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Abrasive flow jet machining (ASJM) is modern manufacturing technique which uses comparatively low-pressure abrasive flow jet for machining various machined surfaces like holes, channels and intricate shapes which is not possible from conventional machining processes. The effect of abrasive particle concentration on the impacting slurry velocity on the surface was examined in the present CFD simulation, resulting in target surface erosion. To predict the impact velocity of abrasive particles hitting the surface, a 2D CFD model was used. The depth of machined surface, surface irregularity and surface removal rate at normal incidence mainly depend on the KE of particle, impact angle, etc. in line with previously published research work on highly pressurised air and water driven abrasive jet. In the present work CFD simulation is performed to predict the effect of solid particle concentration on the impacting slurry jet velocity at the target surface and also turbulence kinetic energy near the surface is studied. As per the CFD results the simulation model predictions the velocity of impacting particle goes on decreasing due to internal frictional resistance between solid and liquid phase and it shows scope of further parametric analysis in this area.

Vacuum preloading combined with prefabricated vertical drains (PVDs) system has been widely used to improve the soft clay with high water content. Clogging is usually formed around the PVDs during the vacuum preloading, impeding the propagation of the vacuum pressure and slowing down the consolidation process. To understand the forming mechanism of the clogging, particle image velocimetry (PIV) technique and particle tracking velocimetry (PTV) technique were adopted in the model test of vacuum preloading test. Through this study, three stages can be identified from the results of water volume discharge rate and maximum displacements versus time. In the first stage, the soil around the PVD is horizontally consolidated, which leads to the rapid formation of clogging. In the second stage, the formation of clogging slows down due to the loss of vacuum pressure, which further reduces the drainage. In the third stage, the clogging tends to be stable, and the drainage consolidation rate is significantly reduced. PTV results show that there is a difference in the displacement of large and small particles during improvement. Two methods were proposed to estimate the thickness of clogging zone, reflecting a growing layer of clogging zone compressed around the PVD. This study provides new insights to investigate the formation mechanism of clogging during vacuum preloading test.

The effects of erbium addition on the rheological properties and microstructure of a semisolid A356 alloy were studied. The semisolid slurries were prepared through the serpentine channel technique before they were thixoformed using parallel-plate compression with cylindrical discs. The grain and globule size decreases as the Er content increases, resulting in an improved and uniform distribution of spherical primary α-Al phase within the semisolid slurry. The addition of the Er modifies the grain morphology and size of the α-Al grains, resulting in a better and more uniform distribution of spherical primary α-Al phase within the semisolid slurry. As a result, rheocast quality index increases with the addition of Er, which is suitable for the thixoforming process. The A356 alloy without Er has the highest viscosity herein. The viscosity decreases, and the flow characteristics of the semisolid feedstock are expected to improve when Er is added as a result of the refinement of primary α-Al and modification of eutectic silicon. Furthermore, the refined semisolid A356 alloys with Er show a slightly larger fraction of high-angle grain boundaries compared to that for the unrefined alloy.

During earth pressure balance (EPB) shield tunnelling in sandy ground, not only foam but also other conditioning agents need to be injected to reduce the permeability of muck and avoid water spewing out of the screw conveyor. Permeability tests were carried out to study the permeability characteristics of conditioned sand under high hydraulic gradients. A low bentonite slurry injection ratio (BIR) enhanced the workability of foam-conditioned sand. As the hydraulic gradient increased, the initial permeability coefficient of conditioned sand increased, and the initial stable period became shorter or disappeared. The BIR had a more significant effect on the permeability of conditioned sand than the foam injection ratio (FIR), and this effect gradually weakened as the hydraulic gradient increased. The initial permeability coefficient of the foam–bentonite slurry-conditioned sand decreased by approximately an order of magnitude compared with that of the foam-conditioned sand. With the addition of bentonite slurry, suitable sand conditioning can accept a higher water content (w) and lower FIR, resulting in suitable ranges of w and FIR that are more flexible. Finally, the mechanism of stabilizing foam under the action of bentonite slurry was discussed by considering the interaction between foam bubbles and fine particles.

