Surface Morphology Of Layers Research Articles

Influences of powder characteristics and recoating conditions on surface morphology of powder bed in metal additive manufacturing

Metal additive manufacturing technology requires a real-time monitoring and feedback control system to assure the quality of the final products. In particular, it is essential to reveal the phenomena of recoating and melting-solidification processes in laser powder bed fusion using a real-time monitoring system because they influence strongly the occurrence of defects. This study was conducted to elucidate the correlation among the powder characteristics, recoating conditions, and surface morphology of a powder bed in the recoating process to determine the relationship between the surface morphology of the powder bed and the final product quality. To this end, a surface morphology measurement system composed of a powder recoating test bench and a layer surface morphology measurement apparatus was first designed and fabricated. Then, it was used to quantify the surface morphology of the powder bed. Specifically, the influences of the different powder characteristics and the recoating parameters of the powder supply ratio and recoating speed on the surface morphology of the powder bed were investigated using various powders of Al-10Si-0.4Mg (AlSi10Mg) alloy and Inconel 718 (IN718) alloy. The surface morphology of the powder bed was measured as the value of 2σ at a resolution of 30 μm in height. It was found that the angle of repose and the basic flow energy of the bulk powder are promising parameters for evaluating the surface morphology. The surface morphology was significantly affected by the powder characteristics and recoating speed. The value of 2σ for the AlSi10Mg powder increased rapidly over a recoating speed of 50 mm/s for all powders. The value of 2σ for the irregularly shaped AlSi10Mg powder was approximately 19 μm, and the 2σ values for the other powders were approximately 17 μm at a recoating speed of 15 mm/s. However, at a recoating speed greater than 300 mm/s, the irregularly shaped powder exhibited better surface morphology than did the spherical powder. The recycling process deteriorated the flowability of the new powder. However, the surface morphology of the spherical recycled powder was similar to that of the spherical powder. Consequently, the correlation among the powder characteristics, recoating conditions, and surface morphology of the powder bed was revealed by employing the surface morphology measurement system. Quantification of the surface morphology of the powder bed using the monitoring system facilitates control of the recoating process to prevent the occurrence of defects.

Low Concentration Acetone Sensing with ZnO-TiO2 Composites Nanoarrays: A Comparative Study Under Light Illumination

