MAY/JUNE 2022 | VOL 180 | NO 4 20 23 31 Climate Neutral Tool Steel Sustainable Materials for Electric Vehicles ASM Reference Publications & Digital Databases Catalog SUSTAINABLE COMPOSITES FOR AUTOMOTIVE GREEN MATERIALS ENGINEERING P. 14

MAY/JUNE 2022 | VOL 180 | NO 4 20 23 31 Climate Neutral Tool Steel Sustainable Materials for Electric Vehicles ASM Reference Publications & Digital Databases Catalog SUSTAINABLE COMPOSITES FOR AUTOMOTIVE GREEN MATERIALS ENGINEERING P. 14

DECEMBER 6–8, 2022 | THE RITZ-CARLTON, NAPLES, FL SAVE THE DATE! Recharge in the company of visionaries, connect with other materials executives who share your fire about the future of the materials world, and unlock new thinking to spark innovation. This year’s summit will convene a powerful collection of groundbreaking innovators and top subject-matter experts, focused on the following domains: • Materials 4.0 — Materials Genome Deployment • Nexus of Data Science and Materials Science • Industry 4.0 — the New Manufacturing Landscape • Materials Sustainability in the 21st Century Plan today to join other materials executives and ASM leaders during this exclusive two-day summit, featuring keynotes, expert panel sessions, and numerous networking opportunities. Be sure to arrive early to relax and network with your peers during an informal golf outing! REGISTRATION OPENS SUMMER 2022

PRESENTS: Forum Highlights: Organizing Committee: SEPTEMBER 13–14, 2022 | NEW ORLEANS, LOUISIANA • Access to three co-located conferences for the price of one! • Joint keynote sessions from prestigious industry experts • Information-packed technical sessions, featuring new and emerging market topics • A diverse exposition showcasing state-of-the-art products and services • Dedicated in-person networking with peers and exhibitors in a devoted thermal spray pavilion on the expo show floor • Additional networking opportunities, including a special evening event at Grand Oaks Mansion with tour of the famous Float Den We’re excited to o er this new forum, filled with new technologies, new market trends, and new market segments! TSS, New Orleans…and all that JAZZ! New Orleans is home to Creole cuisine, rich history, and o ers unmatched southern hospitality. Come for the TSS Forum but stay for a little lagniappe. Plan now to attend. William Lenling, ASM Thermal Spray Society President Rogerio Lima, ASM Thermal Spray Society Vice President and Program Committee Chair NACSC 2022: Charles Kay (Chair), Hannecard Roller Coatings Inc. Jan Cizek, The Czech Academy of Sciences Eric Irissou, CNRC-NRC Bertrand Jodoin, University of Ottawa Andre McDonald, University of Alberta Luc Pouliot, Polycontrols Technologies Peter Richter, Impact Innovations Kumar Sridharan, University of Wisconsin NEM-TS 2022: John Koppes (Co-Chair), TST EngineeredCoating Solutions Andrew Vackel (Co-Chair), Sandia National Laboratories James Ruud, GE Global Research Sanjay Sampath, Stony Brook University TSS Expo Committee Chair: Shari Fowler-Hutchinson, Saint Gobain NORTH AMERICAN COLD SPRAY CONFERENCE 2022 FEATURING: 2022 INTERNATIONAL MATERIALS, APPLICATIONS & TECHNOLOGIES CO-LOCATED WITH:

49 ASM NEWS The latest news about ASM members, chapters, events, awards, conferences, affiliates, and other Society activities. DEVELOPING SUSTAINABLE COMPOSITES FOR AUTOMOTIVE APPLICATIONS Sabah Javaid and Surojit Gupta Automotive manufacturers are making significant investments in the design and development of bioplastics and biocomposites-based components. 14 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 2 Substituting biomass for fossil fuel-based precursors in plastics manufacturing holds promise for achieving sustainability goals. Courtesy of Dreamstime/Candy1812. On the Cover: 64 3D PRINTSHOP Researchers are looking at ways to improve additive manufacturing processes by controlling heat and modifying inks. 27 AEROMAT 2022 SUMMARY Jeff Grabowski and Eli Ross AeroMat’s successful return to inperson meetings featured keynotes and programming on next-generation materials, and for the first time, was colocated with AeroTech.

