Influence Of Solid Loading Research Articles

High solid loading, low viscosity stereolithography 3D printing ceramic cores slurry

The temperature enduring capacity of turbine blades determines the thrust-weight ratio of aero-engines. The heat dissipation efficiency of blades is improved mainly through designing complex internal cooling channel. As a transitional component of blade preparation, the shape of ceramic cores has become gradually complex. The traditional process is difficult to meet the preparation requirements of ceramic core with complex structure due to the limitation of mold. Stereolithography 3D printing provides a feasible technology for the preparation of ceramic cores with complex structures. The key to high-performance ceramic core via the stereolithography 3D printing lies in the prepare ceramic slurry with high solid loading, low viscosity and uniform stability. Choosing suitable dispersant is an effective way to prepare above standard slurry. In this study, the effects of single and dual dispersants on the rheological properties of ceramic slurry were systematically investigated. The action mechanism of the dispersant was analyzed. The functional relationship between solid loading and viscosity was elucidated. The silicon-based ceramic core slurry with 70 vol% solid loading and viscosity of 10520 mPa s (12.6 s−1) was obtained. Through optimizing printing parameters, the complex structure silicon-based ceramic core was fabricated. The influence of solid loading on the microstructure and physical properties of the ceramic core was investigated. The results show that with the increase of solid loading, the shrinkage of ceramic core lowers and the flexural strength of ceramic core strengthens. The successfully preparation of complex structure ceramic core based on high solid loading slurry promotes the extensively implemented of stereolithography 3D printing technology in the field of ceramic core.

Mechanical and dielectric properties of Si3N4-SiO2 ceramics prepared by digital light processing based 3D printing and oxidation sintering

Si3N4-SiO2 ceramics are considered as the preferred high-performance wave-transmitting material in the aerospace field. However, traditional fabrication methods for Si3N4-SiO2 ceramics have the disadvantages of high cost and complicated fabrication process. In this paper, Si3N4-SiO2 ceramics with excellent mechanical and dielectric properties were fabricated by digital light processing-based 3D printing combined with oxidation sintering. Firstly, the curing thickness and viscosity of slurries with different solid loadings for vat photopolymerization-based 3D printing were studied. Then, the effects of the sintering temperature on the linear shrinkage, phase composition, microstructure, flexural strength, and dielectric properties of Si3N4-SiO2 ceramics, and the influences of solid loading on them were explored. The curing thickness and viscosity of the slurry with a solid loading of 55 vol% were 30 μm and ∼1.5 Pa‧s, respectively. The open porosity and the flexural strength of Si3N4-SiO2 ceramic with a solid loading of 55 vol% were 4.3 ± 0.61% and 76 ± 5.6 MPa, respectively. In the electromagnetic wave band of 8–18 GHz, the dielectric constant of Si3N4-SiO2 ceramics was within the range of less than 4, and the dielectric loss remained below 0.09. The method of digital light processing-based 3D printing combined with oxidation sintering can be further extended in the preparation of Si3N4-based structure-function integrated ceramics.

Influence of Solid Loading on the Gel-Casting of Porous NiTi Alloys

Porous NiTi alloys are widely applied in the field of medical implant materials due to their excellent properties. In this paper, porous NiTi alloys were prepared by non-aqueous gel-casting. The influence of solid loading on the process characteristics of slurries and the microstructure and mechanical properties of sintered samples were investigated. The viscosity and the stability of slurry significantly increased with the growth of solid loading, and the slurry had better process characteristics in the solid loading range of 40-52 vol.%. Meanwhile, the porosity and average pore diameter of the sintered NiTi alloys decreased with a rise in the solid loading, while the compressive strength increased. Porous NiTi alloys with porosities of 43.3-48.6%, average pore sizes of 53-145 µm, and compressive strengths of 87-167 MPa were fabricated by gel-casting. These properties meet the requirements of cortical bone. The results suggest that the pore structure and mechanical properties of porous NiTi products produced by gel-casting can be adjusted by controlling the solid loading.

