Influence Of Process Parameter On Diamond-like Carbon Film Deposited By Pulsed Laser Deposition

The purpose of the research is looking for the rules of the influence of the process parameter on the diamond-like carbon films during the Pulsed Laser Deposition of Diamond Films to prepare different quality DLC films according to requirement. This work lays the foundation of the further study of the biocompatibility of DLC films and the clotting problem of mechanical heart valves.The development and problem of the diamond-like carbon film deposited by plused laser deposition are summarized. The development and problem of the biocompatibility of artificial heart valves are reviewed. In order to solve the clotting problem of mechanical heart valves, diamond-like carbon film with biocompatibility was deposited on mechanical heart valves and the tissue engineering method was used to cultured vascular endothelial cell layer to solve the clotting problem.In the experiment of pulsed laser deposited diamond-like carbon film, the distance between the target and the substrate,nitrogen pressure and laser pulse energy were changed independently when other parameters kept unchanged. The microstructure, composition, surface morphology and infrared transmission of the film deposited in different process parameters were studied by Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and Fourier transform infrared spectroscopy. Finally diamond-like carbon film was deposited on mechanical heart valve by pulsed laser deposition and the composition and surface morphology of the film were detected. In order to study the cell compatibility of diamond-like carbon film, tissue engineering method was used to culture human umbilical vein endothelial cells on diamond-like carbon film in vitro.The result demonstrates that: First, the distance between the target and the substrate has a significant impact on the microstructure and surface morphology of DLC films. The increase of the distance will result in the decrease of the sp3 / sp2 ratio, the increase of graphite particle number and the surface roughness of DLC films. Second, during a certain range, with the nitrogen pressure increase, in the film, the sp3 bonds and the doped nitrogen content increase, the number and the volume of graphite particle decreases and the surface roughness of thin film increases. When nitrogen pressure is at 10-3Pa, the infrared antireflection of the film is strongest and the scope of infrared antireflection is widest. However, when nitrogen pressure is at 10-4Pa, the result is contrary. Third, in the nitrogen atmosphere of 10-1Pa , the increase of the pulse energy from 120mJ to 150mJ will reduce the number and the volume of graphite particle ; the content of long chain sp2 bond decreases; the ratio of sp3 / sp2 increases; the nitrogen content of the film increases from 0.6% to 0.79%; the roughness of the film decreases significantly but the infrared antireflection of the DLC film deceases. Fourth, diamond-like carbon film was deposited on mechanical heart valve by pulsed laser deposition successfully, human umbilical vein endothelial cells were able to grow on the diamond-like carbon film and integrated to the film.The research provides a valuable reference for the study and application of pulsed laser deposition and diamond-like carbon films. It is very important to new generation artificial heart valves with the common advantage of both mechanical heart valves and bio-artificial heart valve.