Slurry Deposition Research Articles

Preparation and Characterization of Slurry Aluminide Coating on TP347H FG Stainless Steel

Aluminide coating was prepared on the surface of austenitic TP347H FG stainless steel through a slurry deposition process. SEM (Scanning Electron Microscope), EDS (Energy Dispersive Spectrometer), and XRD (X-Ray Diffraction) analyses were employed to understand the influence of deposition parameters on the microstructures and phase compositions of slurry aluminide coatings. The study found that a two-layered aluminide coating with an interdiffusion layer and an outer layer formed on all conditions. The outer layer mainly consisted of (Fe, Ni)Al phase or (Fe, Ni)Al + Fe3Al + CrSi phases, while those of in the interdiffusion layer are (Fe, Ni)Al + α-Fe + CrxSiy phases. The variation curve of the coating thickness followed a parabolic law as the holding time changed and an index law as the deposition temperature changed, respectively. The shot-peening effect on the formation of aluminide coating was indistinctive for slurry aluminizing at 930 °C. Besides, a controlling method of the thickness of aluminide coatings was proposed by simplifying the diffusion process.

Additive manufacturing of SiSiC by layerwise slurry deposition and binder jetting (LSD-print)

The current work presents for the first time results on the Additive Manufacturing of SiSiC complex parts based on the Layerwise Slurry Deposition (LSD) process. This technology allows to deposit highly packed powder layers by spreading a ceramic slurry and drying. The capillary forces acting during the process are responsible for the dense powder packing and the good joining between layers. The LSD process can be combined with binder jetting to print 2D cross-sections of an object in each successive layer, thus forming a 3D part. This process is named LSD-print.By LSD-print and silicon infiltration, SiSiC parts with complex geometries and features down to 1 mm and an aspect ratio up to 4:1 could be demonstrated.The density and morphology were investigated for a large number of samples. Furthermore, the density and the mechanical properties, measured by ball-on-three-balls method, were in all three building directions close to isostatic pressed references.

Major environmental characteristics of swine husbandry that affect exposure to dust and airborne endotoxins

ABSTRACTInhalation of organic dust or endotoxin in the dust is considered a major risk factor for occupational respiratory illnesses. Eighteen environmental characteristics associated with animal husbandry were surveyed at 36 swine farms in seven provinces throughout South Korea. Association of these factors with levels of indoor inhalable or respirable dust or endotoxin in each type of dust was analyzed using backward stepwise multiple linear regression models. Mean levels of inhalable and respirable dust were 0.5 ± 0.35 and 0.13 ± 0.12 mg/m3 air, respectively, and mean endotoxin levels were 676 ± 463 and 48.4 ± 68.2 EU/m3, respectively, in each dust. Factors negatively associated with inhalable dust levels included pig age, indoor farm temperature, number of pigs in the building, hr/week of indoor farm work, and partly slatted floor. Factors positively associated with inhalable dust levels included floor cleaning by manual scraping and slurry deposit duration. Factors negatively associated with the level of endotoxin in inhalable dust included pig age, temperature, number of pigs, hr/week of indoor farm work, and partly slatted floor. Factors negatively associated with respirable dust level included area of the confinement building, whereas factors positively associated with respirable dust level included the number of pigs and stocking density. Endotoxin levels in respirable dust were negatively associated with h/week of indoor farm work and partly slatted floor. Overall, data suggest that husbandry variables may be adjusted to control dust and airborne endotoxin levels in swine farms.

Cyclic resistance of a decomposed granite

An important issue surrounding the identification of liquefaction susceptibility using laboratory testing is how well the soil sample being tested represents the soil in the field. Undisturbed samples are difficult and costly to obtain, while reconstituted soil samples must have a structure and fabric that represents in situ conditions as closely as possible. Recent laboratory tests on sand samples revealed that liquefaction resistance is strongly affected by the sample preparation technique, as different techniques result in different fabrics and structures. The same may be true for silty sand samples, although they have not been given the same research attention. Thus, this paper presents cyclic triaxial test results on non-plastic silty sand samples (a decomposed granite) and determines the number of cycles required to cause liquefaction, considering different failure criterion as well as different confining pressures, cyclic strength ratios and sample preparation techniques. The techniques include dry and slurry deposition. The experimental results show that the preparation technique does not have a significant influence on cyclic resistance.

