One of the best ways to make cars more fuel efficient is to make them lighter. Aluminum and carbon fiber are light weight structures that are replacing steel in the structure of many automobiles, but bonding them together has always been a problem.
When aluminum comes out of a stamping press, it is coated with oils used in the manufacturing process. Carbon fiber pieces are covered with a layer of chemicals designed to help release them from their molds. Those impurities make bonding the two together a difficult, time consuming task involving lots of hand scraping and scrubbing. The extra time and expense drives up cost, making the resulting products too expensive for mass market applications.
But scientists at Oak Ridge National Laboratory may have found a way to make bonding aluminum and carbon fiber faster and cheaper. They use lasers to replace the tedious and expensive hand preparation process. Once a top layer of material one or two atoms thick is removed, industrial adhesives can bond directly with the aluminum or carbon fiber molecules.
Testing reveals that joints made this new way are 15 percent stronger than joints made the traditional way. What’s more, they can support 16 percent more maximum load and withstand double the displacement at maximum load. Best of all, the joints can absorb 200 percent more energy, making the aluminum/carbon fiber commponents more suitable for applications in which occupant safety is of paramount importance.
The new laser techniques lower the cost of manufacture significantly because they can be automated, which eliminate the need for expensive hand operations.
Breakthroughs in the laboratory often take years to work their way into the production process. ORNL will work with both 3M and Magna International to refine the process and make it compatible with the needs of the assembly line. It will present its findings at a conference sponsored by The Society for the Advancement of Materials and Process Engineering next month.
Source: The Drive