Mardali Yousefpour

The relationship of surface roughness and cell response of chemical surface modification of titanium

Implant surface topography influences osteoblastic proliferation, differentiation and extracellular matrix protein expressions. Previous researches proved that chemical surface modification of titanium implants could be used to improve Bone-to-implant contact. In this study, the surface topography, chemistry and biocompatibility of polished titanium surfaces treated with mixed solution of three acids containing HCl, HF and H3PO4 with different etched conditions for example concentration, time and addition of calcium chloride were studied. Osteoblast cells (MG-63) were cultured on different groups of titanium surfaces. In order to investigate titanium surfaces, SEM, AFM and EDS analyses were carried out. The results showed that surfaces treated with HCl–HF–H3PO4 had higher roughness, lower cytotoxicity level and better biocompatibility than controls. Moreover, addition of calcium chloride into mixed solution of three acids containing HCl, HF and H3PO4 is an important, predominant and new technique for obtaining biofunction in metals for biomedical use including dentistry.

Effect of Nano-oxide addition on corrosion performance of hot dip zinc coating

Corrosion performance of hot dipped zinc coating on low carbon steel was studied at the presence of different nanoand micronsize oxide particles in the liquid zinc bath. Nano-silica, nano-alumina and micro-alumina powders were loaded to the different liquid baths, in the range of 0.05–0.2 wt %. Low carbon steel specimens were immersed in the baths for a constant time of 10s. It was evident that the presence of oxide particles in the liquid bath increased the coating thickness at a constant immersing time; micro-alumina particles provided the thickest coating among the others. Salt spray and potentiodynamic polarization tests were conducted to evaluate corrosion performance of the galvanized coatings, including oxide bearing ones. The results confirmed improvement in corrosion resistance of the nano-oxide bearing zinc coatings; while incorporation of micro-alumina in the bath declined its corrosion resistance. It was shown that incorporation of nano-silica powder in the liquid bath yielded superior corrosion resistance of the zinc layer, in comparison to the other ones. The optimum corrosion performance of zinc coating was achieved via loading 0.1 wt % nanosilica to the liquid zinc bath in this work.

A Study on the Characterization of MASHS Processed Ti-Si-Al System

Many promising titanium aluminides and silicides could be synthesized in Ti-Si-Al system via mechanically activated self-propagating high-temperature synthesis (MASHS). The influence of mechanical activation and initial composition on phase formation, microstructure and synthesis behavior of mechanically activated Ti-rich mixtures in Ti-Si-Al system is investigated. Results indicate that Al can participate in the reaction and forms Ti3Al and TiAl3 phases beside Ti5Si3 phase by using mechanically activated reactants. Si and Al could be substituted each other in titanium aluminide and silicide to form solid solution of Ti3(Si,Al) and Ti5(Si,Al)3. In Ti-Si-Al system, combustion temperature is increased by increasing Si amount in the system while, ignition temperature is decreased profoundly from 1100 to 800 ∘C by applying mechanical activation prior to reaction and increasing Al in the system. In addition, Mechanical activation prior to synthesis gives rise to narrow grain size distribution and more uniform microstructure in comparison with SHS products.

Electrochemical and biological characterization HA/Al2O3-YSZ nano-composite coatings using electrophoretic process: ELECTROCHEMICAL AND BIOLOGICAL CHARACTERIZATION HA/AL2O3-YSZ

In this research work, hydroxyapatite/alumina/YSZ bio nanocomposite coatings on titanium substrate were created by electrophoretic deposition (EPD) and reaction bonding process. By using the EPD process, uniform green form coatings containing HA, yttria-stabilized zirconia (YSZ), and aluminum particles were produced on titanium. After oxidation of aluminum at 660°C and sintering at 850°C, a dense and adherent HA/Al2 O3 /YSZ coating was produced. Scanning electron microscopy, X-ray diffractometric and mechanical tests were employed to investigate the morphologies, compositions, hardness, toughness and bonding strength of the coatings. The corrosion studies and cell culturing experiment were carried out and the results show that the HA/YSZ/Al2 O3 coatings are more bioactive and more resistance to corrosion than HA coatings.

Preparation of Chitosan-based nanocomposites and biomedical investigations in bone tissue engineering

Abstract Chitosan (CS)/Bioglass (BG)/Hydroxyapatite (HA)/Halloysite nanotube (HNT) nanocomposites were deposited on titanium (Ti) by electrophoretic deposition (EPD). The nanostructures with the uniform distribution of ceramic particles into CS polymer were yielded. In vitro experiment depicted CS/BG/HA/HNT is precipitated with apatite particles by immersion into corrected simulated body fluid (C-SBF) at 37 °C. Furthermore, In vitro bioactivity, biomineralization, and cell attachment indicated that all of the coatings have a desirable apatite induced ability and cell compatibility. Finally, biodegradability of CS-BG-HA/HNT nanocomposite verified the degradation ratio of CS-BG-HA-HNT is 4 times more than that of CS-BG-HA. Graphical Abstract