Increase In Deposition Rate Research Articles

Cooling Tower Plume and Drift Concentration in presence of Urban Canyon

This paper presents a computational analysis of the cooling tower plume and drift emitted by mechanical draught cooling towers situated in urban areas. The data from the Wang X (2019) and Briggs plume lift height formula are used to prove results obtained from computational Modeling of cooling tower drift and it was found to be effective. The simulation setup uses a multiphase mixture model for plume analysis and DPM for analysis of drift in the Ansys fluent. The CFD simulation results are accurate within 50 to 100 m with the Briggs plume lift height formula. The effect of wind coming from urban canyons on the cooling tower results in decreased plume lift height and increase drift concentration and deposition rate on the ground.

Mercury deposition to lake sediments near historic gold mines in northern Canada

Mercury (Hg) contamination in aquatic systems can lead to adverse human and environmental health outcomes. Yellowknife, a city in Canada’s Northwest Territories, is a historic mining community, with two large gold mines (Giant Mine and Con Mine) that used Hg amalgamation methods to extract gold between ∼1938 and 1960. We analyzed dated sediment cores from 20 small lakes to investigate the spatial and temporal Hg deposition patterns within 50 km of Giant Mine. Breakpoint analysis of the within-lake z-score normalized anthropogenic Hg flux indicates two significant time periods of changing emission rates. The first is a significant increase in Hg deposition rate (∼1925) during the time of gold exploration in the region and onset of Hg amalgamation (1938) and the second is a significant decrease in deposition rate that begins around the time of the cessation of Hg amalgamation at Giant Mine (∼1959). Sediment Hg concentrations exceeded the Canadian Council for Ministers of the Environment Interim Sediment Quality Guideline (ISQG) for Hg (0.17 mg/kg dw) in 55% of the lakes (n = 11) during mining (1948–1999). All lakes within 5 km of the Giant Mine roaster stack exceeded CCME ISQG during mining (n = 8), with a 4-fold increase in total Hg concentration observed during mining at these near-field (<5 km from stack) sites. We observed evidence of enriched Hg in near-field, mid-field, and far-field sites. The elevated sedimentary Hg concentrations during mining in near-field sites would have posed a hazard to human and wildlife health during the height of emissions, however the significant decrease in Hg concentrations since the closure of mines in the region demonstrate the potential for recovery in these aquatic ecosystems.

Strategies for a scalable multi-robot large scale wire arc additive manufacturing system

Conventional robotic wire arc additive manufacturing technologies enable the rapid production of moderate-sized components using low-cost wire feedstocks and robotic welding systems. Efforts to date have primarily focused on single robot solutions. However, new configurations are possible with coordination of multiple robots and multi-degree of freedom positioners. This paper describes a new multi-agent control paradigm that enables multiple robots to work collaboratively on manufacturing a single component on a rotating platform. The advantages of this approach are increased deposition rate and productivity. This paper demonstrates this control strategy on a 19 degrees-of-freedom platform based on three wire arc additive systems surrounding a single rotating platform.

Effects of N/Si ratio on mechanical properties of amorphous silicon nitride coating

The utilization of silicon nitride coatings has been proposed as an effective method to enhance wear resistance and mitigate the release of metallic ions from biomedical implants. However, the relatively high dissolution rate of low-density coatings remains an obstacle to their implementation. Here, chemical vapour deposition techniques may have advantages over the typically used physical vapour deposition (PVD) methods. Therefore, in this study, silicon nitride coatings were obtained by low-pressure chemical vapor deposition (LPCVD). Since the nitrogen-to-silicon (N/Si) ratio and deposition temperature have been reported as major factors affecting the performance of the coatings, the effects of ammonia (NH3) to dichlorosilane (SiH2Cl2) flow ratio and deposition temperature were systemically investigated in the form of microstructure, mechanical and tribological properties of the coatings. The results revealed that the coatings exhibited a dense structure. As the ammonia flow ratio increased, the surface became smoother, and the hardness and elastic modulus increased and reached the maximum at a flow ratio of 4, giving a hardness of around 27 GPa and an elastic modulus of 290 GPa, respectively. The higher mechanical properties of the coatings deposited at a flow ratio of 4 are attributed to the stronger covalent Si-N bonding, as confirmed by XPS results. However, the coatings deposited at a flow ratio of 2 exhibited the lowest wear rate, at 9.5 10−7 mm3 Nm−1, around one-third of the value of the coatings deposited at a flow ratio of 6, likely due to the high silicon content of these coatings. Increasing the temperature resulted in an increased deposition rate, higher hardness and elastic modulus as well as a lower wear rate, likely due to incomplete reactions at lower temperatures. The generally high hardness and low wear rate indicate that the coatings deposited by LPCVD are promising for application in spinal implants.