1.Introduction In the past decade, numerous efforts have been taken to develop one-dimensional nanomaterials with specific morphologies such as nanowires and/or NAs because of their large surface to volume ratio. These morphologies also offer a possibility for surface modification so their versatile material properties can be used for different applications. ZnO NAs has been widely used as a sensing layer but the major drawbacks of metal-oxide based sensitive layers are their lack of sensitivity at low operating temperatures. In this work, the ZnO NAs are coated with a thin TiO2 layer to form ZnO-TiO2 composite materials. The combination of ZnO and TiO2 has attained significant attention because of the synergistic advantages these materials could contribute [1]. Several studies have used ZnO-TiO2 composites as a gas sensing layer, however there is a void in the literature, especially in NAs structures for acetone sensing. Hence, this work centres on the investigation of tailored ZnO and TiO2 composites in NAs structures under light illumination for their sensing capability towards low concentrations of acetone (<100 ppm). 2.Experimental In this work ZnO-TiO2 based composite NAs were synthesised by coating a thin layer of (~50 nm) TiO2 using low-temperature CVD on the ZnO NAs grown by hydrothermal synthesis. The composition of TiO2 and ZnO added, the annealing temperature and time plays a crucial role in determining the crystal phase of the material [2]. The TiO2 coated ZnO NAs were annealed at 550 °C (1h, air) to form ZnO-TiO2 core-shell NAs and further annealed at 650 °C (1h, air) to form a mixed metal oxide, hence ZnTiO3 NAs. The surface morphology of the sensitive layers developed were studied using FEI Verios 460L SEM instrument. The acetone vapor sensing event included acetone exposure and recovery (under dry air) steps, each set at 5 minutes. All sensors developed were tested toward different acetone concentrations (ranging from 1.2 to 12.5 ppm). The acetone sensing performance was tested under operating temperatures 45 - 350 °C by applying a potential bias of 6 V DC. A UV light source with a wavelength of 365 nm (maximum intensity up to 2024 µW·cm-2) was used for light-assisted gas sensing. 3.Results and discussion The synthesis procedure schematic and the corresponding SEM images are presented in Figure. 1a-e. The ZnO NAs had an average length and diameter of 1.5 µm and ~30 nm, respectively. The images (Figure. 1d-e) suggest that the thicknesses of the NAs increased significantly after the ~50 nm TiO2 coating. The gas sensing performance of the developed sensors showed a poor dynamic range (Figure. 2a) at 85 °C in dark conditions. When illuminated with light, the sensors showed enhanced response magnitudes and dynamic range (Figure. 2b and 2c). The photo excitation of the sensitive layers has been shown to increase the electron carrier density of the layer, which in turn is hypothesized to facilitate the formation of oxygen ions on the surface of the sensor, which results in a significant increase in sensor response magnitude [3]. In comparison to the pristine ZnO control sensor, the ZnO-TiO2 composite NAs had much higher response magnitude. The annealing of the ZnO NAs coated with TiO2 initiates the diffusion of Ti from the titania shell to the zinc core and vice versa. The Zn2+ ions get substituted with Ti4+ ions in the core thereby the ZnO core becomes electron rich and also increases the affinity to adsorb more oxygen on the surface. The possible reason for the ZnO-TiO2 core-shell NAs to have higher response than the ZnO NAs could be the reactivity of TiO2 in tailored NAs morphology with high surface to volume ratio. Further, the formation of ZnTiO3 NAs introduces structural defects and oxygen deficiencies which results in higher oxygen adsorption on their surface in comparison to pure ZnO sensors. The LoD of the ZnO NAs, ZnO-TiO2 core-shell NAs and ZnTiO3 NAs sensors calculated to be 90, 70, 30 ppb respectively and the sensitivity, adsorption (t90-ads) and desorption (t90-des) time are presented in Table. 1. 4.Acknowledgements The support of the Australian Research Council Discovery Project DP150101939 is acknowledged. All authors acknowledge the RMIT Microscopy and Microanalysis Facility (RMMF) for their scientific and technical assistance and for providing access to their comprehensive infrastructure and research facilities.

Magnetic properties and kinetic roughening study of prepared polyaniline: lead ferrite, cobalt ferrite and nickel ferrite nanocomposites electrodeposited thin films

The purpose of this study is preparation of polyaniline–lead ferrite, polyaniline–cobalt ferrite and polyaniline/nickel ferrite thin layers. The electromagnetic pollution is a serious problem in the world that can be solved by electromagnetic interference (EMI) shielding. The EMI layers can be synthesized by conductive layer composed by magnetic particles. Crystallite size of samples was studied by (XRD) analyze via Debye–Scherrer and Williamson–Hall equations. The X-ray diffraction XRD patterns confirm the crystalline structure of the samples. The surface morphology of the composite layers was investigated by scanning electron microscopy (SEM) and the effect of thickness and different composed particles was investigated. The percentage of the constituents and purity of samples was studied by energy dispersive X-ray analysis (EDX) analysis. Also, surface roughness and kinetic roughening of thin films was investigated using atomic force microscopy (AFM). Hysteresis loop of the magnetic samples were analyzed by vibrating sample magnetometer (VSM). These new easy prepared nanocomposites introduce a suitable and effective coating for electromagnetic interference (EMI) shielding.

