The new generation Ti6Al4V artificial heart valve with nanocrystalline diamond coating on the ring and with Derlin disc after long-term mechanical fatigue examination

An artificial heart valve ring made of titanium alloy Ti6Al4V was coated with nanocrystalline diamond (NCD) with the use of RF PACVD technique. Then the heart valve with NCD coating and Derlin disc was tested by means of a long-term mechanical fatigue examination in a home-designed apparatus manufactured at the Technical University of Lodz (Poland).Before and after the mechanical fatigue experiments, the surface of the valve ring was examined by Scanning Electron Microscopy (SEM) and by Raman Spectroscopy. The investigations verified the good quality of the coating covering all the surfaces, even in the most critical points where plasma didn't penetrate well during the coating deposition. Moreover, the comparison of studies before and after mechanical fatigue experiments show that the surface after the experiments is in good condition, still tight, and the range of the NCD layer thickness is the same as before the operation. The Raman spectra indicate that the NCD coating still covers all the surface of the ring (even in the places of the disc–ring interaction during relative motion of the disc).