Effect of SiO2 Interfacial Layer Reduction on MFSFET With 5 nm-Thick Ferroelectric Nondoped HfO2 by Deposition Rate Control

In this research, deposition rate dependence of 5 nm-thick ferroelectric nondoped HfO2 (FeND-HfO2) formed on Si(100) substrate was investigated. The equivalent oxide thickness (EOT) was decreased from 3.2 nm to 2.8 nm by increasing deposition rate of HfO2 from 5.0 nm/min to 6.0 nm/min. The subthreshold swing (SS) of 107 mV/dec. and saturation mobility (μsat) of 150 cm2/(Vs) were obtained with deposition rate of 6.0 nm/min. Furthermore, the threshold voltage (VTH) was controllable as the number of identical erase pulse of 4 V/1 μs, which suggested the VTH control of approximately 10 mV.

Experimental Evaluation of the Deposition Dynamics of Different Petroleum Blends in a Benchtop Heat Exchanger Test Instrument

The article delves into the intricate phenomenon of deposition in heat exchangers and how a piece of equipment known as the benchtop heat exchanger test instrument (BHETI) has been developed to expedite the examination of this phenomenon. The BHETI subjects samples to substantial stress, facilitating the assessment of an oil’s tendency to generate deposits. Tests were conducted on two crude oil blends referred to as blend A and blend B using a BHETI unit. This equipment permits testing under various controlled conditions, including temperature, pressure, and volumetric flow rate. The results indicated that blend A exhibited a higher susceptibility to deposition compared to blend B due to its elevated concentration of light hydrocarbons. The wall temperature exerted a significant influence on the deposition rate, with higher temperatures leading to elevated deposition rates. Conversely, lower oil flow rates resulted in increased deposition rates. Furthermore, extended-term tests unveiled fluctuations in deposition rates over time when blending the two oil samples, suggesting intermittent fouling processes, possibly attributable to thermodynamic imbalances induced by mixing, rendering the oil’s asphaltenes less stable. The outcomes were subjected to analysis employing the Colloidal Instability Index (CII), which indicated that the majority of samples exhibited values exceeding 0.9, signifying asphaltene instability. Additionally, the examination of saturated, aromatic, and NSO (nitrogen, sulfur, oxygen) fractions revealed decreased saturation and increased aromatics after the deposition tests.

Study on particle deposition performance in liquid lead-bismuth eutectic and supercritical CO2 heat exchanger

Lead-bismuth eutectic (LBE) and supercritical CO2 (SCO2) heat exchangers are highly recommended and designed due to their compactness and high thermal efficiency. During heat exchanger operation, however, undesired particle impurities are generated, which deposit on the surface and degrade heat transfer. To predict the deposition distribution, a tube-shell heat exchanger was proposed with LBE as the heat source and SCO2 as the cool source. Based on this proposal, a three-dimensional model was established, and particle deposition characteristics were studied numerically. The results indicated that the inlet section had a high concentration and deposition rate. At the inlet, the deposition rate in LBE was higher than SCO2. Specifically, particle deposition in LBE was concentrated mainly in the inlet section, while it occurred throughout the entire channel in SCO2. An increase of particle diameter and concentration contributed to deposition on both sides. The average deposition rates of LBE and SCO2 showed an increase of 1.04 times and 2.76 times, respectively, when the particle diameter was varied from 2 μm to 6 μm. Similarly, an increase in concentration from 1 % to 2.5 % resulted in an increase of deposition rates of LBE and SCO2 by 3.75 times and 3.68 times, respectively. This implied that the concentration had a stronger impact on deposition. The deposition characteristics of particle species differed in LBE and SCO2. As the particle density increased, the deposition rate decreased in LBE but increased in SCO2. The particle deposition mechanism in LBE and SCO2 was revealed by analyzing the forces acting on particles.