The coaxial mixers enhance the suspension of concentrated slurries in an agitated reactor. In this research work, the complex slurry suspension and dissemination behavior in a coaxial slurry mixing system (comprised of a close clearance anchor rotating with a low speed and an inner axial impeller rotating with a high speed) was analyzed employing ERT (electrical resistance tomography, a non-intrusive flow visualization technique), and computational fluid dynamics (CFD). The numerical models were validated by comparing the axial solid concentration profiles generated using the ERT data and the CFD simulation results. The influences of various important parameters such as the diameter of the inner axial impeller, the inner impeller type, and the inner impeller spacing on the hydrodynamic characteristics of the slurry suspensions in a coaxial mixing vessel were thoroughly analyzed. The radial and axial velocity profiles of solid particles were generated using the validated mathematical models. The assessment of energy loss due to the solid–solid collisions, the particle–fluid frictions, and the particle–vessel wall collisions was conducted. The evaluation of optimum inner impeller clearance and inner impeller diameter is essential to attain a high degree of solids suspension and dissemination in a coaxial slurry mixing system.

In the vacuum treatment of dredged slurries via prefabricated vertical drains (PVDs), both filtration and consolidation may happen to dredged slurries when subjected to the vacuum gradient. Similar to the consolidation, the filtration may provide equally useful information on interpreting the constitutive behavior of the slurry. In this paper, a new approach utilizing the filtration process is devised to evaluate the constitutive behaviors of dredged slurries. The approach is composed of a vacuum filtration device and an iterative curve fitting algorithm. Two types of tests, namely step-vacuum filtration and constant-vacuum filtration followed by compression test, must be conducted on the slurry specimens, and only the time variations of the filtrate discharge should be recorded. On the basis of the recorded data, the curve fitting algorithm is adopted for determining the parameters of the constitutive equations. The effectiveness of the proposed approach is verified through comparing the obtained compressibility and permeability of the slurries with the data provided by the oedometer test and with the empirical relationships from different sources. The comparisons demonstrate that the constitutive relationships determined by the present approach can predict the compressibility and permeability characteristics of dredged slurries with an acceptable degree of accuracy.

This study proposes a new method using the combination of flocculation and prefabricated horizontal drain (PHD) assisted with vacuum pressure for rapid dewatering of high-water-content dredged slurry. First, to demonstrate the superiority of using PHD over the more commonly used prefabricated vertical drain (PVD), experiments were conducted to compare the dewatering performance between the PHD and the PVD. Then six model tests with the proposed dewatering method were performed with various contents of flocculant (anionic polyacrylamide (APAM)) to investigate the effect of APAM content on the dewatering process and soil properties (i.e. undrained shear strength, permeability and compressibility). Furthermore, particle size distributions of the slurry before and after model tests were measured to analyze the dewatering behavior and changes in material properties. Finally, particle loss during vacuum consolidation for various APAM contents were compared to study the flocculation effect on clogging problem. Results indicate that the proposed method can prevent significant bending deformation of the drain board and mitigate clogging of the drain filter and, thus, can significantly accelerate the dewatering process of high-water-content dredged slurry.

The bubble formation dynamics and size manipulation in the slurry of polystyrene microspheres in the microfluidic T-junction were visually investigated by a high-speed camera. Based on the evolution law of the bubble neck width with time, the formation process of bubbles is divided into three stages: filling, squeezing and pinch-off. The particle concentration has an obvious effect on the squeezing stage, while less impact on the filling and pinch-off stages. In the squeezing stage, the evolution of the dimensionless minimum neck width of bubbles with time could be described by a power-law relationship. The increase of the particle concentration or continuous phase flow rate could lead to the increase of body flow of the continuous phase flow rate and the enhancement of the squeezing force acted on the bubble neck, correspondingly, the power-law index α in the squeezing stage enlarges. Moreover, the bubble size increases with the increase of the gas phase flow rate and the decrease of the particle concentration and continuous phase flow rate. However, the effect of the particle concentration on the bubble size weakens with the increase of the continuous phase flow rate. In addition, a new prediction correlation of the bubble size for the slurry system in a T-shape microchannel was proposed with good prediction accuracy.

