SEPTEMBER 2022 | VOL 180 | NO 6 27 30 35 Ultrasonic Defect Detection Decoding Failure Mechanisms ASM Materials Education Foundation Annual Report TERAHERTZ NDE OF CERAMICS, GLASSES AND COMPOSITES NDT AND FAILURE ANALYSIS P. 15
SEPTEMBER 2022 | VOL 180 | NO 6 27 30 35 Ultrasonic Defect Detection Decoding Failure Mechanisms ASM Materials Education Foundation Annual Report TERAHERTZ NDE OF CERAMICS, GLASSES AND COMPOSITES NDT AND FAILURE ANALYSIS P. 15
35 2021 ASM FOUNDATION ANNUAL REPORT ASM’s Materials Education Foundation aims to inspire young people to pursue careers in materials, science, and engineering. EXAMINING CERAMICS, GLASSES AND COMPOSITES WITH NONDESTRUCTIVE TERAHERTZ RADIATION Nicholas J. Tostanoski and S.K. Sundaram Terahertz time-domain spectroscopy is a powerful and nondestructive analytical characterization technique for investigating ceramics, glasses, and composites. 15 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 | S E P T E M B E R 2 0 2 2 2 Macro of automobile carbon fiber skin from Portland Auto Show. Courtesy of Dan Klimke/ Dreamstime. On the Cover: 43 ASM NEWS The latest news about ASM members, chapters, events, awards, conferences, affiliates, and other Society activities. 22 PERSPECTIVE A REVIEW OF ASSUMPTIONS OF FAILURE ANALYSIS A look at how bifilms are created during casting may offer clues to eliminating cracks, tensile fracture, fatigue failure, pitting, and stress-corrosion cracking failures.
4 Editorial 5 Research Tracks 6 Machine Learning 8 Metals/Polymers/Ceramics 10 Testing/Characterization 12 Process Technology 13 Emerging Technology 14 Surface Engineering 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. 6, SEPTEMBER 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. 27 TECHNICAL SPOTLIGHT PHASE COHERENCE IMAGING: ADVANTAGES OF A NEW ULTRASONIC TECHNIQUE A phase coherence imaging method allows inspection of attenuative, noisy, and thick parts, and early detection of small critical defects. 30 STUDYING FRACTURES: RECOGNIZING AND UNDERSTANDING FAILURE MODES Shane Turcott Examining a failed part’s fracture surface is a great source of information as to why and how it failed. 32 ADVANCED MANUFACTURING: PROGRESS AND OPPORTUNITIES This preview describes a panel session and workshop to be held at IMAT on Sept. 13 in New Orleans. The focus is on status and developments needed to achieve the promise of Industry 4.0. FEATURES SEPTEMBER 2022 | VOL 180 | NO 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 | S E P T E M B E R 2 0 2 2 3 27 33 32 30 33 ISTFA 2022 SHOW PREVIEW The 48th International Symposium for Testing and Failure Analysis features the theme of “Chasing Ever-smaller and More Elusive Defects.”
4 Climbing is an exercise in failure. So claims a professional mountaineer in a recent interview. He explains that inhis lineof work, failure is howyou set your goals in climbing and in life. You train and practice various moves until they can be executed perfectly on a summit. Then you train on the next most challenging move and so on. In the world of failure analysis (FA), a problem often presents itself and you must employ all the analytical tricks up your sleeve to get to the root cause. FA itself involves trying one test after another to extrapolate the answer—one hint at a time. Recently, I observed more than 30 high school students as they tried out their FA sleuthing skills. I attended the final presentation and graduation of the Eisenman Materials Camp for Students held at the Dome this July. Each team of students, guided by mentors, was given a case study to solve the mystery of why a specific part failed. Using metallurgical tools including sample preparation, hardness testing, and SEM analysis, the groups presented their findings and theories. It was failure analysis at its finest. The students were impressive in their use of proper terminology and in how expertly they fielded questions from other teams. ASM Past President Sunniva Collins, FASM, who presided over the graduation ceremony, commented on the professional quality of the microstructures presented. While the students were using some destructive analytical methods as they tested various metals, the lead article in this issue of AM&P takes us on an exploration of nondestructive evaluation of unique ceramics, glasses, and composites using terahertz radiation. One of the coauthors, Prof. S.K. Sundaram of Alfred University, was named to the 2021 Class of ASM Fellows for his research in this specialized area of diagnostics. Failure analysis truly spans the gamut of materials and testing methods. Ultrasonic inspection, in the form of phase coherence imaging (PCI), is presented in another article in this issue. PCI offers new options for spotting early flaws in previously challenging use cases, such as when testing thick parts or very grainy materials. If at first you fail, try another novel testing method to crack a difficult FA case. You might also visit ASM’s bookstore to find resources like the new one entitled “Decoding Mechanical Failures” by Shane Turcott. We chiseled off a sample of that article to present in this issue. Here Turcott offers three case studies that explore various types of fractures. Using his own favorite FA sleuthing techniques, he works his way down through each case’s possible causes until he reveals the primary failure mode and describes how to prevent future breaks. Whether drilling down on metallurgical factors of stress rupture or climbing up a mountain peak, the methodology is similar. So perhaps failure analysis is also an exercise in failure—one worth cracking. 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 | S E P T E M 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 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, 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. CRACKING THE CASE Eisenman Materials Camp students analyze a metallurgical failure.
