Authors:György Török, Mária Darányi, Tibor Alpár, and Ákos Kukovecz
Safety matches are at the very core of modern civilization, playing an unnoticed but vastly important part in everyday human activities since the middle of the 19th century. Although the general public is hardly aware of the strict and complex requirements that matches are expected to meet, it takes careful chemical engineering to control the match microstructure in a way that guarantees safe and reliable operation. In this contribution we summarize results obtained in this field by the cooperation of a match manufacturer and two Hungarian universities.
Authors:Gábor Kozma, Dániel Berkesi, Katalin Liptak, Andrea Rónavári, Ákos Kukovecz, and Zoltán Kónya
In this work, the properties of mechanochemically produced (by using mills made from different materials) barium-titanate (BaTiO3) and zinc-titanate (ZnTiO3) perovskites are compared. Mechanochemistry is a process that can cover the energy demand of some reaction pathways between solid materials. This process is called “high-energy milling”, for which not all types of mills are suitable. In our case, a planetary ball mill provided the necessary energy. Using a model, the required energy is determinable; the energy released during an impact of a milling ball (Eb – ball-impact energy), as well as during the whole milling (Ecum – cumulative milling energy). Thus, a milling-energy map was created, with which the applied Eb and Ecum values were visualized depending on the different grinding parameters. The parameters changed were the material of the grinding vessels, the number of grinding balls, and the rotational speed. The transformation was tracked by X-ray diffraction (XRD) measurements, and electron microscopic images (TEM and SEM) of the perovskites produced were taken. This study aimed to draw conclusions that will help later in the synthesis of materials with other perovskite structures by choosing optimal milling parameters.