Synthesis, morphological and thermomechanical characterization of light weight silica foam via reaction generated thermo-foaming process

Low-cost thermo-foaming technique involving sucrose dehydration reaction with H2SO4 has been used for ceramic foam processing. The heat and gas generated during the reaction induces a thermo-foaming effect in the sucrose-ceramic mixture. This converts the sucrose-ceramic slurry into a carbonaceous porous ceramic-scaffold. The converted carbon is seen to agglutinate with the ceramic particles. During sintering, they are removed subsequently, thereby enlarging the pores. Influence of solids-loading, sintering temperature and H2SO4 concentration on the foaming behaviour, pore morphology and thermo-mechanical properties are studied. The fabricated silica foams are found to have porosity within the range of 70 %− 90 % and compressive strength of 0.8–2.8 MPa. The extreme porosity of the silica foams and their intercrystallite pores within the struts results in the low thermal conductivity (0.0943 Wm−1K−1) of the specimens. The fabricated foam is seen as a promising material for insulation applications like catalyst supports, filters and bio-scaffolds.

Influence of the Ink Solid Loading on the Properties of Si Based Electrodes for Li-Ion Batteries

Silicon is a very promising anode material for Li-ion batteries, compared to commercially available graphite, thanks to its ~ x3 and x10 higher volumetric and specific capacity respectively. However, this capacity comes from the high alloyable lithium content (up to c-Li15Si4), inducing a proportional volume expansion (~ 280%)1, which trigger many electrode failure mechanisms. To cite a few, there is (i) the fragmentation of the electrode coating (and possibly delamination), reducing the electrochemically available active materials, and (ii) the destabilization of the SEI because of the ever changing silicon particles morphology, rousing a perpetual electrolyte degradation accompanied by a rising electrode impedance.In the present work, the influence of the slurry solid loading on silicon electrode properties and performances was studied, as the electrode processing appears promising to circumvent those problematics. Indeed, solid loading has already been linked to improved mechanical, morphological and electronic conductivity properties of electrodes2,3 but these studies focus on positive active materials.Experimentally, the influence of solid loading was investigated on a reference and coordinatively reticulated binder. The reference was a poly(carboxylic acid) binder which was made of dissolved NaCMC in pH ~ 3 buffer solution. To obtain the coordinated binder, zinc(II) was simply added in the reference solution as a coordination agent, before mixing the as-prepared solution with silicon submicrometric particles and graphene nanoplatelets (as conductive additive). In order to increase the solid loading, binder solutions were concentrated and simply added in a lower quantity for the mixing. Afterwards, electrodes were prepared by tape casting the slurry onto copper current collector. Finally, electrodes were punched (active mass loading ~ 1.75 mgsi.cm-² and 3.5mgsi.cm-²), dried and transferred into a glove box (H2O and O2 content < 1 ppm) for Swagelok cell assembly (LP30 + 10 w% FEC is used as an electrolyte).Interestingly, references electrodes were the most sensitive to the increase of solid loading, with much improved electrochemical performances. In order to understand those variations, inks and electrodes were thoroughly characterized by ink rheology, electrode coating conductimetry and MEB/EDX for the morphology/composition analysis, whose results will be presented and discussed.

Rheology and processing of UV‐curable textured alumina inks for additive manufacturing

AbstractA UV‐curable resin containing alumina (Al2O3) powder and platelets was developed and characterized using a proof‐of concept tape‐casting system and trialed on a commercially available 3D‐printing platform (Admatec Admaflex 130). The influence of solids loading and solids platelet fraction on resin viscosity and depth of cure was investigated. Resins containing up to 40 vol% solids loading at platelet fractions up to 50% were found to have sufficiently low viscosity for tape casting and cure depths ranging from 0.29 to 0.39 mm. Alumina platelets were observed to lower ink viscosity but also reduce shear thinning behavior compared to inks containing only powder. Printability of inks was assessed by layered tape casting, and verified with a trial build on an Admaflex 130. Due to the low solids loading of the resin, hot pressing at 1300°C and 66 MPa was employed to sinter specimens containing no platelets and 15% platelet fractions, yielding specimens with near theoretical densities (99.7%) and average grain sizes of 0.96 µm and 0.83 µm, respectively. Alignment before and after sintering was assessed by SEM and XRD, with lotgering factors of 0.045±0.005 and 0.114 measured in the green and sintered specimens, respectively.

