Three-dimensional porous poly-lactic acid(PLA) scaffold was fabricated using fused deposition modeling(FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed...Three-dimensional porous poly-lactic acid(PLA) scaffold was fabricated using fused deposition modeling(FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed scaffolds was done by X-ray diffraction(XRD), and no significant phase difference was observed due to the manufacturing process, and the poly-lactic acid retains its crystalline properties. The results of the mechanical properties evaluation by the compression test show that the mechanical properties of the scaffold have decreased significantly with increasing the porosity of scaffold. The microstructure of scaffolds were studied by scanning electron microscope(SEM), showing that the pores had a regular arrangement and their morphology changed with porosity change. The mechanical properties of the poly-lactic acid scaffolds printed using fused deposition modeling, can be adapted to the surrounding tissue, by porosity change.展开更多
The effects of heat treatment on the microstructure and mechanical properties of intermetallic compounds in the interface of stainless steel 321 explosively bonded to aluminum 1230 were investigated in this study. Exp...The effects of heat treatment on the microstructure and mechanical properties of intermetallic compounds in the interface of stainless steel 321 explosively bonded to aluminum 1230 were investigated in this study. Experimental investigations were performed by optical microscopy, scanning electron microscopy, and microhardness and shear tensile strength testing. Prior to heat treatment, increasing the stand-off distance between samples from 1 to 2.5 mm caused their interface to become wavy and the thickness of intermetallic layers to increase from 3.5 to 102.3 μm. The microhardness increased from HV 766 in the sample prepared at a stand-off distance of 1 mm to HV 927 in the sample prepared at a stand-off distance of 2.5 mm; in addition, the sample strength increased from 103.2 to 214.5 MPa. Heat treatment at 450°C for 6 h increased the thickness of intermetallic compound layers to 4.4 and 118.5 μm in the samples prepared at stand-off distances of 1 and 2.5 mm, respectively. These results indicated that increasing the duration and temperature of heat treatment decreased the microhardness and strength of the interface of explosively welded stainless steel 321-Al 1230 and increased the thickness of the intermetallic region.展开更多
The surface treatment is important for titanium and its alloys as promising candidates for dental implantation due to their bioinert surface.Titanium surface samples were modified using H2O2 solution at different time...The surface treatment is important for titanium and its alloys as promising candidates for dental implantation due to their bioinert surface.Titanium surface samples were modified using H2O2 solution at different times up to 72 h to boost their bioactivity.According to the results of the field emission scanning electron microscopy test,some nanostructures are formed on the surface of treated titanium samples and increased in size by increasing the time of treatment up to 24 h.After 24 h of application,the sharpness of nanostructures decreased and the micro-cracks and discontinuity in the coating surface increased.The results of the X-ray diffraction study and Raman spectroscopy revealed that anatase(TiO2)was formed on the surface of treated titanium samples.The peak intensity of Raman spectroscopy increased with an improvement in treatment time of up to 24 h and then decreased due to the discontinuity of the coating.Full wettability and ability to form apatite were reached at 6 h of treatment.It is clear that the treatment time has a significant effect on the surface treatment of titanium using the H2O2 solution.展开更多
In this study,nano-biocomposites of polycaprolactone(PCL)as the matrix and different amounts of nanofluorapatite(nFA)(0,10,20 and 30 wt.%)as the reinforcement were prepared for possible scaffold fabrication using the ...In this study,nano-biocomposites of polycaprolactone(PCL)as the matrix and different amounts of nanofluorapatite(nFA)(0,10,20 and 30 wt.%)as the reinforcement were prepared for possible scaffold fabrication using the fused filament fabrication(FFF)3D printer.Field Emission Scanning Electron Microscopy(FE-SEM)and Energy Dispersive Spectroscopy(EDS)showed that nFA particles were well distributed in the PCL matrix.X-ray diffraction analysis(XRD)and Fourier Transform Infrared Spectroscopy(FTIR)depicted no chemical interaction between the elements of the composite.Differential Scanning Calorimetric(DSC)analysis was then used to assess the thermal properties of the composites,suggesting that this could be due to the amorphous phase formation of the intermolecular hydrogen bonds between PCL and nFA,resulting in the suppression of PCL crystallization.The results of mechanical characterization also showed that the addition of nFA up to 20 wt.%to the PCL increased the tensile and yield strength,as well as reducing the elongation at both yield and failure points and increasing the Young modulus.The best mechanical properties were obtained for the PCL/20nFA composite.Tensile strength and Young modulus were increased by 30%and 179%,respectively;meanwhile,elongation of PCL/20nFA was decreased by 70%,as compared to the naked PCL.These changes could be attributed to the better distribution of the nFA filler in the PCL matrix.According to the obtained results,PCL/20nFA could be regarded as a good composite in terms of the mechanical properties for the regeneration of the bone tissue.展开更多
文摘Three-dimensional porous poly-lactic acid(PLA) scaffold was fabricated using fused deposition modeling(FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed scaffolds was done by X-ray diffraction(XRD), and no significant phase difference was observed due to the manufacturing process, and the poly-lactic acid retains its crystalline properties. The results of the mechanical properties evaluation by the compression test show that the mechanical properties of the scaffold have decreased significantly with increasing the porosity of scaffold. The microstructure of scaffolds were studied by scanning electron microscope(SEM), showing that the pores had a regular arrangement and their morphology changed with porosity change. The mechanical properties of the poly-lactic acid scaffolds printed using fused deposition modeling, can be adapted to the surrounding tissue, by porosity change.