Quality assessment of a new in-mould slurry deposition method for triaxial specimen reconstitution of clean and silty sands

An innovative specimen reconstitution technique for sandy and silty soils that simulates underwater deposition is presented and evaluated. The technique is an upgraded version for triaxial testing of the well-established slurry deposition method. This novel setup integrates the reconstitution mould and the mixing tube into a single unit to avoid transferring the sample from the mixing tube to the mould. This subtle, but critical, modification enables reconstitution of very loose specimens as sample transfer disturbance, which can be significant, is eliminated. The quality of specimens prepared by the new reconstitution method was assessed by experiments on a clean sand from the UK (Ham River sand) and a silty sand from Norway (Øysand). The method, as any slurry-based procedure, is capable of producing homogeneous specimens with high initial degree of saturation, even in the absence of back pressure. The procedure is shown to be suitable for sands with or without fines. Moreover, the new method is able to achieve a wide range of initial void ratios, from very loose to very dense, without imposing any particle crushing in the latter case.

Pulsed 70 kV X-ray sensing behavior of Cu2HgI4 thick films

X-ray photoconductors are widely used in flat panel X-ray detectors in medical and dental imaging systems. In the present work, X-ray photoconductivity measurement of Cu2HgI4 thick film was performed using a real-time intraoral X-ray machine. To perform the sensing measurement, wet chemical derived Cu2HgI4 sample was coated as a thick film by slurry deposition route on top of the tin coated copper patterned electrode. Prior to the sensing measurement, Cu2HgI4 powder sample was characterized using powder X-ray diffraction, scanning electron microscope, energy dispersive x-ray analysis, Fourier transformed infrared spectroscopy and diffused reflectance spectroscopy. These analysis confirms the sample is in single phase with crystallites are in sub-spherical morphologies. The resistance of Cu2HgI4 thick film was measured under the presence and absence of pulsed 70 kV X-ray for various exposure durations from 0.06 to 3.2 s using a Keithley 2450 source meter. Appreciable sensitivity against intraoral pulsed 70 kV X-ray sensing behavior of Cu2HgI4 thick films explore the possibility of utilizing it as a photoconductor for flat panel X-ray imaging detectors.

Effect of Different Sands on One-Dimensional and Hydraulic Consolidation (Radial) Tests of Clay

In settlement problems, the soil type is generally determined by the sand, silt and clay contents. Sieve analysis considers only the percentage of sand, and the grain shape of the sand is ignored. Specifically, sand grains with different characteristics are considered a single type of sand. In this study, variations in the pore size distribution of clay associated with sand particles of different shapes are investigated via consolidation tests. For this purpose, mixtures containing 10%, 20%, 30% and 40% of the two types of sand additions to clay were obtained. Samples of reconstituted clay were prepared using the slurry deposition method. One-dimensional consolidation and radial consolidation (with drainage radially outwards) tests were performed on the samples, and the relationship between the pore size distributions of the mixtures and the consolidation tests was examined. In addition, the mixtures were analysed using helium pycnometry, X-ray diffraction, mercury intrusion porosimetry, Brunauer–Emmett–Teller surface area analysis and scanning electron microscopy.

Corrosion testing of diffusion-coated steel in molten salt for concentrated solar power tower systems

In the course of energy transition the development of sustainable technologies for power generation providing base load supply is of particular importance. In comparison to photovoltaics concentrated solar power (CSP) Systems have great potential to fulfil this requirement by the use of thermal storage systems utilizing molten salt mixtures as heat transfer fluids. For this purpose, molten nitrates are frequently discussed due to their beneficial thermal and physical properties as well as high operation temperatures.In order to protect the piping system from degradation, coatings can be applied on the surface of the employed materials, which are commonly steels or Ni-based alloys. The goal is to achieve cost reduction to ensure an even more competitive position of the CSP technology with respect to other renewable sources on the market.In this study, the corrosion behavior of coated and uncoated ferritic-martensitic steels of type T91 and VM12 in molten salt (mixture of NaNO3 and KNO3) has been investigated under isothermal conditions. The diffusion coatings are based on potentially protective elements such as Al, Si or Cr and were applied on the steels either by pack cementation or slurry deposition. Characterization of the samples was conducted by means of optical microscope and EPMA in order to gain a deeper understanding of the occurring corrosion mechanisms and for the purpose of lifetime analysis.

