Doctor of Philosophy (PhD)
Mechanical and Industrial Engineering
Surface engineering is a multi-disciplinary research area that encompasses disciplines such as materials science, chemistry, mechanical engineering, and electrical engineering. Coating is a surface modification technique in surface engineering, applied on the surface of a substrate (i.e., bulk material), to cover/protect it from environmental degradation or to modify/improve surface properties for specific applications. This PhD research presents an in-depth investigation of sol-gel ceramic coatings to modify surface characteristics of bulk materials for two specific applications: 1) antistatic/antidust applications, and 2) biomaterial implant applications.
First, zirconia antistatic thin films on glass substrates, and their application to polymer-based composites, was studied. Zirconia antistatic coatings were synthesized by a low cost dip coating sol-gel route on glass substrates, then applied to polymer-based composites to potentially improve their dust or water repellent capabilities for aesthetic purposes. The optimized coating with antistatic and dust repellent capability was derived in 50% humidity from a solution containing 15 g ZrCl4/l for all substrates.
Second, hydroxyapatite (HA) coating on various mesh substrates was studied as a composite biomaterial implant, mainly for cranioplasty. In this study, we proposed the design of biocompatible, flexible composite implants by using mesh substrates and customized HA coating as bone regenerative stimulant, derived from a simple sol-gel method.
For metallic mesh substrates, HA-coated stainless steel 316 with mesh size of 200 (1 layer, dip coated by general HA solution) is a good replacement for pure titanium grade 1 regarding biomechanical, biocompatibility, and electrochemical properties. While polymeric or fabric substrate still cannot be used as a replacement for current cranioplasty implants.
Finally, based on observations acquired during HA powder synthesis, the effect of drying bed material on the amount of residue and powder crystalline characteristics was studied. The smallest residue percentage was 1.8%, for pure HA powder dried on aluminum bed. Bed material (glass, aluminum and titanium mesh) did not affect HA powder crystal structure and size. Wetting angle, which relates to surface tension between liquid HA and solid drying bed, was a key factor for the amount of leftover residue.
Naderi, Armaghan, "Characterization of Application-Driven Sol-Gel Coated Meshes and Composites" (2021). LSU Doctoral Dissertations. 5636.