Behavior Of Slurries Research Articles

Effects of dispersant concentration on the properties of hydroxyapatite slurry and scaffold fabricated by digital light processing

For the UV-curable hydroxyapatite (HA) slurry used in digital light processing (DLP), the optimal dispersant concentration is always selected based on the viscosity and stability of the slurry. However, the interaction mechanism between the dispersant and HA particles and its influence on the fabrication process were overlooked. In this study, the dispersion mechanism of BYK111 and its effects on the rheology, stability, and curing behavior of the HA slurry, as well as the linear shrinkage and layer morphology of the HA scaffold, were systematically investigated. The results indicated that changes in viscosity and stability affected the penetration of UV light and the propagation rate of the polymerization reaction. Insufficient dispersion of the slurry (3 wt% BYK111) led to reduced printing precision due to high viscosity, settling, and scattering. Interestingly, the lower viscosity and enhanced stability of HA slurry with 4 wt% BYK111 did not yield both the deepest curing depth and narrowest excess curing width. The high curing accuracy of the HA slurry (4 wt% BYK111) was evidenced by the largest broadening depth. Moreover, the improved slurry performance also helped reduce printing defects and improve surface quality.

Experimental investigation of ice slurry viscosity

This work attempted to conduct an experimental study which demonstrates the effect of the initial concentration of solute on the apparent viscosity of ice slurry in a horizontal circular pipe. The study was conducted on ice slurry based on propylene glycol, varying from 5 to 24% with different ice mass fractions varying from 5 to 25%. During the experiments, the initial concentration of the propylene glycol, ice concentration, and flow rate was modified as parameters. The flow tests were performed on laminar flows. The results of the investigation revealed that the ice slurry behaved like a non-Newtonian fluid, while it sometimes behaved like a Newtonian fluid. The rheological behavior of the ice slurry is reflected by its viscosity. For the shear-thickening behavior, the apparent viscosity increases with increasing the shear rate, and for the shear-thinning behavior, the viscosity decreases with increasing the shear rate, while for the Newtonian behavior, the viscosity remains almost constant. Then it was revealed that the viscosity of the mixture became too high for low shear rates at high ice mass fractions by increasing the concentration of the solute. The power law was used to establish a relationship between the apparent viscosity and the indexes of flow and consistency of ice slurry.

Sedimentation Behavior of Flocculant-Treated Dredged Slurry under Filtration of Woven Geotextiles

Geotextile tubes have offered a cost-effective and convenient solution for the treatment of dredged slurry in recent years. Despite their benefits, the dewatering process of this method remains cumbersome and time-consuming. The incorporation of flocculants into dredged slurries has been shown to mitigate the clogging of geotextile tubes, thereby enhancing the efficiency of the dewatering process. To quantify the impact of flocculant addition on the dewatering performance, a series of laboratory tests were conducted to investigate the sedimentation behavior of flocculant-treated river-dredged slurries under filtration of woven geotextiles. The impact of different flocculants is evaluated with the sedimentation rates of dredged slurries, specifically nonionic polyacrylamide (NPAM) and cationic polyacrylamide (CPAM). Results demonstrated that both NPAM and CPAM, at an optimal concentration of around 250 mg/L, could substantially increase the settling rates of slurries when filtered through geotextiles. At equivalent flocculant concentration, NPAM outperforms CPAM in accelerating sedimentation rates. It is also evidenced that adding flocculants can significantly augment the particle size and permeability of slurries. After adding flocculants, the water content and dry density of the final sediments exhibit a more uniform distribution in the vertical direction compared to the original slurry. Furthermore, scanning electron microscopy was employed to analyze the micromorphology of the final sediments treated with different NPAM concentrations. The results showed that the slurries exhibited significant void structure under treatment with the optimal concentration of NPAM, demonstrating the flocculants’ effectiveness in enhancing the dewatering process of river-dredged slurries when filtered with geotextiles.

