Hydrogen getters are not sexy, but they are reliable. Sandia has been in the getter business for nearly 20 years through a flourishing partnership with Vacuum Energy Inc., which has the exclusive license to the technology.
“This is really the textbook case of how technology transfer should work,” says Tim Shepodd, manager of Materials Chemistry Dept. 8223. “We developed our hydrogen getters for applications in nuclear weapons. Then they were commercialized, which kept the program going at Sandia, and they have come back to us for plutonium transport.”
More than meets the eye — Tim Shepodd (8223) describes Sandia’s hydrogen getters program as a “sweet story of technology transfer.” Originally developed to scavenge hydrogen from nuclear weapons nearly 20 years ago, Sandia’s getters were licensed to Vacuum Energy Inc. for use in vacuum-insulated refrigerator panels, waterproof flashlights, flares, and most recently, plutonium transport. (Photo by Randy Wong)
About 15 years ago, Brad Phillip of Vacuum Energy approached Sandia for help removing gases from vacuum-insulated refrigerator panels to extend the product life, improve efficiency, and decrease size. Seeing the potential for hydrogen removal applications, Vacuum Energy licensed Sandia’s getter technology.
If you’ve used a waterproof flashlight, there’s a good chance you’ve encountered one of Sandia’s getters. Each year, Vacuum Energy sells millions of Sandia’s getters to flashlight manufacturers. The getters, which are about the size of a pencil eraser, scavenge the hydrogen that accumulates in the sealed compartment to prevent an explosion.
Hydrogen is ubiquitous because moisture is always present, despite efforts to remove it. Water reacts with metals, making metal oxides and hydrogen gas. Hydrogen is also dangerous, especially when it builds up in sealed compartments, because it is chemically reactive and has a large explosive range with air and high thermal conductivity.
“Have you ever opened your TV remote to change the batteries and noticed that the old batteries are bulging slightly? That’s hydrogen pressure,” explains Tim. “A typical AA battery is semihermitically sealed, so when it fails, it fails suddenly.” That released hydrogen can be ignited with static electricity, such as static generated from sliding across a synthetic bed comforter or carpet.
The getters contain unsaturated organic compounds that react directly with the hydrogen and remove it from the atmosphere, a process called “gettering.” If oxygen is present, the getter enables the hydrogen to react with the oxygen to form water in a controlled catalytic reaction. Tim describes getters as being like ice cream, with many different flavors designed to work in high or low temperature, radioactive, or noxious gas environments. While the flashlight getters are pellets, getters are also used in powder, spray coating, and sheet form.
Easy to get rid of
“It’s easy to get rid of hydrogen,” says Tim. “The challenge is to move an explosive atmosphere below an explosive concentration in a controlled fashion. That’s what our technology does extremely effectively without igniting anything — it moderates the reaction by never letting the temperature get to the ignition point.”
About five years ago, Vacuum Energy expanded the getter application space into flares. Flares are sealed to enable a chemical reaction when they are exposed to oxygen. That sealed compartment, like a waterproof flashlight, can become explosive if too much hydrogen builds up inside.
Tim says he receives several calls each year about new uses for hydrogen getters. “The common theme is often water. I’ve been contacted repeatedly by submarine and buoy operators, even water-themed Las Vegas shows,” he explains. “We are always looking for new applications.”
In many of those calls, Tim says, people tell him they have a hydrogen problem but they have no idea how much hydrogen they are dealing with. Sandia’s getters can be used to determine the extent of hydrogen build-up, as you can count the number of hydrogen atoms absorbed by a getter over a set period of time.
Last year Sandia’s getter passed rigorous DOE testing for use in plutonium transport. Tim says that without getter commercialization, Sandia never would have been able to develop the technology for this application. Vacuum Energy is now supplying getters to DOE’s Savannah River Site.
Biggest hurdle
“The biggest hurdle was that the plutonium shipping container contains a mixture of carbon dioxide and air, and getters had never been used in that environment before,” says April Nissen (8223), who oversaw the testing for Sandia. “We had to ensure that the getters would perform perfectly in those conditions. Failure is not an option.”
An important component of the testing was how the getters performed as they aged in the radioactive environment. Recently, April ran tests on a getter that had been in service for two years and found that they performed better than the laboratory-aged samples, which were subjected to worst-case conditions. “The getters sailed through a very rigorous set of tests,” says April. “We knew the technology would perform, but you never expect this sort of thing to come off without a hitch.”
Another potential getter application is in radar sources, which can degrade and malfunction when exposed to hydrogen. “A lot of people have an issue with hydrogen-sensitive devices that are placed with or in microchips and sealed,” says Tim. “Existing technology used for radar sources deactivates very quickly when exposed to room air, making this technology very difficult to work with.”
Tim presented Sandia’s getter solution at the Advanced Technology Workshop on RF and Micro-wave Packaging, sponsored by the International Microelectronics and Packaging Society last month in San Diego, Calif. An advantage of Sandia’s technology is that it can be worked on in air for several hours before it needs to be sealed. “Our technology also has orders of magnitude less equilibrium water vapor over the surface of the material, minimizing the chance of corrosion, and it passes low ionic content test,” says Tim. “Our presentation was very well received. We are definitely expanding this line of business.
Sandia’s getter work has taken Tim and other researchers in some unusual directions. About a year and a half ago, a salmon supplier asked Sandia for help in maintaining a specific environment in shipping containers that were cooled using a technology that leaked a little hydrogen.
“If the supplier could keep the fish at a certain pressure and temperature consistently, they could change their shipping method and save a lot of money,” he says. “So for a few months we had refrigerators out in the lab with trays full of salmon and getters as we worked on the environment.”
Another aspect of the project was quantifying the odor emitted by the salmon to determine what factors might be changed to keep the fish fresher. “That’s the beauty of working at Sandia,” says Tim. “You never know what kind of project you’ll be working on next — salmon or radar sources or something else totally unexpected.”