OCTOBER 2022 | VOL 180 | NO 7 17 21 27 Vat Polymerization for Medical Applications Future of Digital Engineering Design SMST NewsWire Included in This Issue BINDER JET 3D PRINTING ADVANCES METAL INJECTIONMOLDING ADDITIVE MANUFACTURING P. 13
OCTOBER 2022 | VOL 180 | NO 7 17 21 27 Vat Polymerization for Medical Applications Future of Digital Engineering Design SMST NewsWire Included in This Issue BINDER JET 3D PRINTING ADVANCES METAL INJECTIONMOLDING ADDITIVE MANUFACTURING P. 13
The Volume includes articles on 3D printing and bioprinting of surgical models, surgical implants, and other medical devices: • The introductory section considers developments and trends in additively manufactured medical devices and material aspects of additively manufactured medical devices. • The polymer section considers vat polymerization and powder bed fusion of polymers. • The ceramics section contains articles on binder jet additive manufacturing and selective laser sintering of ceramics for medical applications. • The metals section includes articles on additive manufacturing of stainless steel, titanium alloy, and cobalt-chromium alloy biomedical devices. • The bioprinting section considers laser-induced forward transfer, piezoelectric jetting, microvalve jetting, plotting, pneumatic extrusion, and electrospinning of biomaterials. • Finally, the applications section includes articles on additive manufacturing of personalized surgical instruments, orthotics, dentures, crowns and bridges, implantable energy harvesting devices, and pharmaceuticals. Selected articles are now published digital-first in the ASM Digital Library at dl.asminternational.org in advance of the full volume release. ORDER TODAY! Visit asminternational.org/hbvol23a or call 800.336.5152. FORMATS: Print: $380$345 / ASM Member: $285$255 ISBN: 978-1-62708-390-4 Product Code: 06050G COMING SOON! ASM Digital Library: $97 / ASM Member: $75 EISBN: 978-1-62708-392-8 ASM Digital Library price is for one-year single user access. Pages: Approx. 450 PREPUBLICATION PRICING! ASM HANDBOOK, VOLUME 23A: ADDITIVE MANUFACTURING IN BIOMEDICAL APPLICATIONS VOLUME EDITOR: ROGER J. NARAYAN The new ASM Handbook Volume 23A provides a comprehensive review of established and emerging 3D printing and bioprinting approaches for biomedical applications, and expansive coverage of various feedstock materials for additive manufacturing. asminternational.org
2023 INTERNATIONAL MATERIALS, APPLICATIONS & TECHNOLOGIES OCTOBER 16–19, 2023 | HUNTINGTON PLACE | DETROIT, MICHIGAN REGISTRATION OPENS SPRING 2023 asminternational.org/web/imat-2023 • Additive Manufacturing • Archaeometallurgy and Ancient Metalworking • Characterization of Materials andMicrostructure through Metallography, Image Analysis, andMechanical Testing: Fundamental and Applied Studies • Corrosion and Environmental Degradation • Emerging Technologies • Failure Analysis • Functional Materials and Structures: Solving Barriers to Adoption • Joining of Advance and Specialty Materials (JASM XXII) • Light Metal Technology • Materials4.0:Materials Information intheProductLifeCycle • Materials Behavior & Characterization • Materials for Energy & Utilities • Medical / Biomaterials: Driving for DeliveredPatient Value • Materials & Processes for Automation • Metals, Ceramics, and Composite Materials: RawMaterials, Processing, Manufacturing Methods, Applications, Environmental E ects • Phase Stability and Di usion Kinetics (PSDK XV) • Processing and Applications • Sustainable Materials & Processes ABSTRACTS ARE SOLICITED IN THE FOLLOWING TOPIC AREAS: ADVANCED MATERIALS AND MANUFACTURING TECHNOLOGIES SUBMIT YOUR ABSTRACT TODAY! SUBMISSION DEADLINE: FEBRUARY 24, 2023 IMAT 2023 CALL FOR ABSTRACTS IS OPEN CALL FOR ABSTRACTS ORGANIZED BY: PARTNERED WITH: CO-LOCATED WITH:
44 ASM NEWS The latest news about ASM members, chapters, events, awards, conferences, affiliates, and other Society activities. USING BINDER JET 3D METAL PRINTING TO ADVANCE METAL INJECTION MOLDING Donald F. Heaney and Nicholas Eidem Binder jet 3D metal printing is the ultimate bridge between prototypes and production of metal injection molded parts. 13 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 | O C T O B E R 2 0 2 2 2 Metal injection molding set up. Courtesy of Advanced Powder Products Inc. On the Cover: 56 3D PRINTSHOP Wooden sheets that change shape after drying and carbon-fiber-reinforced thermoset composites that solidify as they print. 12 NANOTECHNOLOGY Researchers are converting fish waste into useful carbon-based nanomaterials and using nanolattices to dissipate energy.