4 Editorial 5 Research Tracks 6 Machine Learning 7 Process Technology 8 Metals/Polymers/Ceramics 10 Testing/Characterization 12 Emerging Technology 13 Energy Trends 63 Editorial Preview 63 Special Advertising Section 63 Advertisers Index 64 3D PrintShop TRENDS INDUSTRY NEWS DEPARTMENTS Check out the Digital Edition online at ASM International serves materials professionals, nontechnical personnel, and managers wordwide by providing high-quality materials information, education and training, networking opportunities, and professional development resources in cost-effective and user-friendly formats. ASM is where materials users, producers, and manufacturers converge to do business. Advanced Materials & Processes (ISSN 0882-7958, USPS 762080) publishes eight issues per year: January/February, March, April, May/June, July/August, September, October, and November/December, by ASM International, 9639 Kinsman Road, Materials Park, OH 44073-0002; tel: 440.338.5151; fax: 440.338.4634. Periodicals postage paid at Novelty, Ohio, and additional mailing offices. Vol. 180, No. 4, MAY/JUNE 2022. Copyright © 2022 by ASM International®. All rights reserved. Distributed at no charge to ASMmembers in the United States, Canada, and Mexico. International members can pay a $30 per year surcharge to receive printed issues. Subscriptions: $499. Single copies: $54. POSTMASTER: Send 3579 forms to ASM International, Materials Park, OH 44073-0002. Change of address: Request for change should include old address of the subscriber. Missing numbers due to “change of address” cannot be replaced. Claims for nondelivery must be made within 60 days of issue. Canada Post Publications Mail Agreement No. 40732105. Return undeliverable Canadian addresses to: 700 Dowd Ave., Elizabeth, NJ 07201. Printed by Publishers Press Inc., Shepherdsville, Ky. 20 SUSTAINABILITY AT UDDEHOLM: A STUDY IN PRODUCING CLIMATE-NEUTRAL TOOL STEEL Robert Gustafsson and Berne Högman Uddeholm devoted a week to study sustainable development opportunities, reducing their carbon emissions and analyzing ways to produce tool steels more sustainably. 23 SUSTAINABLE MATERIALS FOR ELECTRIC VEHICLES: WEBINAR ROUNDUP A webinar collaboration between ASM International and the Materials Research Society brought together a panel of speakers to discuss the challenges and opportunities on the horizon as electric vehicle designers and manufacturers search for materials with sustainability characteristics. 29 IMAT 2022 PROGRAM HIGHLIGHTS IMAT—the International Materials Applications & Technologies Conference and Exhibition—and ASM’s annual meeting will be held in New Orleans, September 12-15. FEATURES MAY/JUNE 2022 | VOL 180 | NO 4 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 3 20 31 29 23 31 ASM REFERENCE PUBLICATIONS & DIGITAL DATABASES CATALOG Our vast, authoritative reference library offers the most comprehensive and up-to-date materials information.

4 Decades ago, my dad, a civil engineer, was involved in the development of solar paneled huts that protected water pumps in our hometown and kept them from freezing. He passed away recently, and in going through memorabilia, my sisters and I were reminded that a perk of our dad’s job when we were kids was being invited to enjoy the beautiful great outdoors—hiking, boating, and fishing— with other engineers’ families at Camp Muskingum in Ohio. After one excursion in the 1970s, we found ourselves on the cover of Ohio Engineer magazine. Those trips helped build our appreciation for nature and were reassurances that the engineering community valued, protected, and reveled in it as well. In recent years, my dad had been very intrigued by electric vehicle (EV) technology and the ecological promise it holds. He just missed seeing the late April release of “Lightning,” Ford’s first all-electric F-150. But I know he would have enjoyed the articles in this issue focused on sustainability in the auto industry. One article provides a summary from key thinkers in the area of sustainablematerials for EVs, based on a webinar jointly presented by ASM International and the Materials Research Society. Much of the webinar discussion centered around materials and recycling issues for EV batteries. In addition to those challenges, speaker Kristin Persson from the University of California, Berkeley reported that charging stations are not well maintained or properly policed. Sometimes a charger is not operational. Other times, a car is parked in front of one for longer than the allotted time, with no ticketing or fines. These basic logistical challenges need to be worked out before we will see a large growth in EV adopters. A different angle on sustainability in the automotive sector is presented in the lead article. Researchers from the University of North Dakota discuss the increasing use of bioplastics in auto parts as a means to reduce greenhouse gas emissions. Yet, they conclude, more needs to be done on the cost considerations side to make them viable. In other environmental news, protocols around steel production are getting a refresh as the industry looks for greener processes. The World Steel Association reports that in 2020, every metric ton of steel produced emitted almost twice that much carbon dioxide (1.8 tons) into the atmosphere. An encouraging case study from Uddeholm shows how their new sustainable process for tool steel production reduced 90% of the company’s CO2 emissions. Results worthy of emblazonment. ASM members who wish to discuss these green topics in greater detail can look to the recently formed Sustainable Materials Engineering Technical Committee, chaired by John Wolodko, FASM, of the University of Alberta. Let us know if you’d like to be involved. There is so much human potential to solve ecological issues with materials science. It will be fascinating to see what today’s and tomorrow’s engineers can do—across the globe or in their own hometowns—to carry on the work of all those who came before. A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 ASM International 9639 Kinsman Road, Materials Park, OH 44073 Tel: 440.338.5151 • Fax: 440.338.4634 Joanne Miller, Editor Victoria Burt, Managing Editor Frances Richards and Corinne Richards Contributing Editors Jan Nejedlik, Layout and Design Madrid Tramble, Production Manager Press Release Editor EDITORIAL COMMITTEE Adam Farrow, Chair, Los Alamos National Lab John Shingledecker, Vice Chair, EPRI Somuri Prasad, Past Chair, Sandia National Lab Beth Armstrong, Oak Ridge National Lab Margaret Flury, Medtronic Surojit Gupta, University of North Dakota Nia Harrison, Ford Motor Company Michael Hoerner, KnightHawk Engineering Hideyuki Kanematsu, Suzuka National College of Technology Ibrahim Karaman, Texas A&M University Ricardo Komai, Tesla Scott Olig, U.S. Naval Research Lab Amit Pandey, Lockheed Martin Space Satyam Sahay, John Deere Technology Center India Kumar Sridharan, University of Wisconsin Jean-Paul Vega, Siemens Energy Vasisht Venkatesh, Pratt & Whitney ASMBOARDOF TRUSTEES Judith A. Todd, President and Chair of the Board David B. Williams, Vice President Diana Essock, Immediate Past President John C. Kuli, Treasurer Burak Akyuz Ann Bolcavage Elizabeth Ho man Navin Manjooran Toni Marechaux U. Kamachi Mudali James E. Saal Priti Wanjara Ji-Cheng Zhao Sandra W. Robert, Secretary and Executive Director STUDENT BOARDMEMBERS Shruti Dubey, AndrewRuba, David Scannapieco Individual readers of AdvancedMaterials & Processes may, without charge, make single copies of pages therefrom for personal or archival use, or may freelymake such copies in such numbers as are deemed useful for educational or research purposes and are not for sale or resale. Permission is granted to cite or quote fromarticles herein, provided customary acknowledgment of the authors and source is made. The acceptance and publication of manuscripts in Advanced Materials & Processes does not imply that the reviewers, editors, or publisher accept, approve, or endorse the data, opinions, and conclusions of the authors. PASSING THE GREEN TORCH Myself in center with sister and dad on Ohio Engineer cover.

