Methods

Citation

Liskiewicz, T. (2015), "Methods", Anti-Corrosion Methods and Materials, Vol. 62 No. 6. https://doi.org/10.1108/ACMM-07-2015-1561

Methods

Article Type: Methods From: Anti-Corrosion Methods and Materials, Volume 62, Issue 6

A new way to image surfaces on the nanoscale

A multi-institutional team of scientists has taken an important step in understanding where atoms are located on the surfaces of rough materials, information that could be very useful in diverse commercial applications, such as developing green energy and understanding how materials rust.

Researchers from Northwestern University, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory and the University of Melbourne, Australia, have developed a new imaging technique that uses atomic resolution secondary electron images in a quantitative way to determine the arrangement of atoms on the surface.

Many important processes take place at surfaces, ranging from the catalysis used to generate energy-dense fuels from sunlight and carbon dioxide to how bridges and airplanes corrode, or rust. Every material interacts with the world through its surface, which is often different in both structure and chemistry from the bulk of the material.

The study is published on June 17 by the journal Nature Communications:

We are excited by the possibilities of applying our imaging technique to corrosion and catalysis problems, said Laurence Marks, a co-author of the paper and a professor of materials science and engineering at Northwestern’s McCormick School of Engineering and Applied Science. The cost of corrosion to industry and the military is enormous, and we do not understand everything that is taking place. We must learn more, so we can produce materials that will last longer.

To understand these processes and improve material performance, it is vital to know how the atoms are arranged on surfaces. While there are many good methods for obtaining this information for rather flat surfaces, most currently available tools are limited in what they can reveal when the surfaces are rough.

Scanning electron microscopes are widely used to produce images of many different materials, and roughness of the surface is not that important. Until very recently, instruments could not obtain clear atomic images of surfaces until a group at Brookhaven managed in 2011 to get the first images that seemed to show the surfaces very clearly. However, it was not clear to what extent they really were able to image the surface, as there was no theory for the imaging and many uncertainties.

The new work has answered all these questions, Marks said, providing a definitive way of understanding the surfaces in detail. What was needed was to use a carefully controlled sample of strontium titanate and perform a large range of different types of imaging to unravel the precise details of how secondary electron images are produced:

We started this work by investigating a well-studied material’, said Jim Ciston, a staff scientist at Lawrence Berkeley National Laboratory and the lead author of the paper, who obtained the experimental images. This new technique is so powerful that we had to revise much of what was already thought to be well-known. This is an exciting prospect because the surface of every material can act as its own nanomaterial coating, which can greatly change the chemistry and behavior.

“The beauty of the technique is that we can image surface atoms and bulk atoms simultaneously”, said Yimei Zhu, a scientist at Brookhaven National Laboratory. “Currently, no existing methods can achieve that”.

Les Allen, who led the theoretical and modeling aspects of the new imaging technique in Melbourne, said, “We now have a sophisticated understanding of what the images mean. It now will be full steam ahead to apply them to many different types of problems”.

More information is available from: http://www.lbl.gov

Reliable and safe corrosion protection

3M Dyneon PTFE and 3M Dyneon TFM Modified PTFE belong to the group of fully fluorinated fluoropolymers. They are characterised by almost universal chemical resistance and high thermal stability. For that reason, they are particularly well-suited for use as corrosion protection of metallic components. TFM Modified PTFE is the second generation of PTFE. In comparison with standard PTFE, this material impresses, among other things, with an improved performance profile leading to a greater safety and profitability.

The complexity of the requirements in modern plant construction is constantly increasing – from sustainable production to the health and environmental protection to efficient, economic performance. 3M Dyneon TFM Modified PTFE offers a well-balanced solution for many different applications. In recent years, this fluoroplastic has proven itself in particular as a lining and sealing material in plant engineering and construction apparatus.

