Comparative Evaluation of Titanium Feedstock Powder Derived from Recycled Battlefield Scrap vs. Virgin Powder for Cold Spray Processing.

Gas-atomization is extensively used to produce metallic feedstock powders for additive manufacturing processes, including gas dynamic cold spray processing. This work explores the potential utility of on-demand recycled titanium scrap feedstock powder as a viable substitute for virgin powder sources. Three recycled titanium powders were atomized from different battlefield scrap sources using a mobile foundry developed by MolyWorks Materials Corporation. Recycled titanium alloy powders were compared against virgin Ti-6Al-4V powder to verify there were no significant variations between the recycled and virgin materials. Powder characterization methods included chemical analysis, particle size distribution analysis, scanning electron microscopy (SEM), Karl Fischer (KF) titration moisture content analysis, X-ray diffraction (XRD) phase analysis, microparticle compression testing (MCT), and nanoindentation. Results indicate that recycled titanium powder provides a viable alternative to virgin titanium alloy powders without compromising mechanical capabilities, microstructural features, or ASTM-specified composition and impurity standards. The results of this work will be used to aid future research efforts that will focus on optimizing cold spray parameters to maximize coating density, mechanical strength, and hardness of recycled titanium feedstock powders. "Cold spray" presents opportunities to enhance the sustainability of titanium component production through the utilization of recycled feedstock powder, mitigating issues of long lead times and high waste associated with the use of conventional virgin feedstock.

Establishing a Framework for Fused Filament Fabrication Process Optimization: A Case Study with PLA Filaments.

Developments in polymer 3D printing (3DP) technologies have expanded their scope beyond the rapid prototyping space into other high-value markets, including the consumer sector. Processes such as fused filament fabrication (FFF) are capable of quickly producing complex, low-cost components using a wide variety of material types, such as polylactic acid (PLA). However, FFF has seen limited scalability in functional part production partly due to the difficulty of process optimization with its complex parameter space, including material type, filament characteristics, printer conditions, and "slicer" software settings. Therefore, the aim of this study is to establish a multi-step process optimization methodology-from printer calibration to "slicer" setting adjustments to post-processing-to make FFF more accessible across material types, using PLA as a case study. The results showed filament-specific deviations in optimal print conditions, where part dimensions and tensile properties varied depending on the combination of nozzle temperature, print bed conditions, infill settings, and annealing condition. By implementing the filament-specific optimization framework established in this study beyond the scope of PLA, more efficient processing of new materials will be possible for enhanced applicability of FFF in the 3DP field.

Evolution of Fe-Rich Phases in Thermally Processed Aluminum 6061 Powders for AM Applications.

Gas-atomized powders are frequently used in metal additive manufacturing (MAM) processes. During consolidation, certain properties and microstructural features of the feedstock can be retained. Such features include porosity, secondary phases, and oxides. Of particular importance to alloys such as Al 6061, secondary phases found in the feedstock powder can be directly related to those of the final consolidated form, especially for solid-state additive manufacturing. Al 6061 is a heat-treatable alloy that is commonly available in powder form. While heat treatments of 6061 have been widely studied in wrought form, little work has been performed to study the process in powders. This work investigates the evolution of the Fe-containing precipitates in gas-atomized Al 6061 powder through the use of scanning and transmission electron microscopy (SEM and TEM) and energy dispersive X-ray spectroscopy (EDS). The use of coupled EDS and thermodynamic modeling suggests that the as-atomized powders contain Al13Fe4 at the microstructure boundaries in addition to Mg2Si. After one hour of thermal treatment at 530 °C, it appears that the dissolution of Mg2Si and Al13Fe4 occurs concurrently with the formation of Al15Si2M4, as suggested by thermodynamic models.

Application of Mass Finishing for Surface Modification of Copper Cold Sprayed Material Consolidations.

