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Solar thermal storage ceramic materials use photothermal power generation technology to store heat energy, which is an important way to use clean energy and reduce carbon emissions. In this paper, MgAl2O4 ceramics were prepared by pressureless sintering with fused magnesia and α‐Al2O3 as the primary raw materials and TiO2 as the additive. The phase composition, microstructure, physical properties, thermal shock resistance, and thermal physical properties of MgAl2O4 thermal storage ceramics were studied. The results show that the main crystalline phase of B4 is MgAl2O4 and the secondary crystalline phase is MgTi2O5. Ti4+ is dissolved into MgAl2O4 lattice, which distorts the lattice, reduces activation energy, and promotes sintering. The sample B4 (69.73 wt% α‐Al2O3, 30.27 wt% fused magnesia, and 7 wt% TiO2) sintered at 1510°C had the best comprehensive physical properties, and its bending strength and bulk density were 89.41 MPa and 3.27 g/cm3, respectively. After 30 thermal shock cycles, the bending strength of the sample B4 is slightly lost. The thermal stress generated during the expansion and contraction of the grain volume led to the decrease of the bending strength. From room temperature to 1000°C, the specific heat capacity of sample B4 is.44–1.25 J/(g·K). The heat capacity increases with the increase of temperature, and the heat storage density increases. The heat storage density is 1218.75 kJ/kg (1000°C). Heat capacity increases with temperature due to intensified lattice vibration at high temperatures. Therefore, magnesia alumina spinel ceramics show great potential in solar thermal energy storage. [ABSTRACT FROM AUTHOR]

The absorptivity of solar thermal absorber materials affects the heliothermal conversion efficiency of concentrated solar power systems. The solar absorbing ceramics were prepared by the fixed mixture of bauxit, Fe2O3, and TiO2 with adding CuO in different percentages. The absorptivity and thermal shock resistance with the effect of adding CuO in different percentages were studied. Fe2O3 and TiO2 have excellent optical properties, and CuO decreases the material's band gap to boost the electronic transition and increase the material absorptivity. The results showed that the material is sintered at 1380°C with an excellent absorptivity of 94.00% in the spectrum range of 0.3–2.5 μm, and the bending strength is 132.94 MPa. The bending strength was increased by 21.07% after 30 thermal shock cycles (1000°C‐room temperature, air cooling). The liquid phase facilitates the synthesis of hercynite with excellent high temperature properties. The hercynite improves the thermal shock resistance of the material. [ABSTRACT FROM AUTHOR]

Zirconia‐corundum‐mullite composites were prepared from andalusite, ZrO2, and α‐Al2O3 and evaluated for application as solar thermal storage materials in this study. The effects of ZrO2 concentration (0–25 wt%) and sintering temperature(1500–1650°C) on the bending strength, phase composition, microstructure, dimensional stability, and thermal shock resistance of the samples were investigated. The results showed that sample C2 (containing 10 wt% ZrO2) sintered at 1600°C exhibited the best properties. A portion of Y2O3 existed in ZrO2, which excited a small amount of t‐ZrO2 in the sample after sintering, while the other portion of Y2O3 was separated from ZrO2 and participated in the formation of a high‐temperature liquid phase. The liquid phase reduced the dimensional stability of the sample. However, the liquid phase could also promote sintering, reducing the optimal sintering temperature, with lower sintering temperatures increasing the dimensional stability of the sample. Once again, the C2 sample exhibited the highest thermal shock resistance, with a strength loss of 2.76 MPa after 30 thermal shock tests. The thermal storage density(25–1100°C) of C2 was 1121 kJ/kg. In summary, sample C2 exhibits a high degree of dimensional stability and thermal shock resistance and can thus be used as a reliable solar thermal storage material. [ABSTRACT FROM AUTHOR]

In order to study the performance and feasibility of magnesia‐alumina spinel (MgAl2O4) ceramics for thermal storage in solar thermal power generation, MgAl2O4 was prepared by theoretical composition using α‐Al2O3 as aluminium source, fused magnesia, magnesite, and light burned magnesia as different magnesium sources and kaolin as additive. The effects of magnesium source and the additive on sintering properties, thermal shock resistance and thermal properties of MgAl2O4 ceramics were researched. The results shown sample A1 (with fused magnesia) sintered at 1670°C possessed the optimum comprehensive properties, the bending strength increased by 7.71% after 30 thermal shock times (room temperature‐1000°C, air cooling), the specific heat capacity was 1.05 J/ (g·K). Therefore, the MgAl2O4 ceramics exhibited great potential in high‐temperature thermal storage material. [ABSTRACT FROM AUTHOR]

Selecting suitable ceramic powders for the preparation of UV‐curable ceramic suspensions, which are well suited for printing processes and production of high‐performance ceramic components, is a crucial factor in the practical industrial application of digital light processing (DLP) stereolithography. Therefore, this study aims to provide a comprehensive evaluation of alumina ceramic parts fabricated via DLP stereolithography using a variety of alumina powders with varying sizes and morphologies. Experiments were conducted to examine the rheological response, recoating performance, and curing behavior of UV‐curable alumina suspensions. Additionally, the thermal decomposition behavior of three‐dimensional (3D)‐printed green‐bodies, as well as the physical and mechanical properties of 3D‐printed sintered alumina components were thoroughly investigated. The best physical and mechanical performances were achieved by printing 55 vol% suspensions prepared using near‐spherical AA04 alumina powders (median diameter.4 μm). This study elucidates the effects of ceramic particle size and morphology on the entire technological process of DLP‐based ceramic stereolithography, thereby establishing the guidelines for the fabrication of high‐performance 3D‐printed ceramic objects in industrial and engineering production by selecting appropriate ceramic powders. [ABSTRACT FROM AUTHOR]