4 Editorial 5 Research Tracks 6 Machine Learning 7 Emerging Technology 8 Metals/Polymers/Ceramics 10 Testing/Characterization 12 Nanotechnology 55 Editorial Preview 55 Special Advertising Section 55 Advertisers Index 56 3D PrintShop TRENDS INDUSTRY NEWS DEPARTMENTS Check out the Digital Edition online at asminternational.org/news/magazines/am-p 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. 7, OCTOBER 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. 17 ADDITIVE MANUFACTURING: VAT POLYMERIZATION FOR MEDICAL APPLICATIONS Hideyuki Kanematsu, Dana M. Barry, Rafiqul Noorani, and Paul McGrath Vat polymerization uses ultraviolet light to harden liquid photosensitive resins into medical products such as surgical models and artificial limbs. 21 TECHNICAL SPOTLIGHT THE FUTURE OF DIGITAL ENGINEERING DESIGN: DISCOVERING OPTIMUM DESIGNS FASTER Multidisciplinary optimization techniques provide a novel method for rapid product development that also meets sustainability goals. 24 DINING METALLURGY 101 Quentin R. Skrabec, Jr. This introduction to the metallurgy of flatware describes the grades and qualities of metals used in typical cutlery and the reasons to choose one set over another. FEATURES OCTOBER 2022 | VOL 180 | NO 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 | O C T O B E R 2 0 2 2 3 17 27 24 21 27 SMST NEWSWIRE The official newsletter of the International Organization on Shape Memory and Superelastic Technologies (SMST). This biannual supplement covers shape memory and superelastic technologies for biomedical, actuator applications, and emerging markets, along with SMST news and initiatives.
4 New Orleans was a fitting location for this year’s IMAT conference and exposition. Everything about the Crescent City—named for its shape as it hugs the Mississippi River—beckons to transport you beyond the mundane. Your senses are enlivened by old world steamboats, colorful horse-drawn buggies and clanging trolleys, wrought iron balconies wrapped in climbing flowers, Dixieland sounds at every turn, and mouthwatering gumbo with locally reeled seafood. The city naturally awakens the senses. But perceptions were heightened for other reasons too. For many attendees and exhibitors, IMAT 2022 was the first attempt at convening since 2019. Everything seemed enhanced. The greeting of old colleagues was warmer. The meeting of new ones was richer. And the celebrations were grander, with the new ASM Fellows Induction Ceremony and the Annual Awards Dinner each recognizing three years’ worth of honorees. Throughout the event, the benefits of in-person networking—so long on hiatus— were obvious. Business was conducted, introductions made, emails exchanged, talks applauded, and stories and laughter were heard. The ASM family was together again. One particularly interesting keynote talk was given by Dr. Kathryn Beers of NIST’s Circular Economy Program. She provided several definitions of the circular economy. One by the Ellen MacArthur Foundation posits that we need to “transform the throwaway economy into one where waste is eliminated, resources are circulated, and nature is regenerated.” To that end, NIST has established the following three pillars as their priority areas: materials science and design, data and precision tools, and environmental impact assessment. Beers directed us to the nist.gov website, which is teeming with free reports related to the three pillars. Her most quotable statement on recycling: “Tires are a bigger problem than teabags.” Continuing with this IMAT conference theme, an inaugural Affiliate Society panel on the circular materials economy was well attended on the show floor. While chaired by Prof. Christopher Berndt, FASM, TSS-HoF, a representative from each of ASM’s affiliates discussed sustainability through their industry’s unique lens. The talks sparked a lively Q&A with the audience. Likewise, a panel session on “Advanced Manufacturing: Progress and Opportunities,” expertly moderated by William E. Frazier, FASM, will be summarized in a future issue of AM&P. A sneak preview is that Industry 4.0 marks a new era of innovation in materials processing. Among the many tools at our disposal are data and analytics as well as additive manufacturing (AM), the focus of this issue. If traditional subtractive manufacturing is classical music, then perhaps additive manufacturing is jazz. Read this issue to see how AM has given the world a new construct: a breaking of the mold and reinventing with endless possibilities. And perhaps that’s what our reunion at IMAT in New Orleans did for us as well. The ASM family was together again but in a vibrant and reimagined way. joanne.miller@asminternational.org 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 | O C T O B E R 2 0 2 2 ASM International 9639 Kinsman Road, Materials Park, OH 44073 Tel: 440.338.5151 • Fax: 440.338.4634 Joanne Miller, Editor joanne.miller@asminternational.org Victoria Burt, Managing Editor vicki.burt@asminternational.org Frances Richards and Corinne Richards Contributing Editors Jan Nejedlik, Layout and Design Allison Freeman, Production Manager allie.freeman@asminternational.org Press Release Editor magazines@asminternational.org 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 Bhargavi Mummareddy, Youngstown State University Scott Olig, U.S. Naval Research Lab Christian Paglia, SUPSI Institute of Materials and Construction 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 David B. Williams, President and Chair Pradeep Goyal, Senior Vice President Navin Manjooran, Vice President Judith A. Todd, Immediate Past President John C. Kuli, Treasurer Burak Akyuz Amber Black Ann Bolcavage Pierpaolo Carlone Elizabeth Ho man Toni Marechaux André McDonald U. Kamachi Mudali James E. Saal Sandra W. Robert, Executive Director STUDENT BOARDMEMBERS Jaime Berez, Ashlie Hamilton, Nicole Hudak 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. ASM’S JAZZ ERA ASM awardees gather while enjoying a lively brass band.
