In view of the clogging problem associated with submerged entry nozzles (SEN) used for aluminum-killed steel, the reaction behavior between the SEN and molten steel with high Al content with the influence of an external electric field is studied in this paper. The results showed that the application of an effective and positive voltage to the walls of the SEN would promote the decarburization of the SEN itself and the interfacial reaction between nozzle material and molten steel containing aluminum. On the contrary, these behaviors would be inhibited under the control of the negative voltage. Therefore, with the polarity of electric field applied on the SEN, it is necessary to determine whether the critical factor leading to clogging is the content of the Al2O3 inclusions or Al alloy content in the steel.

To lower the sintering temperature and improve the mechanical properties of aluminum titanate (AT, Al2TiO5) flexible ceramics, γ-Al2O3 is employed to partially replace the α-Al2O3 as the starting powder. The results show that the addition of γ-Al2O3 is sufficient to promote the reaction, improve the flexibility, raise the strength, and accelerate the grain growth of AT flexible ceramics when sintered at 1300°C. With that, the combination of optimum fracture strength (∼33.52 MPa) and high flexibility (∼1.05%) is obtained when the addition of γ-Al2O3 is 20 wt.%. As compared to the virgin, the optimization of 21.67% in fracture strength and 176% in strain can be obtained. It is believed that the increase of crack deflection and branching should take the responsibility. However, the mechanical strength degrades with the increase of sintering temperature, which is caused by the grain defects that reduce the bearing capacity of AT grains and lead to the grain fracture model transition. In addition, the effect of γ-Al2O3 content on AT grain growth transfers from promotion to inhibition with the increase of sintering temperature. The main reason is that the growth of the nanocrystals at AT grain boundary causes the uneven distribution of the intermediate phase, leading to the roughening transition of the boundary and hence reducing the grain growth rate. On these bases, the grain growth mechanism that dominates by grain boundary is proposed. It is believed that the discovery of this study will provide a new grain growth model and the reference for solving the abnormal grain growth or grain growth stagnation.

For the sake of enhance the sinter ability and electrical conductivity of BaZr0.1Ce0.7Y0.2O3-δ (BZCY) electrolytes, a modified aqueous gel-casting method was applied to synthesize high sintering active and high conductive BZCY nano-powders. The new approach makes it easy to obtain pure perovskite. The highly sintering active purity-phase of BZCY nano-powder (particle size of 50∼100 nm) was obtained by calcining at 1100°C for 2 h. Nano-powders effectively reduce the sintering densification temperature and successfully prepare BZCY electrolyte with relative density > 96 % at 1450°C, and promote grain growth with an average grain size of 2.36 μm. Benefiting from this, improved electrical conductivities (e.g., 12.4×10−3 S cm−1 at 700°C, in wet air) are obtained. The NiO-BZCY/BZCY/LSCF-BZCY anode-supporting single cell shows a peak power density of 0.75 W cm−2 at 700°C while taking ambient air as oxidants and wet H2 (∼3 vol.% H2O) as fuels.

A material extrusion (MEX) technology has been developed for the additive manufacturing of continuous carbon fiber–reinforced silicon carbide ceramic (Cf/SiC) composites. By comparing and analyzing the rheological properties of the slurries with different compositions, a slurry with a high solid loading of 48.1 vol% and high viscosity was proposed. Furthermore, several complex structures of Cf/SiC ceramic composites were printed by this MEX additive manufacturing technique. Phenolic resin impregnation–carbonization process reduces the apparent porosity of the green body and protects the Cf. Finally, the reactive melting infiltration (RMI) process was used to prepare samples with different Cf contents from 0 to 2 K (a bundle of carbon fibers consisting of 1000 fibers). Samples with Cf content of 1 K show the highest bending strength (161.6 ± 10.5 MPa) and fracture toughness (3.72 ± 0.11 MPa·m1/2) while the thermal conductivity of the samples with the Cf content of 1 K reached 11.0 W/(m·K). This study provides a strategy to prepare Cf/SiC composites via MEX additive manufacturing and RMI.