The surface roughness of additively manufactured (AM) components can have deleterious effects on the properties of the final part, such as corrosion resistance and fatigue life. Modification of the surface finish or parts produced by AM processes, such as cold spray, through methods such as mass finishing, can help to mitigate some of these issues. In this work, the surface evolution of as-produced copper cold sprayed material consolidations was studied through mass finishing. Three different copper powders attained by different production methods and of different sizes were used as feedstock. The surface topography of the cold spray deposits was measured as a function of the mass finishing time for the three copper cold spray samples and analyzed in terms of relative area and complexity, revealing an inverse correlation relating material removal rate and hardness/strength of the cold sprayed deposits. The material removal rate was also affected by the quality of the cold spray deposition, as defined by deposition efficiency (DE). Large initial drops in relative area and complexity are also likely due to the removal of loosely bonded powders at the start of mass finishing. Based on this study, the cold spray parameters that affect the rate of mass finishing have been explored.

On the emergence of antibacterial and antiviral copper cold spray coatings.

In this literature review, the antipathogenic properties and contact-mediated antibacterial and antiviral performance of copper cold spray surfaces are assessed and compared with alternative antimicrobial materials that are able to kill and/or inactivate infectious agents via direct contact. Discussion is also provided concerning the suitability of copper cold spray material consolidations as biocidal and viricidal surfaces that retain long-term functionality as a preventative measure against fomite transmission of pathogenic agents and hospital-acquired infections from contaminated high-touch surfaces. Numerable alternative antimicrobial coatings and surfaces that do not rely upon the oligodynamic action of copper are detailed. Given the ongoing need for recognition of said alternative antimicrobial materials by authoritative agencies, such as the U.S. Environmental Protection Agency, the relevant literature on non-copper-based antipathogenic coatings and surfaces are then described. Furthermore, a wide-ranging take on antipathogenic copper cold spray coatings are provided and consideration is given to the distinctive grain-boundary mediated copper ion diffusion pathways found in optimizable, highly deformed, copper cold spray material consolidations that enable pathogen inactivation on surfaces from direct contact. To conclude this literature review, analysis of how copper cold spray coatings can be employed as a preventative measure against COVID-19 was also presented in light of on-going debates surrounding SARS-CoV-2's non-primary, but non-negligible, secondary transmission pathway, and also presented in conjunction with the inevitability that future pathogens, which will be responsible for forthcoming global pandemics, may spread even more readily via fomite pathways too.

On the Elemental Impact Factor, a Method to Determine an Alloy's Compositional Influences upon Phase Stability and Metallurgical Material Properties.

Design-driven materials engineering is gaining wider acceptance with the advancement and refinement of commercially available thermodynamic software as well as enhanced computing power. Computationally designed materials are a significant improvement over the more common and resource-intensive experimental approach to materials design by way of trial and error. While not entirely eliminating experimental methods for alloy design, thermodynamic and kinetic models provide accurate predictions of phases within a given alloy, which enables material properties to be calculated. Accordingly, the present paper introduces a new technique that offers a systematic method of material design by way of utilizing commercial computational software, which has been termed the elemental impact factor. In turn, the present manuscript considers Al 6061 as a proof-of-concept metallic alloy system for elemental impact factor substantiation. Effects of chemical composition on resultant equilibrium and metastable material phases as well as properties can be efficiently assessed with the elemental impact factor framework for metallurgical materials design. Desired phases or properties may be produced by adding elements with a positive elemental impact factor, while deleterious phases or undesired properties may be reduced by adding elements with a negative elemental impact factor. Therefore, the elemental impact factor methodology was presented and then demonstrated herein with examples that showcase the technique's potential applications and utility for integrated structure-processing-property-performance analysis.

Antimicrobial Copper Cold Spray Coatings and SARS-CoV-2 Surface Inactivation.

This article contextualizes how the antimicrobial properties and antipathogenic contact killing/inactivating performance of copper cold spray surfaces and coatings and can be extended to the COVID-19 pandemic as a preventative measure. Specifically, literature is reviewed in terms of how copper cold spray coatings can be applied to high-touch surfaces in biomedical as well as healthcare settings to prevent fomite transmission of SARS-CoV-2 through rapidly inactivating SARS-CoV-2 virions after contaminating a surface. The relevant literature on copper-based antipathogenic coatings and surfaces are then detailed. Particular attention is then given to the unique microstructurally-mediated pathway of copper ion diffusion associated with copper cold spray coatings that enable fomite inactivation.