Methane emission factor of open deposits used to store swine slurry in Southern Brazil

Abstract: The objective of this work was to contribute to the establishment of a baseline for the methane emission factor for the management of swine manure, considering the current practice of raw manure storage in two open deposits in parallel, in Southern Brazil. Methane (CH4) emissions were continuously measured in three PVC tanks of 3 m3, during 180 days, in the summer. As the content of volatile solids of pig slurry ran out in approximately 130 days, the CH4 emission factor was calculated as B0= 0.48 m3kg-1VS. Although this value is higher than the B0 estimated by Intergovernmental Panel on Climate Change for Latin America (0.29 m3 kg-1 VS), it is in agreement with the B0 estimated for developed countries (0.45 and 0.48 m3 kg-1 VS, for the US and EU, respectively). The graphic of accumulated CH4-C emission x time fitted a sigmoidal, kinetic model (r2= 0.998) that showed a good correlation when tested with the emission data collected from a slurry deposit, under field conditions, in winter. This suggests that the model reproduces the CH4 emission kinetics in the region. By applying the reviewed state law rules (retention time of 50 instead of 120 days), estimates by the sigmoidal equation show that it is possible to reduce in more than 80% methane gas emission.

3D printing of porcelain by layerwise slurry deposition

The Layerwise Slurry Deposition is a technology for the deposition of highly packed powder layers. A powder bed is achieved by depositing and drying layers of a ceramic suspension by means of a doctor blade. This deposition technique was combined with the binder jetting technology to develop a novel Additive Manufacturing technology, named LSD-print. The LSD-print was applied to a porcelain ceramic. It is shown that it was possible to produce parts with high definition, good surface finish and at the same time having physical and mechanical properties close to those of traditionally processed porcelain, e.g. by slip casting.This technology shows high future potential for being integrated alongside traditional production of porcelain, as it is easily scalable to large areas while maintaining a good definition. Both the Layerwise Slurry Deposition method and the binder jetting technologies are readily scalable to areas as large as >1 m2.

Electrochemical promotion of nanodispersed Ru-Co catalysts for the hydrogenation of CO2

Electrochemical promotion of the CO2 hydrogenation to CH4 and CO on a nanodispersed Ru-Co catalyst has been achieved via slurry deposition of the nanodispersed catalyst on an interlayer Ru film deposited on a BZY (BaZr0.85Y0.15O3) proton conducting solid electrolyte disc. The effect of current is nonFaradaic, with Faradaic efficiency values as high as 60 and leads to a reversible variation of the selectivity to CH4 between 16% and 41%. Due to thermal spillover of protons on the Ru-Co catalyst surface, the open circuit selectivity to CO is quite high, i.e. up to 84% and similar values are obtained via negative potential application, i.e. proton supply to the Ru catalyst film deposited on BZY before the deposition of the nanodispersed catalyst. These results underline the similarity between electrochemical promotion and metal support interactions when using proton conducting supports. They also show the usefulness of electrochemical promotion for mechanistic investigations. The electrochemical promotion of nanodispersed catalysts is a promising step for the practical utilization of electrochemical promotion.

Investigation of wax-based barite slurry and deposition for 3D printing landslide model

Deposition-based 3D printing has been proposed as a novel method for building the landslide model, especially its porous slide zone, to accurately mimic equivalent material properties and porous structure, which has been not yet achieved by traditional the manual or semi-auto compacting method. As an initial attempt, this research firstly selects barite powder and its wax additive formula for 3D slurry deposition, manipulating the relationship between the stress field control and the porosity of forming materials. It finds that the binder additive formulation of liquid paraffin 3 wt.%, solid paraffin 12 wt.%, stearic acid 1.8 wt.%, palm wax 4.8 wt.% could provide best dispersion of barite powder for slurry deposition. The additive binder with over 20 wt.% enables the proper 3D slurry deposition process, proving the capability of build landslide model via layer-by-layer forming process. The well-dispersed stable barite slurry paste is able to provide better mechanical properties for 3D formed parts. The sintering of the various slurry specimens could reach compressive strength up to 2.7 MPa as well as offer the strength lower than 0.5 MPa, providing wide range of mechanical property. Besides, the removal of wax additive binder during the sintering process enables the formation of well-distributed micro pores, which could assist in mimicking the material structure of weak slip zone. Hence, this study has achieved a combined development of material formulation, 3D printing slurry deposition and sintering approach, showing great potential to achieve synchronous controlling of material properties such as stress and seepage field in the 3D printed landslide model.

Electrode Slurry Particle Density Mapping Using X-ray Radiography

The internal structure of a porous electrode strongly influences battery performance. Understanding the dynamics of electrode slurry drying could aid in engineering electrodes with desired properties. For instance, one might monitor the dynamic, spatially-varying thickness near the edge of a slurry coating, as it should lead to non-uniform thickness of the dried film. This work examines the dynamic behavior of drying slurry drops consisting of SiOx and carbon black particles in a solution of carboxymethylcellulose and deionized water, as an experimental model of drying behavior near the edge of a slurry coating. An X-ray radiography-based procedure is developed to calculate the evolving spatial distribution of active material particles from images of the drying slurry drops. To the authors’ knowledge, this study is the first to use radiography to investigate battery slurry drying, as well as the first to determine particle distributions from radiography images of drying suspensions. The dynamic results are consistent with tomography reconstructions of the static, fully-dried films. It is found that active material particles can rapidly become non-uniformly distributed within the drops. Heating can promote distribution uniformity, but seemingly must be applied very soon after slurry deposition. Higher slurry viscosity is found to strongly restrain particle redistribution.

