Tóm tắt

Supersonic atmospheric plasma spray (SAPS) technique is a classical method which is employed to coat therncarbon/carbon (C/C) composites by nano-hydroxyapatite (HAp) powders to decrease the biologically inert,rnhydrophobic drawbacks of substrate surfaces. In recent years, profiting from the promoting of energy con-servation and environmental protection, more emphasis was placed on industrial manufacturing to simplify thernexperimental steps. This paper aims to study the preparation of nano-HAp coatings by suspension plasma sprayrn(SPS) instead of the original SAPS technique. A denser, more uniform and less defective coating is successfullyrnfabricated on C/C substrate using SPS technique. More important, fewer surface flaws in SPS coating could bernobserved by scanning electron microscopy (SEM) which shows that the large drawbacks of the coating haverndisappeared during spraying process. Meanwhile, except for HAp, phase compositions of the SPS coating appearrnwith slight calcium oxide (CaO, 0.8%) and tricalcium phosphate (TCP, 30.7%), and then all CaO as well as TCPrnphases transform into dicalcium phosphate anhydrous (DCPA, 60.6%) after microwave-hydrothermal (MH)rntreatment. Thermal analysis (TG/DSC) reveals that SPS coating (97.51%) has a higher thermal stability than thatrnof the SAPS coating (82.37%). Also, in comparison, the SPS coating after MH treatment (SPS-MH coating)rnexhibits better thermal properties (92.76%). In addition, compared to the SAPS and SPS coatings, due to thernmoreflaw reduction and phase transformation, SPS-MH coating shows a better biological properties according tornthe surface microstructure in simulation body fluid (SBF) solution and cell spreading area on coating. Thernhighest corrosion resistance with the current density of 3.9798 × 10rn−7rnA/cmrn2rnand a potential of 0.0419 V isrnachieved for SPS-MH coating.