The abstract reads as follows:

The microstructure of conventional and nanomaterial Cu cold spray coatings is explored to understand why nanomaterial Cu cold spray performs better than conventional Cu cold spray in the contact killing of Influenza A Virus [19]. Powder, single-splats from laser induced projectile impact testing (LIPIT), and consolidated cold spray coatings are imaged using Scanning Electron Microscopy (SEM). Sample composition is confirmed using Energy Dispersive X-Ray Spectroscopy (EDS) and X-ray Diffraction (XRD). Results show nanomaterial Cu to have a much smaller grain size than conventional Cu. Nanoindentation is used to confirm microstructural differences, showing nanomaterial Cu to have greater hardness. LIPIT and consolidated cross-sections identified grain refinement at the particle-substrate interface for both nanomaterial and conventional Cu. Follow-on work with corrosion testing will be performed to better understand Cu ion release rate in relation to the differing material microstructures for antimicrobial applications.

Follow the authors on ResearchGate here: 

https://www.researchgate.net/publication/341915120_Microstructural_Characterization_of_Conventional_and_Nanomaterial_Copper_Cold_Spray_Coatings 

The article's abstract reads as follows:

The dependence-based relationship between the hardness of a small volume of polycrystalline metallic material and the material's crystallographic orientations has been established for systems. Typically, these systems are comprised of hexagonal close packed orientation, such as β-Ti alloys, dual-phase steels, and FeCrAl alloys. Recently, advances in nanoscale-instrumented indentation testing of materials via nanoindentation have shown that the grain orientation dependence of a measured hardness also holds for cubic structured polycrystalline metal systems. In order to contribute to this debate, this work takes a precursory look at the effect of grain orientation on nanoindentation hardness in gas-atomized metallic powders. Grain orientation was measured using electron backscatter diffraction and hardness using nanoindentation. These powders offer the unique challenge of having much smaller grains than those typically researched. It was found that even in face centered cubic gas-atomized Al 6061 powder there is a noteworthy difference in hardness as a function of grain orientation. Though this work demonstrates the influence of grain orientation upon measured nanomechanical properties for a gas-atomized alloyed aluminum powder, additional work will be required to explore and develop an explicit relation between grain orientation and cold spray processing. However, discussion surrounding potential implications for cold spray materials consolidation were provided herein.

The article can be read free of charge by way of either of the following links:

https://www.researchgate.net/publication/341926219_Initial_Observation_of_Grain_Orientation_Dependent_Nanoindentation_Hardness_of_Al_6061_Gas-atomized_Powder 

https://www.vibgyorpublishers.org/content/ijmmp/fulltext.php?aid=ijmmp-5-050 

The TMS Annual Meeting & Exhibition made its way to San Diego, California in 2020, hosting over 4,000 engineers, scientists, and business leaders to share recent innovations in materials research. The Cote Research Group left its mark on the event, sharing one presentation and three posters on the novel work being done at WPI.

Postdoctoral fellow, Kyle Tsaknopoulos, presented her work on “Additive Manufacturing Powders for Solid State Additive Manufacturing Processing”. This research evaluated the use of a novel aluminum alloy designed specifically for additive manufacturing (AM). Results prove that designer powders are indeed viable for AM processing, though more work is needed to completely understand the ramifications of using these new alloys on processing and performance capabilities. This work was complemented by the poster of graduate student, Jack Grubbs, titled “Comparing Traditional and Designer Alloy Feedstock Powders for Additive Manufacturing”.

Two other Cote Research Group graduate students, Matt Gleason and Chris Massar, presented their posters in San Diego. Matt presented his poster, “Evaluation of Two Novel Techniques to Characterize the Bond Strengths of Cold Sprayed Single Particle Impacts”, where he highlighted new methods to ascertain the bond strengths of cold-sprayed single particles. Chris gave an update on his work, “Optimization of Heat-Treatment on Recycled Stainless Steel Powder for Cold Spray Applications”, where he noted that battlefield scrap steel can indeed be recycled for use in cold spray, given that proper heat treatment protocols are utilized before processing.

Additionally, Zeiss Microscopy presented on collaborative research with the Cote Research Group, "4D Nanoscale Imaging of Powder Feedstock Processing for Additive Manufacturing" in the Additive Technologies session, which was very well received.

The Materials Science & Technology (MS&T) conference is attended by over 3,200 materials researchers from across the world. The Cote Research Group presented four research papers, including an invited talk by Professor Cote, "Increasing Retention in Women in STEM Professions for the Perspectives" for the Emerging Materials Professionals symposium. Positive feedback from attendees was so overwhelming, ASM International will turn this presentation into an interactive webinar!