Low Damage Scalable Pulsed Laser Deposition of SnO2 for p–i–n Perovskite Solar Cells

Pulsed laser deposition (PLD) has already been adopted as a low damage deposition technique of transparent conducting oxides on top of sensitive organic charge transport layers in optoelectronic devices. Herein, SnO2 deposition is demonstrated as buffer layer in p–i–n perovskite solar cells (PSCs) via wafer‐scale (4 inch) PLD at room temperature. The PLD SnO2 properties, its interface with perovskite/C60, and device performance are compared to atomic layer deposited (ALD) SnO2, i.e., state‐of‐the‐art buffer layer in perovskite‐based single junction and tandem photovoltaics. The PLD SnO2‐based solar cells exhibit on par efficiencies (17.8%) with that of SnO2 fabricated using ALD. The solvent‐free room temperature processing and wafer‐scale approach of PLD open up possibilities for buffer layer formation with increased deposition rates while mitigating potential thermal or physical damage to the top organic layers. This is a promising outlook for fully physical vapor‐processed halide PSCs and optoelectronic devices requiring low thermal budget.

Martensitic ternary FeCrMn thin films sputtered from austenitic AISI 202 stainless steel target: Phase transition and corresponding magnetic properties under the influence of deposition rate

The nanostructured materials exhibit quite different properties from their bulk counterparts. Therefore, in this work, phase transition from a commercial austenitic AISI 202 (Bulk FeCrMn) stainless steel to martensitic ternary FeCrMn thin films under variation of deposition rate were studied. The films were easily sputtered onto a flexible amorphous polymer substrate from the target by a DC magnetron. X-ray diffraction analysis showed that austenitic phase of the target converted into a mixture of martensitic and a very weak of austenitic phase of the films at the deposition rates of 0.04 and 0.06 nm/s. With a further increase of the deposition rate, martensitic phase in the films increased, and at the highest deposition rate, the film with 100 % martensite phase was obtained. According to magnetic analysis, austenitic target consists of paramagnetic and ferromagnetic components as oppose to the paramagnetic phase stated in the literature. The films obtained by sputtering of austenitic target have ferromagnetic character with an increasing saturation magnetization, MS as the deposition rate increases. The increase of the MS from 117 to 346 emu.cm−3 may be explained by the increase of the % martensite that may increase the ferromagnetic character. Also, the increase of the coercivity of the films from 31 to 196 Oe may have come from the increase of % martensite and the increase of grain sizes with increasing deposition rates which may induce the stress in the films. It is seen that the nanostructured ternary FeCrMn thin films exhibit quite different phase and corresponding magnetic properties from their bulk counterpart. With sputtering, martensitic phase transition of ternary FeCrMn thin films can be controlled by varying deposition rates. It presents a potential usage for data storage and micro electric-electronic devices on flexible substrates.

