Manufacturing Bits: Nov. 17

Speedy nano-scale subs; new aluminum alloys for cars.


Speedy nano-scale subs
For years, researchers have been developing nano-scale submarines. In theory, nano-subs could be used in various applications. For example, they could navigate inside the human body and transport medicine to various organs.

The problem? Most nano-subs use or generate toxic chemicals, according to researchers from Rice University.

Seeking to solve the problem, Rice University has developed what it calls a unimolecular submersible nano-machine. The structure, which operates like a nano-scale sub, consists of merely one molecule and 244 atoms.

Powered by ultraviolet light, the nano-sub has a tail-like propeller. The sub can move in one direction, but it can’t steer. With each revolution, the structure can move 18nm. But at a million revolutions a second, the nano-sub’s top speed is one inch per second.

Rice has created light-driven, single-molecule submersibles that contain just 244 atoms. (Illustration by Loïc Samuel)

Rice has created light-driven, single-molecule submersibles that contain just 244 atoms. (Illustration by Loïc Samuel)

The sub’s motor is devised using a 20-step chemical process. The motor operate like a flagellum, which is a lash-like appendage that protrudes from certain cells. In operation, the sub’s motor completes each revolution in four steps.

The technology proves that nano-subs can propel through solutions of moving molecules of about the same size. “This is akin to a person walking across a basketball court with 1,000 people throwing basketballs at him,” said James Tour, a researcher at Rice, on the university’s Web site.

New aluminum alloys for cars
The Department of Energy’s Oak Ridge National Laboratory, FCA US and Nemak are teaming up to develop new and lightweight aluminum alloys for cars.

Researchers hope to speed up the development of new high-temperature aluminum alloys for automotive cylinder heads. The overall idea is to develop new fuel-efficient technologies that would enable cars to reach 54.5 miles per gallon by 2025.

The project is part of a new initiative to develop 300 degrees Celsius-capable, high-strength aluminum alloys. The material is expected to be 25% stronger than current alloys. It can withstand temperatures that are 50 degrees Celsius higher than current materials.

Oak Ridge is modelling the atomic structure of new alloys. The idea is to select the best candidates for experimentation. For this, researchers will use DOE’s Titan supercomputer, the second fastest computer in the world. Titan is a supercomputer built by Cray. It uses AMD’s Opteron processors in conjunction with Nvidia’s Tesla GPUs. It uses 18,688 CPUs paired with an equal number of GPUs.

Researchers will use Oak Ridge’s scanning transmission electron microscopy (STEM) and atom probe tomography techniques. This will allow researchers to examine the location and chemistry of each atom in the alloy matrix.

Atomic structure of new alloys (Source: Oak Ridge)

Atomic structure of new alloys (Source: Oak Ridge)

“Aluminum has been in mass scale production for more than a century, but current cast aluminum alloys cannot withstand the temperatures required by new advanced combustion regimes,” said Oak Ridge researcher Amit Shyam. “Our goal is to take high-temperature cast aluminum where it has never been.”

The goal is to develop the technology in four years. “The aggressive goals of these projects compress about half a century of typical materials development into a four-year project,” said DOE program manager Jerry Gibbs, on Oak Ridge’s Web site.