توليد ومشخصه يابي نانو كامپوزيت آلياژ منيزيم-فلوئور آپاتيت زيست تخريب پذير

چكيده انگليسي :

Fabrication and Characterization of Biodegradable Magnesium Fluorapatite Nanocomposite Mehdi Razavi Mohammadhossein Fathi Mahmood Meratian Department of Materials Engineering On January 2010 Language Persian Abstract Magnesium based implants have the potential to serve as biocompatible osteoconductive and biodegradable implants for load bearing applications These implants would be temporarily needed to provide mechanical support during the healing process of injured or pathological tissue Moreover the metallic implants such as pins screws and plates used for repairing the bone defects have to be removed by a second surgery after the bone was healed Since the repeated surgery will increase the morbidity and the health costs then the use of biodegradable metallic implants with a good biocompatibility is expected to overcome the limitations of conventional metallic biomaterials and remove the second surgery In spite of the immense potential of biodegradable magnesium alloys the fast biodegradation rates of magnesium based implants in the physiological environments impose severe limitations in many clinical applications If the implants being made of the magnesium alloys are used to repair the diseased bone tissue they are possible to lose the mechanical stability before the healing of bone tissue due to the rapid biodegradation Recently some researches have been done to slow down the biodegradation rate of magnesium alloys Besides improving the biodegradation rate of magnesium alloys the biocompatibility should also be considered Also the mechanical properties of magnesium alloys were low for the load bearing applications and the corrosion resistance also needed to be improved furthermore Design and preparing of a nanocomposite based on magnesium alloy might be an approach to this challenge The aim of this work was to prepare and characterize of biodegradable magnesium fluorapatite nanocomposite and to evaluate the effect of fluorapatite FA nano particles content on microstructure mechanical properties and bio corrosion behavior of a nanocomposite AZ91 FA made of AZ91 magnesium alloy as matrix and FA nano particles as reinforcement for load bearing applications Novel AZ91 FA with 10 wt 20 wt and 30 wt of FA nanocomposites were produced by AZ91 magnesium alloy powders and FA nano particles using a blend press sinter powder metallurgy PM method Microstructure mechanical properties and bio corrosion behavior of the prepared AZ91 FA nanocomposites and also the AZ91 magnesium alloy as control sample were evaluated The results showed that the presence of the FA nano particles in the AZ91 magnesium alloy matrix led to significant improvement in hardness and elastic modulus The AZ91 FA nanocomposite with 20 wt of the FA nano particles showed the highest yield strength and with the increase of the FA content in the AZ91 FA nanocomposites the ductility decreased The AZ91 FA nanocomposites presented increased corrosion resistance compared to the AZ91 magnesium alloy and the corrosion resistance of the AZ91 FA nanocomposites increased with an increase in FA content The AZ91 FA nanocomposite with 20 wt of the FA nano particles showed optimum mechanical properties as well as the corrosion resistance The addition of fluorapatite nano particle reinforcements to magnesium alloys accelerate the formation of an apatite layer on the surface which provides improved protection for the AZ91 matrix It is suggested that the formation of an apatite layer on the surface of magnesium alloys can contribute to the improved osteoconductivity of magnesium alloys for biomedical applications Keywords Magnesium alloys Fluorapatite nano particles Nanocomposite materials Powder metallurgy Mechanical characterization Electron microscopy

رضوي، مهدي

توليد ومشخصه يابي نانو كامپوزيت آلياژ منيزيم-فلوئور آپاتيت زيست تخريب پذير

متالوژي پودر , مشخصه يابي مكانيكي , ميكروسكوپ الكتروني