Laser Nitriding And Cladding Of Gradient Biological Coating On Titanium Surface

To improve the biological performance and corrosion resistance of the pure titanium,in this paper,the bioactive glass was fabricated by Sol-Gel method.Then the bioactive glass was fused on the titanium surface by laser cladding method.In addition,the gradient antibacterial coating was fabricated by adding different contents of Ti powder and Ag nanoparticles?Ag-NPs?.The bioactive glass was fused on the surface of titanium nitride?TiN?coating,which was fabricated on pure titanium surface using the laser nitriding method.The phase and morphology of the bioactive glass powders and biological coatings were analyzed by XRD?FTIR?TG-DSC?BET?SEM and EDS.The bonding strength between the substrate and coating was measured by the coating adhesion scratcher.The corrosion resistance of the coating was assessed by electrochemical workstation.The main conclusions are as follows:?1?In this paper,1#and 2#bioglass powders were prepared by Sol-Gel method,and heat treated at 700°C.The main crystal phase of 1#bioglass was Na₂Ca₃Si₆O₁₆and CaSiO₃,and that of 2#was Na₂Ca₃Si₆O₁₆.The average specific surface area of 1#and 2#bioglasses measuerd by BET is 10.59 m²/g and 12.67 m²/g,respectively.The bioglass strength is generally negatively correlated with apparent porosity,and the strength shown the tendency to increase first and then decreased as the sintering temperature increases.The hydroxyapatite deposite formed on the surface of the two bioglasses after soaking in SBF for a period of time.The two bioglasses prepared in this paper have certain biological activities.?2?In this paper,the TiN coating was fabricated on the titanium surface by laser nitriding.The effect of different laser power and rate,sandblasting on titanium surface or not on the formation of TiN coating were investgated.After sandblasting,the more effective laser energy can be absorbed.Meanwhile,the XRD shown that the diffraction peak of the TiN formed on the sanded titanium surface is stronger.The c-TiN?PDF#38-1420?and TiN_0.3?PDF#41-1352?were the main phase of the TiN coating fabricated in this paper.The TiN coating,fabricated by laser nitriding with parameter of 300W,1.0m/min,possessed obvious three-dimensional?3D?and porous structure,and shown a stronger diffraction peaks.The result of the electrochemical testing carried out in the SBF shown that the corrosion resistance of the titanium was improved significantly after laser nitriding.The 1#bioactive-glass coating was prepared on TiN surface by laser clading.The wettability of the coating and the bonding strength between the coating and the substrate were improved by the laser nitriding on titanium surface.?3?In this paper,Antibacterial porcelain layers containing Ag nanoparticles were synthesized on Ti by laser-fusion method.During the laser-fusion process,the CaTiO₃phase was formed because of the chemical reaction between porcelain and Ti,which led to a strong metallurgical bonding between the antibacterial coatings and Ti.Due to the high temperature gradient perpendicular to the laser scanning direction,a coating with dendrites structure was formed on Ti.When Ti content is 20wt%,the dendrite among the coating is not obvious,the surface of the coating has the best smoothness,and the bonding strength between the coating and the substrate is the highest.The bioactive coating was soaked in SBF for a period of time.The result shown that the content of calcium phosphate deposited on the bioactive coating surface will increase as time extends.However,the bioactivity of the coating presented a decrease trend with the increasement of titanium content.The antibacterial property of the coating can be improved with much more addition of the Ag-NPs.However,the existence of the titanium has no effect on the antibacterial property of the coating.