Maximum Deposition Rate Research Articles

Tomography-based characterization of ice-air interface dynamics of temperature gradient snow metamorphism under advective conditions

Snow at or close to the surface commonly undergoes temperature gradient metamorphism under advective flow, which alters its microstructure and physical properties. A functional understanding of this process is essential for many disciplines, from modeling the effects of snow on regional and global climate to assessing avalanche formation. Time-lapse X-ray microtomography was applied to investigate the structural dynamics of temperature gradient snow metamorphism exposed to an advective airflow in controlled laboratory conditions. Experiments specifically analyzed sublimation and deposition of water vapor on the ice structure. In addition, an analysis of the ice-air interface dynamics was carried out using a macroscopic equivalent model of heat and water vapor transport through a snow layer. The results indicate that sublimation of the ice matrix dominated for flow rates < 10−6 m3 s−1 while during increased mass flow rates the water vapor deposition supplied by the advective flow counteracted sublimation. A flow rate dependence of water vapor deposition at the ice interface was observed, asymptotically approaching an average estimated maximum deposition rate on the whole sample of 1.05 · 10−4 kg m−3 s−1. The growth of microsized whisker-like crystals on larger ice crystals was detected on microscope photographs, leading to an increase of the specific surface area and thus suggest a change of the physical and optical properties of the snow. The estimated values of the curvature effect of the ice crystals and the interface kinetic coefficient are in good agreement with previously published values.

Quantifying the resuspension of sediment and associated metallic contaminants with fallout radionuclide measurements in a channelized river draining an industrial catchment

Contamination of river sediment reaches problematic levels in industrialised regions. This study investigates the relevance of using beryllium-7 (7Be), a short-lived environmental radionuclide (53 days half-life), for quantifying the deposition and resuspension of sediment and associated metallic contaminants in a heavily polluted channelized river of Northern France (The Lower Scarpe River). Activities in 7Be were measured in bed and suspended sediments collected each month over a hydrological year. Suspended sediments were analysed for metal contents (Pb, Zn, Cd, Cu). The determination of short-term sediment dynamics is based on the variation of total 7Be inventory between two successive samplings. Total inventory of 7Be consists of two components, i.e., the residual inventory and the new inventory. Inventories of 7Be in sediment varied from 1 to 135 mBq cm−2. Observed spatial and temporal variations reflected the dynamic behaviour of sediment in the studied channel section. The succession of sediment deposition and resuspension periods was demonstrated during the study, with maximum deposition and erosion rates of 0.3 ± 0.2 and −0.46 ± 0.05 g cm−2 month−1, respectively. A sediment resuspension rate of 0.06 g cm−2 month−1 supplied to the water column a flux of 12, 13, 23 and 145 μg cm−2 month−1 of Cd, Cu, Pb and Zn, respectively. During this 15-month study, 28 to 50 % of Pb that was deposited in the riverbed sediment was resuspended, thereby contributing to the (short term) degradation of water quality. The present work provides a useful tool for examining the role of sediment as a sink or source of contamination for the water column. It produces knowledge of how sediment processes affect the fate and the transport of contaminants and the implications for future downstream fluxes.

Numerical simulation of multiple polysilicon CVD reactors connected in series using CFD method

This study proposes a novel process in which multiple polysilicon chemical vapour deposition (CVD) reactors are connected in series, and this setup is investigated using computational fluid dynamics (CFD). A three‐dimensional CFD theoretical model is proposed to describe the various transport phenomena in the reactor, and this model is validated by comparing the reactor outlet temperatures of the simulation results and the data obtained using an industrial polysilicon CVD reactor. This model was then used for analyzing the production cost and growth rate of the traditional and proposed CVD processes. The simulation results show that the polysilicon production cost in the traditional and proposed processes is lowest for 0.091 mol/mol (9.1 mol %); the maximum deposition rate is achieved for 0.25 mol/mol (25 mol%). On the other hand, if the operation pressure increases from 101 to 607 kPa, the average production cost can be reduced from 86.26 to 39.88 $/kg; and the average growth rate can be raised from 1.68 to 4.18 µm · min−1. In addition, compared with the 1‐reactor process, the cost of the 2‐reactor process is 21.9 % lower, and the 3‐reactor process is 26.9 % lower. Finally, in the novel process, changing the chlorine hydride of the feed in the reactor 2 from 0.1 g/g (10 wt%) to 0.02 g/g (2 wt%), the average production cost can be reduced by 35.5 %.

