The Preparation Of Biological Bone By Direct Laser Deposition

Global population growth and the increasing trend of population aging, as well as transportation, natural disasters and other accidents which occur frequently, which increase the demand for bone graft or replace. Among a variety of biological bone materials has been developed, metal and metal based biological materials with excellent mechanical properties has been widely accepted in the field of clinical implant. Recently, with the development of Laser Direct Deposition Modeling Technology, the preparation of biological bone materials by this method has been one of key researches. Titanium alloy and cobalt-chromium alloy materials with the basic characteristics of biological bone have been the important materials studied by Laser surface treatment and Laser Direct Deposition Modeling Technology.In this study, a Ti-based bio-bone coating and a Co-Cr-based bio-bone coating on TC4 substrate, and a cobalt chromium composite material with a high and thick size on Q235 substrate were prepared by Laser Direct Deposition Modeling Technology. The structure, properties and preparation mechanisms of the samples were studied by using means of metallographic microscope, scanning electron microscopy, transmission electron microscopy, XRD, hardness, friction and wear and electrochemical analysis methods. The results show that:The best deposition process parameters of Ti-based bio-bone coating are power 1500W, scanning speed 300mm/min and spot size 7.18mmx4.30mm, which the cracking trend of the gradient coating sample is the least. The ceramic zone on top of the coating has loose microstructure, and porosity evenly distributed on the surface, all of which is in favor of the bone tissue in growth. The bio-ceramic phase of the coating is composed of HA, CaTiO3, Ca3 (PO4)2, the hardness of top coating reaches up to 1900HV.The deposition process parameters of Co-Cr-based bio-bone coating are power 1400W, scanning speed 440mm/min and spot size 7.6mmx4.5mm, the optimized content of ZrO2 in the second gradient layer is 2wt.%, the optimized content of ZrO2 in the third gradient layer is 3wt.%, the thickness of the sample is about 3mm, it has good wear resistance. The bio-ceramic phase of the coating is composed of CaTiO3、Co2Ti4O and TiO3, the hardness of top coating reaches up to 1500HV.The thickness of Co-Cr composite biological materials prepared by Laser Direct Deposition Modeling Technology is 7mm, the study found that Y2O3 had obvious effect to eliminate laser forming cracks, transformation between a-Co and s-Co and structure refinement. The cracks in deposition layer are successfully eliminated due to the adding of 2wt.%Y2O3 in the powder, the hardness of the Co-Cr composite biological materials is 450HV, it has good wear resistance. The corrosion resistance of the cobalt chromium biological composite samples with three kinds of Y2O3 content in acid oral environment was all higher than that in neutral environment, the corrosion rate of the sample with 2wt.%Y2O3 content was the lowest in both environments.