Supercritical CO2 fracturing is a potential waterless fracturing technique which shows great merits in eliminating reservoir damage, improving shale gas recovery and storing CO2 underground. Deep insight into the proppant-transport behavior of CO2 is required to better apply this technique in the engineering field. In the present paper, we adopted a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) approach to simulate the proppant transport in a fracking fracture with multiple perforation tunnels. Previous experiments were first simulated to benchmark the CFD-EDM approach, and then various pumping schedules and injection parameters (injection location, multi-concentration injection order, multi-density injection order and injection temperature) were investigated to determine the placement characteristics of proppant. Results indicate that the swirling vortex below the injection tunnels dominates the proppant diffusion in the fracture. The velocity of fluid flow across the proppant bank surface in multi-concentration injection shows a positive correlation with the proppant concentration. Injecting high-density proppant first can promote the transportation of low-density proppant injected later in the fracture to a certain extent Decreasing the initial injection temperature of supercritical CO2 slurry helps enhance the particle-driving effect of fluid and improve the performance of supercritical CO2 in carrying proppant.

With the rapid development of modern industry, high-grade paving asphalt is massively required to meet the demands for modern transportation. As one of additives, natural asphalt is indispensable since it can improve the performance of paving asphalt in all aspects. However, the application of non-renewable natural asphalt is increasingly restricted by its limited reserves. It is imperative to find alternative approaches to produce high-grade paving asphalt. Fluid catalytic cracking (FCC) slurry oil is an ideal soft component for producing paving asphalt due to its high content of aromatics and resins. However, its bad ageing resistance limits its application to only low-grade paving asphalt. In the present work, a novel approach for producing high-grade paving asphalt was investigated using chemically modified FCC slurry oil and deoiled asphalt (DOA). The FT-IR and NMR results showed that dehydrogenation and condensation reaction occurred during the ageing process. From a series of aliphatic alcohols and aldehydes, propanal was selected as a proper modifier to improve the ageing resistance of FCC slurry oil. The propanal-modified slurry oil possessed more substituted aromatic units and less aromatic hydrogen atoms than other modified slurry oils, thus showing better ageing resistance. With the increase of length of aliphatic chains in modifier, the modified slurry oil contained more and longer alkyl substituent group on aromatics. Compared with the cross-linked oil (slurry oil modified by cross-linking agent), modified slurry oil possessed similar ageing resistance but higher flowing ability. Also, the effect of operation conditions on the kinematic viscosity of modified slurry oil were investigated. Blended with modified slurry oil, the penetration ratio of asphalt product increased from 53.7 to 66.2, which met the standard of 70# paving asphalt. Both the microscopic observations and FT-IR results indicated that modification process effectively reduced the oxidation degree of asphalt product, thus increasing the ageing resistance. Consequently, with aid of this process, high-grade paving asphalt was readily produced from low value oil from downstream products of refinery, instead of the depleting natural asphalt.

Slurry reactors are popular in many industrial processes, involved with numerous chemical and biological mixtures, solid particles with different concentrations and properties, and a wide range of operating conditions. These factors can significantly affect the hydrodynamic in the slurry reactors, having remarkable effects on the design, scale-up, and operation of the slurry reactors. This article reviews the influences of fluid physical properties, solid particles, and operating conditions on the hydrodynamics in slurry reactors. Firstly, the influence of fluid properties, including the density and viscosity of the individual liquid and gas phases and the interfacial tension, has been reviewed. Secondly, the solid particle properties (i.e., concentration, density, size, wettability, and shape) on the hydrodynamics have been discussed in detail, and some vital but often ignored features, especially the influences of particle wettability and shape, as well as the variation of surface tension because of solid concentration alteration, are highlighted in this work. Thirdly, the variations of physical properties of fluids, hydrodynamics, and bubble behavior resulted from the temperature and pressure variations are also summarized, and the indirect influences of pressure on viscosity and surface tension are addressed systematically. Finally, conclusions and perspectives of these notable influences on the design and scale-up of industrial slurry reactors are presented.

Filter cake is critical to maintaining the stability of the excavation face of an underwater shield tunnel in a high-permeability stratum. In a high-permeability formation, generating an effective filter cake on the excavation face is difficult with a pure bentonite slurry, which penetrates the ground and may not achieve the required suspension pressure. Determining how to efficiently and quickly form a thin and low-permeability filter cake on the tunnel working face has become a key engineering problem in the construction of slurry shield tunnels in high-permeability strata. In this study, the relationship between slurry viscosity and the slurry pressure gradient of pure bentonite was established by performing slurry permeability experiments. The influence of slurry viscosity on the formation of the filter cake in a high-permeability formation was studied under different pressure gradients. In addition, the effect of additive particle size on the slurry filter cake formation was analyzed by introducing additives with different particle sizes to pure bentonite slurries with different viscosities. The test results indicate that (1) for the pure bentonite slurry, the critical initial pressure gradient can be used as a rough indicator of the formation of the filter cake, and the relationship between the critical maximum pore diameter and the average pore diameter of the formation can be compared to establish and analyze the formation law of the slurry filter cake; (2) adding particles to the slurry can enhance the effect of the pure bentonite slurry; and (3) adding coarse-grained materials can effectively improve the film-forming effect. The slurry is more compact when the particle size is close to the average pore size of the formation.