(Invited) Electroless Deposition of Ruthenium Using Sodium Borohydride Reducing Agent: A Mechanistic Study Using Electrochemical Quartz Crystal Microbalance

Further miniaturization of interconnects and devices to keep up with Moore’s law in the 21st century requires materials innovation. Copper, as the interconnect metal has been the workhorse of the semiconductor industry for the past two decades. As wire dimensions shrink below 20 nm in future technology nodes, the ability of copper to meet the conductivity and reliability benchmarks is strained1. One metal that becomes attractive at smaller dimensions (<10 nm) is ruthenium, due to its high conductivity and electromigration resistance2. Traditional routes for metallization of ruthenium includes physical vapor (PVD), chemical vapor (CVD) and atomic layer deposition (ALD). PVD suffers from its line-of-sight, non-conformal deposition process that is not suitable for narrow, high aspect ratio geometries. CVD and ALD processes are slower and more expensive than PVD. Here we present an electroless deposition process (ELD) for ruthenium that overcomes some of the obstacles associated with the aforementioned processes. ELD is inherently selective which yields conformal coating in challenging geometries. Furthermore, ELD has lower cost of ownership due to relatively inexpensive precursors and significantly higher deposition rate than ALD and CVD. Here, sodium borohydride is used as the reducing agent for electroless deposition of Ru, and the effects of temperature, precursor and ligand concentrations on ruthenium growth rate are characterized. A linear increase in deposition rate is observed with increasing temperature and ruthenium concentration. A critical borohydride concentration is observed at ~2 g/L, where the maximum deposition rate is obtained. The mechanism of the ruthenium deposition process (reduction half-reaction) is further investigated via electrochemical quartz crystal microbalance (EQCM) analysis to probe the role of pH and complexation. Ru deposition on Cu initiates at a potential of -1.05 V vs. Ag/AgCl reference electrode, and further analysis indicates that a high pH of the electrolyte is needed to suppress any side reaction(s) and to form kinetically active ruthenium-hydroxy complexed species. Finally, some challenges to integration and different applications for an electroless deposited Ru are highlighted. Figure 1: (a) Linear potential scan of the background electrolyte and the electrolyte containing Ru precursor. Increase in current density is observed at potential <-1.05 V vs. Ag/AgCl. Coupled quartz crystal microbalance analysis (b) confirms Ru deposition at potentials more cathodic than -1.05 V vs. Ag/AgCl.

High-speed deposition of highly (001)-oriented SrCO3 films prepared using laser chemical vapor deposition

Highly (001)-oriented SrCO3 films were prepared using laser chemical vapor deposition. The degree of (001) orientation of the SrCO3 films increased from 60% to 100% as the deposition temperature increased from 848 to 923K. The surface morphology of the (001)-oriented SrCO3 film was characterized by polygonal grains with striped facets, and pyramidal grains formed on the surface. The deposition rate increased as the deposition temperature increased, and the maximum deposition rate of the highly (001)-oriented SrCO3 film was 205μmh−1.