The aim of this work is to prepare interlocking prismatic mullite from low-cost associated rare-earth kaolin. High-performance mullite was synthesized by reaction sintering using calcined associated rare-earth kaolin and α-Al2O3 as raw materials and micro- and nano-La2O3 as additives. The mineralogical, morphological, and chemical characteristics of calcined associated rare earth kaolin were analyzed, and the effects of the addition of micro- and nano-La2O3 and sintering temperature on the phase transformation, sintering process, microstructure, and mechanical properties of mullite were studied. The results show that the associated rare earth elements Ce, Th, and Y in calcined kaolin are mainly light rare earth elements, which are mainly endowed in the interlayer structure of K-bearing clay minerals. The addition of La2O3 can promote the growth of secondary mullite grains and accelerate the secondary mullitization process. The relative densities of mullite samples adding 4 wt.% micro/nano La2O3 and sintered at 1500°C for 4 h were 92.72% and 93.4%, and the micro Vickers hardnesses were 11.32 and 12.35 GPa, respectively. The mullite sample with 2 wt.% nano-La2O3 had the most interlaced prismatic grains, resulting in the highest flexural strength of 157.8 MPa.

Given that the kinetics of the thermal degreasing process of alumina ceramics based on stereolithography apparatus (SLA) has not been investigated, the mechanism of crack generation is still not fully revealed. This paper aims to elucidate the mechanism of crack generation in the degreasing process of alumina ceramics and to establish a kinetic model for alumina ceramics. Two sintering atmospheres, air, and argon, were selected for the degreasing tests at 100°C–700°C. The reaction products and mass changes of alumina ceramics were analyzed by TG-FTIR and TG-DSC (heating rates of 5, 10, and 15°C/min, respectively). Meanwhile, Boswell, Friedman, Ozawa, and DAEM model was used to describe the nonisothermal kinetics of the SLA alumina ceramic degreasing process. The results showed that setting the holding time to 400°C–425°C could promote the slow release of heat from the alumina ceramics. The thermal degreasing stage of the ceramic generated fewer cracks in the argon atmosphere than in the air atmosphere. The corresponding average activation energy values were 105.40 kJ/mol (Boswell model), 112.48 kJ/mol (Friedman model), 108.14 kJ/mol (Ozawa model), and 101.36 kJ/mol (DAEM model). The results of the study could provide an invaluable reference for the fabrication of defect-free SLA alumina ceramics.

Ceramic membranes with high porosity and excellent separation efficiency are necessary for the efficient treatment of large-scale wastewaters. However, the conventional ceramic membranes are usually prepared by particles-packing, which inhibits the advances of separation efficiency because of the low porosity and connectivity. Here, a fibrous ceramic membrane with mullite whiskers-interlocked structure was prepared by gas-solid reaction. The effects of aluminum fluoride (AlF3) on the formation and growth of mullite whiskers, and then the permeability and selectivity of the ceramic membranes were investigated. With the increase of AlF3 contents, the mullite phase evolved from needle-like, rod-like to flake-like structure, thus the catalyst accelerated the growth of mullite whiskers in the diameter direction. For the ceramic membrane sintered at 1400°C, the porosity increased from 58% to 76% while the average pore sizes increased from 0.65 to 3.93 μm because of the whisker-constructed structures. For the ceramic membrane sintered at 1450°C, the emulsion flux increased stably from 295 L/(m2·h) to 992 L/(m2·h) with the increase of trans-membrane pressure, and the oil rejection exceeded 98%. Thus, this study provides a feasible strategy for the preparation of ceramic membranes with high porosity and excellent separation performances.