Influence of Delta Wing on Wall Erosion Characteristics of Mitred Pipe Bends Handling Coal Slurries

The present work investigates the influence of delta wing vortex generators placed inside circular mitred pipe bends, handling high density and erosive coal slurries. Coal slurry flowing at different Reynolds numbers ranging from 2000 < Re < 10,000 is tested. Mitred bends having a flow turning angle (α) of 45°, formed by joining segments of pipe, with varying number of joints (1, 2 and 3) were assessed numerically. Delta wing was positioned inside the pipe at different angles (β = 30°, 60°, 90°, 120° and 150°). Coal slurry viscosity and density varied to understand the influence of solids loading (φ = 30%, 35%, 41%, 42%, 43%, 44%) on the wall erosion characteristics. Computational studies are carried out on a 90° turning circular sectioned smooth pipe bend to study the impact of various turbulence models, and the results are validated with appropriate results from the literature. A turbulence model having good correlation with the literature results is identified and adopted in the present study. Highest turbulent mixing at the pipe outlet and reduced peak wall shear stress were considered as criterion for selecting best delta wing orientation, though with a higher pressure drop penalty. Unique delta wing induced vortex flow evolutions in the streamwise direction is reported.

Hydrothermal carbonization of sewage digestate at wastewater treatment works: Influence of solid loading on characteristics of hydrochar, process water and plant energetics

Nowadays the sludge treatment is recognized as a priority challenge to the wastewater industry due to the increasing volumes produced and tighter environmental controls for its safe disposal. The most cost-effective process for sewage sludge is the anaerobic digestion but raw digestate still contains high levels of organic matter that can be transformed into an energy carrier by using processes like Hydrothermal Carbonization (HTC). In this work, the influence of solid loading (2.5, 5.0, 10.0, 15.0, 17.5, 20.0, 25.0 and 30.0% solids w/w) on the composition of hydrochar and process water was studied, together with an evaluation of product yields, solubilisation of organic carbon and biomethane potential of process waters from HTC processing (250 °C, 30- minute reaction time). Hydrochar yields ranged from 64 to 88%wt, whereas the concentration of soluble organic carbon increased from 2.6 g/L in the raw digestate to a maximum of 72.3 g/L in the process water following HTC at the highest solid loading. Furthermore, process modelling with Aspen Plus shows that the integration of AD with HTC to wastewater treatment works provides a significant positive energy balance when process water and hydrochar are considered as fuel sources for cogeneration.

Influence of solid loading on densification behavior, micromorphology and dielectric properties of Ba0.67Sr0.33TiO3 ceramics fabricated by a novel DCC-HVCI method

Ba0.67Sr0.33TiO3 (BST) ceramics with highly improved dielectric performance were fabricated by a novel direct coagulation casting via high valence counter ions (DCC-HVCI) method. The influence of solid loading on densification behavior, micromorphology, and dielectric performance of the samples was investigated. With the increase of solid loading from 40 to 50 vol%, the maximum densification rate of BST ceramics increased from 0.090 to 0.122 s−1, and the densification temperature decreased from 1424 to 1343 °C, which indicated that high solid loading could promote the densification behavior of samples during sintering. BST ceramics fabricated by the DCC-HVCI method showed uniform grain size and microstructure, which was beneficial for the dielectric properties of BST ceramics. Samples obtained from 45 vol% suspensions possessed the lowest dielectric permittivity (εr ≈ 2801), and the dielectric loss (tanδ≈0.0262) was about 1/10 of that of dry-pressed samples (tanδ≈0.301), which could be attributed to the composition homogenization.