Postdoctoral fellow, Kyle Tsaknopoulos, presented two research papers on her work on developing a deeper understanding of feedstock powder by modeling and characterization for additive manufacturing applications, both of which were well received and found to be insightful into a rapidly developing area. The papers were: “Analysis of Metallic Feedstock Powder for Solid-state Additive Manufacturing” and “Characterization of Gas Atomized Aluminum Alloy Powder for Additive Manufacturing Applications.”

Ph.D. student, Chris Massar, presented on his research, “Characterization of Titanium Powder Produced from Battlefield Scrap for Additive Manufacturing.” This work characterizes a novel titanium powder produced by Molyworks Materials Corporation using recycled battlefield scrap material.  The research reveals that the powder is very competitive in its materials and mechanical properties, despite being made with a mobile process using scrap material.

Three posters were also presented by the group, including one presented by Ph.D. student Jack Grubbs, “Investigation of Traditional vs. Designer Feedstock Powders for Additive Manufacturing.” This work highlights the differences between novel “designer” feedstock powder developed exclusively for powder additive manufacturing (AM) processes. Current results indicate that designer powders for AM yield novel microstructures rarely seen in conventional feedstock, which may have significant impacts on the properties and performance of cold-sprayed deposits.

Another poster by graduate student Matt Gleason entitled “Development of a Technique to Evaluate the Bond Strengths of Cold Sprayed Single Particle Impacts” explores several novel methods that can be used to assess the bond strength of single cold spray splats.  

Professor Cote also presented a poster highlighting the group’s technique on “Microstructural Evolution Simulation for Property Prediction in Solid State Additive Manufacturing.” This work assists in developing novel metal feedstock powder for additive manufacturing techniques by simulating the powder properties, thereby reducing inefficient trial and error methods.

Professor Cote Co-Organizes World Congress on Integrated Computational Materials Science in Indianapolis, IN

The Cold Spray Action Team (CSAT) conference has emerged as the largest annual gathering of researchers, engineers and industry members focused on cold gas-dynamic spray manufacturing and applications. Since the first CSAT meeting was held at WPI in 2011, participation has experienced continued growth each year. 2019 was no exception to this trend as WPI's Cote Research Group and Solvus Global co-hosted the gathering at WPI and Solvus's headquarters in Worcester, MA, drawing more than 370 attendees from the international cold spray community. Speakers included members from industry (UTRC, Solvus Global, Lockheed Martin, and more), government labs and facilities (PNNL, ARL, NAVAIR, among others) and academia (Tampere University, Florida International University, and the University of Nottingham in partnership with The Welding Institute located in the UK). Needless to say, attendees represented a diverse array of community members, including personal from Moog, Northeastern University, MIT, VRC Metal Systems, WPI and Spee3D, to name a few.

Members of The Cote Research Group who attended CSAT 2019 included post-doctoral fellow Kyle Tsaknopoulos, Professor Danielle Cote, and graduate students Bryer Sousa, Christopher Massar, Matthew Gleason, and Jack Grubbs. Beyond simply attending the conference, both Matthew and Bryer presented research posters covering some of the ongoing work by our research group. Bryer's poster was titled "Spherical Nanomechanical Characterization of Novel Nanocrystalline Cu Cold Spray Manufactured Materials" and served to demonstrate the way in which mechanical flow curves can be obtained without the need for conventional tensile testing for a novel anti-pathogenic biomaterial fabricated via cold spray . On the other hand, Matthew focused upon "Surface Metrology for Cold Spray," which identified and applied techniques that can assist cold spray investigators interested in characterizing the surface roughness of their coatings, as well as correlating it to processing parameters and behavior.

The advent of numerical and computational methods, coupled with more affordable computational capacity, has enabled materials and manufacturing engineers to explore and optimize production through numerical analysis and simulation. Numerical methods have become so valuable to materials scientist that one of the leading professional societies in the field, The Minerals, Metal & Materials Society (TMS), held the 13th International Conference on Numerical Methods in Industrial Forming Processes (NUMIFORM 2019) in Portsmouth, NH, in 2019. As a “renowned forum for the exchange of ideas that advance the state-of-the-art in numerical simulations of material forming processes,” doctoral student Bryer Sousa was pleased to learn that his talk titled “Validation of the Cold Spray Through-Process Model as Applied to Solid-State Dissimilar Metal Joining via Dynamic Nanomechanical Testing” was accepted to this conference. Mr. Sousa is looking forward to the 14th conference in 2022.

