Controllable preparation of SiC coating protecting carbon fiber from oxidation damage during sintering process and SiC coated carbon fiber reinforced hydroxyapatite composites

摘要

As a kind of ideal artificial bone materials, poor mechanical properties especially brittleness of pure hydroxyapatite (HA) have limited its clinical application. In order to achieve pressureless sintering of carbon fiber (CF) reinforced HA bioceramics, SiC coating was successfully prepared on CF surface by low pressure chemical vapor deposition (LPCVD). The structure, morphology, and thickness of the SiC coating are controllable. The SiC coated CF (SiC-CF) reinforced HA composites (SiC-CF/HA) were prepared via pressureless sintering at 1373 K for 20 min. The bending strength of the SiC-CF/HA composite reaches its maximum achievable value of 28.4 MPa, when 0.5 wt% of SiC-CF was added. It is almost three times that of pure HA sintered under an identical condition. The corresponding fracture toughness is as high as 1.28 MPa.m(1/2), which are 26.6% and 19.5% increase over those of HA and CF/HA composites, respectively. The enhancements of the bending strength and fracture toughness are mainly due to enhancing and toughening mechanism (crack-bridging and pull-out of SiC-CF). In practice, SiC coating acts as an oxygen diffusion barrier to prevent the oxidative damage of CF caused by dehydroxylation of HA during pressureless sintering. Furthermore, the SiC coating has the ability to form a transitional SiO2 layer in an oxidizing atmosphere which fills the cracks of the coating, enhances the interfacial compatibility, and lessens the interfacial stress. The study provides additional insights into the feasibility of SiC-CF/HA composites as load-bearing implant materials in clinical applications. (C) 2018 Elsevier B.V. All rights reserved.