Improving the properties of TiC steel bonded cemented carbides by optimizing the slurry rheology, printing path and shape design of 3D gel printing

TiC steel bonded cemented carbide was modeled by an extrusion-based 3D gel printing(3DGP) method. The rheological behavior of slurry was studied to control the slurry extrusion and modeling. The effects of printing parameters, printing path and modeling complexity were researched to get a printed sample without defects. The results indicated that the slurry with a solid loading of 50 vol% (85 wt%) was prepared, and its viscosity change is very little during 24 h in case of a higher shear rate like a nozzle. The viscosity of the slurry decreases with increasing the extrusion pressure and nozzle diameter. The skewed pattern of filaments eliminated pores in printed samples in comparison with the rectangular pattern under the condition of straight lines of the printing path. Pores at the corners of a model can be eliminated by changing the printing path from concentric lines to zigzag lines or two sets of slanted parallel lines. The modeling complexity without a support structure can be revealed by printing tilt cylinders with different angles, and the local parts on a model with a tilt angle of <45° can be printed accurately without designing a support structure. Improving the 3DGP procedure based on these experiences, the TiC steel bonded cemented carbide samples had properties similar to those prepared by conventional powder metallurgy methods.

Improving the rheological characteristics of fly ash water slurry using aqueous extract of Diascorea hispida

ABSTRACT Transportation of high-concentration slurry is a specialized field that requires a deep understanding of the rheological behavior of slurry. Fly ash, a fine, powdery residue of pulverized coal combustion in power plants, is transported in pipelines as a slurry with water as a carrier medium and flow-improver additives. The current research aims to compute the rheological properties of the fly ash-water slurry by adding 0.1 to 1 g/mL of Diascorea hispida extract as a natural drag reducer or flow improver. In addition to the effect of D. hispida, other parameters such as temperature, addition of fly ash, and fly ash-bottom ash mixture on the rheological performance of fly ash-water slurry have been investigated. The economic effect of the developed dispersant, D. hispida, has been examined by applying Darby – Melson combined equation by varying the slurry flow rate from 1 m/s to 3 m/s at a fixed 250 mm pipe diameter. The slurry head loss, solids conveying rate, hydraulic power need, and specific power consumption at different .D hispida concentrations were calculated.

Fabrication and characterization of ZrO2(3Y)/Al2O3 micro-ceramic gears with high performance by vat photopolymerization 3D printing

To date, overcoming the trade-off between high solid loading and print accuracy and strength, achieving high-performance and fine ZrO2 micro-ceramic components through vat photopolymerization 3D printing remains challenging. In this study, the effects of dispersant, particle size and solid content on the dispersion, rheological behavior and stability of ZrO2 ceramic slurry were systematically studied, and complex, fine and high-performance ZrO2 micro-ceramic gears were successfully prepared. Then, the microstructure, mechanical properties, tribological properties and surface quality were evaluated. The results show that the rheological behavior of the slurry is the best when the optimal dispersant content is 3.5 wt%. With the increase of solid content, the sintering shrinkage of ZrO2(3Y)/Al2O3 ceramics decreased, while the relative density, compressive strength, flexural strength, fracture toughness and hardness increased. The prepared micro-ceramic gears not only have fine structure, but also have dense microstructure and good mechanical properties. The relative density, compressive strength, flexural strength, fracture toughness and hardness strength of ZrO2(3Y)/Al2O3 ceramics can reach 98.53 %, 1900 MPa, 648 MPa, 6.4 MPa × m1/2 and 13.40 GPa, respectively. In particular, this study couples the printing accuracy and strength with the solid load. By adjusting the relationship between the fixed load and the shrinkage rate, the printing of samples with different sizes is realized, which breaks through the accuracy limit of the printing equipment and provides a new idea for the preparation of micro-ceramic gears.