To repair the damaged SiC coated C/C composites, a double-layer system including a Sm-doped borosilicate glass external layer and a Si SiC inner layer was prepared by a slurry-based laser cladding technique. Isothermal oxidation experiment and indirect/direct thermal-radiation measurements were performed. The results showed that the absorbance of borosilicate glass to the laser at 900–1200 nm was improved significantly by Sm-doping. Consequently, the repaired coating with a more compact structure and better oxidation resistance was obtained. After oxidation at 1773 K for 10 h, the mass loss of the damaged sample could be reduced by 74.98% with repairing. By increasing laser-absorption and reducing viscosity, the thermal-radiation property of the repaired coating was enhanced to decrease the surface temperature greatly. A repair system with excellent thermal protection performance was achieved.

As an excellent promising tritium breeding material, Li2TiO3 ceramic pebbles will be required in large quantities in the future. For this reason, a fully automatic pneumatic eject device based on an improved wet process was employed in the mass-preparation of Li2TiO3 ceramic pebbles. The operating principle of the equipment, the preparation process parameters and the performance of the Li2TiO3 ceramic pebbles have been studied. The results showed that the spheroidization and solidification process of slurries droplets in the molding medium were critical to the sphericity of pebbles, and the size of the green pebbles was related to the droplet dropping speed、the control pressure and the nozzle inner diameter. It is revealed that more than 90% of the pebbles had an eccentricity of less than 1.1, and the diameter distribution was concentrated between 0.98 mm and 1.03 mm. The Li2TiO3 ceramic pebbles with the average grain size of 3.7 μm, the crushing load of 67 N, the relative density of 85.6%, and the porosity of 19.96% can be obtained after sintered at 1100 °C for 2 h. Also, the average pore size was 1.3 μm and the distribution was relatively concentrated. Therefore, this method is expected to meet the future demands of Li2TiO3 ceramic pebbles with excellent performance in bulk quantity.

In pursuing high precision and high-quality surface of silicon carbide (SiC) substrates for electronic applications, however, the processing efficiency on Si-face has long been a difficult challenge compared to that of the C-face. Conventional polishing slurries are aqueous-based due to its unparalleled compatibility with most of chemical reagents, and have been widely studied and well understood. The chemical reactivity of all added accelerating agents in aqueous polishing systems is constrained by the prevalent presence of water as a solvent. On the other hand, non-aqueous polishing systems have not been well explored. In this report, reactive non-aqueous organic systems containing polar hydroxyl groups are evaluated as a high efficiency processing vehicle for Si-face polishing of SiC on fixed abrasive pads (FAPs). The surface quality of SiC is surprisingly improved while the polishing efficiency is accelerated on a diamond FAP in presence of methanol compared to those using water, and are further improved when organic acids are introduced to the reactive non-aqueous fluids. Contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis on the polished SiC surface are completed to assist us to shed light on the removal behavior and to explore and elucidate the removal mechanism of non-aqueous system fluids on FAPs. The initial positive results from this reactive non-aqueous polishing system serves our community as a promising approach for the ultra-precision polishing on other hard-to-process semiconductor and ceramic materials.

Spent MoSi2 heating elements were used to fabricate MoSi2, ZrB2/MoSi2 and MoSi2-ZrB2/MoSi2 oxidation resistant coatings via a two-step process of slurry painting and spark plasma sintering. Cracks appeared in simple MoSi2 and ZrB2/MoSi2 coatings, whilst MoSi2-ZrB2/MoSi2 coating was crack-free as CTE mismatch was reduced. Mo5Si3 and MoB diffusion layers formed under MoSi2-ZrB2 transition layer in MoSi2-ZrB2/MoSi2 coating, revealing good metallurgical combination between the substrate and coating. On one side the silica layers covering MoSi2 and ZrB2/MoSi2 coatings displayed diffused cracks after oxidation at 1773 K for 100 h, on the other side it was dense and continuous for MoSi2-ZrB2/MoSi2 coating, showing low oxidation rate constant at 1773 K. Furthermore, MoSi2-ZrB2 transition layer in MoSi2-ZrB2/MoSi2 coating possessed good short-term oxidation protective properties at 1873 and 1973 K since the formation of ZrSiO4 improved the stability of Si-O-Zr composite oxide scale and diminished the oxygen permeability, therefore demonstrating good high-temperature oxidation resistance.

