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Summary of Chemistry doctoral thesis: Electrodeposition of hydroxyapatite/modify carbon nanotubes coating on alloys to apply for bone implants

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Objectives of the thesis: Selecting of suitable conditions to synthesize HAp-CNTsbt nanocomposite coating on 316LSS and Ti6Al4V; HAp-CNTbt coating has biocompatibility and protection ability for the substrate in comparison with HAp coating.
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Summary of Chemistry doctoral thesis: Electrodeposition of hydroxyapatite/modify carbon nanotubes coating on alloys to apply for bone implants GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY INSITUTE FOR TROPICAL TECHNOLOGY SUMMARY OF PhD THESIS IN CHEMISTRY ELECTRODEPOSITION OFHYDROXYAPATITE/MODIFY CARBON NAOTUBES ON ALLOYS TO APPLY FOR BONE IMPLANTS Specialization: Theoretical and Physical chemistry Code: 9 44 01 19 Hanoi 2019 1The dissertation completed at:Academic supervisors:1.2.Reviewer 1:Reviewer 2:Reviewer 3: 2 INTRODUCTION Reason to choose the topic Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is the main inorganic component in humanbones and teeth, has high biocompatibility. HAp is applied in medicine with different forms:powder, ceramic, composite and coating. Synthetic HAp has the same composition in naturalbone and has good biocompatibility. However, pure HAp coating has a relatively highsolubility in physiological environment and poor mechanical properties leading to fasterdegradation of the material and reducing the fixed ability between the implant material andthe host tissue. Some reports show that the doping of carbon nanotubes to create HAp-CNTcomposite significantly improves the mechanical properties of materials such ascorrosion resistance and mechanical strength. The thesis: Electrodeposition ofhydroxyapatite/modify carbon nanotubes coating on alloys to apply for bone implantsshows investigation to synthesize HAp-CNTsbt coating on 316LSS and Ti6Al4V. Objectives of the thesis:- Selecting of suitable conditions to synthesize HAp-CNTsbt nanocomposite coating on316LSS and Ti6Al4V.- HAp-CNTbt coating has biocompatibility and protection ability for the substrate incomparison with HAp coating.• Main content of the thesis:1. Study on effect of the scanning potential range, scanning rate, number of scans, CNTbtamount, and synthesis temperature on the characteristics of HAp-CNTbt coating. Selecting ofsuitable conditions for synthesie HAp-CNTbt/316LSS and HAp-CNTbt/ Ti6Al4V materials.2. Determination of roughness, elastic modulus and hardness of 316LSS, Ti6Al4V,HAp/316LSS, HAp/Ti6Al4V, HAp-CNTbt/316LSS, and HAp-CNTbt/Ti6Al4V.Determination of dissolutione of HAp and HAp-CNTbt coating in 0.9% NaCl solution.3. Research on biocompatibility and electrochemical behavior of 316LSS, Ti6Al4V,HAp/316LSS, HAp/Ti6Al4V, HAp-CNTbt/316LSS, and HAp-CNTbt/ Ti6Al4V in SBFsolution. CHAPTER 1: OVERVIEW1.1. Overview for Hydroxyapatite1.1.1. Properties of Hydroxyapatite1.1.1.1. Structural propertiesHydroxyapatite (HAp) exists in two structural forms: hexagonal (hexagonal) and monoclinic(monoclinic). Hexagonal HAp is usually formed during synthesis at temperatures between25 and 100 °C. The monoclinic form is mainly created by heating the hexagonal HAp at850 °C in air, then cooling to room temperature.1.1.1.2. Physical propertiesHAp exists in crystal with some parameters: molar mass of 1004.60 g, density of 3.08 g/cm3,hardness in the Mohs scale by 5, melting temperature of 1760oC, and boiling temperature2850 oC. The dissolution of HAp in the water is 0.7 g/L. HAp crystals usually have rod-shape, needle-shape, scale-shape, fibrous-shape, spherical-shape, and cylindrical-shape. 31.1.1.3. Chemical properties• HAp reacts with acids to form calcium salts and water.• HAp is relatively thermally stable, which is decomposed slowly at temperature range of800°C ÷ 1200°C, to form oxy-hydroxyapatite.• At bigger temperatures (> 1200°C), HAp is broken down to β - Ca3(PO4)2 (β - TCP) andCa4P2O9 or CaO.1.1.1.4. Biological properties HAp has a high biological compatibility, non-toxic, non-allergenic to the human bodyand has high antiseptic properties.1.1.2. Methods of synthesis of hydroxyapatite coatinga. Physical methodThe physical method is the method of creating HAp coating from ions or phase transition.These methods have the advantage of being able to easily fabricate HAp coating with athickness of µm. Several physical methods are used: plasma, vacuum evaporation andmagnetron sputtering [2, 37].b. Electrochemical methodElectrochemical method has many advantages in making thin coating on metal or alloys forbiomedical applications. Electrochemical technique is a simple technique that allows thesynthesis of HAp coating at low temperatures. The obtained HAp coating is of high purity,good adhesion to the substrate and we can control the coating thickness. HAp coating withthickness of nm size are synthesized on different substrates by electrochemical method suchas: Electrophoresis method, Anode method, Cathode dep ...

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