The current transformer mechanism and structural properties of novel Al/BODIPY/pSi and Au/BODIPY/pSi heterojunctions

In this study, the performance of BODIPY dye-based organic layers was investigated with diode applications. Gold (Au) and aluminum (Al) rectifier contacts were evaporated on the BODIPY dye-based organic layers. The effect of the Au and Al metal contacts were examined under different illumination and frequency conditions. The surface morphology of the organic layers was characterized with an atomic force microscopy. The electrical measurements, such as current-voltage, capacitance-voltage and conductance-voltage, were measured in the dark and at room temperature. The photovoltaic performance of the organic layers was investigated under various illumination conditions. Eight devices were made with four different organic materials using the Au and Al metal contacts. The effects of Al and Au on the devices were compared with the electrical measurements. It was concluded that the performance of the devices made with Au was better, as there was oxidation in the devices made with Al.

Composition uniformity and large degree of strain relaxation in MBE-grown thick GeSn epitaxial layers, containing 16% Sn

We systematically investigate the compositional uniformity, degree of strain relaxation (DSR), defect structure and surface morphology of GeSn epitaxial layers with 16% Sn, grown by low temperature molecular beam epitaxy (MBE) on Ge-buffered Si(001) substrates. Combining atom probe tomography, reciprocal space mapping, cross-sectional transmission electron microscopy, and atomic force microscopy analyses, we demonstrate that for a layer thickness of , a high DSR (∼70%) can be achieved, while maintaining compositional uniformity at the atomic scale. We find no evidence of Sn clustering in the bulk, or Sn segregation to the surface, for at least this value of . The observed compositional uniformity contrasts the well-established phenomenon of strain-relaxation enhancement of Sn content in chemical vapour deposition (CVD) growth of GeSn. The defect structure leading to strain relaxation in these MBE-grown GeSn epitaxial layers is also distinctly different from that observed in CVD growth of the alloy. We observe the co-existence of highly strain-relaxed and pseudomorphically strained regions in the grown epilayers, tentatively explained by bunching of threading dislocations. Considering that MBE growth of GeSn epitaxial layers, with such high-Sn content and layer thickness, has not been reported before, our results are encouraging for future improvements in design and fabrication of group-IV-based mid-infrared photonic devices.

Effects of MOVPE Growth Conditions on GaN Layers Doped with Germanium.

The effect of growth temperature and precursor flow on the doping level and surface morphology of Ge-doped GaN layers was researched. The results show that germanium is more readily incorporated at low temperature, high growth rate and high V/III ratio, thus revealing a similar behavior to what was previously observed for indium. V-pit formation can be blocked at high temperature but also at low V/III ratio, the latter of which however causing step bunching.

Study on Preparation and Ns-Laser Damage of HfO&amp;lt;sub&amp;gt;2 &amp;lt;/sub&amp;gt;Single Layers

The effects of the main parameters of argon flux, oxygen flux and beam voltage on the surface morphology, transmittance spectrum and laser damage of the HfO2 single layers prepared by ion beam sputtering are studied. The HfO2 amorphous single layers have porous surface morphologies. Different processes will cause differences in coatings absorption and surface morphology, which in turn will cause changes in the spectral transmittance curve. The ion beam sputtering HfO2 single layers have high content of argon (4.5% - 8%). The laser damage of HfO2 single layers is related to argon inclusions and non-stoichiometric defects. The changes of argon flux and beam voltage have a greater impact on argon content and O/Hf ratio. When the argon content in the coatings is lower and the O/Hf ratio is higher, the laser damage thresholds of the HfO2 single layers are higher.