The Waste Treatment and Immobilization Plant (WTP) will process and stabilize nuclear waste stored in tanks on the Hanford Site. At the WTP, the tank waste will be combined with glass-forming chemicals to make a melter feed slurry that can be vitrified in joule-heated melters. Technetium-99 (99Tc), a long-lived radionuclide present in tank waste, is semi-volatile from a glass melt at elevated temperatures. A small laboratory-scale melter system has been designed by PNNL to operate under radioactive conditions, giving it the ability to vitrify actual tank waste and gain information about melter feed processability and the partitioning of components of interest. This study describes two runs performed in a duplicate system with non-radioactive simulants of Hanford tanks 241-AP-107 and 241-AN-105 to gain insight into the relationship between the retentions of 99Tc and its non-radioactive surrogate Re while also investigating the effects of increasing the reducing agent such as sucrose during vitrification on processing and the retention of semi-volatile components in the glass product. The results from these runs align with the general trends of greater retention in the glass of Re compared to 99Tc and the improved retention in the glass of Re with increased reducing agent.

Active and selective structured RuO/AlO catalysts for CO methanation using a flow simulating CO-rich reformate gases from WGS and PROX units (H excess, CO presence and 300 ppm CO concentration) were prepared. Both, the RuO/AlO powder and the slurry prepared from it for its structuration by washcoating of the metallic micromonolithic structure, were also active and selective. Both the slurry (S-RuAl) and micromonoliths (M-RuAl) were able to completely and selectively methanate CO at much lower temperatures than the parent RuAl powder. The optimal working temperature in which the CO conversion is maximum and the CO conversion is minimized was determined to be from 149 °C to 239 °C for S-RuAl and from 165 °C to 232 °C for M-RuAl, whilst it was from 217 °C to 226 °C for RuAl powder. TPR, XRD and TEM measurements confirmed that the changes in the activity and selectivity for CO methanation among the considered catalysts can be related with modifications in the surface particle size of ruthenium and its reducibility. These were ascribed to the metallic substrate, the presence of PVA and colloidal alumina in the slurry preparation, the aqueous and acidic media and the thermal treatment used, resulting in a more active and selective catalysts than the parent powder.

In the present work, nanostructured hydroxyapatite (HA)-containing coating was prepared on a Ti surface by ultrasonic mechanical coating and armoring (UMCA). A Ti plate was pre-coated with HA slurry, followed by UMCA, which was achieved by high-frequency ZrO2 ball bombardment. The UMCA process comprised several cycles of pre-coating and ball bombardment, providing high amounts of HA and good coating adhesion. The coating mainly consisted of nano-HA particles (less than 10 nm) and a small amount of Ti. Furthermore, the deformation structures of the Ti surface region were characterized in a nanocrystalline layer with a grain size of 50–200 nm. Additionally, the coating exhibited improved bioactivity and corrosion resistance in Hanks’ balanced salt solution than the Ti surface. Furthermore, the in vitro cytotoxicity test assessed that the HA-containing coating was non-cytotoxic.

In this work, a new approach to fabricate B4C/SiC ceramic hollow microsphere was established through combination of slurry-coating and precursor conversion method. Firstly, different slurries were prepared using modified B4C powder with addition of PCS and LPCS. Subsequently, slurry was coated on a POM microsphere, followed by crosslinking, POM decomposition and heat-treatment at 1100 °C. Finally, the B4C/SiC hollow microspheres with average diameter of 1.6–1.9 mm and thickness of 10–60 μm were obtained. The roughness (Ra) of outer surface was as low as 40.3 nm with high sphericity of 99.6%. Deoxidation was also explored by heat treatment at 1700 °C. The oxygen content was decreased from 11.06 wt.% to 0.37 wt.%, and crush load was promoted from 1.73 N to 4.50 N. The preparative method of B4C/SiC ceramic hollow microspheres in this work can be easily extended for large-scale production.