Deposition of riverine suspended solids in a shallow bay (Bay of Koper, Gulf of Trieste, northern Adriatic Sea)

Deposition of riverine suspended solids affects operations in ports located in the proximity of river mouths. The Rižana River is the main source of riverine solids in the shallow Bay of Koper (Gulf of Trieste, northern Adriatic Sea). The mean discharge increases rapidly in relation to high precipitation, typical of spring and autumn. During such events, the runoff leads to torrential river flow with high concentration of suspended solids which are consequently deposited in the port zone. Turbidity (NTU) measurements were performed during 2011–2013 in the Rižana and Badasevica Rivers and in the inner part of the bay influenced by fresh water inflow. In parallel, the concentrations of total suspended solids (TSS) and suspended organic matter (SOM) were measured gravimetrically, the latter after combustion, and their grain size distributions were determined using a laser granulometer. The maximum turbidity values in the bay were found in the sea surface layer during the river flood. The linear regression model between TSS and turbidity (NTU) TSS = 1.01 × NTU + 0.91 showed strong positive correlation. The regression analysis between turbidity and SOM also showed strong correlation with a regression equation SOM = 0.12 × NTU + 0.85. The impact of SOM on measurements was hypothesized by the rather poor model fit of the regression analysis between TSS and river discharge, which is mainly related to high SOM variations. The grain size spectra of riverine and nearshore surface TSS in the proximity of the river mouth were skewed and sorted with the mode size mostly around 10 μm. Considering the TSS mass in the sea surface layer, the yearly TSS input into the bay is estimated to be ~18 × 103 t. Using the average TSS concentration in the Rižana River and the average Rižana River discharge, the yearly input would be ~2 × 103 t. The discrepancy between both calculated inputs is probably related to the TSS input during high river discharge which occurs in short periods. A maximum deposition rate of 80 g m2 day−1 is mostly restricted to the second port basin. Less than 50 % of the introduced TSS settles within the second port basin during mean river flow conditions. The regression model was found to be a useful tool to estimate TSS and SOM concentrations from turbidity data in rivers and the coastal sea, thus providing an evaluation of riverine TSS and SOM input and deposition into the small bay, which in turn affects local port activities.

Vapor wall deposition in Teflon chambers

Abstract. Teflon chambers are ubiquitous in studies of atmospheric chemistry. Secondary organic aerosol (SOA) formation can be underestimated, owing to deposition of SOA-forming vapors to the chamber wall. We present here an experimental protocol and a model framework to constrain the vapor–wall interactions in Teflon chambers. We measured the wall deposition rates of 25 oxidized organic compounds generated from the photooxidation of isoprene, toluene, α-pinene, and dodecane in two chambers that had been extensively used and in two new unused chambers. We found that the extent of prior use of the chamber did not significantly affect the sorption behavior of the Teflon films. Among the 25 compounds studied, the maximum wall deposition rate is exhibited by the most highly oxygenated and least volatile compounds. By optimizing the model output to the observed vapor decay profiles, we identified that the dominant parameter governing the extent of wall deposition of a compound is its wall accommodation coefficient (αwi), which can be correlated through its volatility with the number of carbons and oxygens in the molecule. By doing so, the wall-induced deposition rate of intermediate/semi-volatile organic vapors can be reasonably predicted based on their molecular constituency. The extent to which vapor wall deposition impacts measured SOA yields depends on the competition between uptake of organic vapors by suspended particles and the chamber wall. The timescale associated with vapor wall deposition can vary from minutes to hours depending on the value of αw,i. For volatile and intermediate volatility organic compounds (small αw,i), gas-particle partitioning will dominate wall deposition for typical particle number concentrations in chamber experiments. For compounds characterized by relatively large αw,i, vapor transport to particles is suppressed by competition with the chamber wall even with perfect particle accommodation.

Experimental Process of Tungsten Inert Gas Welding of a Stainless Steel Plate

This experimental study was carried out to analyse the effects of process parameters on metal deposition rate of TIG welded stainless steel plate of SS304 grade. The main aim of varying process parameters is to achieve maximum metal deposition rate. Tungsten Inert Gas Arc Welding is a commonly used welding technique due to its versatility and ease that can be maintained in almost all type of working conditions. Stainless Steel (SS304) possessing high strength and toughness is usually known to offer major challenges during its welding. In this present work, design of experiment (DOE) approach was used to plan and design the experiments to study the effect of welding process parameters on metal deposition rate of TIG welded SS304 stainless steel plate. Four input parameters—current, gas flow rate, root face and welding time—were selected to ascertain their effect on the metal deposition rate.L9 orthogonal array technique is used to formulate the experimental layout and to analyse the effects of process parameters on metal deposition rate of TIG welded SS304 stainless steel plate.

