Features - December 2012

NETL's Materials Expertise Solves Energy Problems

Over one billion tires are manufactured annually, created from synthetic rubber, natural rubber, fabric and wire, and other compound chemicals.
Over one billion tires are manufactured annually, created from synthetic rubber, natural rubber, fabric and wire, and other compound chemicals.

What is materials science? In the simplest terms, you could call it “the study of stuff. ” The different objects you use daily, from the clothes you dress in every morning to the synthetic rubber tires that you drive home on in the evening, are all comprised of different types of stuff. Understanding how that stuff is created, what uses it can have, how it can be altered and improved, and even the creation of totally novel and unique stuff, is what materials science is all about.

Defining “materials” is a tricky proposition because, by definition, materials are anything made of matter; they can be natural, like wood or bone, or man-made, like plastic. Most materials can be classified by a few broad categories, including: ceramics, metals, glass, polymers, and biomaterials. Additionally, there are materials like composites, which are composed of two or more separate materials. Through the combination of different materials, a new material with radically different – and possibly improved – properties can be created.

Bone has been used for making tools throughout human history. This is a die made from bone found at Cantonment Clinch, an American fort used in the Civil War. Picture by Kolby Kirk.
Bone has been used for making tools throughout human history. This is a die made from bone found at Cantonment Clinch, an American fort used in the Civil War. Picture by Kolby Kirk.

Materials science covers an incredible range of activity and is so diverse that it has applications spanning from medical devices to super computers to rocket engines. Materials scientists go by many names, like polymer engineer or metallurgist, and are employed in research labs, industry, and academia. Still, as varied as they are, the approach to materials science is the same across the board: examine the underlying structure of a material, its natural properties, the impact processing has upon it, its performance characteristics, and ultimately determine what a material can do. (And if it can't do what they need it to, material scientists create a material that can!)

They've Got the Right Stuff!

Due to the advent of synthetic fabric, the leisure suit was propelled to the height of fashion in the 1970s. Picture by Daniel Hartwig.
Due to the advent of synthetic fabric, the leisure suit was propelled to the height of fashion in the 1970s. Picture by Daniel Hartwig.

For the last hundred years, the National Energy Technology Laboratory (NETL) has been seeking solutions for the energy challenges facing our nation. Material sciences have been an important facet of this history. From materials that improve energy efficiency to materials that save lives, NETL's materials aptitude is expressed through an integrated, multi-scale, multi-discipline program that pairs computational science with validation tests, conducted at appropriate scales and in the correct conditions to produce innovative materials. For example, NETL has developed functional materials (e.g., refractories, thermal barrier coatings, gas separation technologies, and electrochemical materials) and structural materials (e.g., advanced steels and super alloys) for applications in the extreme environments generated by fossil energy systems.

NETL employs a myriad of materials engineers, metallurgists, ceramic engineers, and geologists, as well as chemists, chemical engineers, and mechanical engineers. Focus areas are as diverse as the scientists, with research conducted in the areas of advanced combustion, advanced gasification, fuel cells, turbines, catalysis, and batteries.

Material researchers at NETL work in advanced facilities designed for synthesizing novel structural and functional materials through preparation methodologies and thermal treatment methods. Metal, ceramic, polymer, and composite materials can be fabricated from proof-of-concept through bench scale. NETL even has capabilities that allow researchers to melt, cast, forge, and heat-treat materials for a variety of industrial uses, and assess corrosion, erosion, creep, and wear in severe environments matching those found in advanced energy conversion processes. These abilities serve as a bridge, moving materials efficiently from the laboratory and pilot scale to commercialization.

From materials that improve energy efficiency to materials that are saving lives, NETL is producing an impressive variety of materials.

Ceramics: Not Your Grandmother's China

When the word ceramics is mentioned, the images that immediately come to mind are earthenware bowls and plates. Although clay was one of the earliest ceramic materials, many different types of ceramic materials are now integral to a variety of fields, from medicine to industry. These materials can be amazingly durable—a far cry from dainty cups in a china cabinet. Most ceramic materials tend to be strong, stiff, brittle, chemically inert, and non-conductors of heat and electricity, but their properties vary widely. Porcelain, for example, is widely used to make electrical insulators, but some ceramic compounds are superconductors, which provide no resistance to electricity with no loss of electrical power. Other ceramic compounds are used in power plants and are capable of withstanding elevated temperatures, pressures, and corrosive environments.

CMC shrouds in a GE Energy F-class utility gas turbine.
CMC shrouds in a GE Energy F-class utility gas turbine.