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 | S E P T E M B E R 2 0 2 2 5 COPPER NANOMESH MURDERS MICROBES Scientists from the University of Tokyo, the Korea Research Institute of Bioscience and Biotechnology, and the RIKEN Center for Emergent Matter Science, Japan, developed a wearable antimicrobial nanomesh material that sticks to skin, killing microbes almost instantly. The team first created tiny copper strands and spun them together randomly to build a mesh, then applied pressure to flatten it. At three microns thick, the result is so thin that it cannot be seen by the human eye or felt when touched. But it is bendable and stretchy, making it suitable for a variety of uses. One of the main products the team envisions is a surface cover for smartphones and tablets. Testing shows that the nanomesh does not affect device performance. The mesh could also be applied to surfaces that serve as common bacteria and virus transfer sites such as doorknobs and light switches. Another idea is to develop a coated glove that is so thin the user is unaware of its presence. This could provide the best protection possible because so many microbes are transferred through RESEARCH TRACKS hands. The researchers say their nanomesh is superior to copper films already in use because it is more potent due to its larger surface area, giving it more opportunity to kill microbes. www.u-tokyo.ac.jp/en. MEASURING MAGNETIZATION Researchers from Lancaster University, U.K., University of California San Diego, Moscow Institute for Physics and Technology, and Radboud University, the Netherlands, are discovering how quickly magnetization can be created in amaterial. The team studied iron and rhodium (FeRh), a common magnetic alloy that exhibits a transition in both its structure andmagnetismwhen heated just above room temperature. The scientists found that FeRh undergoes a transition into its ferromagnetic phase in three stages: the excitation of the laser pulse induces a large number of tiny magnetic domains in the material; magnetization A newly developed antimicrobial copper mesh kills microbes nearly instantly. of all domains aligns along one particular direction; and individual domains grow into a large single domain, completing the transition into its ferromagnetic phase. Understanding these stages in regard to inducing a well-defined magnetization with a light pulse enables the possibility of using FeRh in future data storage technology. The study involved using intense, ultrashort laser pulses to rapidly heat FeRh with a brief artificial stimulus lasting a quadrillionth of a second. When interacting with the material, the laser pulse raised the temperature by a few hundred degrees Celsius at timescales shorter than a billionth of a second. The team used a novel double pump time-resolved spectroscopy technique developed at Radboud University. Two laser pulses were used for double pumping: The first acts as an ultrafast heater while the second pulse one helps generate the electric field. By detecting this field at multiple time lapses between the two pulses, researchers were able to observe how quickly magnetization emerges in the material. www.lancaster.ac.uk. The temperature hysteresis of the FeRh magnetization shows a characteristic first-order phase transition. Courtesy of Nature Communications.
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 | S E P T E M B E R 2 0 2 2 6 MACHINE LEARNING | AI DEEP LEARNING EXPLORES HIGH-ENTROPY ALLOYS Supercomputer simulations are helping scientists discover new types of high-entropy alloys (HEAs). Researchers recently used the Stampede2 supercomputer of the Texas Advanced Computing Center located at The University of Texas at Austin for newwork on these special alloys. The approach could be applied to finding new materials for batteries, catalysts, and more without the need for expensive metals such as platinum or cobalt. “High-entropy alloys represent a totally different design concept. In this case we try to mix multiple principal elements together,” says Wei Chen, an associate professor at the Illinois Institute of Technology. For the study, Chen and his colleagues surveyed 14 ele- ments and the combinations that yiel- ded HEAs. They then performed high- throughput quantum mechanical calculations to determine the stability and elastic properties of more than 7000 of these HEAs. Next, the team took this large dataset and applied a “Deep Sets” architecture—an advanced deep learning architecture that generates predictive models regarding the properties of new HEAs. The Deep Sets approach uses the elemental properties of individual HEAs to build predictive models that can predict the properties of a new alloy system. “We developed a new machine learning model and predicted the properties for more than 370,000 high-entropy alloy compositions,” says Chen. utexas.edu. AI HELPS ROBOTS NAVIGATE ENVIRONMENT Researchers at MIT, Cambridge, Mass., developed a method to 3D-print materials with tunable mechanical properties that sense how they are moving and interacting with the environment. The team creates these sensing structures using just one material and a single run on a 3D printer. To accomplish this, the researchers began with 3D-printed lattice materials and incorporated networks of air-filled channels into the structure during the printing process. By measuring how the pressure changes within these channels when the structure is squeezed, bent, or stretched, engineers can receive feedback on how the material is moving. The new method opens opportunities for embedding sensors within architected materials, a class of materials whose mechanical properties are programmed through form and composition. Controlling the geometry of features in architected materials alters their mechanical properties, such as stiffness or toughness. For example, in cellular structures such as the lattices printed by the team, a denser network of cells makes a stiffer structure. This technique could someday be used to create flexible soft robots with embedded sensors that enable the robots to understand their posture and movements. It might also be used to produce wearable smart devices that provide feedback on how a person is moving or interacting with their environment. “The idea with this work is that we can take any material that can be 3D-printed and have a simple way to route channels throughout it so we can get sensorization with structure. And if you use really complex materials, then you can have motion, perception, and structure all in one,” explains MIT graduate student Lillian Chin. mit.edu. Data-driven workflow used to map the elastic properties of high-entropy alloys. Courtesy of Chen et al. 3D-printed crystalline lattice structures with embedded fluidic sensors. The air channels enable researchers to measure howmuch force the lattices experience when they are compressed or flattened.