The application of imperialist competitive algorithm for optimization of deposition rate in submerged arc welding process using TiO2 nano particle

We used a novel optimization algorithm based on the imperialist competitive algorithm (ICA) to optimize the deposition rate in the submerged arc welding (SAW) process. This algorithm offers some advantages such as simplicity, accuracy and time saving. Experiments were conducted based on a five factor, five level rotatable central composite design (RCCD) to collect welding data for deposition rate as a function of welding current, arc voltage, contact tip to plate distance, welding speed and thickness of TiO2 nanoparticles coated on the plates of mild steel. Furthermore, regression equation for deposition rate was obtained using least squares method. The regression equation as the cost function was optimized using ICA. Ultimately, the levels of input variables to achieve maximum deposition rate were obtained using ICA. Computational results indicate that the proposed algorithm is quite effective and powerful in optimizing the cost function.

The microstructure and optical properties of SiNx deposited by linear microwave chemical vapor deposition

SiNx films are synthesized on Si substrates in a home-made linear microwave plasma enhanced chemical vapor deposition system at different microwave powers, duty cycles, substrate temperatures, and ratios of silane (SiH4) flow to ammonia (NH3) gas flow. The effects of technological parameters on morphology of film surface, stoichiometric proportion, refractive index and deposition rate of SiNx film are characterized by scanning electron microscopy (SEM) and elliptical polarization instrument, and the relationships among stoichiometric proportion, refractive index and deposition rate are investigated. The results from SEM analysis indicate that the surfaces are smooth and the elements are homogeneously distributed in the films obtained under different deposition parameters. The ratio of SiH4 flow to NH3 gas flow and the duty cycle are the most critical factors determining the refractive index which can be changed from 1.92 to 2.33. The thickness measurements show that the deposition rate of SiNx film is affected by microwave power, duty cycle, substrate temperature and flow ratio. The maximum deposition rate achieved in the paper is 135 nm·min-1.

Electrophoretic Deposition of Gallium with High Deposition Rate

In this work, electrophoretic deposition (EPD) is reported to form gallium thin film with high deposition rate and low cost while avoiding the highly toxic chemicals typically used in electroplating. A maximum deposition rate of ~0.6 μm/min, almost one order of magnitude higher than the typical value reported for electroplating, is obtained when employing a set of proper deposition parameters. The thickness of the film is shown to increase with deposition time when sequential deposition is employed. The concentration of Mg(NO3)2, the charging salt, is also found to be a critical factor to control the deposition rate. Various gallium micropatterns are obtained by masking the substrate during the process, demonstrating process compatibility with microfabrication. The reported novel approach can potentially be employed in a broad range of applications with Ga as a raw material, including microelectronics, photovoltaic cells, and flexible liquid metal microelectrodes.

Preparation and Properties of Electroless Ni-P-&lt;i&gt;β&lt;/i&gt;-SiC Composition Coating

Through orthogonal test of Ni-P chemical plating process optimization to determine the optimum process recipe, the Ni-P-β-SiC composite coating were prepared by chemical plating method. The deposition rate, microhardness, composition and organization of Ni-P-β-SiC composite coating are observed and analyzed by scanning electron microscopy (SEM), vivtorinox microhardness tester, X ray diffraction (XRD) and energy spectrum analysis (EDS). The influences of β-SiC particle concentration in bath on the solution of composite coating deposition rate and microhardness. The results show that the influence of composite coating deposition rate and microhardness are NiSO4•6H2O, NaH2PO2•H2O, C3H6O3, and PH. The optimum process conditions: NiSO4•6H2O 25 g/L, NaH2PO2•H2O 27 g/L, C3H6O327 ml/L, PH 5.2. It was found that the Ni-P-β-SiC composite coating with 5g/Lβ-SiC particles exhibited a maximum deposition rate and microhardness, the deposition rate of composite coating is 12.32μm/h, microhardness is 567.93HV0.05.

