Additive manufacturing (AM) using Laser Powder Bed Fusion (L-PBF) enables the fabrication of complex metal components with high precision. However, the as-printed surfaces often exhibit high roughness, residual stresses, and partially fused particles, which can negatively impact the mechanical performance, corrosion resistance, and fatigue life. Surface treatments are therefore required to improve surface integrity, reduce defects, and enhance functional properties such as corrosion resistance. This study explores the impact of chemical and mechanical post-processing methods including pickling, clean hot isostatic pressure (HIP), Hirtization, shot peening (SP), and isotropic super finishing (C.A.S.E.) on the microstructure, surface composition and topography of L-PBF printed HIP treated 316L stainless steel surfaces in relation to their corrosion resistance and extent of metal dissolution in artificial tap water with and without chlorides (1 and 3 wt% Cl⁻). Corrosion studies were also performed in NaCl (2.1 wt% Cl⁻) based on the ASTM G61 standard. The utilization of a combination of electrochemical, chemical, microscopic, and spectroscopic techniques discerned notable differences for the differently surface treated AM 316L in terms of microstructure, surface topography, surface roughness, surface oxide composition and barrier properties, metal dissolution, corrosion resistance as well as pitting corrosion resistance.

The toxicity of micro- and nanoparticles in cell culture studies is influenced by factors like particle size, agglomeration, dissolution of the particles, and methodological factors like sonication protocols. The main aim of this study was to investigate the influence of sonication on the particle size, dissolution, cytotoxicity, and dosing accuracy of nickel (Ni) metal and Ni oxide (NiO) particle dispersions. Such investigations are important to enable studies on the cellular uptake of different Ni substances in lung cells. The effect of sonication was evaluated in ultrapure water, two types of cell media, and A549 human lung cells using the tip and water bath methods. Extended sonication significantly decreased particle size and increased particle dissolution, emphasizing the need for optimized sonication conditions tailored to the specific particle type and study design. Observed findings demonstrate that the sonication step potentially can have a large impact on the results due to changes in particle characteristics, size, and dissolution, properties which are highly dependent on the particle type, solution composition, and sonication parameters. Although only small differences were observed in the limited assessment of cytotoxicity (A549 cells) in this study, further investigation is required to determine the impact of sonication on toxicity. This study also emphasizes the need to evaluate transferred dose samples due to the evident effects of agglomeration, sedimentation, and losses during sample transfer of particle dispersions. The study clearly illustrates that the choice of sonication protocol is particularly critical for toxicity studies, which are the basis of government regulatory decisions and human exposure limits.

Knowledge of corrosion (degradation of materials involving electrochemical and other chemical processes) is important for many engineering and science disciplines. Up to 875 billion dollars could be saved globally if existing corrosion knowledge had been applied. Industry and education assessors have identified corrosion education as a key area of higher education currently lacking in many engineering programs. In this paper, we present the design of a course in corrosion and surface protection given to engineering students in different materials science and chemistry Master’s programs at KTH Royal Institute of Technology, Stockholm, Sweden. We discuss the course design in terms of the students’ learning approach, concept learning, perceived usefulness of the course, psychology of predicting one’s future responsibilities for potential corrosion failures, and the need for future educational developments. We recommend including actual and real corrosion cases in corrosion classes to increase corrosion awareness, concept learning, and long-term memory of corrosion problems and concepts. Teaching a sense of responsibility for future corrosion failures is a challenging task that demands alternative and innovative approaches.

The effect of blue light on atmospheric corrosion of Cu and on the antimicrobial properties was explored upon exposure mimicking the condition of hygienic surface disinfection. The results show that blue light illumination enhanced the formation of Cu2O, resulting in a slightly increased corrosion resistance of Cu without pre-deposited NaCl, whereas the enhanced formation of Cu2O, CuCl and/or Cu(OH)3Cl on copper with pre-deposited NaCl caused concomitant corrosion product flaking and a reduced corrosion resistance. The blue light induced enhancement of Cu corrosion led to increased surface roughness and more pronounced integration of bacteria within the corrosion products.

The increasing use of weathering steels (WS) has raised concerns regarding the diffuse emission of alloying elements. This research paper investigates the release of iron (Fe) and the alloying elements (Cr), copper (Cu), manganese (Mn) and nickel (Ni) from two commercially available WS at urban field conditions in Stockholm, Sweden, during 1 year and in the laboratory at simulated urban conditions. The amount of released metals is evaluated and compared with recommended levels of metals in drinking water and the formation and evolution of the protective patina is studied in parallel to assess the influence on the metal release process. Only minor amounts of the alloying elements are released and is only linked to the outermost surface composition of the patina during the very beginning of the exposure. The released amounts are found to be lower compared with the corresponding levels recommended by the World Health Organisation for drinking water.