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 | S E P T E M B E R 2 0 2 2 8 METALS | POLYMERS | CERAMICS TriTech Titanium Parts, Detroit, was launched earlier this year as a spin-off of AmeriTi Manufacturing, which was sold to Kymera International on the same day. AmeriTi was founded in 1984 to focus on titanium products from recycled material. TriTech produces net shape, complex titanium parts using 3D binder jet printing, metal injection molding, and investment casting. tritechtitanium.com. Levidian Nanosystems, U.K., and Adamant Composites Ltd., Greece, signed a joint development agreement to collaborate on enhancing composite materials with Levidian’s unique graphene. Over the next three years, the companies will incorporate sustainable graphene into a wide range of composite materials. The goal is to develop fabrics, prepreg, resin, adhesives, and coatings for applications in the automotive, aerospace and space, and wind energy industries. levidian.com. BRIEFS NEURON-INSPIRED POLYMER HEALS ITSELF Researchers at theNingbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences proposed a neuron-inspired, all-around telechelic polymer with impressive mechanical and physical properties, rapid self-healing ability, adhesion, triboelectricity, and aggregate-induced emission fluorescence. Inspired by the axon structure of neurons, the team synthesized a telechelic polymer with a three-arm structure. The 2-ureido-4 pyrimidinone terminates each arm and its length is well controlled within a small range to reduce entanglement density, thereby improving the polymer’s self-healing efficiency. In addition, extensive urea groups are embedded into each arm to construct a hierarchical hydrogen bonds (H-bonds) network. By adjusting the arm length, the polymer’s mechanical performance can be easily tuned. The polymer exhibits Aluminum’s relatively low conductivity can be a limitation in some real-world applications. Courtesy of Shannon Colson/ PNNL. CONDUCTIVE ALUMINUM COMING SOON Researchers at Pacific Northwest National Laboratory (PNNL), Richland, Wash., are working on ways to increase the conductivity of aluminum and make it economically competitive with copper. The team believes their results could lead to a highly conductive aluminum that could revolutionize everything from vehicles and electronics to the power grid. Although aluminum is one-third of the price and weight of copper, it is only about 60% as conductive, limiting its applications. “For years, we thought metals couldn’t be made more conductive. But that’s not the case,” says PNNL materials scientist Keerti Kappagantula. “If you alter the structure of the metal and introduce the right additives, you can indeed influence its properties.” To begin learning just how much aluminum conductivity could be increased, the PNNL team worked with colleagues at Ohio University, Athens, to identify the effects of temperature and structural defects in aluminum conductivity and develop an atom-by-atom recipe to increase its conductivity. This type of molecular simulation had not been done for metals before. The scientists turned to semiconductors for inspiration because previous research had successfully simulated conductivity in these silicon-based materials as well as some metal oxides. The team adapted these concepts to work with aluminum and simulated what would happen to the metal’s conductivity if individual atoms in its structure were removed or rearranged. These tiny changes added up to big gains in total conductivity. The model’s ability to simulate real-world conditions came as a welcome surprise. The researchers plan to see how much they can increase the conductivity of aluminum in the lab to match their theory with experimental results. pnnl.gov. Sample applications of the telechelic polymer. Courtesy of NIMTE.