Growth and Properties of Amorphous Erbium‐doped Aluminum‐yttrium Oxide Films Deposited by Aerosol‐UV‐Assisted MOCVD

Erbium‐doped yttrium‐aluminum oxide films (Er:Y2O3‐Al2O3) are deposited by aerosol‐assisted metal‐organic (AA‐MO)CVD. The effects of the humidity of the carrier gas and UV assistance on their structure and optical properties during the deposition are investigated as a function of the substrate temperature and the aluminum mole fraction (Al2O3 mol.‐%) in the liquid solution. The effect of substrate temperature is studied for a constant Al concentration of 33.33 mol.‐% of Al‐acac in the solution. The maximum deposition rates are reached under lower air humidity and with UV assistance in a surface temperature range between 350 and 460 °C. Nevertheless, as‐deposited Er:Al2O3‐Y2O3 films show a very low organic contamination when depositions take place under high air humidity and with UV assistance. The film composition is strongly dependent on air humidity, showing a very high aluminum content when working with a high humidity of the carrier gas, and yttrium‐rich when working with a low humidity of the carrier gas. The refractive index of Er:Al2O3‐Y2O3 films under these conditions is relatively high, reaching 1.76 when deposited at 460 °C.The effect of composition is studied at a substrate temperature of 410 °C. The effect on film composition when varying the aluminum mole fraction in the liquid solution is studied. The most influential parameter is the high air humidity, which induces stronger variation on the layer composition for the same liquid composition.

RF sputtering of polycrystalline (100), (002), and (101) oriented AlN on an epitaxial 3C-SiC (100) on Si(100) substrate

In this paper, the RF sputtering of polycrystalline AlN thin film on epitaxial 3C-SiC(100) on Si(100) substrate is presented. The effect of nitrogen concentration, deposition temperature and sputtering pressure are studied. These parameters are optimized to improve the crystal quality and deposition rate. Nitrogen concentration was varied from 40% to 100%, and it was found that the maximum deposition rate was observed at 40%. The RF bias power on substrate was also varied from 100 to 400 W, and it was observed that the deposition rate increases proportionally. The process temperature was varied from 200 to 400 °C to see the effect on the crystal quality and deposition rate; it was found that temperature variation does not yield significant shifts. This paper is able to demonstrate a successful RF sputtering of a polycrystalline AlN (100), (101), and (002) on epitaxial 3C-SiC(100) using RF power supply of 550 W.

Analysis and Multi-objective Optimisation of Surface Modification Phenomenon by EDM Process with Copper-Tungsten Semi-sintered P/M Composite Electrodes

In the present experimentation work, attempts have been made to model, analyse and optimise the surface modification phenomenon in electrical discharge machining process using response surface methodology. The central composite second order rotatable design has been chosen for designing the experiments and response surface methodology was applied for developing the mathematical models. Efforts has been made to correlate the four input process parameters; peak discharge current, pulse-on time, pulse-off time and tool electrode powder compaction pressure with two output responses; surface deposition rate and surface roughness. Results obtained were presented in the form of three dimensional surface plots. Analysis of variance had been performed to check the adequacy of the developed mathematical models as well as significance of each term comprising the models. Statistical software was used to construct the plots to analyse the influence of individual input process parameter on output responses. Composite desirability function approach was used for multi-objective optimisation of the developed models. Optimal parameter combinations for achieving maximum surface deposition rate and minimum surface roughness have been observed and presented in the form of contour plots. The optimal predicted results were experimentally verified, matched well with the predicted results.