文摘The effects of heat treatment on the microstructure and mechanical properties of intermetallic compounds in the interface of stainless steel 321 explosively bonded to aluminum 1230 were investigated in this study. Experimental investigations were performed by optical microscopy, scanning electron microscopy, and microhardness and shear tensile strength testing. Prior to heat treatment, increasing the stand-off distance between samples from 1 to 2.5 mm caused their interface to become wavy and the thickness of intermetallic layers to increase from 3.5 to 102.3 μm. The microhardness increased from HV 766 in the sample prepared at a stand-off distance of 1 mm to HV 927 in the sample prepared at a stand-off distance of 2.5 mm; in addition, the sample strength increased from 103.2 to 214.5 MPa. Heat treatment at 450°C for 6 h increased the thickness of intermetallic compound layers to 4.4 and 118.5 μm in the samples prepared at stand-off distances of 1 and 2.5 mm, respectively. These results indicated that increasing the duration and temperature of heat treatment decreased the microhardness and strength of the interface of explosively welded stainless steel 321-Al 1230 and increased the thickness of the intermetallic region.
基金This work was financially supported by Grant-in-Aid(Nos.19K10250 and 18K09686)from Scientific Research of the Japan Society for the Promotion of Science(JSPS).
文摘The surface treatment is important for titanium and its alloys as promising candidates for dental implantation due to their bioinert surface.Titanium surface samples were modified using H2O2 solution at different times up to 72 h to boost their bioactivity.According to the results of the field emission scanning electron microscopy test,some nanostructures are formed on the surface of treated titanium samples and increased in size by increasing the time of treatment up to 24 h.After 24 h of application,the sharpness of nanostructures decreased and the micro-cracks and discontinuity in the coating surface increased.The results of the X-ray diffraction study and Raman spectroscopy revealed that anatase(TiO2)was formed on the surface of treated titanium samples.The peak intensity of Raman spectroscopy increased with an improvement in treatment time of up to 24 h and then decreased due to the discontinuity of the coating.Full wettability and ability to form apatite were reached at 6 h of treatment.It is clear that the treatment time has a significant effect on the surface treatment of titanium using the H2O2 solution.
文摘In this study,nano-biocomposites of polycaprolactone(PCL)as the matrix and different amounts of nanofluorapatite(nFA)(0,10,20 and 30 wt.%)as the reinforcement were prepared for possible scaffold fabrication using the fused filament fabrication(FFF)3D printer.Field Emission Scanning Electron Microscopy(FE-SEM)and Energy Dispersive Spectroscopy(EDS)showed that nFA particles were well distributed in the PCL matrix.X-ray diffraction analysis(XRD)and Fourier Transform Infrared Spectroscopy(FTIR)depicted no chemical interaction between the elements of the composite.Differential Scanning Calorimetric(DSC)analysis was then used to assess the thermal properties of the composites,suggesting that this could be due to the amorphous phase formation of the intermolecular hydrogen bonds between PCL and nFA,resulting in the suppression of PCL crystallization.The results of mechanical characterization also showed that the addition of nFA up to 20 wt.%to the PCL increased the tensile and yield strength,as well as reducing the elongation at both yield and failure points and increasing the Young modulus.The best mechanical properties were obtained for the PCL/20nFA composite.Tensile strength and Young modulus were increased by 30%and 179%,respectively;meanwhile,elongation of PCL/20nFA was decreased by 70%,as compared to the naked PCL.These changes could be attributed to the better distribution of the nFA filler in the PCL matrix.According to the obtained results,PCL/20nFA could be regarded as a good composite in terms of the mechanical properties for the regeneration of the bone tissue.
