Nano-Materials

Nano-Silicon Carbide SiC

Nano-materials contain only a few thousand or tens of thousands of atoms, rather than the millions or billions of atoms in particles of most conventional materials. They are materials with structural features, like particle and grain sizes, in the range of 1-100 nanometers (nm) (1 nm is one millionth of a millimeter). For comparison purposes, the average width of a human hair is 100,000 nanometers, while a single particle of smoke is 1,000 nanometers. Nanostructures can be obtained in a variety of materials including metallic, ceramic, semi-conductor, and diamond. The examples below explain different types of nano-materials, which could potentially be utilized to produce building products that are harder, stronger, and more durable.

Nano-Ceramics are a type of nano-material with nanometer-sized particles embedded in a matrix that contains a large volume of material at the component interface due to the small particle size (some fibers developed are smaller than a DNA molecule). It is generally recognized that the smaller diameter fibers are more effective in strengthening ceramics, metals, or plastics. The University of Delaware has a U.S. Army-funded Center for Composite Materials. One of their objectives is to develop nano-ceramics for high strain conditions.

Nano-Structure Metals and Metallic Glass - With this technology, the structure of metal or glass material is denser then traditional forms of the same material. Johns Hopkins University is working on high-strength nano-structure metals. Extensive research has also been conducted by DARPA's Structural Amorphous Metals (SAM) program (see www.darpa.gov/dso/thrust/matdev/sam/index.html) and the NanoSteel Co. (see www.nanosteelco.com) regarding the production and utilization of bulk and sheet-steel materials.

A range of possible properties for nano-structured metals exist, including a steel material with the hardness of alumina ceramics and the strength of carbon-based fibers. Other potential attributes could include higher strength-to-weight ratios than titanium alloys, superior corrosion resistance over nickel-based alloys, and significantly increased weldability. One issue with nano-structure metals is that the higher strength and durability creates low-ductility. Johns Hopkins University is working on lower strain hardening technologies to help combat this characteristic.

Johns Hopkins University is also developing metallic glass composite materials for anti-armor applications. This would result in a material that is impact resistant and has extremely high strength. Possible applications include kitchen and bath fixtures, flooring, or advanced panel products.