Production of Pressed Porous Glass-Ceramic Carbon Fiber Biocomposites for Medical Applications

Pressed porous glass-ceramic carbon fiber biocomposites were produced from hydroxyapatite/glass and nanostructured carbon fibers. The specific features of the production process, as well as the composition, macrostructure, microstructure, and porosity of these biocomposites, were studied. The prospects for their medical applications, particularly in surgical osteoplasty, were identified. The starting materials included calcium phosphate glass ceramics derived from biogenic hydroxyapatite, featuring both bound and migrating glass phases, and activated nanostructured carbon fibers. The glass ceramics with a bound glass phase were produced by sintering powder mixtures of biogenic hydroxyapatite and sodium borosilicate glass, while those with a migrating glass phase were produced through mechanical mixing of biogenic hydroxyapatite and sodium borosilicate glass powders. The fine activated nanostructured carbon fibers used in the biocomposites were obtained by the mechanical grinding of a woven material from activated nanostructured carbon fibers. This material resulted from the controlled stepwise pyrolysis of hydrocellulose fabrics, followed by high-temperature vapor activation of the nanostructured fiber surface. To make cylindrical biocomposite samples, the fine activated nanostructured carbon fibers were blended with moistened mixtures of biogenic hydroxyapatite glass ceramics with bound and migrating glass phases and subjected to semidry pressing and incremental sintering with holding at 800 degrees C. The selected process parameters enabled the production of pressed carbon fiber biocomposites with the desired composition and showed the ability to control their porous structure, achieving a relative density of 0.36-0.41, by regulating the behavior of the glass phases and the sintering of the reinforcing component. The biocomposite structures were examined by scanning electron microscopy. Energy-dispersive X-ray analysis was conducted to determine the chemical composition of the samples. The structures of the composites were analyzed and compared on the basis of their sorption capacities, determined from benzene adsorption-desoprtion isotherms using the gravimetric method. Analysis of the macrostructure, microstructure, and surface morphology of transverse and longitudinal sections of the biocomposites revealed a multiporous amorphous-crystalline microstructure, arising from the varying behavior of the glass phases, the presence of chaotically oriented short fine nanostructured carbon monofibers with diameters of several microns and a developed system of micro- and macropores on their surface, and spatial multidirectional hollow channels formed through the complete or partial combustion of the fibers.