structured & Amorphous Materials Inc., Houston, and the American Foundry Society added to the nearly $5 million from TIP, the nano project is estimated to cost $10 million through Jan. 31, 2015. But as one of the tenets of TIP implies, risking those funds could yield great rewards. According to Weiss, increases in
strength of between 100 and 120% have been accomplished using 2% volume fraction of nanoparticles in metal matrix composites. “Obvious applications are going to
be in the transportation market, like military, aerospace and commercial cars,” Weiss said. “With the mechanical improvements, you can design parts significantly lighter.” Li compares the strengthening of
the alloy with nanoparticles to that of strengthening via heat treatment. “Traditionally, aluminum and mag-
nesium need heat treatment to im- prove strength, which is nano-scale precipitation from the age hardening process,” he said. “Nanoparticles strengthen in the same way. But heat treatment takes a long time and high temperature. Solving that [with nanoparticles] would be significant.” The general rule is nanoparticles
can give aluminum and magnesium the strength of gray iron along with slightly higher elongation. At the same time, ductility and toughness are unaffected. “Nanotechnology gives us what I call
a free lunch,” said Robert Hathaway, vice president of materials and pro- cesseses for Oshkosh. “We can increase our mechanical properties without reducing the ductility or toughness of the material. The particles are so small, machinability should still be good.”
Nano in the Field
Oshkosh is interested in nano- technology to help cut weight in its products, particularly defense vehicles. Hathaway recalled a vehicle his com- pany worked on 12 years ago for the military. The vehicle had to be lifted by a helicopter, so the weight guide- lines were strict and challenging. The team was counting pounds and ounces
Nanoparticles’ appeal is that they can give specific properties to certain materials. The nanoparticles in this illustration are tuned to optimize their magnetic proper- ties. Their discovery could lead to a low- cost technology for cleaning arsenic from drinking water.
May/June 2010
These cubes of cobalt (left), measuring about 50 nanometers wide, show scientists that on the nanoscale, a change in shape is a change in property. Unlike smaller spherical co- balt nanoparticles, nanocubes melt and fuse (right) when illuminated by a transmission electron microscope and possess different magnetic characteristics than the nanospheres.
to meet the limit, he remembered. Oshkosh found a way to meet the challenge without nanotechnology at the time, but the tiny pieces of matter could open up new and easier ways to lighten the load for future applications. Weight-saving through the use of nanoparticles will influence the com- mercial sector, as well. “Every pound saved [in the weight of the vehicle] is a pound more of re-
fuse or concrete a customer can haul,” Hathaway pointed out. “Lightweight components may be more expensive, but if it means fewer trips to the plant or field, it pays for itself.” As part of the nano-research, Osh-
kosh’s role is to assist in characterizing the material. The company’s research team is studying tensile samples sent to its lab to look at how the samples fracture and measure particle spac-
Metal Casting Design anD PurChasing 35
These silicon carbide nanoparticles used with magnesium casting alloys have an average particle size of a little less than 50 nanometers.
Photos courtesy of the National Institute of Standards and Technology
Photo courtesy of Xiaochun Li, Univ. of Wisconsin-Madison
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68