Study Of Multi Walled Carbon Nanotube-reinforced Hydroxyapatite Composites Consolidated By SPS

In this paper,HAP ceramics,HAP/CNTs composite ceramics,xCNTs-HAP/yCNTs-HAP laminated composite ceramics and HAP/45S5 biological glass laminated composite ceramics were prepared by spark plasma sintering(SPS).The effects of sintering process and CNTs content on the microstructures,phase transformation and mechanical properties of HAP ceramics and HAP/CNTs multiphase ceramics were systematically studied.On this basis,the preparation ideas of HAP/CNTs layered composite ceramics with different CNTs content were creatively put forward.With orthogonal experiments,the significant factors affecting the mechanical properties of xCNTs-HAP/yCNTs-HAP layered composite ceramics were discussed.The optimum combination scheme is calculated and verified.In order to improve the mechanical properties of HAP as well as its biodegradability,the preparation method of HAP/45S5 Bioglass laminated composite ceramics was put forward and sintered at different temperatures.The microstructure,physical properties and mechanical properties of the sintered body were studied,and the feasibility and application prospect of the preparation method were discussed.It is found that when sintering temperature reaches 950?,HAP grains grow from spherical to columnar in HAP ceramics.When sintered at 1000 ?,HAP began to decompose partially.The properties of sintered body are the best when the sintering temperature is 900?.Dense HAP/CNTs composite ceramics can be successfully prepared by SPS technology.The effects of CNTs content and sintering temperature on the properties of sintered bodies were discussed.It was found that the densification of HAP/CNTs composite ceramics could be achieved by SPS sintering at 900?.At this temperature,HAP began to decompose.The presence of CNTs shifted the chemical equilibrium and made HAP decompose more easily.The strengthening mechanism of carbon nanotubes was discussed.HAP/1 wt.%CNTs composite ceramics sintered by SPS at 900? have better comprehensive properties.Compared with SPS sintered HAP ceramics,its flexural strength,fracture toughness and fracture work are increased by 166%,1 69%and 184%,respectively.xCNTs-HAP/yCNTs-HAP laminated composite ceramics were prepared by precast lamination method and SPS sintering.The effects of the number of layers,the combination of CNTs content and the thickness ratio of layers on the properties were investigated.The results show that the laminated composites exhibit anisotropy in mechanical properties and stress-strain curves.The orthogonal test method was adopted to examine the factors in the design of layered structures.According to the test results,the optimal process parameters were selected and verified.Compared with HAP/lwt.%CNTs composite ceramics,the bending strength and fracture work of the samples under this process were increased by 64.4%and 744%respectively,and the mechanical properties of the compact bone were achieved.The idea of fabricating HAP/45S5 Bioglass laminated composite ceramics was put forward.The effects of sintering temperature on the physical and mechanical properties of HAP/45S5 laminated composite were investigated.The interfacial bonding,atomic migration and diffusion at different temperatures were analyzed.The existence of 45S5 hinders the growth of HAP grain.The bending strength and fracture work of the sintered body are the highest at 950?,which are 82.2%and 500%higher than that of pure HAP sintered body,respectively.The mechanical properties of the sintered body meet the requirements of the scaffold material.The presence of 45S5 Bioglass can regulate the degradation of the final system to enhance its biological response,showing a greater trend of binding growth to host bone while maintaining its mechanical integrity.Therefore,HAP/45S5 Bioglass laminated composites have good prospects as scaffold materials.