Mesophilic bioleaching performance of copper, cobalt and nickel with emphasis on complex orebodies of the Democratic Republic of Congo: a review of dynamic interactions between solids loading, microbiota activity and growth

The copper, cobalt and nickel ores are still currently mined in the world. Its complex mineralogy creates extraction challenges by means of conventional metallurgical methods. Meanwhile, dealing with mesophilic strains in leaching process requires a compromise between solid loading and microbiota activity and growth. That is why, the influence of solid loading with fine or coarse particulates, the cell disturbance during the metal–microbes interactions depending upon the influence of gangue nature as well as metallic ions concentration on bacterial tolerance and the chemical and biological pathways involved in bioleaching mechanism of complex ores are summarised in detail in this paper. The current trends in mechanism research and diverse discovered set of microbiota and bacterial population coupled with bacterial adaptation methods contribute to optimise and improve the metals leaching performance and knowledge. In addition, the different existing complex mineralogical structures elaborate a main indirect mechanism with two different transitory mechanisms, before metal is converted into metal sulphate as wealthily explained in this comprehensive review. More data for cost analysis concomitant with extraction efficiency of metals using mesophilic bioleaching process are needed. However, it does not mean that other options are excluded in order to set a bio-hydrometallurgical chain. In fact, to consider also the concentration and purification of the pregnant leaching solution via phase separation and solvent extraction will be helpful. This obeys to the idea of option trees, where possible options are then systematically gaged with respect to critical criteria.

Influence of Solid Loading and Ratio of Monomers on Mechanical and Dielectric Properties of Hybrid Ceramic Composites

Hybrid ceramic (SiO2-Si3N4-Al2O3) composites were prepared by gel casting process, a near net shape technique. The effects of solid loading and monomers ratio on flexural strength, porosity, room temperature dielectric properties and thermal conductivity were investigated. Methylacrylamide (MAM) and N, N1- methylenebisacrylamide (MBAM) were used as monomers because of their low toxicity. The hybrid ceramics were sintered to a temperature of 1250 °C and the monomer content kept constant at 10 wt%. The flexural strength of the ceramics increases and porosity decreases with increase in solid loading. The flexural strength increases up to a certain stage and then decreases by showing an optimum point at monomer ratio of 10:1. The maximum flexural strength and minimum porosity obtained were 95.12 MPa, and 28.5% respectively. The dielectric constant and dielectric loss were increased slightly by the addition of Si3N4-Al2O3 and found to be 4.822 and 0.00351 at a frequency of 30 MHz at room temperature. The minimum thermal conductivity at room temperature of the composite was found to be 0.2131 W/mK.

Influence of Solid Loading on the Granulation of 3Y-TZP Powder by Two-Fluid Spray Drying

The influence of solid loading in the slurry composition on the morphology of 3Y-TZP granules fabricated by two-fluid spray drying was investigated for solid contents varying between 30 wt% and 50 wt%. The resulting 3Y-TZP granules showed a sphere-like shape with diameters of 40 - 70 μm. However, a donut-like shape and a few cracks were observed on the granule surfaces fabricated using the slurry with 50 wt% solid content. The green density after cold isostatic pressing at 200 MPa was 2.1 - 2.2 g/cm3, and a homogeneous fracture surface was obtained by complete destruction of granules. After sintering at 1500°C for 2 h, all specimens had relative densities of 96.2 - 98.3%. With increasing solid content, the relative density decreased from 98.3% to 96.2%, but the grain size increased from 0.3 μm to 0.6 μm. Highly sinterable zirconia granule powder could be obtained by controlling the slurry composition. Key words: Zirconia, Granule morphology, Spray drying, Sintered density

Influence of solid loading on the rheological, porosity distribution, optical and the microstructural properties of YAG transparent ceramic