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 | O C T O B E R 2 0 2 2 5 ALGORITHM FIXES 3D PRINTING ERRORS Engineers at the University of Cambridge, U.K., developed a machine learning algorithm that can find and fix a wide range of different 3D printing errors in real time, and can be easily added to new or existing machines to enhance their capabilities. 3D printers using the algorithm could also learn how to print new materials by themselves. Researchers have been working on automated 3D printing monitoring, but existing systems can only detect a limited range of errors in one part, one material, and one printing system. The Cambridge team trained a deep learning computer vision model by showing it nearly one million images captured automatically during the production of 192 printed objects. Each image was labeled with the printer’s settings, such as the speed and temperature of the printing nozzle and flow rate of the printing material. The model also received information about how far those settings were from good values, enabling the algorithm to learn how errors arise. Using this approach, the team was able to build an algorithm that is generalizable and can be applied to identify and correct errors RESEARCH TRACKS in unfamiliar objects or materials, or even in new printing systems. In the future, the trained algorithm could be more efficient and reliable than a human operator at spotting errors, say researchers. With the support of Cambridge Enterprise, the university’s commercialization department, researcher Douglas Brion formed Matta, a spin-off company that will develop the technology for commercial applications. www.matta.ai. INSIGHT INTO DISORDERED MATERIALS Researchers at the National University of Singapore (NUS) developed a human-explainable machine learning system that quickly identifies previously unseen novel structures in disordered materials without help from humans. The team created a machine learning framework that can learn the universal vocabulary and grammar used to describe disordered systems. Using this framework, they discovered that a wide range of disordered materials can be logically decomposed into recurring motifs and related compositional rules. These motifs are the building blocks Example image of the 3D printer nozzle used by the machine learning algorithm to detect and correct errors in real time. Courtesy of Douglas Brion. that can vastly simplify how to understand and classify complex disorders in real materials. The scientists used a sequence of mathematical expressions known as Zernike polynomials to quantify the subtle structural and chemical features within atomic arrangements. These special mathematical expressions can effectively model the features despite different atomic orientations. To overcome the limited signal fromeach atom, the team generalized a single-particle imaging approach that automatically reveals distinct building blocks (i.e., motifs) within disordered materials. Having learned the motifs from tens of thousands of atoms in an automated manner, the team could now discover how these motifs self-assemble into complex but disordered hierarchies. They found that some disordered materials can be described by just a handful of motifs, yet these few motifs create diverse structures due to complex motif-motif hierarchies. Other materials start with a continuous range of motifs, thereby blurring the boundaries between their motifs and hierarchies. The team hopes to turn this framework into a companion artificial intelligence application for microscopes to rapidly make sense of disordered materials. www.science.nus.edu.sg. Fundamental pentagonal motifs follow a three-level hierarchy to form increasingly complex larger motifs. Courtesy of Science Advances.
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 | O C T O B E R 2 0 2 2 6 MACHINE LEARNING | AI MODEL PREDICTS PROMISING HEA ALLOYS Researchers at Texas A&M University, College Station, working with colleagues at the DOE’s Ames National Laboratory, Iowa, developed an artificial intelligence (AI) framework capable of predicting high-entropy alloys (HEAs) that can withstand extremely high temperature, oxidizing environments— such as those found in gas turbines used for power generation and aircraft propulsion. The method could significantly reduce the time and cost of finding new alloys by decreasing the number of experimental analyses required. “The next step of revolutionizing turbine technology is to change the material that is used to fabricate components, such as the blades, so that they can operate at higher temperatures without oxidizing catastrophically,” says Professor Raymundo Arroyave, FASM. When looking at different types of alloys for turbines, there is significant attention around HEAs. One unique characteristic of these alloys is that they become more stable at higher temperatures, offering the potential for use in extreme environments. The A&M team developed an AI framework capable of predicting the oxidation behavior of HEAs. The model combines computational thermo d y n am i c s , machine learning, and quantum mechanics to predict the oxidation of HEAs made of arbitrary chemical compositions— in minutes instead of years. Using the framework, the scientists predicted the oxidation behavior of multiple alloy compositions. They sent these predictions to the Ames team to test their findings and verify that the framework accurately demonstrates if an alloy would or would not resist oxidation. “This tool will help screen out alloys that will not work for our application needs while allowing us to spend more time and create a more detailed analysis of alloys that are worth investigating,” says Arroyave. tamu.edu. COLOR-CODED X-RAY DATA Along with several universities, the DOE’s Argonne National Laboratory, Lemont, Ill., developed a method for creating color-coded graphs of large volumes of data from x-ray diffraction (XRD). The team believes this could greatly accelerate future research on structural changes on the atomic scale induced by varying temperature. “What might have taken us months in the past now takes about a quarter hour, with much more fine-grained results,” says Argonne physicist Raymond Osborn. The team calls their new method “x-ray temperature clustering,” or XTEC, and it draws on unsupervised machine learning using methods developed at Cornell University. This type of machine learning does not depend on initial training with data already well studied. Instead, it learns by finding patterns and clusters in large data sets without such lessons. These patterns are then represented by color coding. As a test case, XTEC analyzed data from beamline 6-ID-D at the Advanced Photon Source, taken from two crystalline materials that are superconducting at temperatures close to absolute zero. By applying XTEC, the team extracted an extraordinary amount of information about changes in atomic structure at different temperatures. “Because of machine learning, we are able to see material behavior not visible by conventional XRD,” says Osborn. “And our method is applicable to many big data problems in not only superconductors, but also batteries, solar cells, and any temperature-sensitive device.” anl.gov. Scientists recently developed a framework capable of predicting the oxidation of high-entropy alloys that could be used in gas turbines. Courtesy of Texas A&M Engineering. Machine learning provides a colorcoded map of x-ray data based on the temperature dependence of each region. Courtesy of PNAS.org. https://doi. org/10.1073/pnas.2109665119.
