NACE International

 
2nd Quarter 2014
Volume 5, Number 2
 
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In This Issue:

Leadership: Technical Committee Participation

 

TEG 474X – Nanotechnology and Corrosion

 

Dr. Harvey Hack Elected President of NACE International

 

Something to Celebrate …

 

The Latest Published NACE Standards and Reports

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TEG 474X – Nanotechnology and Corrosion

Nanoscience and nanotechnology are concerned with materials typically in the size range from 100 nm down to atomic. In this range, materials can have different or enhanced properties compared with the same macro-scaled systems. A number of studies have shown that nanomaterials are characterized by unique and improved optical, mechanical, electronic, and chemical properties that may lead to potentially useful technological applications.

Two main reasons for this change in behavior are an increased relative surface area and the dominance of quantum effects. This creates fascinating new possibilities for tuning the physical and chemical properties of materials by controlling the size of constituent domains and the manner in which they are assembled. It involves engineering of functional systems at the molecular scale. Nanotechnology Research and Development has evolved largely over the last two decades, and nanoscale materials are already in use and having profound effects in certain industries. The potential of nanotechnology in developing corrosion resistant coatings and alloys is immense. Nanotechnology also can be used as a next-generation corrosion control tool.

Technology Exchange Group (TEG) 474X, “Nanotechnology and Corrosion,” was established in 2013 under Specific Technology Group (STG) 60, “Corrosion Mechanisms,” to discuss and promote the scope and implementation of this technology in various fields like DOD, Oil and Gas, Semiconductors etc. TEG 474X will be sponsoring its first symposium on “Nanotechnology and Corrosion” at CORROSION 2015 in Dallas, Texas, USA, March 15 – 19, 2015.

This symposium will focus on understanding the unique aspects of materials required for corrosion monitoring and protection. The goal of this symposium will be to bring together researchers and engineers to provide a forum for discussing and advancing current needs for new materials in corrosion control. The symposium will provide a synergistic platform for nanomaterial engineering, which will drive the development of novel nanotechnologies for corrosion.

Forms of Nanomaterials

Nanomaterials are classified as 0-, 1-, 2- and 3-dimensional structures where at least one dimension is less than 100 nm. Figure 1 presents this classification and provides examples of each form of nanostructures, including clusters/spheres, nano wires, polymers, thin films and bulk specimens. Since the surface properties of nanomaterials dominate bulk, by controlling the surface/volume aspect (particle radius, film thickness or grain size), it is possible to develop materials whose physical properties will be related to surface.

Figure 1: Different Forms of Nanomaterials

New Technologies for Corrosion Monitoring

The transition from a bulk to a surface-controlled regime is presented in Figure 2 for Fe-particles. The significant increase in the specific surface area from 0.5 to 400 m2/g corresponds to the reduction in particle radius from 1 µm to 2 nm. The increase in surface area results in increasing chemical reactivity, making some nanomaterials useful as catalysts, sensors, and inhibitors. These material systems can play an important role in the development of nanosensors and new technologies for corrosion monitoring.

Figure 2: The Surface Properties in Nanomaterials will Dominate Bulk when Particle Size is Reduced below 100 nm.

An example of increased chemical reactivity observed for Fe-nanoparticles is presented in Figure 3, which shows that nanoparticles oxidized much faster than bulk specimens.

Figure 3: Comparison of Raman Spectra Obtained for Nano and
Bulk Fe Specimens Showing Enhanced Chemical Reactivity of
Fe-Nanoparticles for Oxidation.

Engineering “Smart” Coatings

Nanotechnology can also bring new tools for corrosion protection related to superior corrosion resistant coatings. Advanced macromolecular design and chemistry can be done at interfaces involving equilibration between two or three phases. Patterning at the micron- and nano-scale is important, as it enables control of 2-D chemistry.

These specific surface-initiated polymerization systems, such as linear polymers, homopolymers, block copolymers or hyperbranched (Figure 4), are known as polymer brushes and offer fascinating opportunities for the development of high-quality protective coatings and functional composite materials.

Figure 4: Grafted Polymer and Nanostructured Brushes on Surfaces.

An example of such surface engineering is presented in Figure 5, which shows patterning control on the nanometer range. In addition, nanostructured materials engineering extends the possibility of engineering “smart” coatings that can release corrosion inhibitors on demand when the coating is breached, stressed or when an electrical or mechanical control signal is applied to the coating. Inhibitors can be delivered in fullerene-based capsules, as presented in Figure 6.

Figure 5: Use of Electronanopatterning Methods with AFM.

Figure 6: Fullerene-based Nanomaterials for Inhibitors.

Benefits of Using Nanotechnology

Some of the benefits of using Nanotechnology in corrosion control include:

  • Nanostructures with enhanced chemical reactivity can be used as nano-coupons for corrosion monitoring on the surface level.
  • Nanoparticles are used as corrosion inhibitors and as nano-reservoirs for delivering inhibitors, including their effect on improving coatings and hermitic sealing.
  • Nanoscale patterns and composites are able to produce non-wetting surfaces that prevent adsorption and aqueous media from making its way to the coating and the underlayer.
  • Nanoscale analysis using surface sensitive tools like surface probe microscopy and surface plasmon spectroscopy to probe changes in coating integrity or analyze the mechanism and dynamics of the corrosion event.
  • Materials that have hierarchical order up to the nanoscale serve as inspired or bio-inspired materials for corrosion mitigation.

The study and application of nanomaterials in corrosion control are just beginning, and an understanding of the relationships between their properties and their materials engineering on a molecular level seems to be key to the realization of nanomaterials’ full potential in corrosion control.

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