Researchers from Canada and Iran have found that mixing carbon fibers into polymer-based brakes is a way to create "self-lubricating" brakes. The Institution of Mechanical Engineers reported that this new development is "very important for the automotive and railroad industries," and could mean a new generation of brakes that is more efficient and resistant to wear and tear. The discovery was made by an international team of researchers from Sharif University of Technology in Iran, UBC Okanagan in British Columbia and the University of Toronto.
According to the abstract published in Elsevier, the research team discovered that not only does carbon fiber reduce the wear rate of phenolic resin-based composite friction materials, it also decreases the friction coefficient (the relationship describing the frictional force between two objects and their normal reaction) and also suppresses the fade at high content.
Phys.org, quoted one of the researchers, Engineering Assistant Professor Mohammad Arjmand, who said "Our findings show that the newly designed carbon fiber polymer brakes represent an acceleration in the science of deceleration and could be a real boon for the industry and consumers alike."
Smaller brake pads may be a result of this discovery, according to Arjmand. The new, smaller pads would be more efficient and cost-effective, tolerating higher temperatures and greater friction. This would lead to cars and trains becoming more affordable, efficient and functional, he added.
The big picture of braking research
Phys.org provided some perspective on the brake market, saying that conventional brake pad materials are usually available in three categories: metallic, ceramic and organic. All possess benefits and drawbacks related to their design, such as cost, durability, noise, slow response time or higher temperatures during use.
According to U.S. National Highway Traffic Safety Administration statistics cited by Phys.org, brake-related problems are responsible for nearly 22 percent of vehicle component failures, and vehicle component failure accounts for nearly two percent of crashes.
To address this reality, the researchers focused their attention on improving features like composite breakdown during high temperatures, durability, friction and wear testing.
Nanomaterial cocktails – the new frontier
Assistant Professor Arjmand hinted at the direction future studies will take, saying "As we continue to develop nanomaterials and mix them with polymers to develop multifunctional composite cocktails that can address issues such as friction, wear, and heat distribution at the molecular level, we will continue to help the industry evolve."
Despite the tremendous commercial potential of discoveries like self-lubricating brakes, however, the nanomaterial research field connected with braking technology appears to be led by a rather exclusive community of investigators. "No researcher in Canada is currently working in this area," Arjmand said.
On the other hand, composite materials research continues making great strides in other areas. For example, a recent study of multi-layered fiber-metal laminates appears to hold great promise for developing lighter, crashworthy materials for use in vehicles and other safety-related structures.
The reasoning behind new braking materials
The process of braking relies greatly on the durability and efficiency of the materials used to manufacture high-stress, low-friction components like brake shoes or calipers – materials such as steel, cast iron, aluminum and ceramics. Although asbestos was once the most popular choice for brake systems because of its ability to withstand high-friction conditions, its associated health hazards have led the industry to seek safer alternatives.
Consequently, according to Frictionmaterials.com, ceramics, copper, steel, iron, mineral, cellulose, aramid, chopped glass, rubber and brass are now employed in the creation of composite materials used in brakes. The value of these materials lies in qualities like strength and friction resistance found in the original powders and fibers, which are often retained (or even enhanced) in new composite mixtures and combinations.
Research studies, such as the recently completed one described earlier which examined self-lubricating, carbon fiber and polymer braking materials, is critical to further advancements in brake material design. This research, combined with actual field experience in the automotive and transportation industries, as well as continued progress in chemical and materials engineering, will ultimately result in benefits for manufacturers and consumers alike.
In the long run, new composite materials will bring about lower maintenance and operating costs, greater wear life for both components and vehicles, improved functionality and better overall consumer satisfaction.
If you are an engineer working on braking systems, whatever the specific mode of transportation, ask for a complimentary brake testing consultation from Greening.