Manual dismantling, shredding, and mechanical grinding of waste from electrical and electronic equipment (WEEE) at recycling facilities inevitably lead to the accidental formation and release of both coarse and fine particle aerosols, primarily into the ambient air. Since diffuse emissions to air of such WEEE particles are not regulated, their dispersion from the recycling plants into the adjacent environment is possible. The aim of this interdisciplinary project was to collect and characterize airborne WEEE particles smaller than 1 mu m generated at a Nordic open waste recycling facility from a particle concentration, shape, and bulk and surface composition perspective. Since dispersed airborne particles eventually may reach rivers, lakes, and possibly oceans, the aim was also to assess whether such particles may pose any adverse effects on aquatic organisms. The results show that WEEE particles only exerted a weak tendency toward cytotoxic effects on fish gill cell lines, although the exposure resulted in ROS formation that may induce adverse effects. On the contrary, the WEEE particles were toxic toward the crustacean zooplankter Daphnia magna, showing strong effects on survival of the animals in a concentration-dependent way.

The EU Water Framework Directive stipulates that all EU waterways shall have good chemical and ecological status by 2027. Methodologies are described for how to assess and classify waterbodies and make 7-year management plans. Aquatic risk assessment methodologies and environmental quality standards are defined and a biotic ligand model methodology is available to assess the influence of water chemistry on the ability of aquatic organisms to take up metals. Aquatic status classification practices of naturally occurring river basin-specific metals are discussed, specifically how Cu and Zn water quality criteria guideline values have been adopted and defined for Swedish coastal and estuarine waters and how well they represent possible ecological risks. Calculations of bioavailability and ecotoxicity are conducted using recognised models for the Strommen-Saltsjon water body in Stockholm, in which naturally occurring metals, especially Cu, have among the highest background concentrations of Sweden. Proposals are made to improve risk assessment methodologies to better reflect the vitality of living organisms, and to what extent current levels of these metals in Swedish waterways may influence their welfare. The study concludes that a more local assessment including, e.g., studies of the benthic fauna would be relevant for ecological status classification.

Atmospheric aerosol pollutants are considered for the first time for the durability evaluation of non-metallic photovoltaic materials on the example of pristine and Al2O3-encapsulated Al-doped zinc oxide (AZO) window layers. The AZO samples were exposed to a varied temperature and humidity cycle, completed or not by a daily deposition of (NH4)2SO4 or NaCl aerosols, typical pollutants in rural and marine environments, respectively. The samples exposed with and without the pollutants were compared after 1 and 2 weeks of the test. Optical transmittance and conductivity significantly degraded only for the samples exposed with the pollutants. Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy evidenced localized dissolution of the AZO film and chemical modification of the Al2O3 encapsulation. The most severe degradation was caused by (NH4)2SO4, which was attributed to the high stability of soluble [Zn (NH3)42+] complexes. The Al2O3 encapsulation improved chemical and physical stability of AZO in the presence of (NH4)2SO4 but not in the presence of NaCl. The latter can be explained by pitting corrosion of Al2O3. Optical transmission curves are coherent with the AZO layer thinning in the presence of NaCl and very localized AZO dissolution (most likely grain boundary etching) in the presence of (NH4)2SO4. The enhanced degradation of encapsulated AZO in the presence of atmospheric aerosol pollutants suggests that they cannot be neglected in the evaluation of barrier protection capacities of novel encapsulates and, more generally, in the outdoor durability assessment of novel photovoltaic materials and devices. 

Short‐ and long‐term zinc runoff are studied at field and laboratory conditions to show that a laboratory setup can simulate field conditions and to investigate how prepatination influences the zinc runoff process. Results from four differently patinated zinc surfaces exposed at laboratory conditions, seven consecutive individual 4‐h rain events, and exposure at field conditions for 2 years show that the laboratory setup does simulate field conditions provided that the limitations of the laboratory are considered. It is also determined through corrosion product characterization that denser established corrosion products (patina) have a lower runoff than bulky porous or newly formed corrosion products.

Increasing the use of hygienic high-touch surfaces with antimicrobial properties in health care and public spaces is one way to hinder the spread of bacteria and infections. This study investigates the antimicrobial efficacy and surface reactivity of commercial laminate and powder coated surfaces treated with silver-doped phosphate glass as antimicrobial additive towards two model bacterial strains, Escherichia coli and Bacillus subtilis, in relation to surface weathering and repeated cleaning. High-touch conditions in indoor environments were simulated by different extents of pre-weathering (repeated daily cycles in relative humidity at constant temperature) and simplified fingerprint contact by depositing small droplets of artificial sweat. The results elucidate that the antimicrobial efficacy was highly bacteria dependent (Gram-positive or Gram-negative), not hampered by differences in surface weathering but influenced by the amount of silver-doped additive. No detectable amounts of silver were observed at the top surfaces, though silver was released into artificial sweat in concentrations a thousand times lower than regulatory threshold values stipulated for materials and polymers in food contact. Surface cleaning with an oxidizing chemical agent was more efficient in killing bacteria compared with an agent composed of biologically degradable constituents. Cleaning with the oxidizing agent resulted further in increased wettability and presence of residues on the surfaces, effects that were beneficial from an antimicrobial efficacy perspective.