Thread: Interesting industrial technology of the day

Originally Posted by USSWisconsin

Very interesting to see this technology being used on a macroscopic scale - we have used it on semiconductors (microscopic scale) for decades - We used ebeam etching to build reticles for the stepper at Cray Research in the mid 1990's (a reticle is a pattern for a microscopic printed circuit, a photolithographic stepper prints the pattern accross the wafer to make many chips on one wafer - it is used in other fabs too). Beam deposition was also used in chip fabrication for quite a while - for implanting atoms into transistors and other things. But building parts you can see and handle without magnification is something new - and very cool.

You've had an interesting career Wisconsin!

Advance Could Challenge China's Solar Dominance - Technology Review

Monday, November 21, 2011
Advance Could Challenge China's Solar Dominance

New technology could tip the balance back in favor of some solar-panel manufacturers outside China.

By Kevin Bullis

Chinese solar-panel manufacturers dominate the industry, but a new way of making an exotic type of crystalline silicon might benefit solar companies outside of China that have designs that take advantage of the material.

GT Advanced Technologies, one of world's biggest suppliers of furnaces for turning silicon into large crystalline cubes that can then be sliced to make wafers for solar cells, recently announced two advanced technologies for making crystalline silicon. The new approaches significantly lower the cost of making high-end crystalline silicon for highly efficient solar cells.

The first technology, which GT calls Monocast, can be applied as a retrofit to existing furnaces, making it possible to produce monocrystalline silicon using the same equipment now used to make lower quality multicrystalline silicon. It will be available early next year. Several other manufacturers are developing similar technology.

It's the second technology, which the company calls HiCz, that could have a bigger long-term impact. It cuts the cost of making a type of monocrystalline silicon that is leavened with trace amounts of phosphorous, which further boosts a panel's efficiency. This type of silicon is currently used in only 10 percent of solar panels because of its high cost, but could gain a bigger share of the market as a result of the cost savings (up to 40 percent) from GT's technology. The technology will be available next year.

A standard solar panel, made of multicrystalline silicon, might generate 230 watts in full sunlight. A panel the same size made of monocrystalline silicon could generate 245 watts. But phosphorous-doped monocrystalline silicon (also called n-type monocrystalline) enables a type of solar panel that generates 320 watts, a huge leap in performance.

Most Chinese solar manufacturers have focused on multicrystalline silicon solar panels. Companies such as U.S.-based Sunpower have focused on the advanced monocrystalline panels, and have designed cells to exploit its properties. Such companies will benefit as the HiCz technique developed by GT Advanced Technologies becomes more common.

"There's a potential shift in the market," says Vikram Singh, general manager for the photovoltaic division at GT Advanced Technologies. He says some western companies could become more competitive because they have technologies to take advantage of the materials.

Several other companies are developing technologies similar to Monocast, including solar-panel makers in China, such as Suntech and the Dutch equipment maker ALD.

The HiCz technology can be considered the next step on the way to higher-efficiency solar cells. It can be used to make monocrystalline silicon, even the phosphorous-doped type, for about the same cost as the Monocast technology. HiCz could allow a leap from cells that convert 16 to 18 percent of the energy in sunlight into electricity to ones that can convert 22 to 24 percent, thus decreasing the cost per watt of solar power. But it can't be retrofitted to existing equipment, which could slow its adoption.

The conventional way to make monocrystalline silicon is to introduce a seed crystal into a pool of molten silicon and slowly draw it out—as you do, it forms a large tube-shaped chunk of silicon called a boule, in which all of the atoms are lined up in the same orientation. This is usually done in a batch process, but the HiCz process makes it possible to continuously feed in raw silicon to the melt, along with whatever trace elements are needed to give it the desired electronic properties. The continuous process is more productive, which means fewer machines are needed, reducing costs. It also produces high yields when introducing materials including trace elements such as gallium and phosphorous. GT estimates the process can reduce the costs of making monocrystalline solar by between 20 and 40 percent.

Copyright Technology Review 2011.

More on 3D printing from MIT Tech Review.

Layer by Layer - Technology Review

Layer by Layer

With 3-D printing, manufacturers can make existing products more efficiently—and create ones that weren't possible before.

January/February 2012
By David H. Freedman



Buildup: GE made the aircraft engine *component on the left by using a laser to melt metal in precise places, beginning with the single layer seen on the right. Credit: Bob O’Connor


The parts in jet engines have to withstand staggering forces and temperatures, and they have to be as light as possible to save on fuel. That means it's complex and costly to make them: technicians at General Electric weld together as many as 20 separate pieces of metal to achieve a shape that efficiently mixes fuel and air in a fuel injector. But for a new engine coming out next year, GE thinks it has a better way to make fuel injectors: by printing them.

