ORNL Turns to Neutrons to Investigate Performance of Engine Cylinder Head Made from 3D Printed Mold and New Aluminum Alloy

A research team from Oak Ridge National Laboratory (ORNL) worked with several industry partners to use a 3D printed sand mold and neutrons to investigate how a new high-performance aluminum alloy was performing in a running gasoline-powered engine. Neutrons have unique properties that let them penetrate materials, like the aluminum-cerium (Al-Ce) alloy, without causing any damage, so they can give scientists a close look at the details of a material’s atomic structure. While neutrons and 3D printing technology have been studied together at ORNL before, using neutrons to check out a material’s performance in a running engine was a first for ORNL’s Spallation Neutron Source (SNS) research facility.

The goal was to see how high-performance Al-Ce, which could potentially be a boon for the automotive world, would hold up the stress and heat of an internal combustion engine. The SNS facility’s VULCAN instrument was used to evaluate a new cylinder head that was cast from the alloy, which ORNL developed with Eck Industries. VULCAN uses neutrons to measure stress and strain on large industrial samples.

Ke An, the VULCAN’s lead instrument scientist, said, “This was the first time an internal combustion engine has been run on our diffractometer, and, as far as we know, on any other.”

The team worked with ORNL’s Manufacturing Demonstration Facility and its National Transportation Research Center to 3D print sand molds, which were used to cast the Al-Ce cylinder head. Sand casting is a metal casting process where the mold material is, obviously, sand. The process produces detailed metal molds, and has been used to help make 3D printed wingnuts in the past. The cylinder head component was retrofitted to a prototype engine that had been specially designed for the VULCAN.

Thanks to remote ignition from VULCAN’s control room, the engine was stopped and restarted multiple times over a three-day experiment, and the researchers were able to “see” the material’s high-temperature stability while the engine was operating, thanks to neutron diffraction.

ORNL materials scientist Orlando Rios, who led the neutron experiment and also explores the use of cerium as a strengthening agent for aluminum alloys through the Critical Materials Institute, said, “Our experiment confirmed that our alloy outperforms other aluminum alloys at elevated temperatures. The automotive industry is currently interested in alloys that can hold up to high-heat demands of new, energy-efficient technologies. Our aluminum-cerium composition shows exceptional stability at temperatures above 500 degrees Celsius [932 degrees Fahrenheit], which is unheard of for aluminum alloys.”

The reason the team wanted to measure the material’s performance under actual operating conditions was because materials, while they may seem strong, experience extreme temperatures and complex forces during internal combustion.

“We really took the engine through its paces. It was probably the loudest experiment to take place at SNS,” Rios said.

“The entire team was impressed by the quality of the data from VULCAN, especially given that the neutrons had to travel through an entire engine structure before being observed by our detectors to supply information on the cylinder head at work. That is truly remarkable.”

ORNL postdoc Michael Kesler and University of Tennessee’s Bredesen Center Fellow Zachary Sims worked with Rios with the project. An, who is working to streamline the proof-of-concept for future users of the VULCAN, said that it was very effective to collaborate across various disciplines between ORNL and other industry partners for the experiment.

“This was a fundamental experiment not only to better understand this alloy but also to provide some broader analysis that will allow new alloys, not only aluminum compounds, to be processed in this way. The experiment demonstrates the benefits of coupling fundamental science with early stage research and development of new materials and technologies,” said Rios. “We hope what we are learning through this experiment can be applied to many other materials in a wide range of applications.”

There are several ways that the new aluminum alloy could improve automotive engines, and if the material can one day be combined with 3D printing technology, the possibilities are far-reaching.

“With an aluminum alloy stable at high temperatures, engines could run hotter, and components could be made lighter, boosting efficiency and fuel economy,” said Lt. Eric Stromme, a Navy Tours with Industry Fellow who also helped with the project.

The team’s research was sponsored by the Department of Energy’s Office of Energy Efficiency and Renewable Energy through the DOE’s Critical Materials Institute and the Department of Energy’s Office of Science. Other partners include Ames National Laboratory, the Lawrence Livermore National Laboratory, and Idaho National Laboratory.

Discuss in the ORNL Neutrons forum thread at 3DPB.com.

[Source/Images: ORNL]