Studying of the effects of bias voltage on structure, mechanical properties and adhesion behavior of blood platelet of diamond-like carbon films

Summary form only given. Diamond-like carbon (DLC) films have received a great deal of attention recently as a variety of applications for optical and protective coatings because of its unique properties, such as high hardness, excellent wear resistance, low friction coefficient, thermal stability, chemical inertness, and wide band gap. This paper intend to investigate the effect of synthesis process of direct current magnetic filter cathode vacuum arc (DC-MFCVA) on the properties of DLC films for biomedical applications. Different bias voltages from 0 to -200 V were used to prepare DLC films. Four-probes measurement was employed to evaluate the resistant of the films. The results of resistant show that the resistant increases with the increase of bias voltage. Sp/sup 3/ fraction investigated using X-ray photoelectron spectrum (XPS) show almost not variant, and which round about 57.7%. The ratio of sp/sup 3/ to sp/sup 2/ ranges form 1.35 to 1.40. It is revealed from the XPS spectrum that with the bias voltage increasing, the core level engendered shifts toward low energy direction. The mechanical properties of the films were tested by micro-hardness and pin-on disk wearing. The result show the hardness under 0.245 N load at first decreased from 578 HK to 491 HK with bias voltage, then increased to 530 HK. While that of uncoated stainless steel is 347 HK. Pin-on disk testing shows the average friction coefficient remain under 0.107. The morphology and the width of wearing race were observed by optical microscope and by scanning electron microscopy (SEM). The results show that the DLC films present excellent wear resistance. Platelet adhesion on DLC films was investigated to evaluate the interaction of blood with DLC films. It shown that the deformation tendency of platelet on synthesized DLC films (-50 V and -100 V) were lower than the platelet adherent on Low temperature pryolytic isotropic carbon.