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 | S E P T E M B E R 2 0 2 2 9 excellent mechanical performance with stiffness of 97.9 MPa, strength of 22.5 MPa, elongation at break of 1470%, and toughness of 159.3 MJ.m-3. After 30 minutes of self-healing, the toughness of the synthesized polymer can recover to 92%, indicating a significantly rapid self-healing ability. The extensive H-bonds provide the polymer with excellent adhesion as the lap-shear strength can reach up to 20.7 MPa when bonded with iron plates, the highest value reported for hot-melt adhesives. Potential applications include energy storage, flexible sensors, and intelligent displays, as well as underwater marine uses such as anticounterfeiting, encapsulation, and adhesion. https://english. cas.cn. HALF-METAL EXHIBITS ZERO MAGNETIZATION A research group at TohokuUniversity’s Institute for Materials Research, Japan, reports successfully synthesizing a “half-metal” material, achieving a rare accomplishment in the pursuit of zero magnetization. Half-metals can dramatically enhance the performance of electronic devices. This is due to their 100% spin polarization, which allows them to behave as metals in one spin direction, and insulators/semiconductors in the other. Most successful instances of half-metals are ferromagnetic, meaning their spin arrangement is aligned. A n t i f e r r o - magnetic-like half- metals, where the spin aligns in an antiparallel nature, are desirable because no magnetic stray field candisturb it, even if integrated at Spin arrangement of magnetic moments in ferromagnetic, antiferromagnetic, and ferrimagnetic materials. Courtesy of Rie Umetsu. high density. To date, only two cases of these antiferromagnetic-like half-metals have been reported. Following specific development guidelines, the team created a compound consisting of iron, chromium, and sulfur. The new material completely loses its magnetization at low temperatures. The researchers believe the results of this study will initiate new innovations in the spintronics field. www.tohoku.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 | S E P T E M B E R 2 0 2 2 charge, lithium ions flow from one side of the battery to the other. With this in mind, the team built a lithium-ion battery that uses a special material at one end—a compound whose magnetism changes as lithium ions enter or leave it. This makes it possible to measure the battery’s level of charge by tracking changes in the material’s magnetism, the researchers say. The team’s magneto-ionic material is made from vanadium, chromium, and cyanide, plus an aqua ligand. buffalo.edu. TESTING | CHARACTERIZATION ‘FRUITCAKE’ STRUCTURE IN ORGANIC POLYMERS The field of organic electronics has benefited from the discovery of new semiconducting polymers with molecular backbones that are resilient to twists and bends, meaning they can transport charge even if they are flexed into different shapes. It had been assumed that these materials resemble a plate of spaghetti at the molecular scale, without any long-range order. However, an international team of researchers found that for at least one such material, there are tiny pockets of order within. These ordered pockets are stiffer than the rest of the material, giving it a “fruitcake” structure with harder and softer regions. The work was led by the University of Cambridge and Park Systems UK Limited, with KTH Stockholm in Sweden, the Universities of Namur and Mons in Belgium, and Wake Forest University in the U.S. Measurements of the stiffness of the material on the nanoscale showed that the areas where the polymers self-organized in- to ordered regions were harder, while the disordered regions of the material were softer. Studying and understanding the mechanical properties of these materials at the nanoscale could help scientists finetune those properties and make the materials suitable for a wider range of applications including next-generation microelectronic and bioelectronic devices. www.cam.ac.uk. MAGNETS MONITOR BATTERY LIFE A team of scientists at the University at Buffalo is using a magnetic material to monitor the remaining life in rechargeable batteries. A new study shows how a magnetic material can be used to help monitor the amount of life left in a rechargeable battery before it needs to be recharged. As lithium-ion batteries charge and dis- Researchers at the University of Minnesota Twin Cities discovered how subtle structural changes in strontium titanate, a metal oxide semiconductor, can alter the material’s electrical resistance and impact its superconducting properties. They say the results could help guide materials design related to superconductivity and create more efficient semiconductors for electronic device applications. twin-cities.umn.edu. BRIEF Studies of an organic polymer reveal variations in hardness at the nanoscale. Courtesy of University of Cambridge. Yulong Huang holds a lithium-ion battery with a cathode made frommagneto-ionic material. Courtesy of Douglas Levere/ University at Buffalo. HIGHLY REPEATABLE COLORCHANGING PROPERTY Hackmanite was discovered by researchers at the University of Turku, Finland, to be color-changing when exposed to UV radiation repeatedly without wearing out. The results show that the inexpensive hackmanite, which
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 | S E P T E M B E R 2 0 2 2 1 1 is easy to synthesize, also has high durability and multiple applications. The research group has been investigating and developing the properties of hackmanite for almost a decade. Applications such as personal UV monitoring and x-ray imaging have been developed based on hackmanite’s ability to change color. Hackmanite changes its color from white to purple under UV irradiation, eventually turning back to white if no UV is present. Until now, the structural features enabling repeated changes have been poorly understood. Through their work investigating three natural minerals—hackmanite, tugtupite, and scapolite—the researchers are gaining a clearer picture. These color-changing minerals are inorganic natural materials, but there are also organic compounds— hydrocarbons—that can change color reversibly due to radiation exposure. However, these hydrocarbons can only change color a few times before their Hackmanite turns purple under UV irradiation, and color fades back to white in minutes under regular white light. Courtesy of Mika Lastusaari. molecular structure breaks down. This is because the color change involves a drastic change in their structure, and undergoing this change repeatedly eventually breaks the molecule. Previously, scapolite has been known to change color much faster than hackmanite, whereas tugtupite’s changes are much slower. According to researchers, the durability of the inorganic natural materials under investigation is due to the strong 3D cage-like overall structure of these minerals, which is similar to that of zeolites. In detergents, for example, the cage-like structure enables zeolite to remove magnesium and calcium fromwater by binding them tightly inside the pores of the cage. The group is currently exploring numerous applications for hackmanite, such as replacing LEDs and other light bulbs with the natural mineral as well as utilizing it in x-ray imaging. One of the most interesting avenues that the researchers are also investigating is a hackmanite-based dosimeter and passive detectors for the International Space Station, intended to be used to measure the radiation dose uptake of materials during space flights. www. utu.fi/en.
