XRD pattern also showed the presence of some minor Nd phase. The results of Squid magnetic measurements suggest a nanocrystalline decoupled structure of the Nd-rich alloy in the optimized magnetic state. Measurement of the magnetization loop showed, in spite of small changes in the phase composition, that magnetic properties of the quality material deteriorated during the thermal treatment.

U ovom radu je prikazan proces sinteze mikročestica od prirodnih polimera, alginata i hitozana, kao i neka njihova svojstva. Osnovna primena ovih mikročestica je da se koriste kao potencijalni nosači za aktivne supstance. U tom smislu je ispitivana i difuzija različitih supstanci iz njih. Na alginatne mikročestice dobijene metodom elektrostatičke ekstruzije vršena je apsorpcija tri trejserska indikatora sa različitim molekulskim masama: akridin oranž, plavi dekstran i metilensko plavo. Praćenjem kinetike otpuštanja indikatora iz mikročestica konstruisane su krive otpuštanja koje daju informaciju o uticaju veličine molekula svakog od indikatora na brzinu difuzije iz mikročestica. Da bi se postiglo što sporije otpuštanje indikatora alginatne mikročestice su oblagane hitozanom. Hitozan ima uticaj na smanjenje poroznosti gela, što dovodi do sporijeg otpuštanja trejsersikh indikatora iz mikročestica. Uporedna analiza dobijenih krivih otpuštanja daje odgovor o uticaju postupka dobijanja mikročestica na brzinu difuzije indikatora.