Improving the deposition efficiency and mechanical properties of additive manufactured Inconel 625 through hot wire laser metal deposition

This study focuses on the advantages of hot wire laser metal deposition (HW-LMD) compared to cold wire deposition technology (CW-LMD) for fabricating Inconel 625 alloy. Initially, a comparative study was conducted through single-pass deposition experiments to evaluate the process characteristics of HW-LMD and CW-LMD. The results showed that by increasing the additional resistance heat by 20% during HW-LMD, a significant 92.5% increase in wire deposition rate and a 60.3% increase in energy efficiency were achieved. Additionally, the wire deposition rate of HW-LMD was 1.5 times as high as that of CW-LMD with the identical total energy input. Subsequently, well-formed Inconel 625 bulks were fabricated using both CW-LMD and HW-LMD techniques. The microstructures and mechanical properties of the as-deposited samples manufactured by the two different processes were comparatively studied. Due to the accelerated solidification rate of the molten pool, the columnar dendrites in Inconel 625 samples prepared by HW-LMD were refined, resulting in an average grain size of 12 µm. Furthermore, the precipitation of the Laves phase at the inter-dendrite regions was suppressed. Consequently, an increased microhardness of 258 HV1.0 for HW-LMD samples was obtained. In addition, the HW-LMD samples also exhibited superior tensile strength and elongation, measuring at 837.4 MPa and 55.2% respectively. Based on the aforementioned findings, HW-LMD has demonstrated outstanding capability in improving productivity and mechanical properties, indicating a promising option for efficient additive repair and manufacturing.

Carbon deposition properties and regeneration performance of La2NiO4 perovskite oxide for dry reforming of methane

One of the key points in the development of dry reforming of methane (DRM) is the design of catalysts with high activity and stability. The reactivity and carbon deposition properties of La2NiO4 in DRM, as well as its regeneration performance, were studied. The results showed that the in-situ decomposition of La2NiO4 led to a more uniform distribution of smaller Ni0 particles on the La2O3 matrix compared with the directly loaded NiO/La2O3. A temperature-programmed test revealed that the breakthrough curve temperature for La2NiO4 in DRM was 618 °C. The carbon deposition would carry Ni0 metal away from the La2O3 matrix, making the solid carbon unable to be removed promptly due to insufficient oxygen supply, resulting in an increase in the catalyst's instantaneous carbon deposition rate at 650 °C and 750 °C. The regeneration tests showed that the samples' DRM performance and carbon deposition levels remained relatively stable before and after steam regeneration. However, air-regenerated samples exhibited a hysteresis time in DRM due to sintering. Additionally, CO2 was unable to completely remove carbon deposition from the samples, resulting in a significant increase in carbon deposition when regenerated samples were used for DRM.

Feasibility of cold wire gas metal arc welding AA5052 H-32

The feasibility of applying cold wire gas metal arc welding (CW-GMAW) is evaluated by comparison to standard gas metal arc welding (GMAW) 5 mm-thick AA5052 butt-joints. The results show that the variability in porosity (and potentially overall total) is decreased by feeding 20 or 40 % additional cold wire in CW-GMAW welds, and with weld metal microstructures comparable to standard GMAW welds. In terms of nominal heat input, CW-GMAW offers lower values with increased deposition rates, and thermal distortion could be decreased by feeding 20 or 40 % additional cold wire in CW-GMAW welds. The microstructures in CW-GMAW appear to be more refined compared to standard GMAW.

A fluid model of pulsed direct current planar magnetron discharge

We simulated a pulsed direct current (DC) planar magnetron discharge using fluid model, solving for species continuity, momentum, and energy transfer equations, coupled with Poisson equation and Lorentz force for electromagnetism. Based on a validated DC magnetron model, an asymmetric bipolar potential waveform is applied at the cathode at 50–200 kHz frequency and 50–80% duty cycle. Our results show that pulsing leads to increased electron density and electron temperature, but decreased deposition rate over non-pulsed DC magnetron, trends consistent with those reported by experimental studies. Increasing pulse frequency increases electron temperature but reduces the electron density and deposition rate, whereas increasing duty cycle decreases both electron temperature and density but increases deposition rate. We found that the time-averaged electron density scales inversely with the frequency, and time-averaged discharge voltage magnitude scales with the duty cycle. Our results are readily applicable to modulated pulse power magnetron sputtering and can be extended to alternating current (AC) reactive sputtering processes.

