When fly ash is added to molten aluminum, it produces metal foam that is porous. This porosity reduces the weight of the aluminum-fly ash composite. From the results of his experiment with such composites, Nikhil Gupta and his team at the Polytechnic Institute of New York University says that this material can be used for the non-load-bearing parts of automotives, to reduce the total weight of the automotive unit.
Gupta and his team tested aluminum-fly ash composites under conditions that simulate the high compression forces that occur during automobile accidents. They found this material capable of withstanding this stress because it has the ability to absorb a greater amount of energy as compared to aluminum alone.
As per the results of research by Sulardjaka et al published in the "International Journal of Mechanical & Mechatronics Engineering," adding fly ash into aluminum in a carbothermal reduction process yields a product that is harder and has greater wear resistance. However, there are some drawbacks in the mechanical properties due to the hollow nature of the fly ash particles.
The fly ash is easily obtained from the coal-burning process. By using this to replace part of the aluminum content, manufacturers can cut down on the amount they spend on aluminum, an expensive metal. The aluminum-fly ash composites are lighter in weight and reduce the amount of fuel automotives require. This leads to a further cost reduction and fuel savings for customers.
According to Gupta, aluminum-fly ash composites may be used to replace aluminum-only items, such as lamp posts, doorknobs, highway signs and sliding tracks of windows. This will considerably reduce the weight of these objects and also make them less expensive.