The employment of solar energy in recent years has reached a remarkable edge. It has become even more popular as the cost of fossil fuel continues to rise. Energy storage system improves an adjustability and marketability of solar thermal and allowing it to produce electricity in demand. This study attempted to prepare cordierite/mullite composite ceramics used as solar thermal storage material from calcined bauxite, talcum, soda feldspar, potassium feldspar, quartz, and mullite. The thermal physical performances were evaluated and characterized by XRD, SEM, EPMA, and EDS. It was found that the optimum sintering temperature was 1280°C for preparing, and the corresponding water adsorption was 11.25%, apparent porosity was 23.59%, bulk density was 2.10 mg·cm−3, bending strength was 88.52 MPa. The residual bending strength of specimen sintered at 1280°C after thermal shock of 30 times decreased to be 57 MPa that was 36% lower than that before. The thermal conductivity of samples sintered at 1280°C was tested to be 2.20 W·(m·K)−1 (26°C), and after wrapped a PCM (phase change materials) of K2SO4, the thermal storage density was 933 kJ·kg−1 with the temperature difference (Δ T) ranged in 0-800°C. The prepared cordierite/mullite composite ceramic was proved to be a promising material for solar thermal energy storage. [ABSTRACT FROM AUTHOR]

For lowering sintering temperature of mullite/Al2O3 composite ceramics for solar thermal transmission pipeline, kaolin, potassium feldspar, quartz, and γ-Al2O3 were used as raw materials to in situ synthesize the composite ceramics with pressureless sintering method. Densification, mechanical properties, thermal expansion coefficient, thermal shock resistance, phase composition, and microstructure were investigated. The experiment results demonstrated that the introduction of potassium feldspar and quartz decreased the lowest sintering temperatures greatly to 1300°C. The optimum sample A3 sintered at 1340°C obtained the best performances. The water absorption, apparent porosity, bulk density, bending strength, and thermal expansion coefficient of A3 were 0.04%, 0.12%, 2.71 g/cm3, 94.82 MPa, and 5.83 × 10−6/°C, respectively. After 30 thermal shock cycles (wind cooling from 1100°C to room temperature), no cracks were observed on the surfaces of the sample, and the bending strength increased by −7.96%. XRD analysis indicated that the main phases of samples before and after 30 thermal shock cycles were consistently mullite, corundum, and α-cristobalite, while the content of mullite increased after thermal shock. SEM micrographs illustrated that the mullite grains growth and micro-cracks appeared after thermal shock endowed the composite ceramics with excellent thermal shock resistance. [ABSTRACT FROM AUTHOR]

For lowering the sintering temperature of silicon carbide ceramics used for solar thermal energy storage technology, O'-Sialon and silicon nitride were employed as composite phases to construct Sialon-Si3N4-SiC composite ceramics. The composite ceramics were synthesized using SiC, Si3N4, quartz, and different alumina sources as starting materials with noncontact graphite-buried sintering method. Influences of alumina sources on the physical properties and thermal shock resistance of the composites were studied. The results revealed that the employment of O'-Sialon and silicon nitride could decrease the sintering temperature greatly to 1540°C. The optimum formula G2 prepared from mullite as alumina source achieved the best performances: 66.7 MPa of bending strength, 10.0 W/(m·K) of thermal conductivity. The composition parameter x = 0.4 of O'-Sialon decreased to 0.04 after 30 cycles thermal shock, and the bending strength increased with a rate of 11.0% due to the increase of O'-Sialon grain size, and the optimization of microstructure caused by the transformation of O'-Sialon grains and densification within the samples. The good thermal shock resistance makes the composites suitable for the use as thermal storage materials of concentrated solar power generation. [ABSTRACT FROM AUTHOR]

Si3 N4- Si C composite ceramics used for volumetric receivers were fabricated by pressureless sintering of micrometer Si C, Si3 N4, andalusite, and other minor additions powders. Mechanical, thermal expansion, thermal conductivity, and thermal shock resistance properties were tested at different sintering temperatures. The best sintering temperature of optimum formula A2 is 1360°C, and the bending strength reaches 79.60 Mpa. And moreover, its thermal expansion coefficient is 6.401 × 10−6/°C, thermal conductivity is 7.83 W/(m K), and no crack occurs even subjected to 30 cycles thermal shock with a bending strength increase rate of 4.72%. X-ray diffraction results show that the phase constituents of the sintered products mainly consist of Si C, Si3 N4, mullite, and quartz. Microstructure that is most appropriate and exhibits maximal thermal shock resistance was detected using SEM. The porosity of Si3 N4- Si C ceramic foam prepared from formula A2 is 95%, which provides a rapid and steady action for the receiver. The evaluation of the present foam shows that Si3 N4- Si C ceramic composite is a good candidate for volumetric receivers. [ABSTRACT FROM AUTHOR]