The Steel Industry Meets Nanotechnology

How a new Nano-Manufacturing process is making steel 10x stronger

By Frank Rovella

Seattle-based Modumetal is in the early phases of testing a new type of nanolamination coating process that has the potential to reshape the metal manufacturing industry. By creating multiple discrete layers only nanometers thick they are able to impart characteristics such as high strength and corrosion resistance and do it very economically. Until now, the only way to get these qualities was through the use of high-strength alloys or with methods such as heat treating, ion implantation, or a number of plating and coating processes. All of these can be very cost-effective in limited quantities but, for industries that consume large amounts of steel such as petro-chem, oil & gas, and construction there is no low-cost solution.

The concept of creating laminations using nanolayers is not new; however, Modumetal’s application method is. Previously, nanolaminates could only be created via a vapor deposition process the problem is that it’s expensive and not easily scalable. Modumetal’s process takes a markedly different approach; though simple in nature, its success hinges on precise chemistry and process parameters.  It’s based on hydrolysis, similar to the electroplating process, and utilizes a submersion bath. But, unlike electroplating, it relies on hyper exact amounts of electrical current applied at specific intervals. The bath contains predetermined types of metal ions that allow for the creation of distinct alloys; this means that each layer can be composed of a different material.  Multiple layers may be applied to total up to one centimeter thick. This flexibility in layer composition allows for the engineering of custom nanolaminations that can provide whatever characteristics the application requires.

To understand how high strength and corrosion resistance can be applied to a metal with what is essentially a coating, we need to consider scale. For example, electroplated layer thicknesses typically run between 5 to 100 microns, 1 micron (µ) = 0.00003937 inches, while 1 nanometer (nm) = 0.000000039 inches. This is on the atomic scale; to put that into perspective, 0.1 nm is the diameter of a helium atom.  As the image below highlights, at the nanoscale, our understanding of surface profile changes. There is far more surface area to work with, which means greater adhesion can be achieved. At this scale, the metal ions become a physical part of the substrate. The ability to dial in an alloy combination to address a specific corrosion requirement outside of a steel mill is unprecedented, but the main component that makes this technology so attractive is strength.



Carbon steel surface taken through an electron microscope, the actual
size is 10 micrometers (µm) across that is equal to 10,000 nanometers.

Tensile strength is a material’s ability to withstand pressure before failing, and failing begins with cracking. To demonstrate how nanolaminations can make steel 10 times stronger, think about a sheet of plywood; this is the most common example of a lamination.  Plywood contains multiple layers of materials with different strength characteristics and varying grain structures—the more layers added the greater the strength. The strength is further enhanced when the lamination is nailed or glued into place. Now imagine a cross-section of structural steel with all of its surfaces encapsulated in layers of nanometer-thick superalloys of varying compositions, bonded to the substrate at the atomic level. The advantages are obvious. 

Stress cracking in a cross-section of stainless steel pipe.

The potential this has for large-scale applications such as those found in oil & gas and the construction industries could be a game-changer. But to gain a foothold in manufacturing, a lot more data will be needed, and many questions will need to be answered. Beginning with the application process, will it be better suited for pre or post-treatment? Will ductility be affected, how will it react to rolling or stamping, and what about welding?  The ability to weld treated metals could be one of the key questions; this is essentially a coating—when it’s welded what happens at the joints? Even coatings a centimeter thick will be burned through, leaving a seam of bare substrate. However, these issues may already be moot points, as Modumetal is currently ramping up its production facility in Washington State. Of course, before this resembles anything close to wide-scale adoption, all of the standard bodies including ASTM, API, ASTM, and CEN will have to give it their blessing, and that certainly won’t happen overnight.