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 5 TASTY TURMERIC FORTIFIES FUEL CELLS A team from Clemson University’s Nanomaterials Institute (CNI), South Carolina, and Sri Sathya Sai Institute of Higher Learning in India found a way to combine curcumin, the substance in turmeric, with gold nanoparticles to create an electrode that requires significantly less energy to convert ethanol into electricity versus other methods. Although more testing is needed, the discovery is another step toward replacing hydrogen as a fuel cell feedstock. The team focused on the fuel cell’s anode, where the ethanol is oxidized, and selected gold as the catalyst. Rather than using conducting polymers or metal-organic frameworks to deposit gold on the electrode’s surface, researchers used curcumin due to its structural uniqueness. Curcumin is applied to decorate the gold nanoparticles in order to stabilize them, forming a porous network around them. The team RESEARCH TRACKS deposited the curcumin gold nanoparticles on the surface of the electrode at 100x lower electric current than in previous studies. “Without this curcumin coating, the performance is poor,” says Apparao Rao, CNI’s founding director. “We need this coating to stabilize and create a porous environment around the nanoparticles, and then they do a super job with alcohol oxidation. The next step is to scale the process up and work with an industrial collaborator who can actually make the fuel cells and build stacks of fuel cells for real applications.” SUPER SPEEDY GLASS PRINTING Researchers at Lawrence Livermore National Laboratory (LLNL) and the University of California, Berkeley are using a new 3D printing method to make microscopic objects out of silica glass in mere seconds. The process employs a laser-based volumetric additive manufacturing (VAM) approach, an emerging technology in near-instant 3D printing. The computed axial lithography (CAL) technology developed by LLNL and UC Berkeley is similar to computed tomography imaging. CAL works by computing projections from several angles through a digital model of a target object, optimizing these projections, and then delivering them into a rotating volume of photosensitive resin using a digital light projector. Over time, the projected light patterns reconstruct a 3D light dose distribution in the material, curing the object at points exceeding a light threshold while the vat of resin spins. After the fully formed object materializes, the vat is drained to retrieve the part. The process combines a microscale VAM technique called micro-CAL, which uses a laser instead of an LED source, with a nanocomposite glass resin developed by the German Alcohol, shown as green droplets (top), interacts with curcumin-enveloped gold nanoparticles to efficiently yield energy, depicted as white sparks (bottom). company Glassomer and the University of Freiburg. Using the new approach, the team created glass objects with complex microstructures, exhibiting a surface roughness of just 6 nm and features down to 50 μm. Researchers say the benefit of VAM for micro-optics is that it can produce extremely smooth surfaces without layering artifacts, resulting in faster printing without additional post-processing time. Applications could include micro-optics in high-quality cameras, consumer electronics, biomedical imaging, chemical sensors, virtual reality headsets, advanced microscopes, microfluidics with challenging 3D geometries, and more. Caitlyn Cook, a polymer engineer in LLNL’s materials engineering division, says she and her team will further tune the resolution of VAM and the doses required for a variable range of resolutions and print speeds. In addition, the team is conducting a feasibility study to advance the VAM glass printing efforts for larger optics. “Cracking problems typically arise in larger prints due to shrinkage stresses,” says Cook. “Our teams at LLNL are developing custom formulations to produce larger optics and glass printed parts that will not crack during the debinding and sintering processes.” Microscopic object made of silica glass using volumetric additive manufacturing.

