Study On The Microstructure And Biological Properties Of Laser Cladding Diatomite Bioceramic Coatin

Biomedical metal materials have favourable mechanical properties,but poor biocompatibility.Bone replacement material needs to be replaced every ten years,which will not only bring pain to patients,but also increase the consumption of biomaterials.It is urgent to develop biomaterials with favourable bioactivity and favourable mechanical properties.In this paper,the Ca-P bioceramic coating doped with diatomite（DE）was fabricated on the Ti6Al4V with favourable mechanical properties by broadband-laser cladding.The microstructure and biological properties of the coating were studied by using modern test technology,and the following research results are obtained.（1）The main phases of the doped with DE bioceramic coatings prepared by laser cladding are HA,TCP,CaSiO₄,CaTiO₃,Ca₅（PO₄）₂SiO₄（CPS）.When P=4.8kW,more holes are generated on the surface of the bioceramic coating and the surface of the coating is rough.With the increase of the scanning speed,the holes existing on the surface of the coating gradually decrease;when P=5kW,P=5.2kW,the coating is smoother and less porous.When the power parameter is fixed,with the increase of scanning speed,the number of cracks and the crack width of the bioceramic coating increase,the microhardness gradually decreases,and the thickness of the bioceramic coating increases.When the scanning speed is fixed,with the increase of power,the number of cracks in the coating gradually decreases and then increases,and the microhardness of the coating gradually decreases,and the coating has less cracks,and cracks contribute to the growth of osteoblasts.The longer the bioceramic coating is soaked in SBF,the more bone-like apatite is deposited on the surface of the bioceramic coating.In the early stage of immersion,the bioceramic coating has a higher degradation rate.The results of co-culture of the bioceramic coating with the cells for 6 days indicate that the coating performs favourable biocompatibility,the number and morphology of osteoblasts on the coating surface perform well.Comprehensive analyses indicate that the bioceramic coatings of the process parameters of P=5kW and V=7mm·s^-1have favourable microstructure and biological properties.（2）Under the optimized process parameters P=5kW and V=7mm·s^-1,bioceramic coatings with different DE contents were prepared.XRD showed that,compared with the ceramic coating without DE doping,new phases of CPS and Ca₂SiO₄appeared in the ceramic coating doped with DE,and bioactive phases such as HA,TCP,CaSiO₄and CPS produced by the coating.The characteristic diffraction peak of the HA phase is stronger,and the vibration peak of the 10wt%DE bioceramic coating is near1011cm^-1,and the intensity of the P-O characteristic peak is significantly increase.The cracks of the bioceramic coatings doped with DE are reduce,and the microhardness is increase,and the maximum value of the microhardness reach1778HV.The coatings doped with 5wt%DE and 10wt%DE have fewer cracks and higher average microhardness.The DE-doped bioceramic coating has no toxicity to osteoblasts and has a value-added effect.The cells on the surface of the DE-doped coating have strong adhesion ability,and the pseudopodia of the cells grasp the coating.The longer the soaking time of the bioceramic coating doped with DE in SBF,the more bone-like apatite is deposited on the surface of the bioceramic coating,and the characteristic diffraction peak of HA on the coating surface is gradually enhanced.（3）The intensity of characteristic diffraction peaks of TCP gradually decrease with the increase of Ca/P,and the intensity of characteristic peaks of CaTiO₃gradually stronger.The characteristic peaks of the bioactive phases HA,TCP and silicate have higher intensities.With the increase of Ca/P in the coating,the transverse cracks and longitudinal cracks of the bioceramic coating decrease obviously and the average hardness of the coating increase gradually.The bioceramic coating has favourable biocompatibility and is non-toxic to osteoblasts.With the increase of time,the number of cells on the surface of the bioceramic coating increases and the osteoblasts can maintain favourable morphological of growth.The cellular pseudopod grasp firmly the coating,and the bioceramic coating with Ca/P=1.40 has favourable biocompatibility.From the analysis of the effect of different Ca/P on the bioactivity of the bioceramic coating,the bioceramic coating with Ca/P=1.35 and Ca/P=1.40 is soaked in SBF,more bone-like apatite is deposited on the surface of the coating.The degradation ability of the different Ca/P bioceramic coatings is favourable,and the coating weight increase.The bioceramic coating with Ca/P=1.40 has favourable bioactivity.