In this study, we adopted the novel strategies of the soot template method to construct SiO2 ceramic micro-nano structure surface and polydimethylsiloxane (PDMS) modification to reduce the surface energy. We fabricated a superhydrophobic/superoleophilic NS-PDMS oil–water separation screen by depositing coarse nano-SiO2 ceramic on the surface of 100-mesh stainless-steel screen used as a substrate under the soot template method, which reduced the surface energy with PDMS. The fabricated NS-PDMS screen exhibited excellent superhydrophobic and self-cleaning properties. In particular, the superhydrophobic properties were stably maintained under various harsh conditions. Overall, the screen manifested self-cleaning ability for various water-containing stains, for example, coffee, milk, beer, and soy sauce. The mechanically damaged screen surface still retained its high roughness, and re-modification with PDMS could recover the superhydrophobic surface and oil–water separation performance. This suggests the re-use potential of the damaged NS-PDMS screen, which is vital for cost reduction and resource recycling. We believe that our study makes a significant contribution to the literature, because the fabricated NS-PDMS screen is superhydrophobic, superoleophilic, resistant toward several water-based solutions, chemically and mechanically stable under certain conditions, and can be reused with modification and repair after damage. Therefore, this screen can be broadly used as an oil–water separator.

The new (0.96-x)(K0.48Na0.52Nb0.96Sb0.04)O3-0.04(Bi0.5Ag0.5)ZrO3-x(Fe2O3-In2O3) ceramics with high dielectric, and electromechanical coupling properties were designed. In this work, the effect of KNN-based ceramics lattice distortion (c/a) and microstructure on the electrical properties was explored by varying the doping amount of Fe3+ and In3+. The problem of a large number of oxygen vacancies generated by the volatilization of K and Na can be well solved by introducing Fe3+ and In3+. The bulk density increases significantly and the maximum value is about 4.52 g/cm3.The sample with x = 0.003 has the smallest c/a, and exhibits the best piezoelectric and dielectric properties (d33 = 536 pC/N, εr = 3432 and kp = 55.8 %). Low doping concentration of Fe2O3 is considered a “soft” addition for KNN-based piezoelectric ceramics. The study of this mechanism provides a new idea to regulate the electrical performance of KNN-based ceramics.

Wear resistance is one of the essential properties of grinding media. Good wear resistance is the quality guarantee of preparing high-purity ultrafine powder. This paper mainly studied the influence rule and enhanced mechanism of Sc2O3 on the wear resistance of Al2O3 ceramics. The relationship between Sc2O3 content and sintering properties, wear resistance, and microstructure of ceramics was studied. According to research findings, Sc2O3 could promote the densification of ceramics, improve the morphology of grain boundaries, enhance the binding force of grains, and increase the mechanical property of alumina grain.

In view of the lack of conformal, load-bearing, light-weight, and high temperature-resistant integrated wave-absorbing composites suitable for extremely complex conditions, the gel-casting process was successfully applied to porous Si3N4 wave-absorbing composites in this work. A universal low-slurry for gel casting was prepared by using two dispersants acting together (tetramethylammonium hydroxide solution and sodium lauryl sulfate), which ensured the smooth completion of the gel casting process. Combining the thermogravimetric and differential thermal gravity curves of the composite green body, reasonable parameters of the rubber discharge process are given to avoid the problem of the green body swelling and cracking. The porous TiC/Si3N4 composites were successfully prepared by holding them at 1650°C for 3 h. The bending strength, density, minimum reflection loss, absorption bandwidth, and matched thickness in the P-band of the composites with 30 wt.% TiC addition were 54.08 ± 3.02 MPa, 1.906 g/cm3, -37.75 dB, 1.9 GHz, and 4.1 mm, respectively. The electromagnetic wave loss mechanisms of the composites are a combination of conductivity loss, multiple reflections and scattering, interfacial polarization, and defect polarization.

We prepared sintered reaction-bonded silicon nitride ceramics by using yttria and magnesia as sintering additives and evaluated the effects of nitrogen pressure (0.1–1.0 MPa) on their microstructure, bending strength, fracture toughness, and thermal conductivity. The ratio of β phase in the nitrided compacts varied with the pressure and increased with increasing it. Since many β grains in the nitrided compacts were formed and interlocked each other with a stable three-dimensional structure which restricted the shrinkage during the sintering procedure, many pores remained in the sintered body. Under the middle pressure (0.3–0.5 MPa), the grains grew large because the number of formed nuclei was small. On the other hand, under the high pressures (0.8–1.0 MPa), the grains were relatively fine and uniform because of a large number of nuclei. Since the porosity and grain length depended on the nitridation mechanism, which was affected by the nitrogen pressure, the properties largely varied accordingly. The nitridation at 0.1 MPa gave the best properties in this study.