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 | S E P T E M B E R 2 0 2 2 1 2 PROCESS TECHNOLOGY MAKING STRONGER AIRCRAFT STRUCTURES With a combination of laser technologies and isostatic pressing, scientists from NUST MISIS, Moscow, developed a method to produce composite parts for the aerospace industry while increasing the strength of the finished products by 15%. The resulting titanium-silicon composite material has unique mechanical properties necessary for the creation of air and land transport—high tensile strength and stiffness. Parts made of such composites are in demand by the aerospace industry. The properties of this fiber composite are highly dependent on a complex manufacturing technology. Combining laser technology and hot pressing, the research team’s hybrid array of golf-tee shaped columns on the surface on a 3 x 3 mm diamond sheet. The shape of the golf tees, wide on top and skinny on the bottom, makes the surface of the diamond 98.9% reflective. To test the mirror with a high-power laser, the team turned to collaborators at Pennsylvania State University, State College, Pa. There, in a specially designed room that is locked to prevent dangerous levels of laser light from seeping out and blinding or burning those in the adjacent room, the researchers put their mirror in front of a 10 kW laser, strong enough to burn through steel. Future applications could include semiconductor and industrial manufacturing, deep space communications, and defense purposes. The approach could also be useful for less expensive materials, such as fused silica. Harvard Office of Technology Development has protected the intellectual property associated with this project and is exploring the commercialization opportunities. harvard.edu. A sampling of 3D printed composite parts used in the aerospace industry. Courtesy of Sergey Gnuskov/NUST MISIS. approach addresses the prohibitive challenge of liquid state manufacturing methods for titaniumsilicon composites. The researchers demonstrated the feasibility of their process by manufacturing fiber-reinforced titanium alloy parts with a volume fraction of fibers equal to 17%. X-ray tomography revealed the absence of defects in the obtained part and a good contact between the matrix and the fibers. Tests for three-point bending showed that the composite part created according to the new technology has significantly higher strength and stiffness indicators than the part made of a massive titanium alloy. Currently, the scientific group is working to optimize the technology and expand the range of manufactured parts. en.misis.ru. HIGHLY REFLECTIVE DIAMOND MIRRORS Researchers at the Harvard School of Engineering and Applied Sciences (SEAS), Cambridge, Mass., etched nanostructures onto the surface of a thin sheet of diamond to build a highly reflective mirror that withstood 10 kW Navy laser experiments without damage. Using an ion beam to etch the diamond, the researchers sculpted an BRIEF An engineering collaboration between Lufthansa Technik and BASF, both headquartered in Germany, resulted in the debut of a thin film coating that can be applied to an aircraft’s outer skin to reduce drag. The team describes the new AeroSHARK coating as a durable bionic film that successfully mimics the skin of sharks, optimizing airflow and enabling significant fuel savings. lufthansa-technik.com/aeroshark. Zoomed SEM image of the mirror. Courtesy of Loncar Lab/Harvard SEAS.
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 | S E P T E M B E R 2 0 2 2 1 3 NEW ERA OF 2.5D MATERIALS Nanomaterials researchers at Kyushu University in Japan are investigating new ways to artificially stack 2D materials, introducing so-called 2.5D materials with unique physical properties. A common method for fabricating 2.5D materials is chemical vapor deposition (CVD). Routinely used building blocks for 2.5D materials include graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDCs). Using the CVD method, researchers selectively synthesized a bilayer of graphene, the simplest form of a 2.5D material, using a copper-nickel foil with relatively high nickel concentration as a catalyst. When an electrical field was applied vertically across the bilayer of graphene, it opened a band gap, meaning that its conductivity can be turned on and off. This is a phenomenon that is not observed in monolayer graphene because it has no band gap and stays on all the time. By tilting the stacking angle one degree, scientists found that the material became superconducting. Future applications of 2.5D materials include solar cells, batteries, flexible devices, quantum devices, and devices with very low energy consumption. The next steps will utilize machine learning to further advance the design and synthesis of 2.5D materials. www.kyushu-u.ac.jp/en/. PREDICTING MATERIAL EFFECTIVENESS Penn State, State College, researcher and materials science pro- fessor Zi-Kui Liu, FASM, developed a new cross phenomena theory that goes beyond the phenomenological scientific approach, where observations in experiments are made to describe the relationship of phenomena to each other based on what is observed. The new theory involves what Liu calls zen- tropy theory. Zentropy considers how entropy occurs over multiple scales within a system by integrating quantum mechanics, statistical mechanics, and experimental measurements of thermodynamics. This novel theory of cross EMERGING TECHNOLOGY Natron Energy Inc., Santa Clara, Calif., and Clarios International Inc., Milwaukee, are collaborating to manufacture the first mass-produced sodium-ion batteries with production to begin in 2023. Natron’s batteries are now used in data centers and telecom networks. Future applications may include electric vehicles and grid energy storage. www.natron.energy. BRIEF phenomena can be used by researchers to guide experimental discovery and provide a theoretical understanding of experimental observations. According to Liu, this could enable researchers to predict the best ways to develop new materials with emergent behavior via quantum mechanics and statistical mechanics. Emergent behavior in a system