Tomáš Binar

Degradation of polymeric bellows effecting life cycle of constant-velocity joint

ABSTRACT One broken and three new polymeric constant-velocity boots (bellows) being a spare part of a constant-velocity joint in two military vehicles were analyzed to identify basic composition and to determine if composition or structure of broken bellows differ. Infrared spectroscopy, differential scanning calorimetry, and thermogravimetry were used for analyses. Bellows for both vehicles are produced from thermoplastic elastomer. Broken bellows is chemically degraded and material just from the fracture is deformed plastically. The life cycle of bellows depends especially on applied stress and temperature (that about −20°C seems to be critical due to crystallization of soft segments).

Characteristics of Duplex Treated AISI 304 Stainless Steel

The duplex treatment consisted of a plasma nitriding at 470 °C for 4 h and subsequent coating with TiN layer was applied on AISI 304L stainless steel. The article is concerned to a study of the chemical composition and mechanical properties of duplex system. GDOES method, laser confocal microscopy, nanohardness and indentation test were employed to characterize the chemical composition, depth profiles, surface morphology, hardness, adhesion. The results show that the duplex surface system possesses a desirable combination of properties especially hardness. Adhesion of PVD coating was increased on nitrided surface.