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 6 MACHINE LEARNING | AI MACHINE LEARNING AIDS RARE EARTHS RESEARCH Scientists at the DOE’s Ames Laboratory and Texas A&M University trained a machine learning (ML) model to determine the stability of rare earth compounds. The team used the upgraded Ames Laboratory Rare Earth database (RIC 2.0) and high-throughput density functional theory (DFT) to build the foundation for their model. High-throughput screening allows researchers to test hundreds of models quickly, while DFT is a quantum mechanical method used to investigate thermodynamic and electronic properties. Based on this collection of information, the new ML model uses regression learning to assess the phase stability of different compounds. Ames scientist Prashant Singh says the material analysis relies on a discrete feedback loop in which the AI/ ML model is updated using the new DFT database, which is based on real-time structural and phase information obtained from the experiments. The process ensures that information is carried from one step to the next and reduces the chance of making mistakes. Project supervisor Yaroslav Mudryk notes that the framework was designed to explore rare earth compounds due to their technological importance, but its application is not limited to rare earths research. The same approach could be used to train an ML model to predict magnetic properties of compounds, develop new process controls for manufacturing, and optimize mechanical behaviors. SELF-DRIVING LAB STUDIES NANOCRYSTALS A research team from North Carolina State University and the University at Buffalo developed a “self- driving lab” that uses artificial intelligence (AI) and fluidic systems to gain knowledge regarding metal halide perovskite (MHP) nanocrystals. These nanocrystals are an emerging class of semiconductor materials that have potential for use in printed photonic devices and energy technologies due to their solution processability, unique size, and composition-tunable properties. They are highly efficient, optically active materials that are under consideration for use in next-generation LEDs. Because they can be made using solution processing, they also have the potential to be made in a cost-effective way. Doping the material with varying levels of manganese can change its optical and electronic properties, such as the wavelength of light emitted, and also introduce magnetic properties. Especially noteworthy is that the new system does all of this autonomously. Specifically, its AI algorithm selects and runs its own experiments: Results from each experiment inform which experiment it will run next—and it keeps going until it understands which mechanisms control the MHP’s various properties. “In other words, we can get the information we need to engineer a material in hours instead of months,” says NC State associate professor Milad Abolhasani. While the work demonstrated in this research focuses on MHP nanocrystals, the system could also be used to characterize other nanomaterials that are made using solution processes, including a wide variety of metallic and semiconductor nanomaterials. A newmachine learning model uses regression learning to assess the phase stability of various rare earth compounds. Courtesy of Ames Laboratory. A new self-driving lab is using AI and fluidic systems to study MHP nanocrystals. Courtesy of Milad Abolhasani.

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 7 PROCESS TECHNOLOGY NEW ACRC FOUNDRY AND LABS The University of California, Irvine (UCI), completed construction of a state-of-the-art metal processing facility for the Advanced Casting Research Center (ACRC) and opened the doors in March. The new foundry and lab include a high-tech vacuum melting system, complete Spectro lab for chemical analysis, digital image correlation system, an Olympus microscopy suite, x-ray computed tomography, a laser powder bed fusion system, and more. Alan Luo, Director of Lightweight Materials and Manufacturing Research Lab at The Ohio State University who attended the opening, comments, “The new ACRC facility has the state-of-theart equipment and lab space for research and development in advanced metal casting and digital manufacturing. It’s a one-of-its-kind center in the United States for fostering industry- academia collaboration, which is indis- Space-based fabrication would leverage native cislunar materials mined and processed in space whenever possible, incorporating advanced materials and components developed on and transported from Earth when necessary. NOM4D’s goal of pioneering offEarth manufacturing maximizes stability, agility, resiliency, and adaptability of space systems. In three 18-month phases, the programwill tackle increasingly challenging concepts. Phase 1 calls for materials and designs that meet stringent structural efficiency targets. Phase 2 will focus on risk reduction and technical maturation. Phase 3 calls for a leap in precision to enable infrared reflective structures that can be used in a segmented long-wave infra- red telescope. Ground-based fabrication of subscale exemplar structures—as opposed to the full structures—will be used to vali- date advanced NOM4D materials, manufacturing capabilities, and design concepts. Importantly, technologies must be designed to survive and maintain precise operation during potentially destructive events, such as lunar storms and micrometeorite impacts. ACRC is nowwell established at UCI, joining its other materials research centers. pensable for the metals and manufacturing sectors in the nation.” acrc.manufacturing. MANUFACTURING IN SPACE In late 2021, DARPA launched its Novel Orbital and Moon Manufacturing, Materials and Mass-efficient Design (NOM4D, pronounced “nomad”) program to develop foundational materials, processes, and designs needed to manufacture large, precise, and resilient systems in space. Specifically, the program focuses on the design of spacebased systems too large to be built on Earth and launched. These structures will have features that enable them to withstand maneuvers, thermal cycles, and physical damage typical of space and lunar environments. With a history of successful DARPA collaborations, the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Md., was chosen to evaluate the operational potential of future adaptive, large-scale, spacebased manufacturing. To address the wide-ranging technical challenges presented by NOM4D, the APL assembled a team of scientists and engineers with deep expertise in materials science, physics, lunar geology, optical sensing, power systems, spacecraft engineering, cislunar space, and more. A successful NOM4D program would truly mark a paradigm shift in manufacturing space structures. BRIEF Wauseon Machine and Manufacturing Inc., Wauseon, Ohio, a provider of robotics automation, tube fabrication equipment, and build-to-print precision machined parts, acquired McAlister Design and Automation LLC, Greenville, S.C., a leading robotics systems integrator. McAlister’s four facilities total 48,000 sq. ft., adding significantly more capacity for automation projects. NOM4D-enabled future concept. Courtesy of Johns Hopkins APL.