refers to characteristics of the whole that are greater than the sum of its parts. Liu pointed to one example based on an ultrasound transducer— the hand-held part of an ultrasound machine—that is used to detect a fetal heartbeat in the womb. The next step will be researching how this novel theory of cross phenomena can be used as a predictive tool to enable more efficient discovery of materials with emergent behaviors including superconductivity, ferroelectricity, and ferromagnetismfor applications in energy conversion, refrigeration, and sensors. psu.edu. Using a stacking method, it is now possible to create 2.5D materials with unique physical properties that can be used in solar cells and quantum devices. Heat from the Sun results in various examples of cross-phenomena such as evaporation of water and photosynthesis for growth of trees and crops. Courtesy of Elizabeth Flores-Gomez Murray. Cross-phenomena Zentropy
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 | S E P T E M B E R 2 0 2 2 1 4 SURFACE ENGINEERING ULTRA-HIGH-RATE COATING TECH Using vacuum plasma, a research team from Toyohashi University of Technology, Japan, created an ultrahigh-rate coating technology for functional hard carbon films. Due to their low friction coefficients, they’re used as protective films with sliding surfaces. The new technology achieved a film deposition rate of more than one order of magnitude faster than existing coating technologies while maintaining the same degree of film quality. The technology has potential applications for improving the functional performance of general-purpose products and other mass-produced products. The research team utilized a unique gas injection method in which two kinds of gas were ejected in a jet shape and mixed in a vacuum. Using this process, the team eliminated the need to form a complex discharge electrode in or around the object being coated. According to researchers, the method could be used as a highly versatile process that has applications for a diverse range of materials and shapes. By achieving ultra-high-rate film formation through this gas injection method, the team has removed the need to form a complex discharge electrode in or around the object being coated, so it can be expected to be used as a highly versatile process that can be applied to a diverse range of materials and shapes. The research team plans to expand the size of the high-speed deposition area for practical application of equipment utilizing this technology. They believe that coating of cylindrical inner walls and complex structures will also become possible through further research and development. In the future, they hope to achieve widespread adoption of this new coating technology and contribute to the creation of a society capable of sustainable development. www.tut. ac.jp/english. PROGRESS REPORT ON GLASS COATINGS A new review article published in International Materials Reviews covers current progress on thermal sprayed Fe-based metallic glass coatings (MGCs). These coatings are receiving widespread attention due to their exceptional combination of mechanical and corrosion properties, along with a low material cost for this specific alloy system. These particular MGCs outperform conventional corrosion-resistant materials and coatings in many cases, inspiring a significant increase in research projects over the past few decades. This review article takes a holistic approach, including an in-depth assessment of all relevant work on the topic, such as corrosion properties, degradation mechanisms, and metallurgical and environmental factors with regard to passive film dynamics and formation of corrosion products. Strategies for improving corrosion properties are also included, along with an attempt to identify various knowledge gaps and determine future research directions. https://doi.org/ 10.1080/09506608.2022.2084670. BRIEF Aalberts surface technologies, Germany, is continuing a rebranding initiative for its U.S. businesses. The following companies will now be called Aalberts surface technologies instead of these different names: Aalberts Surface Treatment, Precision Plating Company, Roy Metal Finishing, Ushers Machine and Tool, Accurate Brazing, Ionic Technologies, Applied Process, and Premier Thermal. aalberts-st.com. Side view of coaxial gas injection plasma jet source with a circular nozzle for Ar plasma jet injection with a central C2H2 injection nozzle at its center. Courtesy of Toyohashi University of Technology. Graphical depiction of the use of thermally sprayed Fe-based MGCs for alleviating corrosion-related degradation. Courtesy of the authors.
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 | S E P T E M B E R 2 0 2 2 *Member of ASM International EXAMINING CERAMICS, GLASSES AND COMPOSITES WITH NONDESTRUCTIVE TERAHERTZ RADIATION N O N D E S T R U C T I V E T E S T I N G 1 Terahertz time-domain spectroscopy is a powerful and nondestructive analytical characterization technique for investigating ceramics, glasses, and composites. Nicholas J. Tostanoski and S.K. Sundaram, FASM* Alfred University, New York
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 | S E P T E M B E R 2 0 2 2 THz WAVES ARE TRANSPARENT TO MANY DIELECTRIC MATERIALS INCLUDING GLASSES, CERAMICS, VISIBLY OPAQUE MATERIALS, CLOTHING, AND PACKAGING MATERIALS, ENABLING NONDESTRUCTIVE IMAGING FOR VARIOUS APPLICATIONS... Terahertz (THz) radiation is on the order of ~1012 Hz or 1 THz, positioned at 0.1-10 THz (100 GHz -10 THz, λ = 3-0.03 mm, and photon energies on the order of 0.41-41 meV). With long wavelengths, these waves are nondestructive and nonionizing, making them ideal for noncontact spectroscopy of materials, specifically ceramics, glasses, and composites. THz spectroscopy measurements probe low-energy interactions within matter and materials, describing molecular rotations and vibrational spectra, crystalline phonon vibrations, low frequency bond vibrations, molecular rotations and vibrations of gases, hydrogen-bonding stretching and torsions of liquids, and charge transport[1-3]. Terahertz time-domain spectros- copy (THz-TDS) enables material