AD: What are carbon nanotubes good for?
JK: In typical plastic materials, static buildup is common. If you build up enough charge, you can get a shock from discharging metal. If that occurs inside the polymer, it can break it down and make it fail, making the polymer age faster. Conductive filler made with carbon nanotubes helps disperse electrical buildup.
AD: Where could this be used?
JK: It could be used as a reinforcing fiber in ceramic-based composites, where they strengthen the material and also improve the electrical conductivity of the composites. If you're going to replace a metallic part due to fatigue failure, you would want to use a ceramic, because it's more fatigue resistant. For gears or bearings, ceramics wear much better. But you can't really use ceramic material, because it's so brittle, it could shatter. If you can make ceramics tougher by adding nanotubes to the material, you could make a part that doesn't need as much servicing. Ceramic bearings reinforced with carbon nanotubes could be used in a race car. They could be in internal parts of a car's transmission. The valves on your car, where you need temperature resistance, are also components that could be replaced with ceramics reinforced with nanotubes. All kinds of machinery contain gears or bearings that could benefit.
AD: How could the resilience of carbon nanotubes help improve existing medical devices?
JK: They could have applications in knee reconstruction and hip implants. These parts usually wear out every five to seven years. If someone gets a hip rebuilt at age 30, they would have to go back and keep getting new surgeries. The current implants are made of titanium and stainless steel. But those materials have drawbacks. They could fail due to fatigue fractures in their metallic components. The addition of carbon nanotubes could increase the fracture toughness of ceramic-based composites. Replacing these parts with ceramic composites can reduce or possibly eliminate the need for additional repair surgeries because the high-strength ceramic composites are less susceptible to fatigue.
AD: Where and how soon will carbon nanotubes show up on the market?
JK: The current high cost of carbon nanotubes will limit their initial application to uses where cost presents no object, such as space flight components and medical devices. As far as consumer products are concerned, this material could show up in high-end sporting goods. People might spend much more than a high-end bicycle frame is worth so they can say they have the latest and greatest. With carbon nanotubes, you could make a lighter bike frame, because single-walled carbon nanotubes have an excellent strength-to-weight ratio, resulting in a very light composite. I am sure someone will develop and market a $5,000 golf club soon after the materials are commercially available, probably within five years.
AD: What needs to happen before such products made with carbon nanotube fibers are commercially produced?
JK: It all depends on somebody finding an application where they're willing to invest in scaling up production that they know they can sell. But first, large quantities of high quality carbon nanotubes must be produced commercially.
JOSHUA D. KUNTZ
Dishes break. Kitchen knives become dull. The ball of an artificial hip implant wears out. The objects that populate our lives erode with the wear and tear of normal use. But that could change if Joshua Kuntz's view of the future prevails. The materials scientist and PhD candidate says that the advent of materials made with carbon nanotubes could keep high-end kitchen knives sharp indefinitely and make dishes shatterproof. Even artificial implants would last beyond just a few years of use.
Kuntz and other scientists at the University of California at Davis' Department of Chemical Engineering and Materials Science recently created a fracture-resistant product by using carbon nanotubes to reinforce and strengthen ceramic materials. A kind of polymer composed of carbon atoms only, single-wall carbon nanotubes are the stiffest and strongest fibers known to man, despite having diameters only nanometers wide. â€œIt's so small, there's no room for defects,â€? says Kuntz.
Materials that incorporate carbon nanotubes have astounding properties. Using them as an ingredient in a ceramic composite creates materials that are tougher than before, without also making them more brittle or breakable. â€œOur research makes possible the use of ceramics in applications where their fragility limited previous use,â€? says Kuntz. American Demographics' Sandra Yin asked him about possible future applications for this tough, highly durable material.