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 8 METALS | POLYMERS | CERAMICS and high-capacity batteries. The name of the new family of 2Dmaterials is transition metal carbo-chalcogenides, or TMCC. It combines the characteristics of two families of 2D materials—transition metal carbides and transition metal dichalcogenides. The latter is a large family of materials that has been explored extensively and found to be very promising, especially for electrochemical energy storage and conversion. However, one downside is their low electrical conductivity and stability. Conversely, transition metal carbides are excellent electrical conductors with much more powerful conductivity. Merging the two families into one is anticipated to have great potential for many applications such as batteries and supercapacitors, catalysis, sensors, and electronics. “We used an electrochemicalassisted exfoliation process by inserting lithium ions in-between the layers of bulk transition metals carbochalcogenides followed by agitation in water,” explains researcher Ahmad Doctoral student William Trehern operating a vacuum arc melter—a synthesis method commonly used to create high-purity alloys of various compositions. Courtesy of Texas A&M Engineering. ALLOY DISCOVERY Using an Artificial Intelligence Materials Selection framework (AIMS), researchers from Texas A&M University, College Station, have discovered a new shape memory alloy. The shape memory alloy showed the highest efficiency during operation achieved thus far for nickel-titanium-based materials. In addition, the researchers’ data-driven framework offers proof of concept for future materials development. The shape memory alloy found during the study using AIMS was predicted and proven to achieve the narrowest hysteresis ever recorded. Essentially, the material showed the lowest energy loss when converting thermal energy to mechanical work. The material showcased high efficiency when subject to thermal cycling due to its extremely small LIFT, a national manufacturing innovation institute based in Detroit, granted a “U LIFT Challenge” project award to the University of Central Florida, Orlando, to further explore metallic alloys used in additive manufacturing (AM). Researchers will establish thermokinetic criteria to determine printability and buildability of metallic alloys for powder bed fusion AM. BRIEF transformation temperature window. It also exhibited excellent cyclic stability under repeated actuation. Typical shape memory alloys are nickel-titaniumcopper compositions. These alloys normally have titanium equal to 50% and form a single-phase material. Using machine learning, the researchers predicted a different composition with titanium equal to 47% and copper equal to 21%. While this composition is in the two-phase region and forms particles, they help enhance the material’s properties, the researchers explain. In particular, this high-efficiency shape memory alloy lends itself to thermal energy harvesting, which requires materials that can capture waste energy produced by machines and put it to use, and thermal energy storage, which is used for cooling electronic devices. More notably, the AIMS framework offers the opportunity to use machine-learning techniques in materials science. The researchers see potential to discover more shape memory alloy chemistries with desired characteristics for various other applications. NEW2DMATERIALS Researchers from Tulane University, NewOrleans, developed a new family of 2D materials with promising applications, including in advanced electronics Michael Naguib, professor at Tulane, is an expert in two-dimensional material and electrochemical energy storage. Courtesy of Paula Burch-Celentano.

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 9 Majed. Unlike other exotic nanomaterials, he continues, the process of making these 2D TMCC nanomaterials is simple and scalable. BREAKING DOWN PLASTIC In a world’s first, a team of researchers from Northwestern University, Evanston, Ill., successfully used metal-organic frameworks (MOFs) to break down polyester-based plastic into its component parts. In addition to demonstrating that MOFs are a stable and selective catalyst, an important bonus of the new process is that one of the resulting component parts, terephthalic acid, is a chemical used to produce plastic. In this way, the method eliminates the need to utilize expensive, energy-intensive production to separate xylenes. “We can do a lot better than starting from scratch when making plastic bottles,” says scientist Omar Farha. “Our process is much cleaner.” For the experimental catalyst, the researchers chose a zirconium-based MOF called UiO-66 because it is easy to make, scalable, and inexpensive. The team used what plastic they had on hand—water bottles that colleagues in the lab had discarded. They chopped them up, heated the plastic, and then applied the catalyst. “The MOF performed even better than we anticipated,” according to Farha. “We found the catalyst to be very selective and robust. Neither the color of the plastic bottle or the different plastic the bottle caps were made from affected the efficiency of the catalyst. And the method doesn’t require organic solvents, which is a plus.” According to the researchers, the work helps address long-standing challenges With Northwestern’s unique degradation process using MOFs, more plastic bottles can be made into new ones instead of ending up in a landfill. associatedwith plastic waste and opens up newareas and applications for MOFs.

1 0 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 eras. The researchers’ new technique, called high-speed stress microscopy, provides a more quantitative way to study this phenomenon by directly measuring the force, stress, and pressure underneath liquid drops as they hit surfaces. The researchers found that the force exerted by a droplet actually spreads out with the impacting drop— instead of being concentrated in the center of the droplet—and the speed at which the droplet spreads out exceeds the speed of sound at short times, creating a shock wave across the surface. Each droplet behaves like a small bomb, releasing its impact energy explosively and giving it the force necessary to erode surfaces over time. The research could help engineers design more erosion-resistant surfaces for applications that must weather outdoor elements. Next, the team plans to study how different textures and materials change the amount of force created by liquid droplets. twin-cities. TESTING | CHARACTERIZATION SOLAR CELLS FOR SPACE A collaborative research team led by the University of Oklahoma, Norman, developed optimal conditions for testing perovskite solar cells for space applications. Perovskite solar cells are creating excitement in the photovoltaics community due to their rapidly increasing performance and their high tolerance to radiation. These properties suggest they could be used to provide power for space satellites and spacecrafts. The team measured the solar cells’ radiation hardness under different conditions. Using lower-energy particles, specifically protons, researchers confirmed that perovskites are radiation hard and that when damaged, they heal quickly. One area of application for the new protocol includes investigating perovskites’ use in permanent installations on the moon, specifically in whether lightweight flexible perovskites could be sent into space folded up and successfully deployed there, or even made on the moon. Future research could explore the utility of perovskite solar cells for space missions to planets like Jupiter that have an intense radiation environment or for satellite missions in polar orbits with high radiation levels. STUDYING DROPLET IMPACTS A new discovery about liquid droplets and their affect on hard surfaces could help engineers design better, more erosion-resistant materials. Using a newly developed technique, researchers from the University of Minnesota Twin Cities were able to measure hidden quantities such as the shear stress and pressure created by the impact of liquid droplets on surfaces, a phenomenon that has only ever been studied visually. Previously, droplet im- pact has only been analyzed visually using high-speed cam- Leica Microsystems will partner with Imperial College London to set up a dedicated imaging hub at the university, which will be equipped with advanced confocal and widefield microscopy systems. The hub will serve as a microscopy knowledge center in optical precision imaging for scientists and researchers, and will also create a space for joint research projects between the two organizations. Zeiss held a ribbon cutting on April 7 at its Zeiss Microscopy Customer Center Bay Area (ZMCC BA) in the company’s new high-tech building designed for customer and employee collaboration in Dublin, Calif. The ZMCC BA houses electron, light, and x-ray microscopes that are supported by resident application experts in life science, materials research, and electronics segments. BRIEFS University of Oklahoma graduate student Sergio Chacon helps undergraduate researcher Rachel Penner set up perovskite solar cell measurements. The image shows the impact liquid droplets can make on a granular, sandy surface (left) versus a hard, plaster surface (right). Courtesy of Cheng Research Group, University of Minnesota.

