International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The changes in the structure of the crystalline graphite are studied during high-energy ball milling (BM) treatment. It was found by XRD analysis the milling time increasing up to 3.5 h leads to the formation of an amorphous phase in the milling process. After 10 h of ball milling treatment, complete amorphization of graphite takes place. It has been shown by high-resolution electron microscopy the individual particles have complex morphology which depends on the BM time. After 1 h of BM carbon materials characterized by an onion-like structure: the individual particles have a spheroidal shape with a size of ~ 10 nm. However, unlike the previous ones after 10 h of ball milling carbon nanomaterials are characterized by a disordered structure, which is typical for amorphous carbon.

In this research work, metallographic investigation of two parts which are implemented to railway wagons breaking system was performed. Both parts are produced from EN-GJS-500-7 nodular iron. One of delivered parts leading nut (part 1) was broken during the exploitation and the second part working nut (part 2) was new. Metallographic investigation based on standard EN 945-1was implemented in order to check the quality of the parts. The reason for breaking of part 1 one was analyzed too. After metallographic preparation, the polished specimens they were analyzed under optical microscope in order to determine form, size, density and distribution of graphite per unite area as first graphite nodules were analyzed after that microstructure of nodular iron. Figures from optical microscope were compared with reference images under the same magnification. After etching the specimens their microstructure was analyzed. It was concluded that quality of the part 2 is much better concerning the requirement of the EN 945 -1 standard.