Enhanced electrochemical properties of sodium‐doped lithium‐rich manganese‐based cathode materials

AbstractIn this work, sodium has been successfully doped into the layered lithium‐rich manganese‐based cathode material through melt impregnation. The as‐prepared samples are characterized by multiple techniques of x‐ray diffraction, scanning electron microscopy, transmission electron microscopy, x‐ray photoelectron spectroscopy and the electrochemical measurements. The results show that sodium doping hardly changes the layered structure and surface morphology of pristine sample. The sample particles of sodium‐doped materials exhibit polygonal shape similar to prism. The sodium‐doped material possesses high rate performance and good cycling stability, and the initial charge and discharge capacity reaches 340.2 mA h g−1 and 249.0 mA h g−1 at a current density of 20 mA g−1, respectively. The initial coulombic efficiency of the first cycle is 73 %. After running 100 repeated cycles at 40 mA g−1 and 100 mA g−1, the discharge capacity could still be maintained at about 230.0 mA h g−1 and 220.0 mA h g−1, respectively. Moreover, the voltage attenuation is effectively suppressed during charging/discharging cycles.

Arc Plasma Deposition of TiO2 Nanoparticles from Colloidal Solution

Surface modifications of metallic biomaterials can in great merit, improve the properties of the hard-tissue implants and in that way contribute to the success of the surgical implantation process. Coating deposition stands out as one of the many surface-modifying techniques that can be used to improve implant surface properties and, in turn, induce successful osseointegration. Deposition of the TiO2 layer on the surface of the metallic implants has a great potential to enhance not only their osseointegration ability but also their biocompatibility and corrosion resistance. In the present study, the possibility of successful deposition of the TiO2 layer on the surface of commercially pure titanium (CP-Ti), as the most commonly used metallic implant material, by spraying the colloidal nanoparticles aqueous solution in the electric discharge plasma at atmospheric pressure was investigated. To characterize the colloidal TiO2 nanoparticle solution, used for the coating deposition process, transmission electron microscopy (TEM) was utilized, while scanning electron microscopy (SEM) and optical profilometry were used to investigate the deposited surface layer morphology and quality. Estimation of the deposited film quality and texture was used to confirm that the arc plasma deposition technique can be successfully used as an advanced and easy-to-apply method for coating the metallic implant material surface with the bioactive TiO2 layer which favors the osseointegration process through the improvement of the implant surface properties. The TiO2 coating was successfully deposited using the arc plasma deposition technique and covered the entire surface of the CP-Ti substrate without any signs of coating cracking or detachment.

Electrochemical Oxidation of Ti15Mo Alloy-The Impact of Anodization Parameters on Surface Morphology of Nanostructured Oxide Layers.

It is well-known that the structure and composition of the material plays an important role in the processes occurring at the surface. In this paper, a surface morphology of nanostructured oxide layers electrochemically grown on Ti15Mo, tuned by applying different anodization parameters, was investigated in detail. The one-step anodization of Ti15Mo alloy was performed at room temperature in an ethylene glycol-based electrolyte containing 0.11 M NH4F and 1.11 M H2O. Different anodization times (ranging from 5 to 60 min) and applied potentials (40–100 V) were tested, and the surface morphology, elemental content, and crystalline structure were monitored by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffractometry (XRD), respectively. The results showed that contrary to the multistep anodization of titanium foil, the surface morphology of anodic oxide obtained via the one-step process contains the nanoporous outer layer covering the nanotubular structure. What is more, the pore diameter (Dp) and interpore distance (Dint) of such layers exhibit different trends than those observed for anodization of pure titanium. In particular, at a certain potential range, a decrease in both Dp and Dint with increasing potential was observed. However, independently on the used anodization conditions, the elemental content of oxide layers remained similar, showing the amount of molybdenum at c.a. 15 wt.%. Finally, the amorphous nature of as-anodized layers was confirmed, and their optical band-gap was determined from the diffuse reflectance UV–Vis spectra. It was found that Eg is tunable to some extent by changing the anodizing potential. However, further thermal treatment in air at 400 °C resulted in the anatase phase formation that was accompanied by a significant Eg reduction. Therefore, we believe that the presented results will greatly contribute to the understanding of anodic formation of nanostructured functional oxide layers with tunable properties that can be applied in various fields.

