Farhad Shahriari Nogorani

Various injuries, such as traffic accidents, bone tumours and other types of trauma, cause extensive damage to human bone tissue. In many cases, the body cannot spontaneously repair these injuries,...

A self‐healing anticorrosion protective was developed for steel st‐37 exposed to the marine tidal zone, which is composed of a multi‐layer polymer coating. The coating includes zinc‐rich epoxy primer, self‐healing microencapsulated embedded epoxy, and a top coat consisting of polyurethane incorporated with silica nanoparticles. The size of microcapsules decreased with increasing agitation during encapsulation, which varies from 4 to 43 µm. Good performance was observed for producing the encapsulated particles with a size of up to 5 µm and more than 90% loading of the embedded healing agent, in which a 1680 rpm agitation along with a pH of 3 for the synthesis environment and a 130 min for the synthesis duration is set. The optimal amount of microcapsules and silica nanoparticles was 10 and 1.5 wt%, respectively. Also, the promised self‐healing anticorrosion coating leads the damaged areas to be fully healed in almost 12 h in the face of harsh conditions. In contrast to the non‐self‐healing one, the healing ability of the developed self‐healing coating shows good barrier properties and leads to a lesser loss of interface adhesion.

The aluminizing behavior of high‐velocity oxy‐fuel sprayed CoNiCrAlY, or NiCoCrAlY‐coated IN738LC alloy has been investigated via asingle or two‐step pack cementation aluminizing processes. The microstructural study showed that a more desirable low aluminum‐containing MCrAlY coating is obtained through single‐step aluminizing. The resultant over‐aluminized coating microstructure consisted of the Co‐containing beta‐NiAl in the aluminide top layer and the Ni−Co−Cr‐based austenitic gamma solid solution matrix decorated with the Co‐containing beta‐NiAl islands in the MCrAlY zone.

Practical applications of thermal barrier coatings with aluminide bond-coats are limited due to oxide scale spallation of the aluminide coating under applied thermal stresses. Considering the positive effects of oxygen-active elements or their oxides on the high temperature oxidation behavior, in this research zirconia was introduced into an aluminide coating. ...