Kyle Tsaknopoulos: April 17th was an exciting day for Ph.D. student Kyle Tsaknopoulos, as she defended her thesis, “Computational Thermodynamic and Kinetic Modeling and Characterization of Phase Transformations in Rapidly Solidified Aluminum Alloy Powders”. In her work, the internal microstructure of various aluminum alloy powders—namely, Al 6061, 7075, 2024, and 5056—were evaluated as a function of thermal processing. A coupled approach of thermodynamic and kinetic modeling, as well as advanced lab-based characterization techniques, allowed for in-depth analysis of the evolution of these microstructures. Congratulations, Dr. Kyle Tsaknopoulos, on your fantastic work!

Kristin Sundberg: WPI undergraduate alumna and Raytheon engineer Kristin Sundberg successfully defended her Ph.D. under Dr. Cote today, entitled, "Application of Materials Characterization, Efficacy Testing, and Modelling Methods on Copper Cold Spray Coatings for Optimized Antimicrobial Properties." Way to go, Kristin!

Derek Tsaknopoulos: Ph.D. candidate Derek Tsaknopoulos defended his thesis titled, “Optimization of Coupled Computational Modeling and Experimentation for Metallic Systems: Systematic Microstructural Feature – Mechanical Property Correlation for Cold-Sprayable Powders”. Derek has been working on powder for cold spray research since the summer of 2013 when he joined the group under Professor Sisson as an intern during his undergraduate studies. Great work Dr. Derek Tsaknopoulos!

The Cote Research Group attended the TMS Annual Meeting for 2019 in San Antonio Texas. The students in the group presented 3 presentations as well as 2 posters at this conference, some even presenting twice! The group also took advantage of the beautiful Texas weather, had dinner along the Riverwalk, and visited the Alamo!

Ph.D. candidate Derek Tsaknopoulos presented his work on “Thermo-Mechanical Property Design through Computational Modeling for Advanced Powder Metallurgy”, where he discussed the coupling of computational modeling and characterization for further understanding powder properties.

Ph.D. candidate Kyle Fitzpatrick-Schmidt presented her work on “Phase Transformations in Al Alloys using Computational Thermodynamic and Kinetic Modeling”, stemming from her recent publications with Caitlin Walde about secondary phases in aluminum alloy powders. She also presented a poster titled, “Compositional Effects on Secondary Phases in Al Alloy Powders”, where she discussed how different alloying elements play a role in the growth of secondary phases in powder.

Graduate student Bryer Sousa presented his work on nanoindentation and the effects of different metallurgical features in powders titled, “The Effect of Secondary Phases, Grain Orientations, and Grain Boundaries on the Nanomechanical Behavior of Rapidly Solidified Al Alloyed Powders.”

Graduate Student Chris Massar presented his first conference poster titled, “Characterization of Steel Powder Produced from Battlefield Scrap for Additive Manufacturing”.

Materials science has emerged as one of the major interdisciplinary fields in the global STEM landscape, bringing together metallurgists, physicists, mathematicians, engineers, chemists, and more to solve some of the worlds most pressing problems by designing new manufacturing methods and materials to meet those very needs. That being said, applying a materials engineering approach requires a nuanced appreciation of the fundamental aspects of the natural world and the relevant physics underpinning the behavior and properties of a given material. One such organization that recognizes this symbiosis between those who study first-principles and how the mechanics of the universe (physicists) and those who exploit this understanding to meet the material needs of our society (materials scientists and engineers) is the American Physical Society. Accordingly, graduate student and member of the Cote Research Group at WPI was one of 1000/s who either attended or presented at the APS March Meeting in 2019, which was held in Boston, MA. 

As a conference presenter, Bryer participated in the "Mechanical, Structural and Thermal Behavior of Metals" conference session supported and sponsored by the APS Division of Condensed Matter Physics. Moreover, the session was chaired by Avadh Saxena of the Los Alamos National Laboratory. Accordingly, the work Bryer presented was titled "Spherical Nanomechanical Characterization of Novel Nanocrystalline Cu Cold Spray Manufactured Materials." As someone who was sought after a physics and chemistry double major while at the University of Maine as an undergraduate student, Mr. Sousa found the experience refreshing and enjoyed sharing spherical nanoindentation methodologies to unveil the cold spray consolidated coating’s stress-strain response and flow behavior when a nano-structured material is considered. Bryer looks forward to attending and presenting at APS in the future.