Hydrothermal growth of CdSe nanorods for bulk heterojunction solar cells applications

Hydrothermal technique is used to prepare CdSe nanorods (NRs) with the aim of using them in bulk heterojunction solar cell. The CdSe NRs are found to have crystallite size of about 8 nm. The CdSe NRs are characterized by energy dispersive X-ray, X-ray diffraction and high resolution transmission electron microscope. The CdSe NRs are blended with poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and used as active layer in the bulk heterojunction solar cells in the structure of ITO/MoO3/MEH-PPV:CdSe NRs/LiF/Al where ITO is indium tin oxide. The effect of CdSe NRs concentration on the photovoltaic properties of the devices has been studied. The surface morphology and topography of the active layers are examined by scanning and atomic force microscopes, respectively. In addition, the UV–Vis spectra of the active layers together with the pure polymer and CdSe are investigated. By varying the concentration of CdSe NRs, the efficiency of the devices is optimized in which a maximum photoelectrical conversion efficiency of about 2% is obtained.

In Vitro Biocompatibility of Surface Corrosion Films upon Magnesium

Biocompatibility is an essential requirement for implantable biomaterials, particularly for magnesium (Mg) and its alloys which are being pursued as biodegradable implants. In this study, the influence of corrosion-products layers upon the surface of pure Mg specimens was evaluated through direct contact with simulated body fluid. The immersion of pure Mg specimens was conducted in Dulbecco’s modified Eagle’s medium (DMEM) at physiological conditions over defined time durations (from 24 h to 14 d). Surface morphology, chemical composition, and cross-sectional structure of corrosion layers were examined by means of focused ion beam, scanning electron microscopy, and x-ray diffraction. Results reveal a duplex Mg(OH)2/CaPO4 corrosion layer was produced upon pure Mg as a result of immersion in DMEM, similar to the in vivo surface corrosion films observed on pure Mg in the murine artery. The concentration of Mg in the surface corrosion film decreased with immersion time, from approximately 64 wt% (1 d) to approximately 22 wt% (14 d). Conversely, Ca and P, representing the key constituents in DMEM, were incorporated in corrosion products, resulting in unique surfaces being presented to cells as a function of Mg dissolution. MG63 osteoblast proliferation assay demonstrates comparative cell viability on all corroded surfaces obtained through immersion in DMEM for 1 d, 3 d, 7 d, and 14 d, varying from 90% to 100%. Cell viability on all corroded surfaces was higher than that of bare metal surface (82%), signifying enhanced biocompatibility of corroded surfaces related to the bare metal surface.

High performance InGaAs channel MOSFETs on highly resistive InAlAs buffer layers

We investigated the effect of growth temperature on the structural and electrical properties of InAlAs layers grown on InP (100) substrates by metalorganic chemical vapor deposition (MOCVD) method. Flat surface morphology of InAlAs layers with root mean square (RMS) surface roughness values below 0.4 nm were obtained at 500 °C and 660 °C, while RMS surface roughness values of InAlAs layers grown in the region of intermediate temperature increase from 0.7 nm at 540 °C to 3.9 nm at 620 °C with increasing growth temperature. This increase in surface roughness is caused by the phase separation of the InAlAs layer, which is divided into In-rich and Al-rich column regions. The resistivity values of the InAlAs layers grown at 500 °C and 660 °C, in which the phase separation was not observed, were analyzed by the transmission line method (TLM) and those values were ~1 × 104 Ω·cm and 0.06 Ω·cm, respectively. We propose that oxygen atoms being incorporated into InAlAs layers during growth were the cause effect explaining the change in resistivity depending on the growth temperature. In order to evaluate high-resistivity InAlAs layers grown at 500 °C for a buffer layer of devices, we fabricated InGaAs-channel metal oxide field effect transistors (MOSFETs). The on/off current ratio values obtained from ID-VG transfer measurement was a value of 6.10 × 105, indicating a high-performance characteristic.

