توليد و مشخصه يابي پوشش كامپوزيتي نانو ساختار هيدروكسي آپاتيت- سيليك با روش سل-ژل بر روي فولاد زنگ نزن 316ال

چكيده انگليسي :

Fabricaton and characterization of nanostructured hydroxyapatite silica composite coating by sol gel method on stainless steel 316L Seyed Mohsen Latifi sm latifi@ma iut ac ir March 15 2010 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors M H Fathi Prof and M A Golozar Prof Abstract High tendency has recently been created toward developing nanostructured composite biomaterials in order to obtain materials with different properties and or multi purpose applications such as repair therapy and reconstruction of bone tissue Presence of silica in many biocompatible and bioactive materials has been found to improve the bioactivity Therefore using sol gel method hydroxyapatite silica HA SiO2 composite nanopowder at 600 C and nanostructured hydroxyapatite silica composite coating on stainless steel 316L at 550 C were prepared and characterized X ray diffraction XRD technique was used to approve suitable phases in the powders and coatings obtained The effect of the silica content on grain size and crystallinity was also evaluated Fourier transform infrared spectroscopy FTIR technique was used to identify the functional groups in composite powders and coatings Transmission electron microscopy TEM technique was utilized to evaluate the shape and grain size of nanostructured composite powders Scanning electron microscopy SEM technique was used to study the powder morphology morphology and surface quality of coating and also coating thickness measurment Energy dispersive X ray analysis EDX was used to determine the elemental analysis of powders and distribution of elements in composite coatings Evaluation of dissolution rate and bioactivity of composite powders and coatings in physiological saline solution carried out for 21 days in a thermodynamically closed system and for 4 days in a thermodynamically open system respectively In order to identify the content of Ca ion release from composite powders and coatings atomic absorption spectrometer AAS was used Also SEM was employed to study the variation of morphology Quality evaluation of bonding strength of coating to substrate carried out based on the ASTM C1624 standard Finally using electrochemical polarization potentiodynamic test corrosion resistance of coated substrates was evaluated The results indicated that nanostructured composite powder consists of hydroxyapatite crystalline phase and silica amorphous phase The crystalinity and crystallite size of hydroxyapatite was decreased by increasing the silica content Powder dissolution experiment in a thermodynamically closed system showed that compare with hydroxyapatite powder in dissolution stage the Ca ion release of composite powder is increased This would also accelerate the apatite creation in reprecipitation stage Evaluation of single phase and composite coatings modified by 2 wt oxalic acid showed high quality surface coating proper bonding to substrate and thickness less than 3 5 m Evaluation of bonding strength of coatings showed that composite coatings compare with single phase coatings have better bonding strength Coating dissolution experiment in a thermodynamically open system showed that due to the presence of silica in composite coatings the Ca ion release could be controlled In addition the coating morphology evaluation after dissolution test indicated morphology chang of precipitated apatites and consequently increasing bioactivity by increasing silica in composite coatings Results of electrochemical polarization tests showed that increasing the silica in composite coatings lead to improve the corrosion behavior of coated substrate as well as biocompatibility Key Words Silica Hydroxyapatite Composite Coating Powder Sol Gel

لطيفي، محسن

توليد و مشخصه يابي پوشش كامپوزيتي نانو ساختار هيدروكسي آپاتيت- سيليك با روش سل-ژل بر روي فولاد زنگ نزن 316ال

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