The Future of Small is Big
Are you up to speed with nanotechnology? Nanotechnology, which is literally the understanding and control of materials on an atomic or molecular scale, has the potential for major improvements in a variety of applications. For this reason, the U.S. government has invested more than $10 billion dollars in nanotechnology over the past decade.
Nanotechnology involves work with nanoparticles, which are about 100 nanometers in size. A nanoparticle is about one thousandth of the width of a human hair – many are even smaller. The practical application of this technology is often called molecular manufacturing. Transitioning from laboratory-scale to full-scale production and manufacturing is a challenge currently facing the industry.
A potential impact of nanotechnology on thermal processing involves the development of new materials. Property enhancements of nanometals include weldability, resistance to intergranular corrosion and cracking, high-temperature creep, greater strength, optimum hardness and improved wear resistance.
Material coatings seem to be the leading nanotechnology. Of the 20 “quick-win” projects currently receiving DOD funding, almost half involve material nanocoatings. It is anticipated that these projects can be commercialized in less than five years.
Many of these nanocoatings are superhard with resistance to certain environments such as water or hydrogen fuels. Another key development characteristic is a very low friction coefficient, which will result in energy savings as coated parts move more freely.
One project at the Savannah River National Laboratory involves developing highly dispersed platinum on electrically conductive supports to be used as a fuel-cell electrode catalyst. The Argonne National Laboratory is working on a project to achieve the highest possible adhesion between superhard nanocomposite coatings and their substrates. This will prevent cracking and delaminating of the coatings under harsh or cyclical real-world operating conditions.
Oak Ridge National Laboratory is working on a project to incorporate nanosized complex-metal boron carbides into a metal-matrix coating. The intended benefit is extending the life and maintenance cycle of any iron-based part by improving the wear resistance.
Hard chrome is a coating that has been used by industry for many years to provide a wear-resistant surface. Unfortunately, this coating technique is environmentally unfriendly and is being replaced by nickel-boride coatings, which have reduced mechanical properties and wear resistance due to a columnar grain structure. It was recently discovered that incorporating minute amounts of nanodiamond in the electroless deposition of the coatings decreases the columnar structure and grain size. This is the primary reason for the improved hardness, corrosion resistance and performance of the coating. Previously, the coatings were heat treated to attain the necessary hardness, but the nanodiamond additives result in the same hardness improvement without increasing the grain size.
Another thermal process involved in nanotechnology is the chemical vapor deposition (CVD) of carbon nanotubes using a metal catalyst-coated substrate in a heated chamber. Two gases are introduced into the chamber. One is a process gas such as ammonia, hydrogen or nitrogen, and the other is a hydrocarbon gas like acetylene, ethylene, methane or ethanol. When the chamber exceeds temperatures of 1300°F (700°C), the carbon atoms break from the hydrocarbon gas and attach to the catalyst particles. Other carbon atoms then attach to it forming a nanotube.
Carbon nanotubes are used in plastics and other materials to create composites with improved electrical, mechanical and thermal properties. Nanowires made from carbon nanotubes allow electrons to travel through them without resistance.
Molecular manufacturing may soon significantly impact the global marketplace. Predictions claim the demand for goods and services using nanotechnologies will grow to $1 trillion and employ two million workers by 2015. Now you know more about this small technology with the big future. IH