Ceramic mask stereolithography additive manufacturing technology has the abilities of fast and accurate printing complex and personalized ceramic parts. However, since the ultraviolet light is strongly blocked by the ceramic particles in the slurry during exposure, the slurry with high refractive index ceramic particles has low cure depth, and serious light scattering. This investigation developed a curable silicon nitride slurry with a high refractive index liquid phase, which significantly reduced the refractive index difference between the liquid phase and the silicon nitride ceramic particles. The high refractive index acrylate monomer and solvent were chosen to increase the cure depth while ensuring the curing accuracy. Compared with the slurry whose liquid phase was pure HDDA, the addition of OPPEA and ACMO in the liquid phase showed a better refractive index increasing effect and the strongest cure depth and dimensional accuracy improvement. POE was verified as a suitable non-reactive high refractive solvent. The composition of 20 wt% OPPEA, 10 wt% ACMO, 40 wt% HDDA, and 30 wt% POE were optimized as the high refractive index liquid phase for 40 vol% solid phase silicon nitride slurry. A finite element analysis model of silicon nitride slurry was established, and the distribution of ultraviolet light intensity in silicon nitride slurry with high refractive index liquid phase was numerically simulated.

This research defines the result of studies on a Sugar cane bagasse ash (SCBA) material through laboratory experiment. The material prepared with mix ratio (0.2 % to 1.0 %), Blast furnace slag as mix ratio proportion (10%), glass fibre as reinforcing materials, cement (10%,15% and 20%) and water (50%,60%) for mix in to homogeneous slurry were added to material. The consequence of mix ratio percentages on density, compressive strength are studied. It was observed that the density of materials with inclusion of glass fibre ranging between 1101 kg/m3 to 1326 kg/m3. The compressive strength of material increases as percentages of cement increase from 10 to 20%. The compressive strength of materials influenced considerably by mix ratio 0.2 % to 1.0 %. The stress–strain outline was observed to be nonlinear for every mix ratio percentage and curing duration.

This article presents the research findings on binary collisions of water droplets and solid particles using three most widely spread ranks of coal. The experimental setup used in this research allowed the variation of the particle size from 0.25 mm to 0.75 mm and the velocity from 0.5 m/s to 4 m/s. The droplet velocity was varied from 0.3 m/s to 6 m/s. The impact angle of attack ranged 0–90°. These variation ranges of initial parameters correspond to promising gas-vapor-droplet technologies such as spray drying, fire extinguishing, water treatment, fuel mixing and combustion, heat and mass transfer power plants, etc. We analyzed the frames showing three collision regimes: coalescence, separation, and disruption. We determined how the temperature of the liquid medium affects the position of droplet collision regime boundaries on the corresponding maps in the B(We) coordinates. We also determined the impact of hydrophilic and hydrophobic behavior of solid particles on the collision characteristics. The size distributions were established for secondary fragments formed during the collision of water droplet and solid particle, as well as the collision of two droplets. The key patterns of the processes under study were singled out for various droplet shapes and size ratios. Finally, we compared the characteristics and conditions of interaction between water droplets and water-based slurries.

In this study, a novel method was proposed for preparing high-flux ceramic membranes via digital light processing (DLP) three-dimensional (3D) printing technology. Two different alumina powders were well dispersed in a photosensitive resin to form a UV-curable slurry for DLP 3D printing. The effects of the grading ratio on the viscosity of the slurry and the porosity, pore size distribution, mechanical strength, roughness, and permeability of the ceramic membranes were systematically investigated. The thermal treatment conditions were also studied and optimized. The obtained ceramic membranes exhibited a uniform pore size distribution, a high porosity, a low tortuosity factor, and an asymmetric structure. The combination of these factors led to a high flux for the 3D-printed ceramic membranes. DLP 3D printing exhibited a good potential to be a strong candidate for the next generation of ceramic membrane fabrication technology.