Formation and properties of mixed copper sulfide (CuxS) layers on polypropylene

The sorption-diffusion method was used to obtain nonstoichiometric copper sulfide layers on polypropylene. Copper sulfide layers consisted of monoclinic structures chalcocite Cu2S and djurleite Cu1.8S. This multiphase composition of obtained thin layers was confirmed by X-ray diffraction spectroscopy. The surface morphology of layers was studied by SEM micrographs and the surface roughness was calculated from AFM data. The value for the direct bandgap for the CuxS thin layers approximately equals 2.53 eV. The changes in mechanical properties (tensile strength analysis) of polypropylene films through the CuxS layer deposition process were investigated.

Experimental Investigation on Recast Layer and Surface Roughness on Aluminum 6061 Alloy During Magnetic Field Assisted Powder Mixed Electrical Discharge Machining

Surface integrity aspects have been recognized as key research areas for manufacturing industries for determining the quality, longevity and reliability of machined engineering components. Magnetic field assisted powder mixed electrical discharge machining (MFAPM-EDM) is technological advancement in EDM process where the performance and stability of process increases by adding the suitable conductive powder in dielectric and using magnetic field. Aluminum 6061 alloy as workpiece was selected due to growing use in aviation, automotive, naval industries. In the present work, the study was conducted on EDM machined aluminum 6061 alloy with aluminum powder added in EDM oil and using magnetic field to analyze the effect of machining parameters on surface roughness, recast layer thickness and surface morphology. The input machining parameters, namely peak current, pulse on duration, pulse off duration, magnetic field and concentration of powder have been varied during the MFAPM-EDM process. Box–Behnken design approach of response surface methodology (RSM) was employed for experimental design to carry out the experiments. Quadratic model for predicting the surface roughness and recast layer thickness was developed using analysis of variance and regression analysis. Improvement in surface roughness and recast layer thickness were observed on machining with MFAPM-EDM process. Surface roughness and recast layer thickness were mostly influence by peak current and pulse on duration followed by concentration of powder and magnetic field. The surface morphology witness lesser cracks, voids, crater and molten debris particles present on the surface of machined aluminum 6061 alloy.

TiO2 paste for DSSC photoanode: preparation and optimization of application method

We propose a simple method of TiO2 paste preparation from titania powder (Degussa) and organic binders (terpineol, ethyl cellulose) for making a continuous photoactive layer of a dye-sensitized solar cell (DSSC). The prepared paste was characterized by using thermogravimetric and X-ray diffraction methods for comparison with commercial paste (Solaronix). The TiO2 layer parameters for applying and annealing were optimized by varying the layer thickness and using different masks. The surface morphology of annealed layers was controlled by optical microscopy. Before TiO2 paste applying and after annealing, the conductive glass (fluorine-tin oxide – FTO) was treated by TiCl4 hydrochloric acid solution. The structure of DSSCs were composed FTO-glass / TiO2 layer sensitized Ruthenium complex (N719 dye)/ iodide-based electrolyte / Pt counter electrode/ FTO glass. The DSSC photovoltaic characteristics were measured under AM 1.5G irradiation and demonstrated to be close to those of photoanodes based on the prepared and commercial pastes.