Parametric analysis of the coating thickness development of electrophoretically deposited carbon nanotube coatings

In this study, the coating thickness evolution of pristine and oxidized carbon nanotubes (CNT) on stainless steel substrates is investigated. Potentiostatic electrophoretic deposition (EPD) is used as a coating technique with two different additives, triethylamine (TEA) and magnesium nitrate hexahydrate (Mg-Nit). Moreover, the depositions are conducted at different voltages (50, 100 and 150 V). Confocal laser scanning microscopy is used to determine the thickness of the CNT depositions after 1, 2, 5, 10, 20 and 30 min. Furthermore, the ability of Hamaker's law to accurately predict coating thickness development is investigated for the thickness evolution on stainless steel. Independent of the additive, the results show that higher voltages lead to increased deposition rates. Comparing the two additives, Mg-Nit generally allows for a higher CNT deposition rate than TEA and forms thicker layers. Coating thickness development can be approximated as linear during the initial 5 min with Mg-Nit and during the initial 20 min with TEA. Finally, Hamaker's law allows for a fairly accurate approximation for the thickness development of CNT coatings with TEA on stainless steel.

Estimating aerosol particle removal in indoor air by ion-enhanced deposition

Small air ions have the ability to charge airborne particles, thereby increasing their accumulation on surfaces. Indoor air purification by applying ionization uses electrostatic particle deposition. Respiratory pathogens, including viruses and respiratory droplets carrying viruses or other pathogens, represent bioaerosols, whose particle size distributions contain increasingly larger proportion of fine and ultrafine particles, as the evaporation process proceeds. We have generated two model aerosols: the nebulized NaCl solution, resembling human saliva, and the cigarette smoke, having relatively low water content. We have conducted real life experiments of such surrogate aerosol particle deposition without ionization, using bipolar ionization, as well as using unipolar negative air ions. Particle number concentrations have been measured in the 10 nm–10 μm particle size range. The calculated deposition rates and aerosol particle half-life times were correlated with bioaerosol pathogens based on the core pathogen sizes. Bipolar ionizers emitting equal concentrations of positive and negative ions had low impact to the particle concentration decrease. Intense negative air ionization resulted in pronounced deposition rate increases, particularly in the particle size range of viruses including the SARS-CoV-2. The impact of negative air ionization was most pronounced in the same size range where the deposition rates without ionization were the lowest. Therefore, the results are very promising from the standpoint of air purification and bioaerosol pathogen removal, bearing in mind that the effect of ions will be most pronounced if the unipolar ion rich air stream is directed towards the breathing zone.

A study of Ni–P electroless coating modified by rare earth oxide (La2O3, Y2O3 and Ce2O3) on pre-phosphorized zirconium alloy

Electroless Ni–P coatings are successfully deposited on the surface of pre-phosphorized zirconium alloy from plating baths containing various concentrations of rare earth oxide (Re Y2O3, Ce2O3 and La2O3). The surface morphology, elementary composition, and structure of coatings are characterized by scanning electron microscopy, energy dispersive X-ray spectrometer and X-ray diffraction, respectively. Gravimetrical method is used to calculate the deposition rate. Electrochemical corrosion resistance of coatings is analyzed using electrochemical workstation. Results revealed that a small amount addition of rare earth oxides does not change the original cauliflower-like morphology and amorphous structure of coatings. When the amount of addition is moderate, the deposition rate and microhardness increase with the increment of the amount of addition, while P content decreases. However, excessive addition can lead to poisoning of the plating bath. Electrochemical corrosion data indicates that the addition of rare earth oxide in the plating solution has little influence on the corrosion resistance of the coating.