In this study, manganese ferrite (MnFe2O4) nanoparticles were produced through flame spray pyrolysis (FSP). To investigate the effects of heat treatment, the nanoparticles were annealed between 400 and 650°C for 4 h in air in a comparative manner. The structural, chemical, morphological, and magnetic properties of the nanoparticles were evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), dynamic light scattering (DLS), and vibrating sample magnetometry (VSM), respectively. The XRD results showed that the nanoparticles synthesized by the FSP method exhibited the MnFe2O4 spinel ferrite structure. The annealing process led to the decomposition of MnFe2O4 into various phases. According to the morphological analysis, the as-synthesized particles were hemispherical–cubic in shape and had an average particle size of less than 100 nm. In addition, the chemical bond structures of the nanoparticles were confirmed in detail by XPS elemental analysis. The highest saturation magnetization was recorded as 33.50 emu/g for the as-produced nanoparticles. The saturation magnetization of the nanoparticles decreased with increasing annealing temperature, while coercivity increased.

It is crucial to synthesize α-Al2O3, which is a multifunctional material, at high temperatures due to the nature of the material. However, this high-temperature preparation process is not energy efficient, which goes against the global aim of carbon neutrality. In this study, we explored the effect of adding 1 wt.% (NaCl) as an additive and a suitable amount of Al(OH)3 in a ball mill to form a precursor. The impact of NaCl and ball milling duration on the phase transition from Al(OH)3 to α-Al2O3 at low temperatures was investigated. After the conversion from Al(OH)3 to γ-Al2O3, the NaCl particles on the surface of γ-Al2O3 act as diffusion channels, helping to accelerate the substance diffusion during the transition from γ-Al2O3 to α-Al2O3, resulting in a lower formation temperature of α-Al2O3, which is 700°C. Additionally, the presence of NaCl results in α-Al2O3 particles growing into hexagonal plates. The α-Al2O3 plates produced from calcining the mixture of Al(OH)3 and NaCl at 700°C have an average diameter of 3 µm, an average diameter/thickness ratio of 10 and a specific surface area of 12.0085 m2/g. These results indicate that low-temperature synthesis of α-Al2O3 powder is possible by using NaCl as an additive instead of molten salt in the ball milling process.

A glass foam (GF) of high specific compressive strength (12.17±1.91 MPa g−1 cm−3) and low thermal conductivity (.121±.001 Wm−1 K−1) was produced from waste glass of photovoltaic module, eggshells, and bentonite clay. The influences of the amount of clay and heat-treatment temperature on the GFs final properties were assessed. X-ray diffraction results and the data of microscopic analyses demonstrated that addition of clay affected the structure and porosity of the GFs, and consequently their mechanical properties. On the basis of the mechanical property (density), the GF that composed of 80% waste glass, 10% clay, and 10% eggshell at the sintering temperature of 900°C was the best. The GFs reported in this study could serve as promising insulators in situations where high load support is required.

Molybdenum ions with high valence states (Mo6+) can contribute to electrical conductivity and optical transmittance. For this reason, zinc oxide (ZnO) nanorods doped with molybdenum metal were fabricated on a glass substrate by ultrasonic spray pyrolysis method. The doping concentrations were between 0–10 mol%. The crystallographic properties of the resulting ZnO samples were examined by the X-ray diffraction (XRD) technique. According to the XRD analysis, it was found that the lattice structure of the samples belonged to the hexagonal (wurtzite) unit cell. The XRD results indicated that the crystals grow in the c-axis (002) direction. The morphological features of the obtained thin films were studied by field emission scanning electron microscopy. The energy-dispersive X-ray spectroscopy results displayed that the Mo ions were in the ZnO lattice. Four point probe method was used to determine the electrical conductivity properties of the samples. The 10% mol doped sample has the highest conductivity with values of between 1.58 × 10−9 and 1.58 × 10−6 (ohm-cm)−1. The optical transmittances of the samples were measured at wavelengths between 300 and 1000 nm. It was observed that the produced films had high optical transparency which was approximately 85%.