Influence of rheological parameters on cement slurry penetration characteristics of novel oscillating grouting technology

Traditional grouting techniques are primarily based on stable-pressure grouting, with slurry penetration performance limited. Research on the penetration behavior of pulsating slurry is relatively scarce, with even less research focused on the influence of slurry rheological parameters.This paper proposes an efficient oscillating grouting technology (OGT) that can generate pressure pulses and periodically change the direction of slurry motion. Through experiments and numerical simulations, its working mechanism is investigated, and the penetration distance of oscillating grouting and steady pressure grouting is compared under different soil parameters (porosity and particle size). The effect of cement slurry rheological parameters (viscosity of the Newtonian fluid and the K, τ0 and n, of the Herschel-Bulkley fluid) on penetration distance, grouting pressure, pressure pulse amplitude, and oscillating frequency are studied. Finally, the correlation analysis between penetration behavior, oscillating parameters, and rheological parameters is conducted. The results show that the oscillatory switching of the slurry is related to the interaction of vortexes within the tool, and the switching process leads to the generation of pressure pulsations. Under different soil parameters and rheological parameters, the penetration distance of oscillating grouting is larger than that of steady-pressure grouting. Furthermore, due to the pressure recovery process within the oscillatory grouting tool, the oscillating grouting exerts less pressure on the soil, which can prevent soil fracturing. The results also indicate that the oscillatory grouting requires a certain level of flow resistance to achieve optimal effect, but excessive resistance can impede the slurry switching process and reduce the penetration distance. And the optimal values for K, τ0 and n are around 0.015 Pa·sn, 1.5 Pa, and 0.5, respectively. According to the correlation analysis, oscillating frequency is positively correlated with penetration distance. Average pressure and rheological parameters are negatively correlated with penetration distance.

A Comparative Study on Microstructure, Segregation, and Mechanical Properties of Al-Si-Mg Alloy Parts Processed by GISS-HPDC and SEED-HPDC.

There are multiple routes to prepare semi-solid slurries with a globular microstructure for semi-solid forming. The variations in the microstructure of semi-solid slurries prepared using different routes may lead to significant differences in the flow behavior and mechanical properties of rheo-diecasting parts. Therefore, it is crucial to have a comprehensive understanding of the microstructure evolution associated with different slurry preparation routes and their resulting effects. In this study, the gas-induced semi-solid process (GISS) and the swirl enthalpy equilibrium device (SEED) routes were employed to prepare semi-solid Al-Si-Mg slurries for their simplicity and productivity in potential industrial applications. The prepared slurries were then injected into the shoot sleeves of a high-pressure die casting (HPDC) machine to produce tensile test bars. Subsequently, the bars underwent T6 treatment to enhance their mechanical properties. The microstructure, segregation, and mechanical properties of the samples were investigated and compared with those of conventional HPDC. The results indicated that the GISS and SEED can produce semi-solid slurries containing a spherical α-Al primary phase, as opposed to the dendritic structure commonly found in conventional castings. The liquid fraction had a significant effect on the flow behavior, resulting in variations in liquid segregation and mechanical properties. It was observed that a higher solid fraction (>75%) had a suppressing effect on surface liquid segregation. In addition, the tendency for liquid segregation gradually increased along the filling direction due to the special flow behavior of the semi-solid slurry with a low solid fraction. Furthermore, under the same die-casting process parameters, the conventional HPDC samples exhibit higher yield stress (139 ± 3 MPa) compared to SEED-HPDC and GISS-HPDC samples, which may be attributed to the small grain size and the distribution of eutectic phases. After undergoing the T6 treatment, both SEED-HPDC and GISS-HPDC samples showed a significant improvement in yield and tensile strength. These improvements are a result of solution and precipitation strengthening effects as well as the spheroidization of the eutectic Si phase. Moreover, the heat-treated SEED-HPDC samples demonstrate higher ultimate strength (336 ± 5 MPa) and elongation (13.7 ± 0.3%) in comparison to the GISS-HPDC samples (307 ± 4 MPa, 8.8 ± 0.2%) after heat treatment, mainly due to their low porosity density. These findings suggest that both GISS-HPDC and SEED-HPDC processes can be utilized to produce parts with favorable mechanical properties by implementing appropriate heat treatments. However, further investigation is required to control the porosities of GISS-HPDC samples during heat treatment.