The GMAW Process Using a Two-Dimensional Arc Deflection with AC Hot Wires

Heat input in gas metal arc welding (GMAW) directly correlates with the applied current. As a result, welding irregularities, such as incomplete fusion and excessive penetration, increase and mechanical properties decrease. One way for adjusting heat input is to use hot wire technology. In this article, a two-dimensional arc deflection in GMAW was presented by simultaneous application of two alternating current (AC) hot wires. It is shown how the positioning of the hot wires and the signal characteristics of the current intensity influenced the deflection pattern and weld quality. It was found that the magnetic fields of the two hot wires overlapped due to the narrow opening between. Therefore, an increased one-dimensional deflection resulted. To obtain a two-dimensional deflection, it was necessary to shield the magnetic fields from each other by means of a ferritic material. By pulsing or phase shifting the current signals, individual deflection patterns were possible. The effect of arc deflection was visualized with highspeed recordings and metallographic investigations. Different deflection patterns were generated to adjust heat input and counteract weld irregularities. The use of hot wire technology allowed an increase in deposition rate by simultaneous improvement of weld quality.

Synthesis of Al Thin Films with High Optical Transmittance by DC Magnetron Sputtering Process Parameter Optimization

Nanostructured Al thin film with higher optical transmittance and electrical conductivity has intensive applications in solar cells and optical and microelectronic devices. This experimental-based research study has optimized the DC magnetron sputtering deposition parameters (sputtering power, sputtering current, voltage, and working gas pressure) for Al thin film deposition to obtain the highest optical transmittance and lower sheet resistance. Optical transmittance, surface roughness, film thickness, sheet resistance, grain size, and surface morphology were characterized using UV-vis-NIR spectroscopy, surface profiler, spectroscopic ellipsometry, four-point probe, and FE-SEM, respectively to determine the effects of sputtering process parameters on Al films’ different properties. Experimental investigations reveal that electrical conductivity, surface roughness, grain size, and deposition rate increase with increasing of sputtering power at certain working gas pressure. At the optimized condition (sputtering power 80 W, working gas pressure 5 mTorr, deposition time 5 min and ambient temperature), the relatively higher optical transmittance in visible region 96%, moderate sheet resistance 0.196 ohm/square and lowest average surface roughness 2.86 nm were obtained for Al thin film. After all, this research study will help to understand the best Al film deposition parameters in terms of optical transmittance and electrical conductivity for future research and industrial applications.

Correlation between plasma characteristics, morphology, and microstructure of sputtered CuAl alloy films with varied target geometry

The effect of target geometry on coating microstructure and morphology is correlated to changes in deposition conditions, plasma characteristics, and film growth during planar and hollow cathode sputtering. The sputtering plasma properties for the two target geometries were characterized via Langmuir probe analysis as a function of power density and Ar pressure to determine the evolution of ion density for each configuration. Films were then synthesized at the low (0.4 W cm−2) and high (1.2 W cm−2) power densities and characterized using x-ray diffraction, scanning electron microscopy, and electron backscatter diffraction to link changes in texturing, morphology, and microstructure with variations in ion density and sputtering deposition conditions caused by target geometry. It was observed that varying target geometry led to an over threefold increase in deposition rate, homologous temperature, and ion density, which altered the morphology and texture of the film without significant changes to the grain size.

Experimental analysis of spray droplet deposition behaviour for centrifugal assisted spinning disc sprayer

The biological effectiveness of insecticides is influenced both by the amount of sprayed material that is left behind on the canopies and by the physicochemical characteristics of the spray solutions. The type of sprayer and its settings, the type of canopy and its density, the stage of tree development, and the variables in the surrounding environment all have an impact on where and how much spray is deposited within canopies. PIV is used in this study to investigate the behaviour of droplet deposition on a three-dimensional prototype of a centrifugally assisted spinning disc sprayer. A variety of rotational velocities are represented here by the aerosol distribution from the exit of the nozzle to −1.5 m and 4 m, respectively. If the mass flow rate is slowed down, the droplet diameter can be increased while maintaining the same rotational speed. This is accomplished by reducing the amount of friction that exists between the spinning disc and the liquid that is being sprayed. This impact is caused by not only an increase in the droplet deposition rate in the direction of downward movement, but also an increase in the mass flow rate. Some droplet particles actually travel upward for certain mass flow rates because they are unable to overcome resistance and have a low density.