Nanostructured organic-inorganic hybrid anti-corrosive coating for highly aggressive marine environment

Research area: Polymer science, nanomaterials, hybrid materials
Supervisors: Prof Naba Dutta and Prof Namita Roy Choudhury  

Description: The estimated annual cost of corrosion worldwide has been estimated to be nearly $300 billion per year. Aside from the cost in dollars, corrosion is a serious problem that directly and definitely contributes to the depletion of natural resources.

The proposed project aims to address the need for environmentally friendly high performance protective coating for active metals such as the carbon steels used in highly aggressive marine environment. Corrosion does not occur in dry air and the rate of corrosion is dormant between 30-35% relative humidity, the critical level being 45%, above which the rate of corrosion accelerates. The majority of metallic materials, particularly active metals such as carbon steel on exposure to such environmental conditions during their applications deteriorate and fail prematurely. Such items may become corroded over relatively short period of time in salt water environment.

Silicate and phosphate based coatings are most frequently used as ceramic anti-corrosion coatings, which are effective, chemically inert, hard and thermally stable. However, their usages are limited by their brittleness, higher processing temperature and the presence of micro-cracks and defects. On the other hand organic coatings can be easily formulated and can form a dense coating with better elastic properties. But polymer coatings are often mechanically weak, display inadequate wetting and adhesion properties to the substrate and poor resistance to heat.

To overcome the limitations new class of hybrid coatings is to be developed using molecular level combination of organic and inorganic components. These hybrid coatings have enormous potential due to the flexibility in chemical approach and ability to tailor the system to specific needs. However, in such systems the resulting nanostructure, degree of organization and the ultimate properties achieved not only depend on the chemical nature of the components used, but also on the nature, extent and accessibility of the inner interfaces that controls the synergy between the two components.

This proposal represents a novel concept for designing high stiffness and high toughness polymeric anti-corrosion coating based on hybrids containing cross-linkable functional groups as the base material. Nano-structured material engineering approach will be employed to create designed interface to open up the possibility of significant enhancement of the macroscopic properties, which is almost impossible or difficult to achieve by traditional methods. We will examine how the tailoring of the surface structure on a nanometer scale can dramatically alter the macroscopic properties of a coatings including film strength modulus and delamination rate. We will also attempt to introduce bio-inspired self-healing character to the hybrid coating, which will enable the coating to repair itself on failure without external intervention to prevent corrosion of the underlying substrate.

The detail characteristics of the coating in nano, micro and macro levels will be evaluated using a wide range of microscopic, spectroscopic and diffraction techniques. The phase behaviour, flow property, film properties, cure characteristics, barrier properties and mechanical behaviour of the films will be evaluated in detail. Viscoelastic behaviour, films, stability and environmental aging behaviour of the coating will also be evaluated to establish structure-property-performance relationship.

Different electrochemical experiment in the laboratory including potentiodynamic polarization methods, electrochemical impedance spectroscopy (EIS), scanning Kelvin probe, SKP and in the field samples will be employed for detail evaluation of corrosion characteristics of the film and predict its long term survival.

Funding: An ARC-Linkage grant application to the Australian research Council (ARC) is currently being assessed. International students should apply for an International Postgraduate Research Scholarship (IPRS) and a UniSA President's Scholarship (UPS). To be eligible for UPS, applicants must have a supervisor willing to nominate them for consideration. Australian students should apply for an Australian Postgraduate Award (APA) and a UniSA Australian Postgraduate Research Award (USAPRA).

Areas of study and research

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