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 | O C T O B E R 2 0 2 2 7 NEW MATERIAL THINKS FOR ITSELF Researchers from Penn State and the U.S. Air Force are developing engineered materials that can think, similar to how humans respond to touch. The work relies on a novel, reconfigurable alternative to integrated circuits. According to lead researcher Ryan Harne, his team’s discovery revealed the opportunity for nearly any material to act like its own integrated circuit—being able to “think” about what’s happening around it. “We have created the first example of an engineering material that can simultaneously sense, think, and act upon mechanical stress without requiring additional circuits to process such signals,” Harne says. “The soft polymer material acts like a brain that can receive digital strings of information that are then processed, resulting in new sequences of digital information that can control reactions.” The conductive mechanical material contains reconfigurable circuits that can realize combinational logic—when the material receives external stimuli, it translates the input into electrical information that is then processed to create output signals. The team demonstrated how the material could use mechanical force to compute complex arithmetic or to detect radio frequencies to communicate specific light signals, among other potential translation examples. According to the researchers, the possibilities are expansive, because integrated circuits can be programmed to do so much. Harne says the material has potential applications in autonomous search-and-rescue systems, infrastructure repairs, and even in bio-hybrid materials that can identify, isolate, and neutralize airborne pathogens. The researchers are now evolving the material to process visual information like it does physical signals. psu.edu. PHOTOVOLTAIC BATTERIES FOR WEARABLES Researchers from the University of Surrey, U.K., developed a renewable and rechargeable battery prototype that could boost the battery life of wearable electronics by tens of minutes with just 30 seconds EMERGING TECHNOLOGY Researchers at Queen’s University Belfast, U.K., developed a degradable plastic film that destroys viruses that land on its surface with ordinary room light. The self-sterilizing film is low cost, can be easily scaled, and could be used in hospitals and food production facilities. The film is coated with a thin layer of particles that absorb UV light and produce reactive oxygen species to kill viruses. www.qub.ac.uk. BRIEF of sunlight exposure. The research team demonstrated how its new photo-rechargeable system, which merges zincion batteries with perovskite solar cells, could allow wearables like smartwatches to spring back to life without plug-in charging. The technology provides a promising strategy for efficient use of clean energy, the team says, and their prototype could represent a step forward to how we interact with wearables and other internet-of-things devices, such as remote real-time health monitors. The researchers’ ultrafast photo-rechargeable system is unique because of the elegant and well-matched structural design between its integrated battery and solar cell, allowing it to demonstrate high energy and volume density comparable to state-of-the-art micro-batteries and super capacitors. In addition to wearables, says the team, the battery could have applications in autonomous power systems and emergency electronics. www.surrey.ac.uk. Novel mechanical integrated circuit materials made from conductive and non-conductive rubber materials sense and react to how forces are applied to them. Courtesy of Charles El Helou/Penn State. Graphical depiction of the device. Courtesy of Energy Storage Materials, 2022, DOI: 10.1016/ j.ensm.2022.06.043.
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 | O C T O B E R 2 0 2 2 8 METALS | POLYMERS | CERAMICS Constellium, Paris, will supply aluminum auto body sheet products for the Mercedes-Benz C-Class produced in Europe, China, and South Africa and sold globally. Constellium will provide aluminum for the hood, roof, tailgate, and fenders of the C-Class from its ASI-certified plant in Neuf-Brisach, France. constellium.com. The DOE’s Oak Ridge National Laboratory, Tenn., was selected to lead an Energy Frontier Research Center focused on polymer electrolytes for nextgeneration energy storage devices such as fuel cells and solid-state electric vehicle batteries. The award will provide $11.5 million over four years. ornl.gov. Solar Atmospheres Inc., Hermitage, Pa., acquired Vac-Met Inc., Warren, Mich. Over the past four decades, Vac-Met developed a strong heat treating business throughout the Midwest. The addition of Vac-Met brings Solar’s commercial vacuum heat treating and brazing facilities to a total of five plants across the country. solaratm.com. BRIEFS magnetic materials (SMMs). According to the team, which includes scientists from the Max Planck Institute for Iron Research (MPIE) and the Technical University of Darmstadt, both in Germany, along with China’s Central South University, the new work paves the way for advanced applications like high-speed motors. Currently employed SMMs are prone to damage under severe mechanical loads. According to the team, introducing nanoparticles into SMMs pins the movement of the domain walls and decreases the magnetizing force. The scientists discovered that the size of the nanoparticles plays a crucial role for both the mechanical strength and ductility of the magnets and their magnetism. The team demonstrated their design concept in a multicomponent alloy system containing iron, nickel, cobalt, tantalum, and aluminum with multifunctional properties. Materials based Mechanochromic and self-healing coatings on diverse substrates. Courtesy of Korea Institute of Science and Technology. SELF-HEALING COATINGS REPORT DAMAGE Researchers at the Korea Institute of Science and Technology, Seoul, developed a new polymeric coating that is self-healing and reports area-specific damage by changing color. In addition, the team’s thermoset polymer can recover its original chemical structure after being disrupted by an external stimulus, thus allowing this material to self-report damage and self-heal multiple times. To make the material, the researchers synthesized a mechanochromic molecule and a thermoset polymer containing a molecule that can be separated and re-formed by temperature. The research team used molecular dynamics simulations to predict and confirm that only certain desired chemical bonds are selectively cleaved when a mechanical force is applied to yield a colored structure. When implemented, the damaged part of the synthesized polymeric coating exhibited purple. When a temperature of 100°C or higher was applied, the material became colorless, processable, and physically healed. The novel multifunctional polymeric coating can be extensively used in automotive, marine, defense, timber, railway, highway, and aerospace industries, and can significantly contribute toward the reduction of industrial waste. In addition, the researchers say, the material can be used as artificial skin for robots, since its functionality is similar to that of skin and doesn’t require an external energy source. www.kist. re.kr/eng. STRONGER SOFT MAGNETIC MATERIALS An international research team created a new design strategy to increase the lifetime of soft So magnetic materials can be made more ductile and stronger through nanoparticles. Courtesy of Tianyi You/Max-Planck-Institut für Eisenforschung GmbH.