exam- ination through transmissionand reflection geometries. Reference and sample scans must be performed under pure nitrogen atmosphere due to absorption of THz waves by water vapor[4-6]. THz-TDS sample requirements include having flat and pristine front and back surfaces, as incident THz waves will interact with the material and the phenomena of transmission and reflections can be observed. To extract optical and dielectric constants from THz-TDS measurements, additional sample constraints include using a homogenous representative portion of the sample with a known thickness. In terms of sample geometry, too thin or thick of a sample results in superposition of THz pulses and multiple reflections, as the THz waves have a wavelength on the order of the sample thickness[5,7]. THz-TDS uses femtosecond laser systems, e.g., Ti:sapphire laser, to produce optical pulses with femtosecond durations (e.g., < 90 fs). A beam spitter splits the beam into pump and probe components. The pump component is transformed into a THz pulse (e.g., < 500 fs) using a photoconductive antenna (PCA) and passes through a sample of known thickness, while the probe component is used to detect the beam using a PCA[1,6,8]. A temporal delay between pump and probe components is performed by increasing the path length of a beam and is critical for detection of THz waves. The reference or probe pulse and the sample or pump pulse time profile are not identical, allowing for comparison and therefore determination of optical and dielectric properties. THz-TDS measures the THz wave temporal electric field (not the intensity), while a reference pulse determines the electric field where the transmitted THz pulse height and phase (peak position) is shifted by the absorption and refractive index of the samples, respectively[5,9]. The transmitted sample time-domain waveform is transformed into the frequency domain, through a Fourier transformation, and the resulting THz wave formamplitude and phase change results in determination of the absorption coefficient and refractive index, respectively. THz-TDS examination of materials allows for determination of optical and dielectric constants or identification of materials through absorption signatures, termed fingerprints, at THz frequencies[1]. Extraction of optic and dielectric constants including a complex refractive index does not require a Kramers-Kronig transformation. Real and imaginary parts of the refractive index are associated with sample thickness, absorption, and conductivity of the materials. THz waves are transparent to many dielectric materials including glasses, ceramics, visibly opaque materials, clothing, and packaging materials, enabling nondestructive imaging for various applications including general identification and quantification of compositional information for use in quality control of packaged materials[10-14]. Other uses include biomedical detection and diagnosis of diseases[15-17] such as skin cancer using reflection imaging, and in the pharmaceutical industry[18-21] to study the crystal structure of drug molecules as well as to determine tablet coating thickness, uniformity, porosity, and defects. Further applications include security and defense[17,22] for use in crowd control, in remote sensing to identify chemical and biological substances or detect prohibited items including drugs, weapons, or explosives, and in communication for high-capacity wireless data transmission at short distances[17]. This article presents a brief overview of THz-TDS as a nondestructive analytical characterization technique used to examine materials, particularly ceramics, glasses, and composites. Recent progress at the Terahertz Waves Science and Technology Laboratory (T-Lab) at Alfred University is also discussed. For more details on THz-TDS, see references 1, 2, 3, and 8. THz-TDS AT ALFRED UNIVERSITY The THz-TDS nondestructive examination and characterization carried out at Alfred University’s T-Lab uses a TeraView Spectra 3000 (TeraView, U.K.) operating in transmission mode under pure nitrogen conditions (Fig. 1). THz spectra are generally collected and averaged five times from 0.2-1.0 THz (material and sample thickness dependent). A mode-locked Ti:sapphire laser centered at 800 nm with a repetition rate of 80 MHz and pulse duration of 100 fs produces incident THz radiation that is divided into pump and probe detection beams. A comparison between reference and sample time delay of the THz pulse is essential to determining optical and dielectric properties. The authors have studied optical and dielectric properties including refractive index, absorption coefficient, and real dielectric constant of ceramics, glasses, and composites at THz frequencies using THz-TDS, particularly changes in structure and properties across a compositional space. Complementary structural studies of materials
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 | S E P T E M B E R 2 0 2 2 and actinides, while fission products, e.g., Cs and Sr, are immobilized in hollandite phases. THz optical and dielectric properties allow for identification and differentiation of all ceramic waste forms due to their unique THz frequency signatures. Figure 2 shows the THz refractive index data for various waste forms. Multiphase waste forms self-heat during storage due to β-decay of fusion products. THz-TDS was performed at a temperature range of 25-200°C. Measured refractive index at 0.5 THz shows an exponential increase with an increase in temperature, allowing for distinction of phases at elevated temperatures during long-term storage (Fig. 3). Fig. 1 — (a) THz-TDS setup at Alfred University’s T-Lab including: (b) transmission configuration sample holder; and (c) TPS Spectra program. allow for THz optical and dielectric properties to be correlated to structural changes. This enables THz-TDS to be used as a critical nondestructive material examination and characterization technique to provide information about the THz refractive index and absorption coefficient and, therefore, material composition and structure. The researchers reported earlier detailed results on THz properties of ceramic waste forms, soda-lime silicate (SLS), Borofloat (BF), alumino-borosilicate (ABS), and calcium aluminosilicate (CAS) glasses, and hydroxyapatite (HA)-calcium zinc silicate glass composites. Currently, the authors are focused on the structure-THz property relationship of borosilicate, tellurite, and chalcogenide glasses and the influence of laser exposure on the glass structure, network, and THz properties. NONCONTACT CERAMICS MONITORING The authors identified THz-TDS as a noncontact method for monitoring multiphase ceramic waste forms for nuclear applications[23]. Single-phase zirconolite (CaZrTi2O7), pyrochlore (Nd2Ti2O7), and hollandite (BaCs0.3Cr2.3- Ti5.7O16 and BaCs0.3CrFAl0.3Ti5.7O16) representative of ceramic waste forms were produced via spark plasma sintering (SPS). Zirconolite and pyrochlore phases immobilize rare earth elements (a) (c) (b)