Laser Surface Nitriding of Ti–6Al–4V Alloy in Nitrogen–Argon Atmospheres

Surface-nitrided layers of Ti–6Al–4V alloy were fabricated using a diode laser in pure and mixed gas atmospheres of nitrogen and argon. The surface morphology, microstructure, hardness, and cracks of the nitrided layers were investigated. In all gas atmospheres, the layers showed smooth and humped regions, and consisted of planar nitrogen titanium (TiN), dendrites, and acicular martensite. The surface roughness was improved dramatically as the nitrogen concentration of the atmosphere was diluted with argon. Overall, the hardness of the nitrided layer was greatest for pure nitrogen and it tended to decrease as the concentration of argon in the atmosphere increased. However, the hardness of the layer for pure nitrogen also decreased rapidly, from the surface to matrix, in comparison to the diluted nitrogen atmospheres. It was shown that the number and size of dendrites, which determine hardness, are controlled by the nitrogen concentration. The dendrites of the nitrided layer were denser and smaller in a pure nitrogen atmosphere, than in diluted nitrogen atmospheres. Longitudinal and transverse cracks were observed in the nitrided layers. These two types of cracks were decreased or even eliminated as the argon concentration of the nitrogen–argon atmosphere was increased. Therefore, by diluting the nitrogen atmosphere with argon, the nitrided layer properties, in terms of surface roughness and cracks, can be improved, but this may also cause a reduction in the layer hardness.

Structural Change in Ag2Te Buffer Layer During Two-Step Closed Space Sublimation of AgGaTe2

An AgGaTe2 layer was prepared using an Ag2Te buffer layer. Ag2Te layers were deposited by the radio-frequency sputtering method. We investigate the variations in the Ag2Te buffer layer surface morphology and composition that take place during annealing. Ag2Te films were annealed in a tube furnace. The composition and surface morphology of the Ag2Te layer were found to vary depending on the thermal annealing temperature and duration. It was confirmed that a dewetting process in the Ag2Te layer occurred with annealing between 200°C and 500°C, and O2 and Mo reacted at 600°C and then became MoO3 compounds. Mo and Te were completely desorbed from the surface at 700°C. This confirmed that the surface morphology of the Ag2Te layer was controlled by the annealing temperature and duration.

The effect of fullerene layer on the aggregates formation in amyloid beta Langmuir-Blodgett films

The investigation of the effect of carbon nanomaterials and lipids on the aggregation particularities of the amyloid beta/Aβ(1-42) layers is important for understanding the generation mechanism of neuronal disorder and how it can be inhibited. Additionally, amyloids are nanomaterials with a wide area of potential applications from nanotechnology to biotechnology. This paper presents a study about the preparation of Aβ(1-42) layer by two different methods, Langmuir-Blodgett (L-B) and drop cast (DC), on Si and Si covered by a layer of Buckminster fullerene, C60, and on the effect of fullerene layer or/and cholesterol (Ch) on the generation of Aβ(1-42) secondary structure forms, relevant for specific applications. AFM, SEM FTIR and Raman analysis offered details about the layer surface topography, morphology and particularities of the secondary structure generated in the process of Aβ(1-42) molecules aggregation. This study showed that the presence of Ch inhibited the formation of fibrils in Aβ(1-42) film deposited by L-B on Si covered by C60. The structures developed during aggregation were correlated with the topography and roughness of the films. The presence of Ch determined a decrease in roughness for L-B film and increase in roughness for DC film deposited on Si covered by C60 layer.

Effect of airbrush type on sprayed platinum and platinum-cobalt catalyst inks: Benchmarking as PEMFC and performance in an electrochemical hydrogen pump

Proton-exchange membrane fuel cells and electrochemical hydrogen pumps are based on membrane electrode assemblies containing Pt catalysts. During their preparation, a catalyst ink is usually applied to the gas diffusion layer. Among the available methods, ink spray using an airbrush can be advantageous for making electrodes at universities and companies. This work compares the suitability of gravity-feed and suction-feed airbrushes during the evaluation of in-house developed Pt and Pt–Co catalysts. The surface morphology of the catalyst layers was analysed by SEM and EDS and related to the preparation technique. The catalysts were compared against an off-the-shelf commercial catalyst. The in-house Pt catalyst afforded similar polarisation curves as the commercial catalyst whereas the Pt–Co catalyst exhibited a slightly lower performance. The suction-feed airbrush was deemed preferable because it produced cracked mud-like, homogeneous and smoother catalyst layers in contrast to the gravity-feed method, which resulted in poor-quality deposits with loose particles, lower Pt utilisation and higher resistance.