Dissertation
Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metal corrosion protection,metal surface treatment > Corrosion control and protection > Metal surface protection technology > Metal complex layer of protection

Study on the Preparation and of Hydroxyapatite Coating on Medical Magnesium Alloy

Author YiYueJun
Tutor PengZhongDong
School Central South University
Course Metallurgical Engineering
Keywords magnesim alloy hydroxyapatite coating corrosionresistence
CLC TG174.44
Type Master's thesis
Year 2012
Downloads 286
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Magnesium and magnesium alloys because of their good mechanical properties and biocompatibility, and can be degraded in vivo, therefore they are potential medical implant materials. However, the corrosion resistance of magnesium and magnesium alloys is poor, magnesium and magnesium alloys are vulnerable to corrosion, can not meet the mechanical performance requirements in their service period, therefore how to improve the corrosion resistance of magnesium and magnesium alloys, is a hot research topic in recent years. Hydroxyapatite (HA) with good biological compatibility and biological activity is one of the major components of human skeleton, and can not easily be decomposed.In this paper, commercial AZ31B magnesium alloy was used as the raw material.HA coating was prepared on magnesium surface by using electrochemical deposition method, self-assembled bionic method and bionic heat method.The corrosion resistance of treated magnesium alloy was tested.HA coating was prepared on magnesium alloy by electrochemical deposition.The effect of deposition voltage, deposition time and deposition solution concentration on the deposition results was been studied, and the surface coating were analyzed. The results showed that:after electrochemical deposition, magnesium alloy was coated by HA coating ont the surface. The appropriate conditions of the deposition was to use a deposition solution concentration with0.1mol·-1CaNO3,0.06mol·L-1NH4H2PO4at a voltage of4.5V deposited210min.Under this condition, magnesium alloy showed good corrosion resistance after treatment.Electrochemical test results showed,after electrochemeical deposited HA coating,the corrosion potential of magnesium was rised from-2.36V to1.60V,and the fitted corrosion current density was reduced from5.64×10-6A·cm-2to4.92×10-8A·cm-2A concept of self-assembly was introduced, HA coating was prepared on magnesium surface by self-assembled biomimetic method. Magnesiumalloy was activated by0.1mol·L-1EDTA,and then was pre-calcificated by0.lmol mol·L-1CaCl2and0.1mol·L-1K2HPO4, finally self-assembled biomimetic prepared.HA coating in solution stimulated body fluid (SBF solution) in solution stimulated body fluid (SBF solution) self-assembled biomimetic.At the initial stage of the bionic,the pH of SBF solution was first decreased and then increased.The bionic treated magnesium alloy showed better corrosion resistance compared with untreated magnesium alloy. HA coating was prepared on magnesim alloy by self-assembled biomimetic treatment. After the treatment, the corrosion potential of magnesium alloy was rised to-1.64V, the corrosion current density was reduced to9.57×10-7A·cm-2.Magnesium alloy showed good corrosion resistance after bionic-heat treatment. Analysis results showed that the main compositon the surface coating was HA and CaPO3(OH) after treatment,and the corroision potential of magnesium alloy was rised to-1.63V while the corrosion current density was reduced to1.92×10-7A·cm-2.

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