1 8 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 | S E P T E M B E R 2 0 2 2 in the glass network for silicate tetrahedra (SiO4), however the AlO4 - tetrahedra has a negative charge that achieves charge compensation though alkali or alkaline earth cations, e.g., CaO. Adding both CaO and Al2O3 creates a neutral charge glass system. CaO ultimately results in depolymerization of the glass network through formation of nonbridging oxygen (NBO) atoms, while also producing over-coordinated or five-fold coordinated aluminum (AlV) and triclustered oxygen (TBO). It is important to note that compositions along the tectosilicate join should contain minimal or near zero NBO atoms. The refractive index of pristine and high repetition rate laser irradiated tectosilicate glasses was studied to densification or rarefaction of CAS, CaO-Al2O3-SiO2, glasses[25]. These are CAS glasses along the tectosilicate, xCaO·xAl2O3·(100-2x)SiO2, where the addition of both calcium and aluminum creates a charge neutral system (R = CaO/Al2O3 = 1). SiO2, Al2O3, and CaO are termed network former, intermediate network former, and network modifier, respectively. CAS glasses are used for display glass applications due to superior mechanical and physical properties, specifically based on the role aluminum plays in the glass network. Aluminum is traditionally four-coordinated (AlIV) along the tectosilicate join and these Al species are in the form of tetrahedrally coordinated aluminum (AlO4 -). Aluminum tetrahedra substitute STUDYING CAS GLASSES FOR DISPLAY APPLICATIONS The authors have reported highlighted refractive index changes from 0.3-0.8 THz of SLS and ABS glasses that had been irradiated using a high repetition rate femtosecond laser system[24]. SLS and ABS measured reduced and increased refractive index consistently throughout the THz region (Fig. 4). Refractive index changes at THz frequencies, obtained using THz-TDS, reflect densification or rarefaction of the glass network due to femtosecond laser exposure. In addition, the researchers correlated changes in the refractive index, at THz frequencies from THz-TDS, Fig. 3 — Refractive index at 0.5 THz of Nd2Ti2O7 and CaZrTi2O7 as a function of temperature from 25-200°C. Fig. 2 — Refractive index as a function of frequency for titanate materials for nuclear waste applications.
1 9 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 | S E P T E M B E R 2 0 2 2 at THz frequencies through THz-TDS. The refractive index at 0.8 THz of pristine glasses was found to increase relative to increasing (Ca+Al)/Si, consistent with density trends. All laser-modified glasses measure positive refractive index changes at 0.8 THz, however silicate-rich glasses, or reduced (Ca+Al)/ Si composition, exhibit larger refractive index changes. THz-TDS is an effective nondestructive technique to measure densification or rarefaction of the glass structure and corresponding larger glass network. CAS glasses along the tectosilicate join show densification from laser irradiation, due to higher measured THz refractive index values following irradiation. It is suspected the densification is due to the ability of aluminum to convert from four to five-fold coordination due to laser irradiation. In an earlier study, the authors examined the CAS glass system and laser-induced structural modification using molecular dynamic simulations[26]. CAS compositions along the tectosilicate join were selected and modeled using the Large-Scale Atomic/ Molecular Massively Parallel Simulator (LAMMPS) with simulated laser exposure applied through a heat flux cross defined region or hotspot/focal region. Localized density changes, coordination number distribution, and short and intermediate range order bond angles and distances between Si and Al species were analyzed and discussed. It was proposed that densification of CAS glass due to femtosecond laser irradiation occurs through conversion of AlIV to AlV and distortions of silica inter-tetrahedral bonding environments including Si-O bond distances and SiO-Si bond angles. Compositions with a lower Al2O3/SiO2 ratio, reflecting a silica-rich glass, densify more due to increased concentration of AlV, which was found to increase with pulse energy. Addition of Al and Ca, at the expense of Si, increases the packing density of the glass structure and network, reducing laser exposure modification to the overall network. EXAMINING HA-GLASS COMPOSITES The authors have characterized HA-glass composites[27], specifically HA and calcium zinc silicate glass composites. THz-TDS is used to determine the refractive index and dielectric constant values, which are correlated to the glass content within defined composites. THz-TDS serves as a nondestructive tool for examining HA-glass composites. Hydroxyapatite (Ca10(PO4)6(OH)2; HA) is the main mineral component of hard tissues, allowing for use in bone repair and replacement. The refractive index and dielectric constant were proven to be viable in determination of glass content found in HA-glass composites from 0.2-1.5 THz, above which cannot be measured due to surface roughness. Dielectric constant and refractive index Fig. 4 — Refractive index of SLS and ABS glasses over 0.3-0.8 THz.
www.asminternational.orgRkJQdWJsaXNoZXIy MTYyMzk3NQ==