V-alloyed ZrO2 Coatings with Temperature Homogenization Function for High-Temperature Sliding Contacts

The effect of V additions on reactively magnetron sputtered ZrO2 coatings was investigated with respect to their structural and mechanical properties. Coatings with different V-contents were co-sputtered from Zr and V targets using an Ar + O2 discharge. The X-ray diffraction patterns show a change from monoclinic (0–2.2 at.% V) to cubic/tetragonal ZrO2 based phase (5.8 at.% V) and finally X-ray amorphous structure at even higher V-content (17.4 at.% V). Hardness and Young\u27s modulus decrease beyond 5.8 at.% V from 17.4 to 7.5 GPa and from 230 to 150 GPa, respectively. At 25 °C, the coefficient of friction (COF) is ~ 0.2 for low V-contents and above 0.5 for high V-contents, respectively. Differential scanning calorimetry of powder samples showed a characteristic exothermic peak at ~ 600 °C, which is due to the formation of the ZrV2O7phase. This phase decomposes above 740 °C in ZrO2 and liquid V2O5. The latter phase provides a self-lubricious layer in the sliding contact, decreasing the COF below 0.2 at 800 °C for V-contents of 17.4 at.%. The endothermic nature of melting of the V2O5 phase is suggested as the basis for thermal management abilities of tribological coatings, where the frictional heat generated in severely loaded sliding contacts and thus local flash temperatures are efficiently reduced

Fatigue strength estimation methodology of additively manufactured metallic bulk material

International audienc

Antibacterial Silicon Oxide Thin Films Doped with Zinc and Copper Grown by Atmospheric Pressure Plasma Chemical Vapor Deposition

Zn-doped and Cu-doped SiOx films were synthesized by atmospheric pressure plasma chemical vapor deposition to study their antibacterial efficiency against Gram-negative Escherichia coli and their cytotoxic effect on the growth of mouse cells. Zn-rich and Cu-rich particles with diameters up to several microns were found to be homogeneously distributed within the SiOx films. For both doping elements, bacteria are killed within the first three hours after exposure to the film surface. In contrast, mouse cells grow well on the surfaces of both film types, with a slight inhibition present only after the first day of exposure. The obtained results indicate that the films show a high potential for use as effective antibacterial surfaces for medical applications