Preparation Of Rare Earth Doped Gradient Bioceramic Coating By Laser Cladding On Titanium Alloy Surface

Hydroxyapatite(HA,Ca₁₀?PO₄?₆?OH?₂)is a biocompatible and bioactive material.Due to its similar structure to bone minerals,it is used in different biomedical applications.TC4 titanium alloy has the characteristics of low density,high specific strength,high fatigue strength and excellent biocompatibility,and is widely used in the field of biomedicine.Boron?B?is an essential element of human physiology,it can promote bone strength,increase the density of bone cells,and increase bone absorption of calcium and phosphorus.In addition,lanthanum oxide?La₂O₃?is an important rare earth oxide,which can improve the tensile and bending strength of HA.Doping with low content of lanthanum oxide can improve the biological activity.At the same time,rare earth oxides can improve the quality problems of the cladding layer during the laser cladding process.This subject further improves the biological activity of the coating and improves the quality problems that occur during the laser cladding process by adding rare earth elements.Firstly,the optimal cladding layer thickness is explored,and the_IIIII optimal laser cladding process parameters are determined.On this basis,different rare earth additions are studied.Through the detection and analysis of the results,the optimal rare earth additions are finally determined.In this paper,a rare earth-doped bioceramic coating was prepared by laser cladding technology,and the phase composition of the cladding layer composition by the amount of rare earth oxide added was studied by scanning electron microscope?SEM?and X-ray diffractometer?XRD?.,Mechanical properties,corrosion resistance and biological activity.After the preliminary exploration of the research group,under the condition that the mass ratio of cladding powder was determined to be5BH:La₂O₃=99.4:0.6?5BH:95wt.%HA+5wt.%CaB₆?,through a series of exploration experiments,the optimal was determined The laser cladding process parameters:laser power P=305 W,scanning speed V=840 mm/min,spot diameter D=2.5 mm,overlap rate 40%,argon flow rate 10 L/min.When rare earth elements are added to the cladding layer,grain refinement can be clearly found.The main phases of the rare earth doped bioceramic coating are:HA,B₂O₃,Ca₃?PO₄?₂,CaTiO₃,CaO through XRD phase detection,CaB₂O₄,TiO,Ti.When the additive amount of La₂O₃ is 0.8wt.%,The hardness shows the highest,the highest hardness is about 2.3 times of the matrix.Compared with the undoped rare earth biological coating,the rare earth doped biological coating has lower corrosion current density,lower corrosion rate and improved corrosion resistance of the cladding layer.The biological activity of the cladding layer was evaluated using the in vitro immersion experiment of SBF Simulated body fluid.It was found that the rare earth elements in the cladding layer can accelerate the deposition of bone-like apatite.Compared with the cladding layer without added rare earth element The amount of stone deposition increases.When0.2⁰.4wt.%La₂O₃ is added to the cladding layer,the cladding layer exhibits good biological activity.