To do it, a laser traces out the shape of the injector's cross-section on a bed of cobalt-chrome powder, fusing the powder into solid form to build up the injector one ultrathin layer at a time. This promises to be less expensive than traditional manufacturing methods, and it should lead to a lighter part—which is to say a better one. The first parts will go into jet engines, says Prabhjot Singh, who runs a lab at GE that focuses on improving and applying this and similar 3-D printing processes. But, he adds, "there's not a day we don't hear from one of the other divisions at GE interested in using this technology."

These innovations are at the forefront of a radical change in manufacturing technology that is especially appealing in advanced applications like aerospace and cars. The 3-D printing techniques won't just make it more efficient to produce existing parts. They will also make it possible to produce things that weren't even conceivable before—like parts with complex, scooped-out shapes that minimize weight without sacrificing strength. Unlike machining processes, which can leave up to 90 percent of the material on the floor, 3-D printing leaves virtually no waste—a huge consideration with expensive metals such as titanium. The technology could also reduce the need to store parts in inventory, because it's just as easy to print another part—or an improved version of it—10 years after the first one was made. An automobile manufacturer receiving reports of a failure in a seat belt mechanism could have a reconfigured version on its way to dealers within days.

Additive manufacturing, as 3-D printing is also known, emerged in the mid-1980s after Charles Hull invented what he called stereo*lithography, in which the top layer of a pool of resin is hardened by an ultraviolet laser. Various methods of 3-D printing have become popular with engineers who want to create prototypes of new designs or make a few highly customized parts: they can make a 3-D blueprint of a part in a computer-assisted design program and then get a printer to spit it out hours later. This process avoids the up-front costs, long lead times, and design constraints of conventional high-volume manufacturing techniques like injection molding, casting, and stamping. But the technology has been adapted to only a limited set of materials, and there have been questions about quality control. Building parts this way has also been slow—it can take a day or more to do what traditional manufacturing can accomplish in minutes or hours. For these reasons, 3-D printing hasn't been used for very large runs of production parts.

But now the technology is advancing far enough for production runs in niche markets such as medical devices. And it's poised to break into several larger applications over the next several years. "We've come to the point when enough critical advances are happening to make the technology truly useful in manufacturing end-use parts," says Tim Gornet, who runs the Rapid Prototyping Center at the University of Louisville.


Pressing print: This photo shows an array of metal jet-engine components printed at GE. Credit: Bob O’Connor

MAKING INROADS

Several techniques can be used to "print" a solid object layer by layer. In sintering, a thin layer of powdered metal or thermoplastic is exposed to a laser or electron beam that fuses the material into a solid in designated areas; then a new coating of powder is laid on top and the process repeated. Parts can also be built up with heated plastic or metal extruded or squirted through a nozzle that moves to create the shape of one layer, after which another layer is deposited directly on top, and so forth. In another 3-D printing method, glue is used to bind powders.

Aerospace companies are at the forefront of adopting the technology, because airplanes often need parts with complex geometries to meet tricky airflow and cooling requirements in jammed compartments. About 20,000 parts made by laser sintering are already flying in military and commercial aircraft made by Boeing, including 32 different components for its 787 Dreamliner planes, according to Terry Wohlers, a manufacturing consultant who specializes in additive processes. These aren't items that have to be mass-produced; Boeing might make a few hundred of them all year. They're also not critical to flight; among them are elaborately shaped air ducts needed for cooling, which previously had to be manufactured in multiple pieces. "Now we can optimize the design of these parts for weight, and we save material and labor," says Mike Vander Wel, director of Boeing's manufacturing technology strategy group. "In theory, this is the ultimate manufacturing method for us." Though the speed limitations of 3-D printing might keep it from ever producing the majority of Boeing's parts, Vander Wel says, the approach is likely to be used in a growing proportion of them.

Boeing's main rival, the European Aeronautic Defense and Space Company (EADS), is using the technology to make titanium parts in satellites and hopes to use it for parts it makes in higher volume for Airbus planes. "We don't yet know what the extent of our use of additive-layer manufacturing there will be yet, but we don't see any show stoppers," says Jon Meyer, who heads research on 3-D printing at EADS's Innovation Works division in England.


Smaller scale: Seen here is a microprinter that GE uses to test new ways of building things out of ceramic materials. Researchers are using the machine to print the transducers used as probes in ultrasound machines; they believe it might save time and money while improving design. Credit: Bob O’Connor

GE's jet engine division may be closer than anyone else to bringing 3-D-printed parts into large-scale commercial production. In addition to the fuel injector, GE is also laser-sintering titanium into complex shapes for four-foot-long strips bonded onto the leading edge of fan blades. These strips deflect debris and create more efficient airflow. Until now, each one has required tens of hours of forging and machining, during which 50 percent of the titanium was lost. By switching to 3-D printing, the company will save about $25,000 in labor and material in each engine, estimates Todd Rockstroh, the GE consulting engineer who heads the effort. The blade edge and the fuel injector will start appearing in engines as early as 2013, and they will be integrated into full-scale production runs in the thousands by about 2016.