A model for proppant dynamics in a perforated wellbore

This paper presents a model to simulate behavior of particle-laden slurry in a horizontal perforated wellbore with the goal of quantifying fluid and particle distribution between the perforations. There are two primary phenomena that influence the result. The first one is the non-uniform particle distribution within the wellbore’s cross-section and how it changes along the flow. The second phenomenon is related to the ability of particles to turn from the wellbore to a perforation. Consequently, the paper considers both of these phenomena independently at first, and then they are combined to address the whole problem of flow in a perforated wellbore. A mathematical model for calculating the particle and velocity profiles within the wellbore is developed. The model is calibrated against available laboratory data for various flow velocities, particle diameters, pipe diameters, and particle volume fractions. It predicts a steady-state solution for the particle and velocity profiles, as well as it captures the transition in time from a given state to the steady-state solution. The key dimensionless parameter that quantifies the latter solution is identified and is called dimensionless gravity. When it is small, the particles are fully suspended and the solution is uniform. At the same time, when the aforementioned parameter is large, then the solution is strongly non-uniform and resembles a flowing bed state. A mathematical model for the problem of particle turning is developed and is calibrated against available experimental and computational data. The key parameter affecting the result is called turning efficiency. When the efficiency is close to one, then most of the particles that follow the fluid streamlines going into the perforation are able enter the hole. At the same time, zero efficiency corresponds to the case of no particles entering the perforation. Solutions for the both sub-problems are combined to develop a model for the perforated wellbore. Results are compared (not calibrated) to a series of laboratory and field scale experiments for perforated wellbores. Comparison with the available computational results is presented as well. In addition, the comparison is presented in view of the parametric space defined by the dimensionless gravity and turning efficiency. Such a description allows to explain seemingly contradictory results observed in different tests and also allows to highlight parameters for which perforation orientation plays a significant role.

Investigation on application of filling mining technology pass through abandoned roadway of reclaimed working face.

This paper aims to analyze the roof stability when the reclaimed working face passes through abandoned roadway. The mechanical model of main roof in abandoned roadway was established for the purpose of theoretical analyses. To ensure the stability of the abandoned roadway, the strength formula of backfill body was deduced. The optimum ratios among different compositions of the filling material were determined by experiment, while the viscosity, bleeding, hydration temperature and compressive strength of filling material were also studied. Test results indicated that the optimum ratio among coal ash, lime and compound activator is 80:15:5, and the ideal water cement ratio is 0.7:1. It was also found that no bleeding occurred, the rheological behavior of slurry presented shear thinning fluid and the hydration temperature of filling body was relatively stable which is mainly maintained at 40°C. The uniaxial compressive strength of filling material with 28 and 90 days curing were 3.35 and 6.62 MPa respectively. Under a confining pressure environment, the filling material presented an obviously plastic deformation. Field test showed that the filling rate was almost 100%, when working face passed through abandoned roadway, the surface of filled body was complete and no roof collapse was triggered. Therefore, a better bonding effect was proved for the filling body.

New Addressable Applications for Rheocasting to Escape from an Oversupplied Market