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 1 1 ALLOYS FOR AIRCRAFT Scientists studying aluminum alloys at the atomic level found patterns that will help improve their structure. Researchers from the Belgorod State University and the Skolkovo Institute of Science and Technology (Skoltech) studied aluminum alloys used in aircraft structures. They say these alloys have a wealth of advantages, such as small weight and resistance to wear and fracture at elevated temperatures, as well as cyclic and shock loads. The findings will be useful for developing new alloys for modern aircraft, according to the researchers. The work focused on the aluminum, copper, magnesium, silver (Al-Cu-Mg-Ag) system used for wing and fuselage skin. Al-Cu-Mg-Ag alloying helps obtain high heat resistance alloys, but the evolution of the alloy’s structure and mechanical properties in various thermal or thermomechanical treatment modes and operating conditions is still not well understood. Working with the Al-Cu-Mg-Ag system, scientists observed the formation of dispersed particles with a thickness of only a few nanometers, making the alloys much stronger despite their small size. “In addition,” explains Skoltech researcher Anton Boev, “the particles turned out to be coherent and fit well into the aluminum matrix, like pieces of a puzzle, although with slight distortions in their atomic structure. Also, we found that the particles’ structure and, therefore, the heat-treated alloy’s Courtesy of Pixabay/CC0 Public Domain. mechanical behavior change according to a certain pattern.” The combination of mechanical properties obtained by the team will help extend the lifetime of aircraft structures made from these materials., www.

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 1 2 STATIONARY HEAT ENGINE A research team designed a heat engine with no moving parts in a collaboration between engineers at MIT, Cambridge, and the National Renewable Energy Laboratory in Golden, Colo. They demonstrated that the heat engine converts heat to electricity with over 40% efficiency—a performance better than that of traditional steam turbines. The engine is a thermophotovoltaic (TPV) cell that passively captures high-energy photons from a white-hot heat source and converts them into electricity. The team’s design can generate electricity from a heat source of between 1900° to 2400°C, or up to about 4300°F. The researchers plan to incorporate the TPV cell into a grid-scale thermal battery. The system would absorb excess energy from renewable sources such as the sun and store that energy in heavily insulated banks of hot graphite. When the energy is needed, such as on overcast days, TPV cells would convert the heat into electricity, then dispatch the energy to a power grid. With the new TPV cell, the team has now successfully demonstrated the main parts of the system in separate, small-scale experiments. They are now working to integrate the parts to demonstrate a fully operational system. From there, they hope to scale up the system to replace fossil-fuel-driven power plants and enable a fully decarbonized power grid, supplied entirely by renewable energy., RICE HUSK LEDs Scientists from Japan’s Hiroshima University created the world’s first silicon quantum dot (SiQD) LED light using recycled rice husks. Searching for a scalable method to fabricate quantum dots, the researchers looked to agricultural waste. Milling rice to separate the grain from the husks produces about 100 million tons of rice husk waste globally each year. The new environmentally friendly, low-cost method transforms this waste into state-of-the-art light-emitting diodes. Nontoxic and abundant in nature, Si has photoluminescent properties, stemming from its microscopic quantum dot structures that serve as semiconductors. Waste rice husks, it turns out, are an excellent source of high-purity silica (SiO2) and value-added Si powder. The team used a combination of milling, heat treatments, and chemical etching to process EMERGING TECHNOLOGY Researchers from the University of Wuppertal and the University of Cologne along with four other German universities and institutes developed a tandem solar cell that reaches 24% efficiency. This sets a new world record as the highest efficiency achieved so far with this particular combination of organic and perovskite-based absorbers. BRIEF the rice husk silica. First, they milled rice husks and extracted SiO2 powders by burning off organic compounds of the husks. Next, they heated the resulting silica powder in an electric furnace to obtain Si powders via a reduction reaction. Third, the purified Si powder product was further reduced to three nanometers in size by chemical etching. Finally, its surface was chemically functionalized for high chemical sta- bility and high dispersivity in a sol- vent, producing SiQDs that luminesce in the orange-red range with efficiency of over 20%. The scientists suggested that the method they developed could be applied to other plants, such as sugar cane bamboo, wheat, barley, or grasses that contain SiO2. These natural products and their wastes might hold the potential to be transformed into nontoxic optoelectronic devices. The scientists would like to see commercialization of their ecofriendly approach to creating luminescent devices from rice husk waste. Graphical depiction of the world’s first LED light created from rice husks and chemically obtained products. Courtesy of ACS. A TPV cell (size 1 x 1 cm) mounted on a heat sink is designed to measure the cell’s efficiency. Courtesy of Felice Frankel.