Fluid escape structures as possible indicators of past gas hydrate dissociation during the deposition of the Barremian sediments in the Recôncavo Basin, NE, Brazil

ABSTRACT: Empty elliptical vesicles are observed in outcrops of Barremian very fine clayey sandstone to siltstone lacustrine slurry deposits of the Pitanga Member (Maracangalha Formation), exposed in the Maré Island, Southern Recôncavo Basin, Brazil. These sedimentary features have been traditionally interpreted as water escape structures triggered by the diapirism of the underlying shales of the Candeias Formation. This work proposes that vesicles were generated during massive gas hydrate dissociation as a result of tectonic activity in a paleolake system. Tectonic uplift would have triggered both the reduction of the confining pressure as well as an increase in lake bottom temperature, resulting in the instability of gas hydrate and causing intense release of both methane - or carbon dioxide (CO2) - and water. On one hand, this proposal has a strong impact on paleoenvironmental interpretations, giving support to the current hypothesis that rocks related to the Pitanga Member would have been deposited under water columns deep enough for gas hydrate formation and subsequent dissociation. On the other hand, it provides new insights on the genesis of fluid escape structures in sedimentary rocks, both lacustrine and marine, providing a paleobathymetric indicator.

Microscopic vertical orientation of nano-interspaced graphene architectures in deposit films as electrodes for enhanced supercapacitor performance

This work reported a novel two-step process to fabricate high-performance supercapacitor films that contain microscale domains of nano-interspaced, re-stacked graphene sheets oriented perpendicular to the surface of current collector substrate, i.e., carbon fiber paper. In the two-step process, we first used ligand molecules to modify the surface of graphene oxide (GO) sheets and manipulate the interspacing between the re-stacked GO sheets. The ligand-modified GOs, i.e., m-GOs, were then reduced to obtain more conductive graphene (m-rGO), where X-ray diffraction measurement results indicated well-controlled interlayer spacing between the restacked m-rGO sheets up to 1nm. The typical lateral dimension of the restacked m-rGO sheets were ~40µm. Then, electrical field was introduced during m-rGO slurry deposition process to induce the vertical orientation of the m-rGO sheets/stacks in the film deposit. The direct current electrical field induced the orientation of the domains of m-rGO stacks along the direction perpendicular to the surface of deposit film, i.e., direction of electric field. Also, the applied electric field increased the interlayer spacing further, which should enhance the diffusion and accessibility of electrolyte ions. As compared with the traditionally deposited “control” films, the field-processed film deposits that contain oriented structure of graphene sheets/stacks have shown up to ~1.6 times higher values in capacitance (430F/g at 0.5A/g) and ~67% reduction in equivalent series resistance. The approach of using electric field to tailor the microscopic architecture of graphene-based deposit films is effective to fabricate film electrodes for high performance supercapacitors.

Rheological Characterization of Aqueous ZrO<sub>2</sub>-Suspension for Additive Manufacturing

Water-based suspensions from commercial Tetragonal stabilized zirconia (3Y-TZP) were produced and characterized with different contents of solids and two different dispersants. According to zeta potential measurements, 3Y-TZP particles showed basic surface characteristics and IEP of around 9 when in aqueous media. The critical volume fraction of solids was about 79.6 wt%, which hindered the processing of more concentrated slurries. Rheological measurements confirmed that well dispersed slurries could be obtained with solid content as high as 79.6 wt.%. The results showed that Triton X-114 was an effective dispersant for preparing well stabilized 3Y-TZP suspensions for the layer-wise slurry deposition process.