The current market change of aluminium HPDC castings started with the “Dieselgate”. First, there was a shift from diesel to petrol engines. In the second step, hybrid and battery-powered cars gained significant market shares in sales statistics. Therefore, lucrative powertrain components are falling away. As powertrain foundries still want to utilize their machines to capacity, they are pushing into the structural castings market. As a result, there is an oversupply of casting machines here, which massively depresses prices and, thus, margins for tenders. With rising energy costs, these declining margins were eaten up, bringing foundries into crisis. Implementing Rheocasting at the existing die-casting cells is the solution to move into new market shares that are now not accessible in conventional HPDC.One of the new applications is electronic housings, high wall thickness parts, and fatigue bearing parts. These parts are commonly manufactured in sand or gravity castings because of their high wall thickness and low tolerance of porosity. Rheocasting is the perfect process for high-wall thickness components. Because of the semisolid melt preparation and the lamellar filling behavior, these components can be manufactured from the same alloy without pores or voids.This flow behavior of the semisolid slurry also results in a longer flow length. Slower casting speeds and lower pressure settings result in lower clamping forces. This gives an advantage in production costs and targets battery constructions made of castings and sheet metal. Structural battery housings must be leak-tight, even in a crash event. Having it in one casting instead of an assembly reduces the leakage area and improves crash performance.Another industry that relies on Rheocasting is the telecommunications industry. The power electronics in these 5G modules are significantly larger and generate much more waste heat. Until now, many antennas have been actively cooled or milled from a block of aluminum. The milled housings are significantly too expensive to enable series production. Therefore, the goal is to reproduce the passively cooled modules in die casting. Due to the process, the thermal conductivity in conventional HPDC is around 120 to 130 W/m*K. Similarly, no slim cooling fins can be formed. Only the Rheocasting process makes it possible to cast other alloys with low proportions of alloying elements, such as AlSi2Mn. This allows fins with a wall thickness of down to 0.4 mm and thermal conductivity of up to 190 W/m*K.Rheocasting enables access to market segments out of reach. These bring an unbeatable cost advantage against the current suppliers: gravity and sand casters. The low cycle time in Rheocasting brings back the high margins needed to sustain the business. Also, these products can be delivered with even better properties on smaller casting machines.

Pressure infiltration behavior and fluid loss of bentonite slurry: a comparative study of two bentonite slurries

Bentonite slurry is frequently used to temporarily stabilize the excavation for slurry tunnel boring machines (TBMs) driving in permeable soils, such as sand and gravel. In this study, two types of bentonite slurries (BS1 and BS2) were subjected to a series of infiltration column tests and modified fluid-loss tests under various pressure levels. Monitoring of water discharge and pore pressures at different depths of the sand bed enabled the identification of two effective sealing patterns during infiltration: the formation of a filter cake and rheological blocking. BS1 exhibited a tendency to form a filter cake, which played a vital role in effectively transferring the applied pressure to the underlying soil skeleton. The application of higher pressure facilitated the rapid formation of a filter cake, resulting in a shorter time span for slurry invasion and minimizing fluid loss. On the other hand, rheological blocking was dominant when using BS2, and the maximum infiltration distance was found to linearly increase with the applied pressure. A comparison between the measurement and a simple prediction model derived from Darcy's law revealed an overestimation of the infiltration distance during slurry invasion. Furthermore, based on the modified fluid-loss test, higher pressure was found to densify the filter cake and result in lower hydraulic conductivity.

Investigation on the rheology, self-shrinkage, pore structure, and fractal dimension of coral powder-cement slurry

There is a significant amount of coral powder in coral aggregates, which has a negative impact on the operational performance, mechanical characteristics, and durability of coral reef sand concrete. The present study investigates the effect of coral powder with varying fineness and content on rheological and self-shrinkage properties using an Anton Paar MCR102 rotational rheometer and YC-BWS bellows self-shrinkage apparatus, respectively. The dynamic yield stress, rheological index, and plastic viscosity are obtained according to the Bingham model, Modified Bingham model, and Herschel-Bulkley model. The pore structures of coral powder-cement slurry are studied using a combination of MIP and SEM tests. Fractal theory is used to characterize the pore size distribution. The results demonstrate that the coral powder-cement slurry exhibits a shear thinning phenomenon. The Herschel-Bulkley model is successful in simulating the rheological behavior of cement slurry. The dynamic yield stress and plastic viscosity increase gradually as the fine coral powder content increases. With the increase in the coarse coral powder content, the dynamic yield stress decreases gradually while the plastic viscosity increases. The self-shrinking value of the coral powder-cement slurry increases rapidly within 1d but gradually stabilize with age. The self-shrinkage value increases with the increase in the coral powder admixture. The self-shrinkage value of the fine coral powder-cement slurry is less than that of the coarse coral powder-cement slurry. It is found that increase in the coral powder reduces the compressive strength of the cement paste, however, cement replacement with 10% coral powder is acceptable. Pore surface fractal dimension and capillary pore volume is able to effectively characterize pore size distribution and pore volume, respectively. Furthermore, the strength has a positive and negative linear relationship with the pore surface fractal dimension and capillary pore volume, respectively. The ratio of pore surface fractal dimension to capillary pore volume can be used as a parameter of the strength model. A linear relationship between the strength and the ratio of pore surface fractal dimension to capillary pore volume is proposed, and the model exhibits high accuracy.

