International Journal of Applied Ceramic Technology最新文献

The potential of electrochemical water splitting to tackle energy and environmental issues has garnered substantial interest. In the present work, an effective ZnS/In₂Te₃ has been constructed by hydrothermal support on a stainless-steel strip and explored for oxygen evolution. The addition of ZnS modifies the band structure of In₂Te₃ and enhances its specific conductivity and capacitance on an intrinsic level, making rapid ion transportation. The optimized ZnS/In₂Te₃ displayed efficient oxygen evolution reaction (OER) performance with an overpotential of 228 mV and a Tafel slope of 111 mV dec⁻¹ with cyclic activity up to 1000 cycles in 1 M KOH solution. ZnS/In₂Te₃ has a large surface area (28 m³g⁻¹) and a charge capacitance of (.037 mF), according to studies using Brunauer–Emmett–Teller and double-layer capacitance. Combining several strategies improves overall electrochemical performance of ZnS/In₂Te₃, making it a promising option for use in state-of-the-art OER.

Dysprosium (Dy)-doped (Y_1−xDy_x)₃Si₂C₂ (x = 0, 0.1, 0.3, 0.5) solid solution ceramics were successfully fabricated using an in situ reaction spark plasma sintering technology, for the first time. The effect of various Dy doping contents (x) on the microstructure, mechanical, and thermal properties of (Y_1−xDy_x)₃Si₂C₂ ceramics was investigated. The (0 2 0) crystal plane spacing of (Y_0.5Dy_0.5)₃Si₂C₂ was 7.813 Å, which was smaller than that of Y₃Si₂C₂, due to the fact that the atomic radius of Dy is smaller than that of Y. The Dy doping facilitated the consolidation of (Y_1−xDy_x)₃Si₂C₂, thus a highly dense (Y_0.5Dy_0.5)₃Si₂C₂ ceramic material with a low open porosity of 0.14% was successfully obtained at a relatively low temperature of 1 200°C. As the content of Dy doping (x) increased from 0 to 0.5, the purity of (Y_1−xDy_x)₃Si₂C₂ ceramics increased from 88.3 to 90.7 wt.%, while the grain size of (Y_1−xDy_x)₃Si₂C₂ ceramics decreased from 0.59 to 0.46 µm. As a result, the Vickers hardness and thermal conductivity of the (Y_0.5Dy_0.5)₃Si₂C₂ material was 7.1 GPa and 9.8 W·m⁻¹·K⁻¹, respectively.

Chromium–corundum, as a common refractory material, is broadly applied in high-temperature kilns due to its superior thermal stability and high melting point. Unfortunately, this refractory is susceptible to corrosion and destruction under extreme furnace conditions by chemical erosion, mechanical wear, and thermal shock, which significantly shortens its useful life. Accordingly, in recent years, the issue of how to improve the slag corrosion resistance, mechanical, and sintering properties of chromium–corundum refractories has aroused widespread attention. In this work, the corrosion behavior and application status of chromium–corundum refractories in Ausmelt furnace, waste incinerator, coal water slurry gasifier, and HImelt melting reduction furnace are analyzed and discussed. To improve the service life of chromium–corundum refractories, the enhancement method and mechanism of sintering performance, mechanical properties, slag corrosion resistance, and thermal shock resistance are also summarized. Finally, some suggestions and prospects are made for the enhancement and longevity of chromium–corundum refractories.

Although the residual stress in one-side coating (type-I coating) on a beam specimen can be determined by comparing the bending deformation before and after coating, the stress of a coated component without bending deformation (type-II coating) is difficult to obtain via conventional methods, especially at high temperature. An image relative method is presented to determine variations in the curvature radius with temperatures for stress analysis at high temperature. A relationship between the residual stresses in type-I and type-II coatings was established so that the residual stress of type-II coating was determined from the measured stress in type-I coating. Thus, the core issue is to measure the temperature dependence of the bending deformation of the sample with one-side coating. The temperature dependence of the residual stress in thermal barrier coatings on metal substrate was obtained by continuously photographing deflections of the beam specimen at temperatures ranging from 20°C to 1000°C, and the residual stress in components with symmetrical coatings in the temperature range was then determined.