1 3 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 EMERGING TECHNOLOGY OPTIMIZED BATTERY RECYCLING In a big step toward the electromobility society of the future, researchers from Chalmers University of Technology, Sweden, developed an optimized recycling process for electric vehicle (EV) batteries to make the recycling of electric car batteries easier, cheaper, and more environmentally friendly. As the use of EVs increases, recycling and recovery processes for their batteries and the critical raw metals used in production are becoming an increasingly important area of research. One method that currently attracts a lot of interest is a combination of thermal pretreatment and hydrometallurgy, in which aqueous chemistry is used to recover the metals. Several companies are developing systems that will use this combination, but the research team discovered that these companies use widely differing temperatures and times in their processes, and that there was a great need for a comparative study to determine the optimal thermal treatment and hydrometallurgical process for recycling lithium-ion batteries. A key finding of the research was that the hydrometallurgical process can be carried out at room temperature. This is something that has not been previously tested but could yield major benefits in the form of reduced environmental impacts and battery recycling costs. The process can also be carried out significantly quicker than previously thought. “Our research can make a huge difference for developers in this area. In some cases, it can be as much as reducing the temperature from between 60 and 80°C down to room temperature, and from several hours to just 30 minutes,” according to the team. The researchers also investigated how the different steps—thermal pretreatment and hydrometallurgy—are affected by each other. An important comparison was made between two different approaches to thermal pretreatment, incineration and pyrolysis. The latter is without oxygen and is considered more environmentally friendly, and the researchers determined that this produced the best results. www. ENER Y TRE DS Syrah Resources, Australia, is investing $176 million to expand its Syrah Technologies graphite processing facility located in Vidalia, La. The project adds 180,000 sq. ft. to the existing 50,000-sq.-ft. building, to support processing of natural graphite into active anode material (AAM) used in lithium-ion batteries for electric vehicles (EVs). The expansion follows an agreement with Tesla to supply natural graphite AAM for EV battery use. BRIEF Electric car lithium battery pack and power connections. Through DOE funding, more ways to recycle lithium-ion battery packs are on the horizon. LITHIUM-BATTERY INITIATIVE A national workforce development strategy for lithium-battery manufacturing was announced by the DOE and will be launched in coordination with the U.S. Department of Labor and the AFL-CIO. As part of a $5 million investment, DOE will support up to five pilot training programs in energy and automotive communities and advance workforce partnerships between industry and labor for the domestic lithium battery supply chain. The announcement follows DOE’s recent release of two notices of intent authorized by the Bipartisan Infrastructure Law to provide $3 billion to support projects that bolster domestic battery manufacturing and recycling. The funding, rolling out in the coming months, will support battery-materials refining, which will bolster domestic refining capacity of minerals such as lithium, as well as production plants, battery cell and pack manufacturing facilities, and recycling facilities.

1 4 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 *Member of ASM International DEVELOPING SUSTAINABLE COMPOSITES FOR AUTOMOTIVE APPLICATIONS Automotive manufacturers are making significant investments in the design and development of bioplastics and biocomposites-based components. S U S T A I N A B L E C O M P O S I T E S 1 Sabah Javaid and Surojit Gupta* University of North Dakota, Grand Forks

1 5 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 Fig. 1 — Different types of (a) bioplastics[2] and (b) fibers[5]. Fig. 2 — Plot of (a) density and (b) tensile strength of natural fibers. Lower limit is plotted from the reference. Data from Table 4, Ref. 6. (b) (a) (b) (a) Substituting biomass for fossil fuel-based precursors in plastics manufacturing holds promise for achieving certain sustainability goals[1]. It is estimated that manufacturing plastics from biogenic resources could reduce greenhouse gas emissions by up to 225%[2]. Further, plastics that feature end-of-life biodegradability have potential to alleviate some of the environmental issues stemming from plastics use[2]. More specifically, bioplastics have emerged as a promising solution. They can be classified into three main categories: (a) bio-based and nonbiodegradable, (b) bio-based and bio- degradable, and (c) petroleum-based and biodegradable (Fig. 1). Currently, global use of bioplastics is <1% of the annual plastics production of roughly 367 million tons. However, it is predicted that bioplastics production will increase from around 2.41 million tons in 2021 to approximately 7.59 million tons in 2026 (>2% of global plastics production)[3]. This article focuses on the potential of biomass and bioplastics in the automotive industry. NATURAL FIBERS Natural fibers such as bamboo, sisal, cotton, jute, kenaf, coir, industrial hemp, and banana have emerged as practical options for natural reinforcements in polymers[4]. Faruk et al. classify fibers according to the schematics in Fig. 1b[5]. Figure 2 shows density and tensile strength for several natural fibers[6]. The combination of low cost, high specific strength, low density, renewability, biodegradability, and good thermal properties make these fibers suitable for a variety of applications[7]. Regarding density, both flax and hemp are 40% lighter weight than glass fibers. Some disadvantages of natural fibers involve quality issues that are further compounded by weather, the hydrophilic nature of the fibers resulting in poor moisture resistance, low fire resistance, limitations on processing temperatures, residual smell, and price fluctuations due to harvesting variations[6,7]. Thus, manufacturers and end users must balance the advantages and disadvantages for large-scale use of these fibers. For example, high quality jute fibers are standardized as Tossa Grade D[7].

