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High-temperature stable thermal storage materials are urgently needed to meet the demand for solar thermal power generation. Herein, Cu–20Si alloy-corundum ceramic composite thermal storage materials are prepared. The thermal storage performance of the composite, and the erosion resistance of ceramic matrix to alloy are investigated during high-temperature (1000 °C) service for 1000 h. The results show that the latent heat of Cu–20Si alloy is increased by 130.76 % to 201.2 kJ/kg compared with the original. Meanwhile, the alloy forms a dense transition layer on the ceramic matrix surface by melting and spreading. Furthermore, the ceramic matrix shows superior erosion resistance to the alloy, owing to the dense structure of ceramic and no chemical reactions between the alloy and ceramic matrix. Finally, test results of long-time service confirm the stability of the composite, which can be used stably for high temperature thermal storage. [ABSTRACT FROM AUTHOR]

Anorthite solar thermal energy storage ceramics were fabricated from magnesium slag solid waste by pressureless sintering. The effects of CaO/SiO 2 ratio and sintering temperature on the physical, chemical, and thermophysical properties of ceramics were explored. X-ray diffraction results demonstrated that thermal shock process contributed to the formation of anorthite, and increasing CaO/SiO 2 ratio promoted the transformation of anorthite (CAS 2) into melilite (C 2 AS). Some micro-cracks were found according to SEM analysis, forming by the mismatch of thermal expansion coefficients among phases. The combined effects of the low thermal expansion coefficient of anorthite and micro-crack toughing endowed the ceramic with good thermal shock resistance. Optimum comprehensive performances were observed in the sample with a CaO/SiO 2 ratio of 0.58 sintered at 1160°C, of which the specific thermal storage capacity was 0.63 J·g-1·°C-1(room temperature). The bending strength increased by 0.22% after 30 thermal shock times (room temperature-800°C, wind cooling). Therefore, the anorthite ceramics exhibited great potential for solar thermal energy storage. [ABSTRACT FROM AUTHOR]

Solar energy absorption and storage of integrated ceramic materials is both the absorption of sunlight and storage of sunlight into thermal energy functional materials. In this paper, the effect of Fe 2 O 3 on the solar absorptivity, thermal storage properties, sintering temperature, and physical properties of mullite-based thermal storage ceramics was investigated. The results show that the absorptivity and thermal storage density of the sample AF4 (Bauxite:50 wt%, Clay:50 wt%, Fe 2 O 3 :11 wt%) after sintering at 1420 °C are 87.2% and 1116.5 kJ kg−1, respectively; and the unit volume of the AF4 sample can provide the power grid with 918.01 kW h of electricity, save 112.91 kg of coal, and reduce 361.33 kg of CO 2 emission. This study systematically elucidated the mechanism of the enhancement of sample absorption caused by Fe3+ doping-induced changes in substrate color, reduction in material forbidden bandwidth, and lattice anharmonic vibration effect, in addition to comprehensively evaluating the feasibility of the optimal AF4 sample for use in solar energy absorbing and storing integrated ceramic materials. [ABSTRACT FROM AUTHOR]

Thermal storage materials are typically made of materials with high thermal storage density, high thermal conductivity and high temperature stability. In this study, corundum-mullite composite thermal storage ceramics were prepared by solid-phase sintering using widely available and low-cost α-Al 2 O 3 , kaolin, and quartz as raw materials. The effects of silicon source and Al 2 O 3 /SiO 2 ratio on the physical properties and structural properties of corundum-mullite composite ceramics were investigated. The results showed that the A3 sample (α-Al 2 O 3 : 85.77 wt%, kaolin: 14.23 wt%) after sintering at 1650 °C had the excellent performance, with thermal conductivity of 15.01 W (m K)−1 (25 °C), thermal storage density of 965.15 kJ kg−1, and bending strength of 145.9 MPa. The multiple ions introduced by kaolin can effectively promote the liquid-phase mass transfer at high temperatures, accelerate the diffusion rate of Si4+, increase the growth rate of mullite, and accelerate the densification process of the samples, which in turn improves the physical properties of the samples. When used in a solar thermal storage system, the A3 sample per unit volume can provide 911.53 kW h of electricity to the grid, saving 112.12 kg of coal and reducing 358.78 kg of CO 2 emissions. [ABSTRACT FROM AUTHOR]

In order to obtain ceramic materials for high-temperature gas-solid separation, the cordierite-mullite-corundum porous ceramics were prepared by particle stacking and pore-forming agent method, with bauxite as aggregate and in-situ synthesized cordierite as binder. Designed four-factor four-level orthogonal experiments for the first time to improve the porosity of the samples. The phase composition and microstructure of the samples were studied by XRD, SEM and other testing methods. The results show that: X6 sample (firing temperature of 1340 °C, 50 wt% binder, aggregate coarse, medium and fine mass percentage 30:50:20, plus 20 wt% charcoal powder, 10 wt% graphite) has the best comprehensive performance, with porosity of 41.51 % and bending strength of 17.88 MPa. Pore size distribution range from 10 to 40 μm. Corundum and mullite, with excellent high-temperature properties formed by the aggregate, are tightly bonded together by cordierite, contributing to the strength of the porous ceramics. The addition of pore-forming agent improves the porosity and forms a stable and uniform pore structure in the porous ceramics. The high porosity and large connected pore size reduce the viscous resistance of the porous ceramics to the gas, improve the filtration performance of the material, and make it expected to be applied in the field of hot gas clean-up. [ABSTRACT FROM AUTHOR]

Solar high-temperature thermal power generation systems require thermal storage materials with excellent thermal shock resistance due to the large temperature difference during operation (in the range of 20–800 °C). In this study, mullite-based absorption and storage integrated ceramics were prepared using low-cost bauxite and kaolin as raw materials and Fe 2 O 3 as additive. The effect of Fe 2 O 3 on the thermal shock resistance of mullite-based ceramics was investigated. The results showed that the absorption and bending strength of sample BK4 (bauxite: 50 wt%, kaolin: 50 wt%, Fe 2 O 3 : additional 11 wt%) increased by 2.98% (89.8%) and 8.00% (147.10 MPa), with a storage thermal density of 1185.75 kJ kg−1 after 30 thermal shock cycles. The mechanism for the excellent thermal shock resistance of the ceramics is revealed from the aspect of the changes in phase and microstructure of the samples induced by the changes in the mass transfer rate during the thermal shock process. It was calculated that a unit volume of BK4 (with a raw material cost of about 154.22 USD) could generate 974.95 kW h of electricity (saving 119.92 kg of coal) when used in a solar thermal storage system. [ABSTRACT FROM AUTHOR]

The influence of binder content, firing temperature, SiC particle size, activated carbon content and activated carbon particle size on gas permeability parameters of porous SiC ceramics were investigated according to their pore structure performances and microstructure. The influencing degree of these preparing conditions on gas permeability parameters were also compared. The results showed that Darcian permeability parameter k 1 and non-Darcian permeability parameter k 2 increase with increasing of SiC particle size, activated carbon content and activated carbon particle size, but with decreasing of binder content and firing temperature. Binder content and activated carbon particle size have more significant effects on k 1 than other three preparing conditions which their influencing degree in descending order are activated carbon content, SiC particle size and firing temperature. The influencing degree of preparing conditions on k 2 and k 1 / k 2 are ambiguous, but it is clear that SiC particle size have largest influence on k 2 and k 1 / k 2. [ABSTRACT FROM AUTHOR]