| The advanced manufacture and surface modification technology has become an important research field of medical artificial bone. Magnesium alloy is a new generation of medical metal materials with the advantage of good mechanical properties, absorbability and non-toxic to human body. Hydroxyapatite is a kind of calcium phosphate which is difficult to dissolve in water. The less solute species can be deposited on the surface of the metal substrate by the electrophoretic deposition. In this paper, the deposition time of electrophoretic deposition, the thickness of HAP coating, and preparation of the artificial bone using hydroxyapatite powder based on AZ31 B magnesium alloy composite were studied. The results obtained are as follows:(1) The coating thickness, bonding strength, micro morphology and main composition of AZ31 B magnesium alloy were studied. The results showed that the sample with short deposition time had high strength coatings(the bond strength ratio of three samples is approximately 5/4/1), the HAP coatings was uniformity and had good density by comparing 3 samples under different deposition time. Electric field intensity was greater at the initial stage, the thickness of the coating is positively correlated with the deposition time. The HAP particles could uniformly deposit onto the surface, pending the substrate surface was completely covered with a coating.When electric field strength decreased significantly, the deposition rate declined, even the compactness of the coating became worse.(2) The change of the weight, the surface morphology, the main composition,corrosion resistance and biocompatibility of AZ31B/HAP composite after corrosion and the change of pH of simulated body fluid were studied. The results showed that the greater thickness specimen resulted in the decrease of corrosion resistance performance and coating density. The adhesion strength between the coating and the matrix was also decrease dramatically. The sample with thinnest coating had bettercorrosion resistance performance and better coating density. But it became particularly rapidly degraded after 15 day. The specimens with moderate coating had higher anti-corrosion properties in simulated body fluid(the ratio of the corrosion rate of the three 1.2/1/8), the pH value of the solution was reasonable. All of them almost had the same biological activity, but the rate of degradation in vivo was different,mainly due to the combined strength and distribution of the coating.(3) Based on the image processing and powder metallurgy technology, the technique route of making artificial bone using AZ31 B magnesium alloy/HAP bio-composite was presented. The image processing in human bone CT slices,three-dimensional model of bone was rebuilt. Then, the bionic artificial bone STL format file was obtained. The outer, the outer surface of bone mold, and the holes frame core were obtained by 3D printer. Finally, according to the variation between the electrophoretic deposition time and thickness, the deposition of hydroxyapatite powder to multi porous magnesium alloy bionic bone surface could be acquired by setting optimal electrophoretic deposition time.The results showed for the first time that the reasonable electrophoretic deposition time could get uniform and dense hydroxyapatite coating. A good coating can effectively control corrosion rate of AZ31B/HAP bio-composite. And the composite material has good biological compatibility. The AZ31B/HAP bio-composite bone provides the scientific basis of making the composite artificial bone for biomedical metallic materials of the development and the preferred surface modification technology. |
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