Environmental impact of mining activities on surface water and sediment qualities around Murgul copper mine, Northeastern Turkey

Mining activities in many countries around the world pose serious pressure on surrounding water bodies. This study assesses the environmental impact of Murgul mine, one of the longest operated open-pit copper mines in Turkey. A long-term monitoring study was conducted on the surrounding surface water bodies to assess the degree of deterioration/recovery in water quality. Stream water, sediment and mine discharge samples were collected along the flow direction from the drainages under the influence of the mine. Sampling was also performed on the upgradient drainages from the mine to determine the background conditions. Water samples collected were analyzed for major ion and metal contents. pH, temperature, EC and DO contents of the water samples were measured in situ. Dissolved and total metal contents of the stream water samples and the mine discharges were also analyzed to determine the dominant transport phase of the metals. Negative effects of the past mining activities on Murgul stream are visible on the streamside with the thick flotation deposits. During monitoring study, the most severe effect of the mining activities on Murgul stream was observed following the leakage of tailing dam. The impact of this incident was observed intensely up to the confluence of Murgul stream and Borcka Dam reservoir, and this was clearly seen in change of pH, EC, sulfate, metal contents and water facies of Murgul stream along flow direction toward Borcka Dam. Al, Fe, Mn, Cu, Zn, Pb and Cd exhibited the highest concentration in the dissolved phase of the stream samples. The impact of discharges from mine on Murgul streambed was enormous, and Murgul stream was classified as heavily polluted water (class IV) according to Turkish inland water quality regulations. Significant increase was also observed in metal contents of the stream sediments taken from the downstream from mine, especially for Cu, S, Zn, As, Ba and Mo. Following the control of leakage, prominent recovery in Murgul stream quality was observed in many parameters and stream water achieved class I–II water quality. Results showed that metal loads transported in the suspended phase of stream were more significant than those in the dissolved phase. Current and past flotation slurry deposits near Borcka Dam reservoir may pose long-term risk for aquatic life in Borcka Dam as a result of metal leaching and need further investigation.

Long term stability of porosity gradient composite cathode controlled by electro-static slurry spray deposition

Proton conducting fuel cells (PCFCs) have attracted much attention due to the lower activation energy of proton transport at intermediate temperatures. The cathode of PCFCs has been studied for enhancement of cell performance. Unlike solid oxide fuel cells (SOFCs), the product of chemical reaction, H2O, is generated in the cathode region. Generally, as the structure of the PCFC' cathode is denser than the anode of SOFC, the vapor is not easily emitted outside of the cathode, and this remaining vapor in the isolated cathode structure has a negative effect on cell performance. In this work, a gradient porous La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF)/BaCe0.7Zr0.15Y0.15O3−δ (BCZY) composite cathode was developed for fuel cells based on the BCZY electrolyte using an electrostatic spray slurry deposition method. The cathode porosity and deposited powder size gradually increased in the direction away from the electrolyte-electrode. The results indicate that the structure of the porosity gradient cathode might enhance the long-term stability in proton conducting fuel cells.

Dense thin YSZ electrolyte films prepared by a vacuum slurry deposition technique for SOFCs

A novel vacuum deposition technique based on a slurry coating is proposed for the preparation of thin yttria-stabilized zirconia (YSZ) electrolyte films on a porous NiO-YSZ substrate for solid oxide fuel cells (SOFCs). The vacuum pressure not only improved the packing density of the electrolyte particles but also enhanced the bonding strength between the anode and electrolyte layers. The polarization resistance of the cell prepared via vacuum deposition decreased from 1.27 to 0.89Ωcm2, which resulted in a remarkable increase in the peak power density from 249 to 292mWcm−2 at 800°C. An anode functional layer (AFL) was also fabricated by the vacuum slurry deposition method in an attempt to increase the three-phase boundaries (TPBs) at the anode/electrolyte interface. The scanning electron microscopy (SEM) images revealed that the sintered YSZ electrolyte film has a crack-free, dense and homogeneous microstructure. These experimental results indicate that slurry vacuum deposition is an effective technique for producing dense thin films for SOFCs and other applications.

Low-Cost Modular Battery Fabrication System Based on 3D-Printed Parts and Microcontrollers

Integrating energy storage into clothing would enable wearable electronics of a more comfortable form factor and weight distribution compared to traditional rigid cells. Work on LTO vs LCO systems by previous groups have demonstrated the material system’s ability to be flexed or produced with scalable methods. In this work we report a low-cost automated fabrication setup to produce flexible LTO/LCO batteries on carbon fiber substrates. The modular thread-coating system reported here takes advantage of cheap Arduino microcontrollers and 3D printed structures for a highly customizable design allowing for rapid prototyping of different material systems. In this particular setup, a stepper motor pulls a fiber through a series of 3D-printed stages where the fiber substrate is subjected to slurry deposition, washing, heating or packaging to produce a functional LTO/LCO battery. The modular system serves as a useful intermediary between initial lab scale research— in which artisanal manual skills are often required from the researcher— and the industrial production process— in which automation and high throughput are paramount. The modular intermediary allows one to mimic mass production at a lab scale to identify challenges and solutions to scaling up a battery architecture for wide use.