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 | O C T O B E R 2 0 2 2 9 on the new alloy system are easier to manufacture and have a higher lifetime than the conventional magnetic materials. The concept of using these alloys is not limited to SMMs but is also applicable for developing advanced alloys with new and unusual combinations of functional andmechanical properties. www. mpie.de/2281/en, www.tu-darmstadt.de/ index.en.jsp, en.csu.edu.cn. ISOLATING RARE-EARTH METALS A research team at the University of Tokyo and the Institute for Molecular Science, Japan, developed a method to isolate the hydrated forms of trivalent ions in a series of rare-earth metals in closed cages. Each cage molecule consists of four organic ligands shaped like triangular plates that are connected by their tips to six palladium ions to make an octahedral cage with two large openings. The rare-earth-metal ion fits into the cage with its nine bound water molecules. The critical feature of the cage are its two caps that cover the openings. These are planar molecules with three negatively charged binding arms that bind to the rare-earth-metal ion’s water molecules through hydrogen bridges. In addition, they are held tight by electrostatic interactions with the positively charged palladium ions in the cage. Not all rare-earth-metal ions are captured equally well by this system. Subtle differences in their radii and preferred modes of hydration determine howwell they fit into the cages. Confinement of hydrophilic metal species in a closed cavity could be an approach for the isolation of rare-earth metals as well as for the development of novel catalysts analogous to metal-containing Graphical depiction of the encapsulation of a hydrated rare-earth-metal ion in a hydrophobic cavity of a synthetic cage. Courtesy of Wiley. enzymes in microorganisms. www.u- tokyo.ac.jp/en/, www.ims.ac.jp/en.
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 | O C T O B E R 2 0 2 2 they call 3DTIPs. The new 3DTIPs, which are manufactured using a single-step 3D printing process, can be utilized for a wider variety of applications—and potential observations and discoveries—than standard, more limited silicon-based probes that are presently considered state-of-the-art. The researchers demonstrated their proprietary technology for producing next-generation AFM probes based on two-photon polymerization 3D printing. The resulting 3DTIPs are softer than their silicon-based counterparts, making them more suitable for AFM applications involving gentler interactions with cells, proteins, and DNA molecules. Importantly, the material properties of 3DTIPs make it possible to achieve scans that are more than 100 times faster than regular silicon probes of similar dimensions. Therefore, 3DTIPs might open the door for acquiring videos that capture bioactivities of proteins, DNA, and even smaller molecules in real time. “We have developed a novel technology for next-generation AFM probes with new materials, improved designs and production processes, novel shapes in 3D, and customized prototyping for a seamless production cycle for application-focused AFM probes,” says lead researcher Mohammad Qasaimeh. “The ability to generate customized AFM probes with innovative 3D designs in a single step provides endless multidisciplinary research opportunities.” TESTING | CHARACTERIZATION ATOMIC-LEVEL TRANSFORMATIONS Scientists at Binghamton University, N.Y., are using transmission electron microscopy (TEM) to examine oxide-to-metal transformation at the atomic level. They’re especially interested in the mismatch dislocations that are ever-present at the interfaces in multiphase materials and play a key role in dictating structural and functional properties. In the new work, researchers used their advancedmethod to test the transformation of copper oxide to copper. By using environmental TEM techniques capable of introducing hydrogen gas into the microscope to drive the oxide reduction while simultaneously performing TEM imaging, the research team was able to atomically monitor the interfacial reaction. Notably, they observed that the transformation from copper oxide to copper occurs in an intermittent manner because it is temporarily stopped by mismatch dislocations. A back-andforth process between experiments and computer modeling helped researchers understand howmisfit dislocations control the long-range transport of atoms needed for the phase transformation. This fundamental information could prove useful in designing new types of multiphase materials and controlling their microstructure, which can be used in diverse applications such as load-bearing structural mater- ials, electronic fabrication, and catalytic reactions for clean energy production and environmental sustainability. binghamton.edu. 3D ATOMIC FORCE MICROSCOPY PROBES A research team out of NYU Abu Dhabi created new atomic force microscopy (AFM) probes in true 3D shapes Based on new experiments on lanthanum superhydride with impurities, researchers at Skoltech, Russia, along with a team of international scientists, established the mechanism behind the highest-temperature superconductivity in polyhydrides observed to date. The discovery could lead to development of materials that conduct electricity with zero resistance at or close to room temperature. www.skoltech.ru/en. Park Systems Corp., Korea, acquired Accurion GmbH, Germany, a manufacturer of imaging spectroscopic ellipsometers and active vibration isolation products. The acquisition adds to Park’s portfolio of atomic force microscopy and white-light interferometric microscopy. parksystems.com. BRIEFS Guangwen Zhou, professor of mechanical engineering at the Watson School of Engineering and Applied Sciences, led the copper study. Courtesy of Jonathan Cohen.