Enhanced mechanical properties and biological responses of SLA 3D printed biphasic calcium phosphate bioceramics by doping bioactive metal elements

Favorable mechanical properties and outstanding bioactivity are necessary for bioceramics used for bone defect repair. The doping of Mg2+ and Fe3+ can improve the mechanical properties and bone regeneration capacity of calcium phosphate ceramics. In this study, magnesia oxide (MgO), ferric oxide (Fe2O3), and iron (Fe) powders are chosen as dopants to enhance biphasic calcium phosphate (BCP) bioceramics, and the MgO-BCP, Fe2O3-BCP, Fe-BCP bioceramics are prepared by stereolithography (SLA) for the first time. The effects of these dopants on the curing behavior of bioceramic slurries, mechanical properties, biodegradation, and cytocompatibility of BCP bioceramics are studied. The addition of 1 wt.% Fe well enhances the flexural strength of BCP from 91.61 MPa to 122.60 MPa sintered at 1250 oC. The addition of 1 wt.% MgO effectively promotes the biodegradation of BCP in simulated body solution (SBF), and enhances the proliferation of mouse pre-osteoblast (MC3T3-E1) cells in vitro. In addition, Fe powder is more suitable as a dopant for SLA 3D printed BCP than Fe2O3 powder, and all the performances of Fe-BCP are better than those of Fe2O3-BCP. The less microstructure defects and slower Fe3+ release rate make Fe-BCP have higher flexural strength and less cytotoxic compared with Fe2O3-BCP. This novel way exhibits beneficial effects of bioactive metal elements on mechanical properties and bioactivity, and indicates SLA 3D printed BCP bioceramic doped with MgO, Fe can be promising candidates for bone defect repair.

Simulations of biomass compression-screw feeding using a compressible non-Newtonian constitutive model

There is global interest in the conversion of biomass into sustainable low-carbon-footprint fuels and chemicals as an alternative to non-renewable fossil feedstocks. Feeding biomass solids into pressurized reactors is one of the key steps in biomass conversion. Predicting mechanical failure and energy requirements for this step helps avoid upstream processing bottlenecks and enables efficient operation of a biorefinery. In this work, we developed a predictive computational model for biomass screw feeders that capture the highly viscous, non-Newtonian and compressible behavior of biomass slurries. Biomass compressible behavior is formulated by an equation of state and the non-Newtonian rheology is represented by a density-dependent viscosity model. Experimental data from two compression screw-feeder systems are presented as a validation for our model. Our model successfully predicted the location of the compressed biomass “plug”, biomass flow rate, and the required torque at different operating conditions for the experimental conditions studied in this work.

Wall slip behavior of cemented paste backfill slurry during pipeline based on noncontact experimental detection

Wall slip behavior of cemented paste backfill slurry during pipeline based on noncontact experimental detection

On the Roles of Cellulose Nanocrystals in Fiber Cement: Implications for Rheology, Hydration Kinetics, and Mechanical Properties.