The consequence of coupling wear (erosion/abrasion) and corrosion is not just simply the sum of wear in the absence of corrosive medium and corrosion in absence of wear. The so-called synergistic effect implies that corrosion is accelerated due to the removal of the passivating layer because of wear. On the other hand, corrosion can accelerate abrasion when the electrochemical dissolution yields a brittle surface layer which can be subsequently removed by abrasion. The synergism between wear and corrosion is complex and the interaction between mechanical and chemical factors governing tribocorrosion is not yet fully understood. This review aims at providing a general and thorough summary of the wear-corrosion interaction focused on stainless steels due to the technological relevance of these materials. It is taken into consideration the influence of the key parameters affecting wear-corrosion, such as the stainless steel type, slurry characteristics (temperature, pH, solid concentration), the erodent properties (particle size and shape), etc. The different models to describe wear-corrosion and the most used apparatus for tribocorrosion testing are also reviewed.

The aim of this work is to enhance the operation life of steel (CF8M) used in turbines. The steel during its operation in power plant undergo severe wear due to erosion. This decreases the life of component as well adds the maintenance cost of hydro-plant. To overcome this problem of erosion and wear, HVOF thermal spray technique is selected to apply the protective layer of WC-Co-Cr on the substrate material. Wear test were done on slurry erosion test rig at different slurry concentrations, slurry jet impingement angles and spray nozzle stand-off distances for coated and uncoated substrates. The orthogonal L4 array was used to design the experimentation after selecting suitable maximum and minimum values of parameters. The wear loss measurements were taken in terms of weight loss after completion of every cycle. The SEM analysis of as such coated samples and eroded samples was done to know the morphology of the surfaces. It was found that the wear resistance of WC-10Co-4Cr coated against slurry erosion on CF8M steel was better than the uncoated substrate.

Pipe lines made of fiber based composite materials was not widely used as accepted mode for carrying potable water or drain water. In mining environment, water is not just a pure water but full of particles and impurities and will be mixture of slurry. This investigation focus on the development of fiber based hybrid composite materials and to study the effect of hybridization on mechanical and tribological properties. The hybridization was achieved by the combination of natural and synthetic fibers. Jute fiber and Glass fiber are respectively chosen for the above mentioned purpose. The objective is to evaluate the properties of these hybrids under same experimental conditions. The tribological studies were done by conducting erosion wear tests using pot erosion tester. Pot erosion testers are the best mode of simulating the erosion taking place in the pipe lines. It is indigenously developed one. Various mechanical tests like tensile, impact, flexural and hardness were conducted on the developed composites. Erosion tests were also conducted on the samples performing well in the Mechanical testing. Erosion tests were done by varying the particle size, concentration, exposure time and the surface impact velocity. Glass fiber panel and Hybrid 1 panel performed well in the tensile test, however in the flexural test, the Hybrid 2 showed a better strength.

In chemical mechanical planarization (CMP), a particle slurry is used in polishing semiconductor wafers. Key to its performance is the size distribution of the particles. We evaluate the potential of an aerosol technique, namely differential mobility analysis (in a liquid nanoparticle sizer, LNS, system) to characterize size distributions of CMP slurries. LNS measurements are compared to size distributions inferred from electron microscopy (SEM), and dynamic light scattering (DLS). LNS measurements are more repeatable than DLS measurements, and for 4 silica slurries, LNS distributions are in better agreement with SEM measurements than DLS. We find also that the LNS can quantify multimodal size distributions. For non-silica slurries, LNS, DLS, and SEM measurements have geometric mean diameters which can vary from another by 10 nm or more. However, because each measurement type is internally consistent, the combination of LNS and DLS, which are automated, yields augmented information on slurry properties.

The corroded microstructures of the Cr2O3–Al2O3–ZrO2 refractory brick in an industrial opposed multi-burner (OMB) coal water slurry gasifier were investigated. It was found that the chromite spinel isolation layer rich in iron and magnesium was formed on the surface of the corroded brick body. By comparing and analyzing the corrosion of different zones in the gasifier, the results indicated that the molten slag entered the brick through the gaps and generated the spinel layer along the edge of the gaps, causing the dense structures of the refractory surface destroyed. In addition, in the high chrome brick corrosion experiment conducted by HTSM, 3 μm sized spinel were observed covering on the surface. The FactSage calculation results showed that the amount of spinel produced would drop significantly as the slag penetrated.

A quartz microreactor containing 28 microchannels of 500 µm width and 105 mm length has been used to photoproduce hydrogen from liquid water-ethanol using an Au/TiO2 photocatalyst and UV light. The photomicroreactor has been tested in two flow configurations: (i) as a catalytic wall photoreactor by coating the microchannels with the photocatalyst, and (ii) as a slurry photoreactor by dispersing the photocatalyst in the liquid mixture of water-ethanol. The catalytic wall photoreactor configuration shows superior performance, with hydrogen yields more than three times higher than those obtained with the best slurry configuration under the same operation conditions.

