The US Navy is a big proponent of additive manufacturing technology, and its use of 3D printers on ships offers self-sustainability in remote areas, allowing sailors and officers to make and repair their own tools, parts, and components on board while out at sea, rather than having to go back in to port. It is disruptive and expensive, not to mention time-consuming, to bring a ship all the way ashore just to fix a small problem like a broken part, but a team of engineers from the University of Connecticut (UConn) has been hard at work developing a solution to this problem.
The UConn engineers have found a way for a Navy ship’s crew to determine the exact point of mechanical trouble on board the ship, which would negate them having to take the ship offline for maintenance. Instead, they could use 3D printing technology to fix, or replace, the bad part while out at sea, saving on both time and money.Associate Professor of Materials Science and Engineering Rainer Hebert, who is also the Director of the Pratt & Whitney Additive Manufacturing Innovation Center at UConn, is leading the research team. The engineers created a device which uses ceramics, on 3D printed metals, to find signals about potential problems and degradation on board, like overheating.
Pamir Alpay, GE Professor in Advanced Manufacturing and Executive Director of UConn’s Innovation Partnership Building, explained, “Essentially, what we’re trying to do is combine two completely separate materials – ceramics and metals – in an additive manufacturing environment. Such a combination in a 3-D printing process is unique and challenging.”
Working with additive manufacturing for both ceramics and metals will open new opportunities across demanding industries, and indeed is an objective for other work around the globe, such as that seen in XJet’s new Carmel system.
Temperature changes can be an indication that there’s a problem on board. The team’s device can carry the weight, while also resisting the temperature variants, of existing components at the same time. Then, it generates a real-time, electrical signal to alert crew members to the temperature change, along with how much strain is placed on the offending part.
The UConn engineers are also working on a manufacturing process that can be deployed in the field, which can produce 3D printed replacement parts on the ship once the original metal-ceramic parts show signs of failure or other issues.
This combination of metal and ceramics was born from the Navy’s aspiration to extend maintenance cycles for its ships. According to Navy staff, ships would not have to be taken offline for repairs and inspections if critical components were able to be monitored in real time and replacement parts could be manufactured at sea.
The UConn system works by depositing ceramic oxide onto a structured, 3D printed component, made out of aerospace superalloy Inconel, that can resist temperature variants. The ceramic oxide, which can sense both strain and temperature variations, offers valuable real-time time monitoring to Navy staff by generating an accessible electrical signal through radio frequencies. So for example, UConn notes that a localized point of stress, like a small crack, can be detected and fixed before becoming a bigger point of failure, and while there is already technology that can alert the crew to temperature fluctuations in specific ship zones, Alpay says that signaling the exact location of these types of issues is new.
The feasibility demonstration for the system’s process was published in a paper last year, titled “Metalorganic solution deposition of lead zirconate titanate films onto an additively manufactured Ni-based superalloy,” in the Acta Materialia journal, and Hebert, one of the authors, says it’s important because metals typically used with ceramics on the surface have “specific characteristics that deviate from those found in additively manufactured metals of the same chemistry.”
Alpay said, “It is a proof-of-concept study that shows it is possible to do this while maintaining functional properties of the oxide.”
There will be necessary extra processing steps once the replacement parts are 3D printed, like surface smoothing and heating parts up in a furnace to give them specific properties, but according to Hebert, if you weigh these steps against the possibility of saving fuel and weight with on-demand, on-site manufacturing and self-diagnostics of structural ship parts, the potential benefits far outweigh the additional processing.
While UConn’s ceramic-metals combination could also be used for automotive and aerospace applications, the Navy has a real need for this kind of technology now. In addition, Hebert also developed a 10-day 3D printing training course for two Naval Air Systems Command (NAVAIR) engineers, in order to provide them with both theoretical background information and hands-on experience. The training will help spread 3D printing knowledge, and its opportunities, limitations, and challenges, in a wider circle in the Navy.
According to Hebert, the potential is real for Naval and defense applications, though he does say that “further basic and applied research is necessary to achieve reproducible results and resilience in field use.”
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