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 | O C T O B E R 2 0 2 2 1 1 The researchers hope that themultifunctional capabilities of the 3DTIPs could bring next-generation AFM tips to routine and advanced AFM applications and expand the fields of high-speed AFM imaging and biological force measurements. nyu.edu. USING SOUND TO TRANSFORM OBJECTS At Tokyo Metropolitan University, researchers successfully used sound wave technology to lift small particles. Their “acoustic tweezers” could already lift things from reflective surfaces without physical contact, but stability remained an issue. Now, using an adaptive algorithm to fine-tune how the tweezers are controlled, they have drastically improved how stably the particles can be lifted. With further miniaturization, this technology could be deployed in a vast range of environments, including space. There are two modes in which the transducers can be driven, where opposing halves of their hemispherical array are propelled in and out of phase. The team’s new insight is that different modes are more suited to doing certain things. Starting with a particle on a surface, an “in-phase” excitation mode is better at lifting and moving the particle close to the surface, with accurate targeting of individual particles only a centimeter apart. Meanwhile, an “out-of-phase” mode is more suited to bringing the lifted particle into the center of the array. Thus, using an adaptive switching between the modes, they can now leverage the best of both modes and achieve a well-controlled and stable lift, as well as more stability inside the trap once it is lifted. This is an important step forward for a futuristic technology that could one day be deployed to manipulate samples that need to be kept strictly contamination free. The team also hopes to find practical applications in space, where competing against gravity is not an issue. www.tmu.ac.jp/english. Photographs highlighting the picking up of a particle from a rigid stage: (a) successfully picking up; (b) upward motion; and (c) successfully maintaining the particle.
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 | O C T O B E R 2 0 2 2 1 2 NANOTECHNOLOGY NANOLATTICES THAT DISSIPATE ENERGY A new material property of 3D nanostructures was discovered for the first time by scientists from the University of Texas at Austin and North Carolina State University, Raleigh. Until now, the unique property—anelasticity, or how materials react to stress over time—had only been found in simple nanostructures like nanowires. In addition to the discovery, the research team also uncovered the internal mechanics of the materials that make this property possible. Researchers studied the anelastic phenomenon by observing how oxide-based nanolattices reacted to bending. The tiny defects moved slowly in response to the stress gradient. When the stress was released, the tiny defects slowly returned to their initial positions, resulting in the anelastic behavior. The researchers also found that when these defects move back and forth, they unlock energy dissipation characteristics. The material could potentially serve as a shock absorber, but because it’s so thin and lightweight, it would be on a very small scale. The researchers say it could have applications in chips for electronics or other integrated electronic devices. Now that they have discovered these anelastic characteristics, further work will focus on how to manipulate them for specific uses. The researchers will examine the geometry of the nanostructures and experiment with different loading conditions to determine how they can optimize the anelastic performance for energy dissipation applications. utexas.edu, ncsu.edu. NANOMATERIAL MADE FROM FISH WASTE Using a simple and convenient method, a research team at Nagoya Institute of Technology in Japan created carbon nano-onions (CNOs) from fish waste. To do this, the team developed a synthesis route in which fish scales extracted from fish waste after cleaning are converted into CNOs in mere seconds through microwave pyrolysis. The novel approach is groundbreaking as it requires no complex catalysts, harsh conditions, or prolonged production. Moreover, this synthesis process yields CNOs with very high crystallinity—a property that’s difficult to achieve in processes that use biomass waste as a starting material. Additionally, during synthesis, the surface of the CNOs is selectively and thoroughly functionalized with carboxylic acid and hydroxyl groups. This is in stark contrast to the surface of CNOs prepared with conventional methods, which is typically bare Nanolattices are tiny, hollowmaterials similar in structure to sea sponges. and must be functionalized through additional steps. Yet another advantage associated with automatic functionalization and high crystallinity is that of exceptional optical properties. To showcase some of the many practical applications of the CNOs, the team demonstrated their use in LEDs and blue light-emitting thin films. The CNOs produced a highly stable emission, both inside solid devices and when dispersed in various solvents, including water, ethanol, and isopropanol. Furthermore, the proposed synthesis technique is environmentally friendly and provides a straightforward way to convert fish waste into infinitely more useful materials. The work may help fulfill several of the UN’s sustainable development goals. Additionally, if CNOs make their way into next-generation LED lighting and QLED displays, they could significantly reduce manufacturing costs. www.nitech.ac.jp/eng. Triangular holes make this material more likely to crack from le to right. Courtesy of N.R. Brodnik et al./Phys. Rev. Lett. Researchers at the University of California, Riverside demonstrated a new magnetized state in a monolayer of tungsten ditelluride. Called a ferromagnetic quantum spin Hall insulator, this one-atom-thick material has an insulating interior but a conducting edge, which has important implications for controlling electron flow in nanodevices. ucr.edu. BRIEF A synthesis procedure developed by NITech scientists can convert fish scales obtained from fish waste into a useful carbon-based nanomaterial. Courtesy of Takashi Shirai.