Meanwhile, says Rockstroh, the company hopes to gain design flexibility by using 3-D printing for more parts. When it recently discovered that a stem in the fuel injector was subjected to excessive levels of heat stress, a redesigned version came out of the printer within a week. "Before, we would have had to redesign 20 different parts, with all the associated tooling," says Rockstroh. "It might not have even been possible." And using 3-D printing to corrugate the insides of some parts can reduce their weight by up to 70 percent, which can save an airline millions of gallons of fuel every year. That prospect has GE looking for ways to print everything from gearbox housings to control mechanisms. "We're going on a major weight-reduction scavenger hunt next year," Rockstroh says.

Automobiles could similarly benefit from lighter parts, and the University of Louisville's Gornet notes that printing processes could cut the weight of valves, pistons, and fuel injectors by at least half. Some manufacturers of ultraluxury and high-performance cars, including Bentley and BMW, are already using 3-D printing for parts with production runs in the hundreds.


Polished: A transducer made in GE’s microprinter (top) and the same transducer after being refined and finished in other machines (bottom). Credit: Bob O’Connor

CHALLENGES TO OVERCOME

If it weren't for the limitations of the technology, 3-D printing would already be much more broadly used. "Speeds are atrociously slow right now," says GE's Singh. Todd Grimm, who heads an additive-*manufacturing consultancy in Edgewood, Kentucky, estimates that the time it takes to produce a part will have to improve as much as a hundredfold if 3-D printing is to compete directly with conventional manufacturing techniques in most applications. That won't happen in the next few years.

Another problem: for now, only a handful of plastic and metal compounds can be used in 3-D printing. In laser sintering, for example, the material must be able to form a powder that will melt neatly when it is hit with a laser, and then solidify quickly. The compounds that meet the necessary criteria can cost 50 to 100 times as much by weight as the raw materials used in conventional manufacturing processes, partly because they're in such low demand that they're available only from small specialty suppliers.

As demand increases with new applications, however, supplier competition should pull prices down dramatically. And the list of available materials is slowly expanding. GE is trying to use ceramics, which would open up new possibilities in engines and medical devices, among other areas.

Simple experience, too, will do much to improve the technology. So far, manufacturers don't have enough data to predict exactly how a part will turn out and how it will hold up, or how production variables—including temperature, choice of material, part shape, and cooling time—affect the results. That can be frustrating, says Singh: "3-D printing often ends up being a black art. A part is made out of thousands of layers, and each layer is a potential failure mode. We still don't understand why a part comes out slightly differently on one machine than it does on another, or even on the same machine on a different day." For example, the layering process tends to build up interlayer stresses in unpredictable ways, so that some parts end up distorted. Porosity can vary within parts as well, leading to concerns about fatigue or brittleness. That could be a big problem in aircraft engines or wing struts. "We know how to make the metals strong enough," says Boeing's Vander Wel. "But we worry about the unpredictability. Can we repeat a result to get 100 parts that are exactly the same? We're not sure yet."

Even with these challenges, time is on the side of 3-D printing, says Vander Wel, and not just because the processes are improving. Engineers are understandably reluctant to embrace a new technology for critical parts when their deadlines and reputations, not to mention the lives of people in airplanes, are at stake. "But younger designers are adapting more quickly," he says. "They're not so quick to say, 'It can't be built this way.'"

David H. Freedman, a science journalist based in Boston, wrote about opto*genetics in the November/December 2010 issue of TR. His latest book is Wrong: Why Experts Keep Failing Us.

http://web.mit.edu/newsoffice/2011/s...sH4vg.facebook

Sun-free photovoltaics


A variety of silicon chip micro-reactors developed by the MIT team. Each of these contains photonic crystals on both flat faces, with external tubes for injecting fuel and air and ejecting waste products. Inside the chip, the fuel and air react to heat up the photonic crystals. In use, these reactors would have a photovoltaic cell mounted against each face, with a tiny gap between, to convert the emitted wavelengths of light to electricity.
Photo - Photo: Justin Knight


Materials engineered to give off precisely tuned wavelengths of light when heated are key to new high-efficiency generating system.
Nancy W. Stauffer, MITEI
July 28, 2011

A new photovoltaic energy-conversion system developed at MIT can be powered solely by heat, generating electricity with no sunlight at all. While the principle involved is not new, a novel way of engineering the surface of a material to convert heat into precisely tuned wavelengths of light — selected to match the wavelengths that photovoltaic cells can best convert to electricity — makes the new system much more efficient than previous versions.