Present work deals with the study of rheological aspects related with finer particles of Fly Ash (FA) slurry suspension. The effect of sodium sulfate as an additive has been studied with three different proportions in basic slurry suspension. Throughout the investigation the shear rate varies from 50 to 200 s−1. In this study, additive shows a promising trend in order to improve the rheology of fine particles slurry suspension. The high viscosity reduction associated with the suspension of FA slurry is characterized by high concentration (CW) of additives. However, reduction rate was more dominating in the case of 0.4 (% by weight) of the additives. Results reveals that additive of above manner provides a suitable and alternate arrangement for transportation of fine particles slurry suspension through pipeline at higher concentration.

This work describes an effective method for the preparation of open-cell ceramic foams for their further use as catalyst supports. The polyurethane sponge replica technique was applied using a ceramic suspension based on a mixture of α-alumina, magnesia and titania and polyvinyl alcohol solution as a liquid component. The polyurethane sponge was etched with NaOH and covered with colloidal silica to obtain better adhesion of the slurry to the walls of the polymeric material onto it. The surface area of the ceramic carrier was increased by adding a layer of γ-alumina. Deposition of an active catalytic phase (Pt) was done by impregnation. Properties of the carriers and the final catalyst were investigated by a number of physico-chemical methods such as TEM, SEM, XRD and computer tomography. Hydrogenation of ethyl benzoylformate was performed to elucidate the catalytic properties of foam catalysts illustrating their applicability.

In this paper, the pressure drop influencing parameters in slurry pipeline have been optimized by using Taguchi’s approach. S/N ratios were calculated by orthogonal array L16 (42) and characterized by using smaller-the-better rule. Pressure drop experimental were conducted on pilot plant test loop having 50 mm diameter. Pressure drop of fly ash slurry was measured with addition of coarser bottom ash at different solid concentrations and flow velocities. The bottom ash addition reduced the pressure drop of fly ash slurry in pipeline and pressure drop increases with the increase in the flow velocity. Flow velocity is the most influencing parameter as compare to the other parameters. The rheological charactertrics of fly ash slurry is also studied with and without addition of bottom ash in order to transport the high solid concentration of fly ash slurry in a pipeline. Apparent viscosity of fly ash slurry suspension with 10, 20 and 30% addition of bottom ash indicates that apparent viscosity of fly ash slurry decreases with the addition of bottom ash due to the presence of coarser bottom ash in fly ash finer particle suspension. The apparent viscosity plays a vibrant role on pressure characteristics of fly ash slurry transportation.

Direct ink writing (DIW) and low-temperature sintering methods were applied to prepare Si2N2O-Si3N4 ceramics for radome materials. Lattices of Si-SiO2 green body were printed by DIW with 78 wt % solid portion of water-based Si-SiO2 slurry, in which silicon particles and silica fume were used as the solid portion and Methylcellulose (HPMC) was used as the dispersant. Effects of HPMC addition on stability and silica fume content on rheological properties of the slurry were studied, respectively. The pseudoplastic mechanism of the slurry was analyzed. The Si-SiO2 green bodies were sintered at 1250 °C–1400 °C in nitrogen. The effect of temperature on phase composition, microstructure, mechanical and dielectric properties of samples was investigated. With the HPMC addition of 0.12 wt% and the silica fume proportion of 30 wt% in solid portion, a stable and pseudoplastic slurry with the yield stress of 110.9 Pa was obtained, which is suitable for DIW. With the decrease of initial holding temperature, more N2 enters the sample and reacts with silicon and silica fume, promoting the generation of Si2N2O and Si3N4. The optimal condition yields Si2N2O-Si3N4 ceramics with apparent porosity of 42.73%, compressive strength of 24.7 MPa, dielectric constant of 4.89 and loss tangent of 0.0054. It is found that columnar Si3N4 comes from a direct reaction between silicon and N2, and fibrous Si2N2O is mainly generated by the reaction between silicon, SiO(g), and N2 through the chemical vapor deposition mechanism. Good dielectric properties are achieved due to high porosity, high proportion of Si2N2O phase and no residual silicon.