The corrosion of slag on refractories usually starts from the matrix, so improving the slag resistance of the matrix is of great significance for the slag resistance of the refractories. To clarify the influence of matrix on the slag resistance of magnesia–carbon refractories, the slag corrosion experiments were conducted at 1873 K on MgO–C refractories, low-carbon MgO–C refractories, and MgO–SiC–C refractories. The results showed that the slag resistance of MgO–C refractories was higher than that of low-carbon MgO–C refractories, and the slag resistance of MgO–SiC–C refractories was superior to that of low-carbon MgO–C refractories. The interaction between MgO–SiC–C refractories and slag generated high melting point phases such as forsterite and spinel, reducing the routes for the slag to infiltrate the inside of the refractories. MgO–SiC–C refractories reacted with slag to increase the viscosity of the slag, the viscosity being 86.3% and 51.9% higher than in the case of low-carbon MgO–C and MgO–C refractories, respectively. Compared with MgO–SiC–C refractories, MgO–C refractories did not exhibit overwhelming advantages in slag resistance. Due to the low-carbon content and good slag resistance, MgO–SiC–C refractories were promising low-carbon magnesia-based refractories for high-temperature industries.

Pyroplastic deformation is still an important defect caused during firing in the manufacture of porcelain tiles when there is no control over the raw materials used in the formulation of ceramic tiles. The present study used mixing design as a tool in the development of pastes formulations for Brazilian porcelain tile manufacturing in order to reduce their pyroplastic deformation. Ceramic industry in Brazil has typical and complex way to set up porcelain tile formulations, using regularly more than a dozen raw materials. Therefore, the originality in this work was understanding the formulation by means of a pseudocomponent-based approach (multiminerals triaxial diagram) and defining parameters that minimize that problem. Eleven different raw materials, supplied by Brazilian ceramic manufacturer, were used and characterized according to their physical–chemical properties. Later, raw materials were divided into three chemical categories and through a simplex-centroid mixture design, defining the maximum limit of feldspar in 70%, 10 formulations in the experimental region were defined. All formulations were analyzed for particle size distribution, bulk density (postpressing and postburning), mechanical strength (postpressing and postfiring), thermal shrinkage, water absorption, and pyroplastic deformation. Thus, formulations that presented the most admissible behavior in the manufacture of porcelain tiles were selected, and tests were carried out for chemical, mineralogical, thermal (differential scanning calorimeter [DSC]/thermogravimetric [TG]), thermal expansion, porosity analysis, and optical fleximeter (pyroplasticity). All results were analyzed using response surfaces with data obtained by analysis of variance (ANOVA). Mixture design method proved to be a valuable tool to observe the behavior of raw materials and to optimization of Brazilian porcelain tile formulations.

Mullite ceramics with high purity and toughness were prepared by hot-press sintering of pyrophyllite at 1300°C using AlOOH nanomaterials with different sizes and morphologies (nanoparticles, nanorods, nanoflakes, and micro-sized sea urchin–like) as additives. Among the four types of AOOH additives, the incorporation of nanoflakes and sea urchins resulted in the formation of a relatively uniformly distributed and tightly packed microstructure within the ceramics, which significantly improved the density and mechanical properties of the ceramic materials. Compared to nano-sized AlOOH, the addition of micron-sized sea urchin–like AlOOH could produce mullite ceramics with best purity and flexural strength. The flexural strength and fracture toughness of ceramics prepared from micro-sized sea urchin–like AlOOH and pyrophyllite reach 427.34 ± 1.99 MPa and 4.68 ± .31 MPa m^1/2, respectively. During the ball milling process, the originally micron-sized sea urchin–like AlOOH particles were broken down into micro- and nano-sized AlOOH particles. The resulted micron and nanoscale AlOOH particles exhibited synergistic and multi-scale effects with pyrophyllite, which contributed to the formation of uniformly sized and densely arranged mullite crystals within the ceramics. Additionally, the bridging between the mullite crystals further improved the mechanical properties of the mullite ceramic material.