The key to this fine-tuned light emission, described in the journal Physical Review A, lies in a material with billions of nanoscale pits etched on its surface. When the material absorbs heat — whether from the sun, a hydrocarbon fuel, a decaying radioisotope or any other source — the pitted surface radiates energy primarily at these carefully chosen wavelengths.

Based on that technology, MIT researchers have made a button-sized power generator fueled by butane that can run three times longer than a lithium-ion battery of the same weight; the device can then be recharged instantly, just by snapping in a tiny cartridge of fresh fuel. Another device, powered by a radioisotope that steadily produces heat from radioactive decay, could generate electricity for 30 years without refueling or servicing — an ideal source of electricity for spacecraft headed on long missions away from the sun.

According to the U.S. Energy Information Administration, 92 percent of all the energy we use involves converting heat into mechanical energy, and then often into electricity — such as using fuel to boil water to turn a turbine, which is attached to a generator. But today's mechanical systems have relatively low efficiency, and can't be scaled down to the small sizes needed for devices such as sensors, smartphones or medical monitors.

"Being able to convert heat from various sources into electricity without moving parts would bring huge benefits," says Ivan Celanovic ScD '06, research engineer in MIT's Institute for Soldier Nanotechnologies (ISN), "especially if we could do it efficiently, relatively inexpensively and on a small scale."

It has long been known that photovoltaic (PV) cells needn't always run on sunlight. Half a century ago, researchers developed thermophotovoltaics (TPV), which couple a PV cell with any source of heat: A burning hydrocarbon, for example, heats up a material called the thermal emitter, which radiates heat and light onto the PV diode, generating electricity. The thermal emitter's radiation includes far more infrared wavelengths than occur in the solar spectrum, and "low band-gap" PV materials invented less than a decade ago can absorb more of that infrared radiation than standard silicon PVs can. But much of the heat is still wasted, so efficiencies remain relatively low.

An ideal match

The solution, Celanovic says, is to design a thermal emitter that radiates only the wavelengths that the PV diode can absorb and convert into electricity, while suppressing other wavelengths. "But how do we find a material that has this magical property of emitting only at the wavelengths that we want?" asks Marin Soljačić, professor of physics and ISN researcher. The answer: Make a photonic crystal by taking a sample of material and create some nanoscale features on its surface — say, a regularly repeating pattern of holes or ridges — so light propagates through the sample in a dramatically different way.

"By choosing how we design the nanostructure, we can create materials that have novel optical properties," Soljačić says. "This gives us the ability to control and manipulate the behavior of light."

The team — which also includes Peter Bermel, research scientist in the Research Laboratory for Electronics (RLE); Peter Fisher, professor of physics; and Michael Ghebrebrhan, a postdoc in RLE — used a slab of tungsten, engineering billions of tiny pits on its surface. When the slab heats up, it generates bright light with an altered emission spectrum because each pit acts as a resonator, capable of giving off radiation at only certain wavelengths.

This powerful approach — co-developed by John D. Joannopoulos, the Francis Wright Davis Professor of Physics and ISN director, and others — has been widely used to improve lasers, light-emitting diodes and even optical fibers. The MIT team, supported in part by a seed grant from the MIT Energy Initiative, is now working with collaborators at MIT and elsewhere to use it to create several novel electricity-generating devices.

Mike Waits, an electronics engineer at the Army Research Laboratory in Adelphi, Md., who was not involved in this work, says this approach to producing miniature power supplies could lead to lighter portable electronics, which is "critical for the soldier to lighten his load. It not only reduces his burden, but also reduces the logistics chain" to deliver those devices to the field. "There are a lot of lives at stake," he says, "so if you can make the power sources more efficient, it could be a great benefit."

The button-like device that uses hydrocarbon fuels such as butane or propane as its heat source — known as a micro-TPV power generator — has at its heart a "micro-reactor" designed by Klavs Jensen, the Warren K. Lewis Professor of Chemical Engineering, and fabricated in the Microsystems Technology Laboratories. While the device achieves a fuel-to-electricity conversion efficiency three times greater than that of a lithium-ion battery of the same size and weight, Celanovic is confident that with further work his team can triple the current energy density. "At that point, our TPV generator could power your smartphone for a whole week without being recharged," he says.

Celanovic and Soljačić stress that building practical systems requires integrating many technologies and fields of expertise. "It's a really multidisciplinary effort," Celanovic says. "And it's a neat example of how fundamental research in materials can result in new performance that enables a whole spectrum of applications for efficient energy conversion."

David L. Chandler contributed to this story

This is really something - very impressive tech, thanks for sharing the article.