Electrodeposition of Thick and Crack-Free Fe-Cr-Ni Coatings from a Cr (III) Electrolyte

The electrodeposition of iron-nickel-chromium coatings is a more environmentally friendly and economical alternative to hard-chrome coatings made from chromium (VI) electrolytes and stainless-steel bulk materials. The aim of the study was to develop a suitable deposition method for thick and low-crack Fe-Cr-Ni coatings. Iron-nickel-chromium coatings were electrodeposited using a more ecological chromium (III) electrolyte with direct current (DC), stepped direct current, and pulse current (PC). The influence of the deposition method on the electrolyte aging, the alloy composition of the coating, and their microstructure was investigated. Corrosion studies of the Fe-Cr-Ni coatings in 3.5% NaCl solution were performed using polarization tests. Furthermore, hardness measurements and scratch tests were carried out to determine the adhesion strength. Phase analyses were performed by X-ray diffraction, and the chemical composition and microstructure were characterized by scanning electron microscopy. Using the stepped DC and PC method, crack-free Fe-Cr-Ni coatings were successfully deposited.

Synthesis of Carbon Nanotubes Using Plant Source and Study their Properties

In this study the normal and activated charcoal were used to prepare normal and activated multi walled carbon nanotubes (MWCNTs) from same plant (Citrus aurantium) which is a source of carbon by Chemical Flame Deposition method (CFDM). The obtained products were analyzed using FESEM, FTIR, XRD, and Raman spectroscopy. The FESEM image of normal charcoal revealed that it has much less nanopores than activated charcoal. The ratios of ID/IG for the normal and activated MWCNTs were 0.85 and 0.91 respectively, which shows that use activated charcoal as a source enhance the disorder and the defects on the carbon nanotubes. The results demonstrate and confirmed that a carbon nanotubes which were prepared from normal and activated charcoal have some disfigurements and have converging diameter nearly (31-88 nm) and (37-70nm) for normal and activated MWCNTs with length about (1-2) μm respectively.

A study of the electrophoretic deposition of polycaprolactone-chitosan-bioglass nanocomposite coating on stainless steel (316L) substrates

In this research, bioglass nanoparticles were synthesized via sol-gel method and a polycaprolactone-chitosan-bioglass nanocomposite coating was formed on SS316L substrate using electrophoretic deposition method. Then, the effects of voltage and deposition time on morphology, thickness, roughness, and wettability of final coating were investigated. Finally, biocompatibility and toxicity of the coating were evaluated. The results showed that increase of both time and voltage enhanced the thickness, roughness, and wettability of coating. Also, increase of deposition time increased the agglomeration. Therefore, it can be concluded that voltage of 20 V and time of 10 min are suitable for the formation of a uniform agglomerate-free coating. The presence of bioglass nanoparticles also led to the increase of roughness and improvement of polycaprolactone hydrophobicity. The results also showed higher bioactivity in polycaprolactone-chitosan-1% bioglass nanocomposite coating sample. This sample had a roughness ( Ra) of 1.048 ± 0.037 μm and thickness of 2.54 ± 0.14 μm. In summary, the results indicated that coating of polycaprolactone-chitosan-bioglass nanocomposite on SS316L substrate could be a suitable surface treatment to increase its in vivo bioactivity and biocompatibility.