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Bioglass Coating on 316L Stainless Steel

Pourhashem, Sepideh | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43585 (07)
  4. University: Sharif University Of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Afshar, Abdollah
  7. Abstract:
  8. Bioactive glasses are able to bond to soft and hard tissues in living body and their application as coating on metallic implants like 316L stainless steel has two important effects: (1) intimate link between bone and materials and (2) corrosion protection of metallic implant in body fluid and protection from tissues in front of corrosion products. Therefore, in this research, 45S5 bioactive glass prepared via sol- gel method was dip coated on 316L stainless steel substrates and its characteristics was investigated.Results of phase analysis showed that by sintering 45S5 bioglass at 600 ˚C for 5 h, an amorph sample with small amount of Na2Ca2Si3O9 was obtained. So, the bioglass coated samples were sintered at 600 ˚C for 5 h.In order to achieve a coating with desired characteristics, one layer and multilayer 45S5 bioglass coated samples and silica- 45S5 bioglass coated samples were prepared and compared and the effects of sol aging and surface preparation of substrates were investigated. Results showed that by aging bioglass sol at 50 ˚C and using sandblasted substrates treated in HNO3, one- layer 45S5 coating with adhesion strength of 6 MPa was obtained. By increasing the number of dip coatings, adhesion strength decreased and cracks formed. Silica- 45S5 bioglass coated samples were crack- free and their adhesion strength was 5 MPa. The electrochemical properties of samples were considered by potentio- dynamic polarization tests in SBF solution which showed that bioglass coatings improved corrosion resistance of 316L stainless steel. Further, in vitro behavior of silica-45S5 bioglass coated samples was considered during 30 days of immersion in SBF at 37 ˚C by XRD, SEM, AAS and potentiodynamic polarization tests that showed the growth of a layer similar to HCA on surface of samples.
  9. Keywords:
  10. Bioactive Glass ; Stainless Steel ; Corrosion ; Bioactivity ; Sol-Gel Method

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