Sc₂O₃–CeO₂–Y₂O₃– stabilized zirconia (ScCeYSZ) nanoparticles with different percentages of stabilizer agents [sample1: 1.8 wt.% (Sc₂O₃) 8.3 wt.% (CeO₂) 1.9 wt.% (Y₂O₃), sample 2: 1.1 wt.% (Sc₂O₃) 9.0 wt.% (CeO₂) 1.9 wt.% (Y₂O₃), sample 3: .5 wt.% (Sc₂O₃) 9.6 wt.% (CeO₂) 1.9 wt.% (Y₂O₃) stabilized zirconia] were synthesized with Pechini method and consolidated by spark plasma sintered method. The results showed that despite the [(sample)₁: 1.8 wt.% (Sc₂O₃) 8.3 wt.% (CeO₂) 1.9 wt.% (Y₂O₃)] had lower density and higher porosity percentage compared to other samples, it had better calcium–magnesium–alumina–silicate (CMAS) corrosion resistance compared to other samples and the yttria-stabilized zirconia nanopowders (nano-YSZ) sample. It was due to the higher acidic nature and tetragonality of the (sample)₁ sintered body compared to other samples and YSZ ceramic in the CMAS corrosive medium. Moreover, the results of phase and microstructural analysis following CMAS corrosion revealed the formation of the monoclinic phase and rod-shaped CaAl₂Si₂O₈ particles on the surface of the sampled sintered sample. However, the nano-YSZ sample corroded homogenously and delamination occurred after the CMAS corrosion test.

Sand-casting molds suffer from surface defects and low strength. An organic–inorganic binder conversion process, wherein an organic binder is converted to an inorganic binder, has been proposed to increase the application temperature of the sand-casting mold and simplify the manufacturing process for precision casting. However, the usable temperature of the typical SiO₂–Na₂O binder system is limited to approximately 1000°C owing to the low liquefaction temperature of the compound. The resulting glass phase (Na₂SiO₃) exhibits low viscosity, and the casting of large objects results in low strength. Therefore, in this study, we propose a SiO₂–Na₂O–ZrO₂ ternary inorganic binder system; the addition of zirconia (ZrO₂) into sodium silicate (Na₂SiO₃) as an inorganic binder was expected to increase the operating temperature of the mold and improve its mechanical properties. The results confirmed that the addition of ZrO₂ improved the mechanical properties by preventing the formation of Na₂SiO₃. In addition, a higher sintering temperature corresponded to smaller and larger amounts of Na₂SiO₃ and Na₂ZrSiO₅, respectively, and thus a higher strength. Therefore, we expect our developed ternary inorganic binder system to be highly advantageous for producing molds for high-temperature and precision casting.

Silicon carbide nanofiber/silicon carbide (SiC_nf/SiC) composites with a laminar stacking structure were prepared by the slurry impregnation hot-press sintering using aluminum (Al) powder, boron (B) powder, and carbon black as sintering aids. SiC_nf paper was fabricated using nanofibers and impregnated with the slurry of SiC_np and sintering aids, and the SiC_nf/SiC preforms were fabricated by the alternating stack of the SiC_nf paper and SiC_np. The pyrolysis carbon and boron nitride interface layers were deposited on the surface of SiC_nf by chemical vapor deposition and vacuum impregnation-pyrolysis methods. The effects of different sintering temperatures on the relative density, porosity, sectional microscopic morphology, and mechanical properties of the composites were investigated. The results show that the fracture toughness of SiC_nf/SiC composites is significantly improved. The mechanical properties of the composites were optimized at a sintering temperature of 1950°C and a sintering pressure of 30 MPa, with flexural strength and fracture toughness of 548 MPa and 15.86 MPa·m^1/2, respectively. The liquid phase Al₈B₄C₇ compound generated at the high temperature promoted the densification of the composites.