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 | O C T O B E R 2 0 2 2 *Member of ASM International USING BINDER JET 3D METAL PRINTING TO ADVANCE METAL INJECTION MOLDING Binder jet 3D metal printing is the ultimate bridge between prototypes and production of metal injection molded parts. Donald F. Heaney, FASM* and Nicholas Eidem Advanced Powder Products Inc. Philipsburg, Pennsylvania B I N D E R J E T A M P R O C E S S 1
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 | O C T O B E R 2 0 2 2 Aligning manufacturing supply chains to meet critical product development milestones is crucial to launching new products on time and on budget. With this result in mind, engineering and supply chain leaders need to be able to iterate through designs to optimize manufacturability and ensure their device or assembly performs as intended. This is especially true when it comes to sourcing small and complex metal components, which can be difficult to produce and hard to scale. Metal injection molding (MIM) has been widely adopted by a variety of industries. MIM manufacturing is positioned to produce medium to high-volume components through the efficiency of dedicated tooling. MIM is a cost-effective alternative to machined components due to its mechanical performance, dimensional stability, scalability, and cost competitiveness. While MIM is optimized for high-volume production, qualifying a MIM component can cost tens of thousands of dollars and take three to six months. This development time is often a major roadblock for design engineers who need to test components in weeks rather than months. The traditional solution is to do what has been done in the past—source machined prototypes. However, this approach does not optimize for high-volume MIM production and can lead to even more challenges down the road when converting from a high-cost machined component to a MIM component. Binder jet 3D metal printing is an additive manufacturing (AM) process that can be used to rapidly produce prototype components, allowing engineers to test their designs quicker than ever before. The MIM process and the binder jet 3D metal printing process share many similarities and complement each other as component manufacturing technologies. In this article, the technologies are discussed together. The purpose is to understand where each one fits, and how one technology can assist to accelerate adoption of the other. Topics discussed include powder types, distortion during sintering, unique capabilities of each method, process development acceleration, and shared capital equipment. Each process is described below. Metal injection molding: Metal injection molding (MIM) is a manufacturing process that combines the most useful characteristics of powder metallurgy and plastic injection molding to facilitate production of small, complex-shaped metal components with outstanding mechanical properties. As a general rule, MIM parts weigh less than 100 grams, feature complex geometries and tight tolerances, and can fit in the palm of a hand. The MIM process begins by mixing a combination of 5-to-25-μm metal powder with polymers to form a feedstock (Fig. 1). This feedstock is then molded into an oversized, geometry-specific tool at high temperatures (120°-250°C) and high pressures. The as-molded geometry is considered “green”—metal powders held together with polymers. The polymer is then removed using either a solvent or an oven incorporating a gas/solid reaction. The geometry is then placed in a furnace with support ceramic. The remaining polymers are removed, and the geometry is sintered and densified into final dimensions at temperatures as high as 1300°-1400°C depending on the alloy. The geometry can then be treated like a piece of solid metal: It can be worked, heat treated, and surface finished. Binder jet 3D metal printing: Metal 3D printing is an advanced AM technology that uses powdered metals to build a 3D component by applying evenly distributed layers. The approach of building a part layer-by-layer gives designers ultimate flexibility because they are not reliant upon machining or tooling to form complicated geometries. The binder jet process starts by vibrating a 10-to-20-μm metal powder—identical to the powder used in MIM feedstock formulation—onto a build platform. This layer of powder is “glued” together with an inkjet head that feeds a binder in a controlled 2D pattern. The bed of powder is lowered by 50-100 μm and a successive layer of powder is vibrated and spread onto the bed of powder, and then glued together. This is repeated until the geometry is built from successive layers (Fig. 2). A 1-cm-high part would consist of 100 to 200 layers of powder that are glued together. This glued part is then removed from the powder bed and the term “green” is used to describe its Fig. 1 — In the metal injection molding process, metal powder is mixed with polymers to form a feedstock, which is then molded into an oversized part and then further treated to achieve final dimensions.
