Assembly - January 2009 - (Page 19) low-friction surface to plastics; and makes plastics more impermeable, conductive and dimensionally stable. It also improves aesthetics by giving the plastic a metal look. In the automotive industry, the material can be used to make oil pans, cylinder head covers, water and oil pumps, gasket carriers, timing chain tensioner arms, transmission housings and components, fuel rails, electric motors, electrical housings and covers, steering components and control arms. It can also be used for sporting goods, appliances, furniture, power tools, and housings for handheld electronics. The researchers tested their process on aluminum aerospace components, so the ultrasonic pretreatment process was particularly important. Although aluminum surfaces are typically covered by 3 to 7 nanometers of natural oxide film, this thin layer provides insufficient protection against corrosion and actually inhibits the adhesion of protective coatings. “ U lt r a son ic pret reat ment is crucial for formation of a uniform film,” says Andreeva. “The surface of ultrasonically pretreated samples exhibits better wettability, adhesion, and chemical bonding with the polymer layers of subsequent coatings. It results in a homogeneous distribution of the polymer film on the aluminum surface.” Coating, Heal Thyself! esea rchers in Ger ma ny have developed a self-healing, nanoscale coating for preventing corrosion in steel and aluminum parts for aerospace, automotive, maritime and energy applications. The environmentally friendly coating is seen as an alternative to hexavalent chromium and other coatings that, while effective, are also toxic. The multilayer coating was created by Daria Andreeva, Ph.D., and a team of researchers at the Max Planck Institute of Colloids and Interfaces (Potsdam, Germany). Their process involves pretreating the surface by sonication and then depositing a series of oppositely charged polyelectrolytes and inhibitors layer by layer. All totaled, the coating is just 5 to 10 nanometers thick. The process forms a “smart” polymer nanonetwork of environmentally friendly organic inhibitors. The various layers do more that act as a barrier to external impacts. They also respond to changes in their internal structure, and they can combine to create different mechanisms of damage prevention and reparation. “Our novel coating [provides] very high resistance to corrosion attack, longterm stability in aggressive media, and an environmentally friendly, easy and economical preparation procedure,” says Andreeva. www.assemblymag.com January 2009 / ASSE M B LY 19 R http://www.dymax.com/seeitcure http://www.assemblymag.com
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.