Barriers to a Timely Discharge From Short-Term Care in VA Community Living Centers.

This study aimed to identify the barriers to a timely discharge from short-term care in Veterans Health Administration (VHA) Community Living Centers (CLCs). Ninety-nine interviews were conducted with CLC staff in leadership and direct-care positions in eight varied CLCs. Major themes identified through qualitative analysis as barriers to a timely discharge were a lack of patients' financial resources, low social support, and reluctance of some veterans and staff to view a timely veteran discharge as their goal. Staff also perceived that barriers were much more difficult to overcome in regions where community-based long-term services and supports were limited or nonexistent. Because VHA has lagged behind Medicaid more generally in terms of investment in these types of services, additional strategies are warranted to achieve the important policy goal of deinstitutionalizing VHA care and returning veterans to their homes in the community.

An Unintended Consequence of Culture Change in VA Community Living Centers.

OBJECTIVE: Although a growing body of evidence suggests that culture change and its corollary, person-centered care improves resident outcomes in the nursing home setting, little is known about the effect of culture change in a postacute setting in which patients receive skilled nursing and rehabilitation services for a relatively short period of time before returning home. DESIGN: Data for this study were collected as part of a larger project to understand the impact of Veterans Health Administration (VHA) policies to shift the mission of VHA Community Living Centers (CLCs) from long-stay custodial care to short-stay skilled nursing and rehabilitative care. RESULTS: Although qualitative data collected during interviews from site visits to eight geographically diverse CLCs suggest an increase in the quality of life and care for veterans, interview data also indicate an unintended consequence. Specifically, staff described how aspects of the homelike environment, relationship-based care delivery, and attention to veterans' preferences that characterize culture change can prolong a veteran's length of stay beyond treatment completion. In addition to providing skilled nursing and rehabilitation, VHA CLCs also serve a latent function of providing a comfortable home and a peer community for veterans to connect and socialize with one another. A congregate living environment for persons with the shared symbolic status of being a veteran is unique to VHA CLCs. Strong bonding among peers and staff as well as staff respect for veterans' service to the country may increase their sense of obligation to keep veterans past their expected discharge date. CONCLUSION: Our findings suggest that the complexities of culture change and veteran- centered care in a short-term care setting may be underrecognized. We discuss how findings may also be relevant for the non-VHA sector.

The rise of concurrent care for veterans with advanced cancer at the end of life.

BACKGROUND: Unlike Medicare, the Veterans Health Administration (VA) health care system does not require veterans with cancer to make the "terrible choice" between receipt of hospice services or disease-modifying chemotherapy/radiation therapy. For this report, the authors characterized the VA's provision of concurrent care, defined as days in the last 6 months of life during which veterans simultaneously received hospice services and chemotherapy or radiation therapy. METHODS: This retrospective cohort study included veteran decedents with cancer during 2006 through 2012 who were identified from claims with cancer diagnoses. Hospice and cancer treatment were identified using VA and Medicare administrative data. Descriptive statistics were used to characterize the changes in concurrent care, hospice, palliative care, and chemotherapy or radiation treatment. RESULTS: The proportion of veterans receiving chemotherapy or radiation therapy remained stable at approximately 45%, whereas the proportion of veterans who received hospice increased from 55% to 68%. The receipt of concurrent care also increased during this time from 16.2% to 24.5%. The median time between hospice initiation and death remained stable at around 21 days. Among veterans who received chemotherapy or radiation therapy in their last 6 months of life, the median time between treatment termination and death ranged from 35 to 40 days. There was considerable variation between VA medical centers in the use of concurrent care (interquartile range, 16%-34% in 2012). CONCLUSIONS: Concurrent receipt of hospice and chemotherapy or radiation therapy increased among veterans dying from cancer without reductions in the receipt of cancer therapy. This approach reflects the expansion of hospice services in the VA with VA policy allowing the concurrent receipt of hospice and antineoplastic therapies. Cancer 2016;122:782-790. © 2015 American Cancer Society.