Fully fluorinated fluoropolymers come out on top

The protection of pipes, tanks and vessels against corrosion is an important factor in the chemical and pharmaceutical industry – for the plant safety and also with regard to the reduction of the continuous operating costs. That is why more and more industrial enterprises use fully fluorinated fluoropolymers such as PTFE. Above all, TFM Modified PTFE impresses with a very good performance due to its high resistance to temperature and chemical attacks.

Improved weldability and low elongation

The molecular weight of TFM Modified PTFE is around five times lower than that of classic PTFE. This reduces the viscosity of the polymer melt. As a result, the TFM particles attach more easily to form a dense, low-void-containing polymer structure. Among other things, this improves the weldability of the products. At the same time, TFM Modified PTFE is characterised in particular at high temperatures by a comparatively low flow behaviour. This is of great importance, for example, for components that are mounted under pretension.

Longer lifetime leads to higher profitability

A further advantage: TFM Modified PTFE has fewer effects on the environment, as the material exhibits better sealing properties in comparison with PTFE where volatile chemicals are concerned. At the same time, a longer lifetime and a lower cleaning requirement lead to shorter plant downtimes and thus to higher profitability of plants.

Areas of use in many industries

The properties of 3M Dyneon TFM Modified PTFE open up a wide range of new applications in many different branches of industry. These include insulation for the electrical and electronics industry, tailor-made solutions for the chemical industry and optimised solutions for the semiconductor industry, for mechanical engineering and for the automotive industry (Figure 1).

Figure 1 - 3M Dyneon TFM Modified PTFE is ideal for corrosion protection of metallic components, as it features almost universal chemical resistance and high thermal stability

More information is available from: http://www.dyneon.eu

Graphene set to make waves in multiple markets due to its innovative capabilities and high performance

Carbon nanotubes and graphene have been competing head-to-head for many of the same applications in recent years. For most applications, the development of carbon nanotubes has been gradually rising, as evidenced by patent trends. Nevertheless, graphene has been making drastic progress. In the form of oxides or nanoplatelets, graphene is in a better position to fulfil market needs, as it is a durable, stretchable and lightweight material.

New analysis from Frost & Sullivan, Impact Assessment of Graphene in Key Sectors, expects market revenues to reach $149.1 million by 2020:

The energy sector is one of the prime markets for graphene and will remain so for the next three years, noted Technical Insights Research Analyst Sanchari Chatterjee. Lithium storage and catalytic system substrates are some of the most demanding application areas of graphene. However, other applications such as energy storage for batteries and capacitors have also been identified.

In the electronics sector, graphene is replacing materials like indium tin oxide. While graphene is widely used in flexible electronics, it can further penetrate this sector for the production of minute electronic components and optoelectronics.

In the next three to five years, the adoption of graphene in the electronics and composites sector will increase. Within this time, a number of new markets such as healthcare and personal care are expected to open up for graphene.

However, the absence of large-scale graphene production in a cost-effective and reproducible manner makes commercialisation a major challenge. Till date, graphene has been developed mostly at the laboratory level as processes like nano-slicing used during industrial-scale production boost costs and hamper the quality of end products. Exfoliation processes have been commonly used though.

“Manufacturers are designing several economical and large-scale production processes to ensure that high-quality graphene can be produced within a short time”, pointed out Chatterjee. “This can significantly reduce commercialisation challenges”.

For instance, although graphene is among the thinnest yet strongest materials in the world, its structural design creates flaws when made into sheets for use in energy applications. This compromises performance. Further, the zero band gap of graphene is a major technical drawback, as it limits the achievable on-off current ratios.

With the reliability of standalone graphene in doubt, research is on to customise graphene to enable manufacturers to use it in its reinforced and hybrid forms. Overall, corrective R&D and innovative commercialisation techniques can help realise the tremendous potential of graphene that ranges from applications in biomedical to anti-corrosion coatings.

Impact Assessment of Graphene in Key Sectors is a part of the Technical Insights subscription, which is an international technology analysis business that produces a variety of technical news alerts, newsletters and research services.

More information is available from: http://www.corpcom.frost.com