| Carbon/carbon composites (C/C) are characterized by excellent biocompatibility, very similar elastic modulus to human bone and fine chemical stability. Also, they possess fine mechanical properties that are suitable for artificial bone. However, as hard tissue restoration and reconstruction materials, these materials have a few drawbacks. Firstly, carbon/carbon composites can not form chemical bond with human bone tissue due to their bioinert property. Secondly, the surface of unprocessed carbon/carbon is hydrophobic, so if it is put into the human body for a long time, the nomadic carbon will flow with the body fluid. Thirdly, the color difference between C/C and human bone is obvious. In order to avoid the decline of the mechanical properties due to the shedding of the surface carbon particles and enhance the bioactivity, people have prepared several biomedical coatings on C/C in different ways. Among these coatings, hydroxyapatite (HA) coatings have been broadly used as bioactive ones on artificial bone materials for their excellent biocompatibility and bioactivity. In the present work, HA, SiC, Diamond like carbon (DLC) coatings were prepared on the materials by means of plasma spraying, surface biomimetic activation, reaction sintering and radio frequency plasma enhanced chemical vapor deposition technologies. The technical parameters optimization of coating preparation, structure and property characterization of the coating were carried out. Meanwhile, according to the demand of clinic application, the constituent, microstructure, hardness, triological behaviors and biological behaviors of C/C were studied. By plasma spraying HA coatings on C/C, C/C+HA coated composite implants were developed and the biological behaviors were studied both in vivo and in vitro. By means of observation of histological sections and radioscopy, the biocompatibility of implant and their interface bonding mechanism with the surrounding tissues were evaluated.The results revealed that the impurity contents of C/C could meet the standard of artificial bone materials. What's more, the 2400℃×2h graphitizing heat treatment could significantly reduce the main impurities in C/C and this material had similar microhardness to human bone. The mechanical properties testing results indicated that C/C have strain rate sensitivity and the reinforced fibers have remarkable effects in arresting propagating cracks and plasticizing. They could satisfy the mechanical demands of bone-repairing materials. The viscose based carbon/carbon composites have low friction coefficient. When they make up the friction pairs in vivo, the carbon particle desquamation might be less. The porous surface structure of scaffold material is beneficial to the direct adhesion, proliferation and differentiation of cells. The animal experiment of viscose based C/C applied in bone defection intramedullary fixation revealed that the bone defect areas were reconstructed by new bone trabecula. Immunohistochemical observations revealed that the implants had good tissue compatibility.The shear tests, phase composition analysis and fracture morphology observation results showed that the 700℃×10min post heat treatment could effectively increase crystallization and purity of the coatings. Through observation and analysis by electron microprobe and scanning electron microscopy, it is concluded that the bond strength of the plasma-sprayed HA coatings on C/C is mainly determined by the interface structure and can be further improved by the post heat treatment. Meanwhile, the implantation in vivo was carried out in hybrid goats. The histological observation revealed that the osteoplaque gradually grew on the surface of the HA coatings directly and the pure C/C surface was covered by the fibrous tissues. No inflammation symptoms were detected in the bone tissue around the implants. When as-sprayed HA coatings were immerged in simulated body fluid, it began to dissolute and the nuclearation as well as the growth of the new phases occurred. This process will provide an environment that is rich of Ca and P and benefit the osteoblast growth on the coatings.In the process of surface biomimetic activation treatment of C/C, concentrated nitric acid pre-oxidation treatment could change the few hydrogen bonds into oxygen-containing functional groups (such as hydroxyl group) on the surface of C/C. When the samples were immerged into the simulated body fluid at 37℃, hydroxyl group polycondensations occurred between the newborn in HA molecule and carbon/carbon composites. In this way, the high bonding strength of newborn HA and C/C was obtained by chemical bond bridging and the bioactivity of C/C was improved. At the same time, SiC modified film was prepared by Si reaction sintered on C/C. This film could lighten the carbon particle desquamation and be suitable as the protective and bonding film for biomedical C/C.Structure and property characterizations of the RF-PECVD prepared DLC film indicated that the type of carbon source gas is the key element to the quality of DLC film. With the deposition time prolonging, the particles that compose the film are growing up, surface roughness of the film is increasing. Under the condition that the flow ratio of CH4 and Ar is 1:20, the RF voltage is 17000V, the electric current is 0.45A and the diposition time lasts for 2h, the DLC film have high content of sp3 carbon atom, uniform thickness, good surface hydrophobic property and low surface friction coefficient. The study of DLC film prepared on the polished PAN based C/C revealed that there were two DLC Film-forming mechanisms. First, the non-homogeneous nucleation of DLC occurred on the pyrolytic carbon that composed C/C. Second, the homogeneous nucleation of DLC occurred in vacuum plasma environment. The surface morphology of C/C greatly influence to the microstructure of DLC film. Due to the dense structure of DLC film, it can be used as transition layer for the top bioactive layer on C/C.
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