Fiber cement reinforced with pulp fibers is one of the key drivers for the decarbonization of nonstructural building materials, where the inclusion of sustainable pulp fibers at high proportions (i.e., > 8 wt %) renders poor workability of fiber-cement slurry with a concomitant loss in mechanical strength. Petrochemical-derived superplasticizers, i.e., polycarboxylates (PCEs), are predominantly used in fiber cement (including cement mortars) because they dramatically improve (content <0.5 wt %) the slurry rheology but reduce the rate of hydration and weaken the strength of the cured composite. Thus, it is crucial to explore renewable and bio-based superplasticizers devoid of any negative traits (if possible) of the conventional PCEs. In this study, we examined wood-derived cellulose nanocrystals (CNCs) as a multifunctional additive in fiber cement (bleached pulp fiber content: 8 wt %). In fiber cement, variation of the content (0.02-4 wt %) of CNCs resulted in improvement in the shear thinning behavior of the fiber-cement slurry and thereafter increased the hydration kinetics at high CNC contents (2-4 wt %). Notably, the flexural strength of the composite also exhibited improvement upon the addition of CNCs; the maximum strength was observed at 4 wt % of CNCs. Overall, the beneficial roles of CNCs afforded >10 wt % (in-total) bio-based content in fiber cement without compromising the mechanical strength and curing time (compared to PCEs); hence, the findings of this study could unravel new avenues in interface engineering of cement composites leveraging the multifunctional features of biomaterials, thus enhancing sustainability.

Temperature-dependent rheological behavior of cathode slurry for lithium-ion battery under steady and dynamic tests

Temperature-dependent rheological behavior of cathode slurry for lithium-ion battery under steady and dynamic tests

Effect of reactive diluent concentration on rheological and curing behavior of zirconia ceramic slurry for DLP printing

AbstractA series of photosensitive zirconia ceramic slurry with adjustable viscosity and cured depth have been presented for the construction of high‐quality zirconia ceramic fabricated by digital light processing 3D printing. The rheological and curing behavior of the slurry can be flexibly optimized by tuning the reactive diluent concentration and category, since the change of dominant position of diluent on viscosity and the different curing mode. Monofunctional reactive diluent (HEA, hydroxyethyl acrylate) exhibits an enhanced dilution effect compared with that of bifunctional reactive diluent (HDDA, 1,6‐hexamethylene diacrylate) due to the lower molecular mass of monofunctional diluent. As a result, the viscosity reaches lower than 2000 mPa·s when the concentration of both HEA and HDDA exceeds 50 wt.%. At the same time, the non‐Newtonian properties of the slurry are also changed, which facilitates the printing process. However, excessive addition of diluent may generate more defects in ceramic green body. Consequently, the cured depth of zirconia slurry can reach 55 and 50 µm, respectively, at the curing time of 3 s while introducing the HEA or HDDA with the concentration below 70 wt.%, and the modified feedstock is promising for high‐quality and low‐defect zirconia ceramic components printing for biomedical applications.

Curing behaviors and mechanical properties of SiC-whisker-reinforced alumina ceramics fabricated with digital light processing

Silicon carbide whiskers (SiCw) have presented great potential to improve the mechanical properties of Al2O3 ceramic. However, effective curing of SiCw/Al2O3 ceramic slurry during digital light processing (DLP) is still challenged due to the high refractive index of SiCw. This paper aims to investigate the effect of SiCw content on rheological properties and associated curing behaviors of ceramic slurry. A modified Beer-Lambert model is proposed to evaluate the curing depth as functions of SiCw content and exposure parameters. The SiCw/Al2O3 ceramic slurries with the whiskers content of 0–16 vol.% are prepared and characterized. The results indicate that the curing depth decreased from 158 to 19 μm at the given exposure energy of 100 mJ/cm2 with the increase of SiCw content. The scattering and absorbance of light result in the decrease of curing depth and the geometrical overgrowth. The rheological properties of ceramic slurry are affected by the agglomerated whiskers. Furthermore, SiCw/Al2O3 ceramics are fabricated by DLP method, based on which the relationships among mechanical properties, microstructures and whiskers contents are determined. Significant effect of reinforcement is obtained in SiCw/Al2O3 ceramic due to whiskers pullout consuming the external loading energy. The microhardness and flexural strength of the SiCw/Al2O3 ceramics with 8 vol.% SiCw are 16.72 GPa and 208.5 MPa, respectively.