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 | O C T O B E R 2 0 2 2 PROCESS COMPARISON Binder jet 3D printing does not rely on custom tooling, so 3D-printed part prototypes can be produced rapidly and delivered in days rather than months. This freedom from tooling along with rapid delivery enables engineers to test much sooner with functional MIM components. Further, powder sharing enables the binder jetting process to take advantage of the bulk buying power of the MIM operation to reduce material costs. Baseline properties and downstream processes are already defined and stable. In addition, the MIM sintering profiles and infrastructure are in place to eliminate capital investment and development costs. Table 1 outlines the comparison in process and component properties. ALLOY PROPERTY COMPARISON 17-4 PH stainless steel is one of the commonly used alloys in both metal injection molding and binder jet 3D printing. In terms of mechanical properties, MIM and binder jet 3D-printed components can achieve comparable densities that exceed the MPIF Standard 35 density for 17-4 PH stainless steel of 7.5 g/cc. In a comparison done by Advanced Powder Products Inc. (APP), Philipsburg, Pa., the mechanical properties of MIM and binder jet 3D-printed components made from 17-4 PH stainless steel and heat treated to H900 were tested. With identical sintering processes, it was empirically proven that APP’s binder jet 3D-printed parts, under the trade name Printalloy, meets the chemical, mechanical strength, and yield point for MIM 17-4 PH per MPIF Standard 35, outlined in Table 2. DIMENSIONAL CAPABILITY Metal injection molded components offer highly precise and repeatable tolerances yet are slightly inferior to machined components. The general rule for MIM production capability is +/- 0.5% of the dimension to obtain a Cp greater than 1.33. This is due to the 20% shrinkage a MIM part experiences during sintering and needs to be factored in when designing for MIM. state. The green part is then ready to be placed in a furnace with support ceramic. The glue is removed thermally, and the geometry is sintered, shrinks, and densifies into final dimensions at temperatures as high as 1300°-1400°C depending on the alloy. Like its MIM counterpart, the 3D-printed geometry can then be treated similarly to that of a solid piece of metal: It can be worked, heat treated, and surface finished. MIM PROCESS DEVELOPMENT Because the binder jet process can use the same powder and sintering profile as MIM, the opportunity exists to perform sintering and secondary process development while the MIM tool is being built. Tooling may take six to 14 weeks to be designed and built. Printed parts can be fabricated immediately, and downstream processes developed and evaluated. In this way, knowledge of how the part should be fixtured during sintering can be explored in parallel to the tool build. Insight into how the part may warp or distort during the MIM process can be gained at this time. Printed components are available for test builds and the downstream processes can be defined with fixturing, methods, and work instructions in place while waiting for the MIM components to be fabricated. In some cases, the printed components may prompt a design change of the MIM process to aid in manufacturability, such as incorpor- ating a flat surface to prevent distortion. Fig. 2 — Schematic of binder jetting process. TABLE 1 — PROCESS COMPARISON Binder jet 3D printing Metal injection molding Investment $0 $25,000+ Lead time Days Weeks Powder 10-20 μm 5-25 μm Binder Dryable liquid Meltable polymer Shape forming Layer by layer (50-100 μm) Injection into custommold Debind No Solvent or gas phase Thermal debind and sintering Same Same Machinability Same Same Heat treat response Same Same
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 | O C T O B E R 2 0 2 2 wall approximately four times higher than its MIM counterpart. On average, the vertical “layered” wall will have a surface roughness of 125 Ra while the “flat” wall will have a surface roughness of 70 Ra. As with MIM, surface treatments can improve the finish of binder jet 3D-printed components. ALLOY DEVELOPMENT Binder jet 3D printing development has accelerated during the past few years. With strong interest in the technology, various research and com- mercial groups are evaluating a wide range of alloys. These alloys are typically produced by gas atomization, which is also used to produce MIM powders. The alloys must be processed in the same sintering equipment as MIM alloys. Thus, if the alloy can be processed by binder jet 3D printing, it can be metal injection molded. 3D printing can be used as a test environment for alloy development that will help grow the MIM industry and lower the price of raw materials. BRIDGING THE DEVELOPMENT GAP Binder jetting is a natural extension of metal injection molding as both processes use many of the same materials and equipment. Binder jet 3D metal printing is the ultimate bridge between prototype and production MIM parts. Metal 3D printing affords speed and design flexibility at a fraction of the cost of MIM, and can save thousands of dollars in tooling costs when bringing any complex, high-volume part to full production. 3D printing used in conjunction with MIM not only saves time and money, but also reduces the risk of faulty parts by serving as a flexible tool for making adjustments when and where required during development. ~AM&P For more information: Nick Eidem, director of business development, Advanced Powder Products Inc., 301 Enter- prise Dr., Philipsburg, PA 16866, 814. 342.5898 ext. 128, neidem@4-app.com. obtain a Cp greater than 1.33, a tolerance of +/- 0.75% to 1% must be used. To improve tolerances, 3D-printed parts are often coined or machined to ensure assembly functionality. SURFACE FINISH The distinct difference between a MIM component and a binder jet 3D-printed component is surface finish. The surface finish of a MIM part is determined by the particle size of the powder and the sintering process and therefore is highly controllable. Without secondary processing, a MIM part can achieve an average surface finish or 32-40 Ra. The surface finish can be improved through a secondary process such as chemically aided vi- bratory surface treatment (such as REM) or electropolishing. Due to the nature of the stereolithographic layered printing process described above, 3D metal printed components have a higher surface roughness than MIM compo- nents. Further, 3D- printed components exhibit a surface finish disparity between the vertical side showing the layers and the top and bottom of the part. In the as-printed state, a 3D-printed component has a surface roughness of the vertical The shrinkage of a MIM component is controlled by custom tooling that is oversized to match the feedstock formulation. It is expected that a MIM part will shrink isotopically toward the center of gravity, although this is not always the case. The dimensional capability of binder jet 3D printing differs slightly when compared to MIM components. Just like a MIM component, a 3D-printed component is scaled approximately 20% larger to account for binder removal and sintering shrinkage. However, with binder jet 3D printing, a 3D-printed component may shrink differently on the x-y plane than on the z plane. To TABLE 2 — ALLOY PROPERTY COMPARISON Process Density, g/cc Hardness, HRC YS 0.2%, ksi UTS, ksi Elongation, % MPIF Standard 35 7.5 38-42 158 172 6 MIM 7.60 41 163.0 179.6 14 Printalloy 7.60 38.5 160.7 180.6 10.3
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