Ceramic matrix composites, known as CMCs, are able to withstand higher temperatures than most metals. These composites consist of ceramic fibers embedded in a ceramic matrix, thus forming a ceramic fiber reinforced ceramic material that is far more durable than monolithic ceramics. In 2006, a full set of silicon carbide-based shrouds were installed in the first stage of a GE Energy F-class gas turbine at a Jacksonville Electric Authority utility in north Florida. The melt-infiltrated ceramic matrix composite allows for higher operating temperatures than metal components. Subsequently, the higher operating temperature means that the gas turbine is more efficient and the power output is greater, in addition to lower emissions and reduced maintenance. Invented at the GE Global Research Center in Niskayuna, NY, and developed as part of an NETL-managed project funded by the Office of Electricity Delivery and Energy Reliability, these CMC components are now being incorporated into GE's other product lines, including aircraft and utility gas turbines.

Polymers: Essential and Ubiquitous

Steel bars bonded with the new adhesive over an area of 1 square inch were able to suspend more than 200 pounds without separating.
Steel bars bonded with the new adhesive over an area of 1 square inch were able to suspend more than 200 pounds without separating.

You come into contact with more polymers every day than any other kind of material, from silk to Silly Putty. In essence, polymers are long, repeating chains of smaller molecules that band together to form much larger molecules, and their uses are just as varied as the forms they come in.

One group of researchers at NETL is incorporating CO2 into polymeric materials similar to epoxy, a versatile product that can be used for a variety of industry functions such as adhesives and protective coatings. These new polymeric materials are made by mixing two liquid components together (a multifunctional cyclic carbonate and a multi-functional amine) to form a cross-linked polymer that is strong and adheres well to aluminum and glass surfaces. In addition to its use an adhesive, the material has potential application as a sealant and binder. This means that the material could be used in multiple applications, from house construction to use in anything that requires a printed circuit board (e.g. , cell phones, televisions, and radios).

As an additional benefit, the technology utilizes CO2, incorporating it into the polymeric materials through multi-functional cyclic carbonates. By selling captured CO2 for use in these products, industry will be able to partially offset CO2 storage costs. Furthermore, the process of creating the material is cost-efficient and environmentally friendly, making it suitable for commercial manufacturing.

Metals: Beyond the Bronze Age

NETL helped develop coronary stents made from a platinum-chromium alloy that are more flexible than traditional stents. The stent was manufactured by Boston Scientific Corporation.
NETL helped develop coronary stents made from a platinum-chromium alloy that are more flexible than traditional stents. The stent was manufactured by Boston Scientific Corporation.

Harnessing the power of metal work had such an impact upon civilization that entire phases of human history are titled after specific metals. Tailoring metal into tools, enhancing their natural properties, and in some cases altering them, constituted some of the first steps towards engineering. Now, materials science research is manipulating metals in astounding ways.

An innovative platinum-chromium alloy, developed by a team of researchers from Boston Scientific Corporation and NETL, is currently being used in manufacturing a new coronary stent. Coronary stents are small, expandable mesh tubes that are placed in a narrowed or weakened coronary artery, allowing the passageway to stay open, and consequentially saving thousands of lives every year. The platinum-chromium alloy gives the stents greater flexibility than the existing stents and also allows them to be more visible on x-rays so they are easier for the surgeon to position.

This amazing alloy is the product of over a decade of collaboration by NETL and Boston Scientific. The unique alloy was custom engineered to avoid or solve many of the problems associated with traditional stents. The platinum-chromium alloy provides physical properties that allow the stent to be thin and flexible. It also improves corrosion resistance, permitting the stent to reside for a longer period in the human body.

Since introduction in 2010, the platinum-chromium coronary stent series has become the leading stent platform in the world, with more than $4 billion in sales. The stent series has captured a 45 percent market share in the United States, and a 33 percent global share of the coronary stent market. Additionally, R&D Magazine recognized this breakthrough technology, naming the alloy one of the 100 most technologically significant products to enter the marketplace in the past year.

Materials Science: Better, Stronger, Faster

These examples are only a few of the many successful materials technology products that NETL has engineered over the years. NETL's Material Science & Engineering Focus Area has a long history of discovery, development, and deployment of affordable, high-performance materials and processes. The program is one of the few places in the world where alloy development, melting, casting, fabrication, physical and chemical analyses and performance testing is performed in one place. NETL helps industrial and academic partners solve problems that would otherwise become barriers to technology commercialization and its onsite research results in numerous licensable patents, national recognition, and technology transfer. Even more importantly, NETL's work fulfills the mission of the Department of Energy, advances science, and improves lives.

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