Nearly as strong as steel, but half as heavy, the addition of Baytubes carbon nanotubes (CNT) from Bayer MaterialScience AG significantly improves the mechanical properties of aluminum powder metallurgy. For example, the hardness of the composite aluminum is then several times greater than that of unalloyed aluminum, tensile strengths comparable to those of steel can be achieved, and the impact strength and thermal conductivity of the lightweight metal can be improved significantly.
"Together with competent partners in industry, we want to exploit the considerable application potential that arises from this optimization in properties,” says Dr. Horst Adams, vice president of Future Technologies at Bayer MaterialScience, explaining: “We are partnering with Alcan, PEAK and Zoz to develop customized, CNT-reinforced aluminum materials.”
Based in Montreal (Quebec), Canada, Alcan Inc. is not only one of the world's largest suppliers of raw materials for aluminum manufacturing, it also is a leading producer of this lightweight metal and products made from it. PEAK Werkstoff GmbH, headquartered in Velbert, Germany, specializes in the development of high-performance aluminum materials, which it uses to produce powder metallurgy semi-finished and finished goods. Zoz GmbH based in Wenden, Germany, is a global supplier of innovative facilities and equipment, in particular for the production of nanostructured materials, and has comprehensive expertise, for example, in the high-energy milling and mechanical alloying of these materials.
Until now, high hardness levels and tensile strengths could only be achieved in aluminum by a complex alloying process based on rare and expensive metals. "Our carbon nanotubes are an attractive alternative to such complicated alloys. Baytubes carbon nanotubes can also significantly reinforce aluminum materials already alloyed with metals," says Adams.
The density of CNT-reinforced aluminum is only around one third that of steel. Therefore, the material can be used in any number of applications in which the goal is to reduce weight and energy consumption. With its combination of high strength and low weight, Baytubes-reinforced aluminum is a welcome alternative to steel, expensive specialty metals such as titanium, and carbon-fiber-reinforced plastics. "This new class of materials has great potential for the production, for example, of screws and other connecting elements, allowing existing manufacturing processes (stamping, CNC) to be retained. Lightweight, heavy-duty components for wheelchairs or athletic equipment are also ideal candidates for the material," says Adams. Promising applications exist too in the automotive and aircraft industries. In addition, Baytubes-reinforced aluminum I-beams could conceivably be manufactured for the construction industry. Because they are much lighter than steel I-beams, they could make it possible to construct taller buildings. Because of their inherent weight, steel I-beams currently are a factor limiting the maximum height of a skyscraper.
Bayer MaterialScience LLC is one of the leading producers of polymers and high-performance plastics in North America and is part of the global Bayer MaterialScience business with nearly 15,100 employees at 30 sites around the world and 2008 sales of 9.7 billion euros. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction, medical, and sports and leisure industries.