Ultrathin polymer films by single molecule deposition

While physical vapour deposition of glass forming materials below their glass transition temperature, Tg, is an exciting route towards glasses with an extremely high packing density, strong kinetic and thermodynamic stability, vapour deposition of polymer systems is less evident and has so far not been investigated systematically.Here we have successfully prepared ultrathin films of low molecular mass polystyrene (800g/mol) by thermal evaporation from the melt into a UHV chamber at a maximum deposition rate of 1nm/h. Samples were studied in situ and in real-time by dielectric spectroscopy, chip-based ac-calorimetry and a quartz crystal microbalance, both during deposition and after reaching the final sample thickness of 5nm.During film growth well below the bulk-Tg, an initially retarded deposition kinetics was observed along with an accelerated dielectric relaxation dynamics compared to the bulk glass transition. Subsequent temperature cycling above the bulk-Tg revealed continuous changes in the (dielectric) glass transition dynamics and finally lead to desorption of the material at elevated temperatures without restoring the “dielectric” bulk glass transition dynamics.In contrast, simultaneous specific heat spectroscopy revealed bulk dynamics, a striking discrepancy that was discussed in terms of a dominant and accelerated response of PS end-groups in the dielectric spectra in combination with terminal sub-chain dynamics and some degree of end-group segregation.

High-Speed Deposition of SiC Thick Film by Halide Precursor

Polycrystalline ڂ˽SiC thick film with mm-scaled thickness was deposited on a graphite substrate using a gaseous mixture of SiCl4 + CH4 and H2 at temperatures ranging from 1573 to 1823 K by chemical vapor deposition. Effect of deposition temperature (Tdep) on deposition rate, surface morphology and preferred orientation has been studied. The preferred orientation changed from &lt;111&gt; to &lt;110&gt; with increasing Tdep. The maximum deposition rate (Rdep) of 1125 ڌ̽˰̸−1 has been obtained. The surface morphology has changed from six-fold pyramid to five-fold facet with increasing Tdep.

Effects of C/Si Ratio on the Structure of β-SiC Film by Halide CVD

Thick (over 1 mm) β-SiC films were deposited at a deposition temperature of 1823 K and a total pressure of 4 kPa by halide CVD using SiCl4 and CH4as precursors, and H2 as carrier gas. The maximum deposition rate was 1125 μm h−1. The SiC films showed strong (220) preferred orientation. The grain size increased from 20 to 100 μm with increasing C/Si ratio.

Microstructure of LiAl&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;8&lt;/sub&gt; and LiAlO&lt;sub&gt;2&lt;/sub&gt; Films Prepared by Laser CVD

α-LiAl5O8, γ-LiAlO2, α-Al2O3and those composite films were prepared on AlN polycrystalline substrates by laser chemical vapor deposition (LCVD), and the effects of total pressure (Ptot) and the molar ratio of Li to Al (RLi/Al) on the morphology and deposition rates were investigated. The typical morphology of single-phase γ-LiAlO2films prepared atRLi/Al&gt; 1.0 andPtot&gt; 400 Pa was granular, whereas γ-LiAlO2films prepared atPtot&lt; 200 Pa and γ-LiAlO2-α-LiAl5O8composite films had pyramidal grains. Single-phase α-LiAl5O8films showed polygonally faceted morphologies. Composite films of α-LiAl5O8and α-Al2O3consisted of carifllower-like and faceted grains. A single-phase γ-LiAlO2film deposited at 200 Pa showed the maximum deposition rate of 48 μm h-1.

Wide pH Range Electroless Copper Deposition at Room Temperature EQCM and CV Study of Autocatalytic Copper(II) Reduction by Cobalt(II)-Pentaethylenehexamine Complexes

Co(II) complex with pentaethylenehexamine was found to be an effective reducing agent in the autocatalytic reduction of Cu(II) to metal (electroless copper plating). Cyclic voltammetry and electrochemical quartz crystal microgravimetry were used to study the autocatalytic Cu(II) reduction by Co(II) in pentaethylenehexamine solutions. Electroless copper plating was studied by measuring the instantaneous copper deposition rate, open-circuit potential and electrochemical parameters of the partial reactions. It was determined that the electrochemically active and easily oxidizable Co(II) complexes with pentaethylenehexamine are formed in a wide solution pH range, from acidic (pH 4.4) to alkaline (pH 9.5) medium. The maximum copper deposition rate at 20 oC was obtained at pH about 5 and is equal to 55.1 µg cm-2/2 min.