Boron nitride (BN) coatings (thickness 20–40 μm) were prepared on graphite substrates by chemical vapor deposition, with precursors of BCl3 and NH3 (ratio of 1:4) and pressure of 500 ± 50 Pa. The influence of the deposition temperature (650°C–1250°C) on the wettability of BN coatings with deionized water was studied. The wetting angle rapidly increases at 1100°C–1250°C, and the wetting-to-nonwetting transition occurs. The crystal structure and surface morphology of the BN coatings were characterized by a stylus instrument, scanning electron microscopy, and transmission electron microscopy. Research shows that the contact angle or nonwettability increases with a higher degree of crystallinity and a lower surface roughness, which were both under the control of the deposition temperature since the pressure and gas flows were kept constant in this study. At a deposition temperature of 650°C–950°C, the increase in the degree of crystallinity dominates; at 950°C–1100°C, the increase in surface roughness takes over. At 1100°C–1250°C, the degree of crystallinity continues to increase, while the surface roughness decreases due to the advantage of nucleation and the breakage of large surface clusters into smaller clusters. This results in increases (650°C–950°C), then decreases (950°C–1100°C) and again fast increases (1100°C–1250°C) in the wetting angle between the BN coating and deionized water and finally in the wetting-to-nonwetting transition (1100°C–1250°C).

Hollow fiber membranes demonstrate various advantages for high performance oxygen separation. However, the small diameters of hollow fibers and the brittleness of ceramics limit their mechanical strength, imposing great difficulties on stack and module development. Gas-tight sealing is another challenge for upscaling of hollow fiber membrane technology. Low temperature sealant materials of epoxy resin or silicon are typically used for hollow fiber stacks, requiring that the sealing portions be located out of hot zone. Consequently, only partial length of hollow fibers participates in oxygen permeation. In this study, upscaling of our recently developed asymmetric hollow fiber-supported thin film membranes is conducted, where individual hollow fibers are assembled in parallel to form a stack. A reliable gas-tight sealing is obtained by combining ceramic paste with conductive adhesive ink cohesively. Comprehensive oxygen permeation test is conducted with the sealing portions being in hot zone and compared with a single hollow fiber membrane. Fundamental mechanism is discussed to understand the performances and their differences. An accelerated long-term test (∼320 h, 16 thermal cycles) demonstrates excellent stability and robustness of the stack and sealing. The characterization of post-test samples further confirms excellent stability and robustness of the phases and microstructures of the stack.

QPAC40 (polypropylene carbonate), with a little decomposition residue, is commonly used as a binder in aluminum nitride (AlN) tape casting. In this paper, we tried to explore its application in silicon nitride (Si3N4) tape casting. By studying the influence of dispersant, binder, plasticizer/binder ratio, and solid loading on slurry and green tape properties, the optimum formulation of the tape casting of Si3N4 slurry was determined, and the green tape with a uniform structure and relative density up to 63.16% was prepared. Si3N4 ceramics were obtained by debinding at 600°C for 1 h in vacuum and gas-pressure sintering at 1830°C for 2 h in N2. The thermal conductivity and flexural strength of Si3N4 ceramics were 56.28 ± 1.21 W/(m·K) and 1130.67 ± 23.58 MPa, respectively. These results indicated that QPAC40 can be used to prepare Si3N4 sheets through tape casting.

For high-power white light-emitting diode devices (WLEDs), phosphor ceramics were widely used because of their high thermal conductivity and temperature resistance. In this study, Y2.998Al5O12: 0.002Ce3+ ceramics were prepared via vacuum reaction sintering and treated by silicon carbide (SiC) abrasives with particle sizes of 8.6, 20, 25, 34, and 50 μm to obtain a single textured surface. The transmittance, reflectance, luminous efficiency (LE) and photoluminescence (PL) intensity of the ceramics were investigated with various surface roughness and different placement. Compared with the double polished (DP) samples, the PL intensity and LE of the single-surface textured ceramics were greatly improved. It was shown that the roughest ceramics placed with the single polished (SP) side facing the direction of the excitation light (the SP-forward YAG: Ce ceramics) showed the best performance.