Stable aqueous dispersed mixture of commercial Al2O3 and Y2O3 nano powders was prepared by ball mill. Ammonium poly meta acrylate (Dolapix CE64) and tetraethyl orthosilicate (TEOS) were added as dispersant and sintering aid, respectively. The effects of slurry solid loading on the fabrication of transparent polycrystalline YAG ceramics by slip casting method were investigated. The rheological properties of slurries with different solid loading (64, 70 and 76 wt%) were studied by measuring the viscosity and shear stress as a function of shear rate. The effect of solid loadings on the porosity distribution was examined. The specimens were vacuum-sintered at 1715 °C for 10 h. Slips with 64 and 70 wt% solid loading behaved as near-Newtonian and as non-Newtonian with thixotropic behavior at 76 wt% solid loading. The relative densities of the green bodies increased from 58.0 ± 0.6% (SD = 0.424) to 64.0 ± 0.3% (SD = 0.228) by increasing the solid loading from 64 wt% to 70 wt% and then decreased to 63.0 ± 0.2% (SD = 0.141) at 76 wt% solid loading. The results showed that the suitable solid loading for fabricating transparent YAG ceramics is 70 wt%. This sample had the narrowest pore size distribution (4–100 nm), homogenized surface fracture of green body, dense microstructure (99.990 ± 0.005% final relative density, SD = 0.003) and the average grain size of 6 µm. It had the highest in-line transmittance, which was approximately 77% at 1064 nm.

Additive manufacturing of WC-20Co components by 3D gel-printing

3D gel-printing (3DGP) is a novel manufacturing technology, which builds a 3D component by depositing and gelating metal slurry layer by layer. In this paper, the hydroxyethyl methacrylate (HEMA) based slurries with WC-20Co solid loading of 47–56vol% were directly formed by 3DGP and then sintered in a vacuum furnace. The WC-20Co slurries exhibited suitable fluidity and shear thinning behavior, which were beneficial for 3DGP forming process. The effects of 3DGP processing parameters, such as the internal diameter of print nozzle and filling rate, on the surface roughness and dimensional accuracy of as-printed green bodies were studied. The influence of solid loading on rheological property of WC-20Co slurry, green density, sintered density and mechanical properties of sintered samples were also investigated. The results show that the samples can be printed with good shape, appropriate precision and homogeneous microstructure. The sintered samples have good shape retention and uniform microstructure. The density, hardness and transverse rupture strength of the optimal sample were 13.55g/cm3, HRA 87.7 and 2612.8MPa, respectively. 3DGP has unique advantages in near-net forming for complex shape WC-20Co components.

Process modeling of gelcast Si3N4ceramics using multi gene genetic programming

The influence of solid loading, monomer content and ratio of monomer to cross linking agent on the flexural strength and the porosity Si3N4 ceramic sintered body were investigated. The high strength porous Silicon Nitride (Si3N4) ceramics were prepared using gelcasting by increasing the monomer content in the slurry and flexural strength of the ceramic composite increases as the solid loading increases and flexural strength decreases as the monomer content increases. The porosity of the ceramic composite decreases as the solid loading increases and porosity increases as the monomer content increases. Flexural strength and porosity were determined as objective functions and a mathematical model is generated using Multi Gene Genetic Programming (MGGP).

Modeling and optimization of process parameters of SiO2-Si3N4 gelcast ceramic composites using RSM

SiO2-Si3N4 ceramic composites with high flexural strength and low porosity were fabricated using gelcasting, a near-net shape fabrication technique, by varying solid loading, Si3N4 content, monomer content and ratio of monomers. Mathematical models were developed using response surface methodology to determine the effect of the process parameters. The influence of solid loading, Si3N4 content, monomer content and monomer ratio were studied with the help of RSM using a central composite face centered design with 6 centre points on SiO2- Si3N4 ceramic composites. The optimal values for maximum flexural strength and porosity were 94.62 MPa and 41.52% respectively.