1 6 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 and biocomposites[17-19]. Henry Ford proposed the idea of using bio-based materials in the early 1930s[17]. These environmentally friendly materials enabled low emissions and lightweight car bodies, which spurred extensive research by Ford Motor Company. On August 13, 1941, at the annual Dearborn Days festival, the first car body made of soybean plastics was unveiled[17]. Soybean, hemp, wheat straw, flax, and ramie were claimed ingredients in the plastic panels, although the exact chemical composition is not available. Nevertheless, it was reported that the car body weight was just two thirds of a standard car of the time. Fig. 3 — Different types of biodegradable plastics[9]. Research into plastic cars was stalled by World War II and war recovery efforts[17]. However, in recent years, Bledzki et al. summarized that natural fibers blended with thermoplastics are well accepted in the automotive industry for use in door liners/panels, parcel shelves, and boot liners[7]. Some examples of fossil fuel-based thermoplastics include polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). Examples of fossil-fuel based thermosets include epoxy, polyester, and vinyl ester. Most of the major car manufacturers including Audi (spare tire lining), BMW (door and head liner panels), Ford (boot liner), Saab (door panels), and Volkswagen (boot lid) have integrated biofibers in their product lists (see Table 6, Ref. 7). By using natural fibers, it is possible to reduce vehicle weight by 34%[8]. As an external application, the 2018 Mercedes-Benz A-Class model uses a natural fiber mat coupled with a thermosetting bonding agent for a sliding sunroof, replacing the traditional sheet steel frame. In 2019, Porsche reported its 718 Cayman GT4 Clubsport as the world’s first car to have exterior parts made of hemp and flax natural fiber-reinforced composites[8]. From these examples, the automotive industry appears to be a pioneer in the design and implementation of sustainable solutions. However, to create a truly sustainable composite system, it is also critical to design a sustainable matrix that can bind the natural fibers. bioplastics[9]. They can be derived by chemical processing, fermentation, and chemical modification of natural products. Polylactic acid (PLA), polyhydroxyalkanoates (PHAs), soy-based resins, and thermoplastic starch are some examples of promising biodegradable bioplastics. PLA is a renewable biopolymer that can be produced from corn and sugarcane[10]. It is one of the most studied sustainable polymers due to its many advantages such as processability, good mechanical properties, biodegradability, and biocompatibility[11]. Brittleness and low toughness are some of its limitations[10]. PHA biopolymers are naturally produced from different microorganisms[12]. Biocompatibility, biodegradability, and a thermoplastic type nature are unique attributes of PHAs[13]. Soybean oil-based triglyceride monomers such as maleinized hydroxylated soybean oil (HSO/M), maleinized soybean oil monoglyceride (SOMG/MA), and acrylated epoxidized soybean oil (AESO) are major components of molding resin and exhibit comparable properties to conventional polymers[14]. Starch is one of the abundant plant-based renewable polysaccharides that is completely biodegradable[15]. For example, thermoplastic starch (TPS) has applications for short life use such as food packaging[16]. AUTOMOTIVE BIOCOMPOSITES: A SHORT HISTORY Figure 4 shows a timeline of automotive applications using bioplastics Porsche’s 2019 718 Cayman GT4 Clubsport is the world’s first car with exterior parts made of hemp and flax natural fiber- reinforced composites. Courtesy of Porsche. GREEN BIOPLASTICS Figure 3 summarizes different types of biodegradable and renewable The “Soybean Car” was unveiled by Henry Ford on August 13, 1941, at Dearborn Days. The steel frame had 14 plastic panels attached to it, made of soybeans, wheat, hemp, flax, ramie, and other ingredients, according to one source. Lowell E. Overly, the car’s chief creator, claims the formula was “…soybean fiber in a phenolic resin with formaldehyde used in the impregnation.” Courtesy of The Henry Ford.

1 7 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 2 costs four times as much as conventional plastics); poor durability; and lack of awareness regarding best practices for disposal[20,21]. From an engineering perspective, it is possible to control strength and durability by focusing on microstructure and a design that incorporates additives such as plasticizers, multicomponent blends, and impact modifiers. Figure 5 shows the schematics of different types of microstructures that can be CHALLENGES AND RECOMMENDATIONS Some critical challenges facing the use of bioplastics include the following: low heat resistance; low strength (for example, starch is a hydrophilic additive that can weaken hydrophobic polymers); confusion between compostability and biodegradability (not all biodegradable materials are compostable); high cost (for example, PHA several car companies have made significant investments in the design and development of bioplastics and biocomposites-based components (Fig. 4). In 2018, a group of researchers from Eindhoven University of Technology in the Netherlands designed a car completely made of biocomposites. The chassis was made of PLA and the car weighed just 360 kg (794 lb), roughly a quarter of the weight of a typical midsize car. Fig. 4 — Application timeline for automotive bioplastics[17-19].