Ultralight alumina ceramic foams with single-grain wall using sodium dodecyl sulfate as long-chain surfactant

A novel and facile method for the fabrication of alumina ceramic foams based on particle-stabilized foam method was proposed. Alumina foams with ultrahigh porosity of 94.7–98.3% (density 0.067–0.210g/cm3) were fabricated for the first time using long-chain surfactant sodium dodecyl sulfate (SDS) as particle hydrophobization modifier. Sintered foams possess single-grain wall and uniform cells with cell size in the range 50–200μm. Ultra-stable wet foams can be fabricated in a very wide pH range (from 4.0 to 9.0) due to strong adsorption ability of SDS on alumina particles, which is beneficial for massive production. Effect of pH value on SDS adsorption and foam properties were studied. The influence of solid loading and sintering temperature on properties of alumina ceramic foams were also investigated. Alumina foams with porosity of 97% have compressive strength above 0.5MPa, which could fulfill the needs of some engineering fields where high closed porosity is beneficial.

The Microbial Ecology of Moderately Thermophilic Mineral Leaching Reactors: The Effect of Solids Loading and Organic Carbon Supplementation on Reactor Performance

Tank bioleaching of refractory sulphidic gold ores is well established, with potential to expand application to base metal concentrates. With increasing commercial tank bioleaching operations, understanding their microbial consortia is essential for process robustness. Recently, it has been shown that the consortia implicated in tank mineral bioleaching of gold-containing pyritic ores are dynamic, responding to the leaching environment. Factors driving the microbial dynamics of these consortia are under investigation, with emphasis also placed on determining the metabolic role of the key players in these consortia. Here, the combined influence of solids loading and organic carbon availability on microbial community dynamics and performance has been studied in agitated, aerated slurry bioreactors at 45°C. The control (autotrophic) and experimental (organic carbon added) reactors performed comparably at low solids loadings (4%, 7% and 10%). At 20% solids loadings, higher ferric iron concentrations (31 g/L vs 25g/L) and sulphide oxidation (66% vs 45%) were observed in the experimental reactor over the control. Under operating conditions used, a shift from bacterially-dominated cultures with L.ferriphilum as major species towards increasing archaeal abundance was observed. Archaeal abundance was higher in the organic carbon supplemented reactor at all solids loadings. The increased microbial diversity with organic supplementation appears to contribute to increased community robustness and associated leaching with increasing stress.

Autohydrolysis Pretreatment and Delignification of Silver Fir Wood to Obtain Fermentable Sugars for Bioethanol Production

Fir wood biomass, non-pretreated and pretreated by autohydrolysis under selective conditions followed by chlorite delignification, was used as a substrate for enzymatic hydrolysis. The influence of solid loading on the enzymatic hydrolysis yield was studied. Compared with non-pretreated wood, autohydrolysis pretreatments at all temperatures tested enhanced enzymatic hydrolysis yields. A total of 33.0 g sugars can be generated from 100 g silver fir wood. The results show that elimination of hemicellulose by autohydrolysis pretreatment and lignin by delignification, before enzymatic hydrolysis, enhances enzymatic overall process yield.

Influence of solid loading on D-xylose production through dilute sulphuric acid hydrolysis of olive stones

The selective hydrolysis of hemicellulose from olive stones was attempted in order to achieve a maximum D-xylose yield. For this aim, batch hydrolysis was conducted under different operating conditions of temperature, acid concentration and solid loading. Firstly, distilled water, sulphuric acid and nitric acid were assessed as hydrolytic agents at different temperatures (200, 205, 210 and 220 °C) and at a fixed acid concentration (0.025 M). Sulphuric acid and 200 °C were selected for the subsequent dilute acid hydrolysis optimization based on the obtained D-xylose yields. The combined influence of solid loading (from 29.3 to 170.7 g olive stones into 300 mL acid solution) and sulphuric acid concentration (0.006–0.034 M) on the release of D-xylose was then estimated by response surface methodology. According to a statistical analysis, both parameters had significant interaction effects on D-xylose production. The results illustrated that the higher the solid loading, the higher the required acid concentration. The decrease in the solid/liquid ratio in the reactor had a positive effect on D-xylose extraction and on the amount of acid used. The optimum solid loading and sulphuric acid concentration were determined to be 50 g (solid/liquid ratio 1/6) and 0.016 M, respectively. Under these conditions, the predicted D-xylose yield (expressed as g of sugar per 100 g of dry matter fed) was 20.4 (87.2% of maximum attainable).