The water content of ceramic paste is an important parameter in ceramic production, which affects the shrinkage and flexural strength of ceramics. A tubular porous ceramic membrane support was prepared by an extrusion method with coal fly ash from power plant as a main raw material, dextrin as a pore forming agent and carboxymethyl cellulose as a binder. Different supports prepared at different water contents in ceramic paste and sintering holding time were characterized. Effects of water content in ceramic paste and sintering holding time on the microstructure, shrinkage, porosity, pore diameter and mechanical strength of the supports were investigated. The support with a paste water content of 0.19 prepared by sintering at 1 150 ℃ for 2 h shows an open porosity of 40.5%, a flexural strength of 23.6 MPa and an average pore diameter of 0.41 μm. The support used in microfiltration of desulfurization wastewater can give a rejection rate of suspended solids of 99.98%. The results provide a research basis for the preparation of low-cost fly ash ceramic membrane support, which is beneficial to a promising application of membrane water treatment.

Magnesium phosphate cement (MPC) is a kind of cementitious material, which involves both acid-base and hydration reactions between MgO and phosphoric acid or water-soluble acid phosphates. It has some application prospects in various fields due to its properties of both cement and ceramic. This paper analyzed the major advances in MPC for last two decades, including the preparation technologies, hydration and hardening mechanism, and material performance of MPC. The application of MPC for structure repair and strengthening, protective coatings, hazardous and radioactive waste immobilization, and dental and prosthetic cements was represented. In addition, some problems and applications of MPC were also discussed.

Alkali-activated concrete (AAC) prepared without cement with the performance of rapid hardening, high strength and good durability, is recognized as one of novel green building materials with a wide application potential. Chloride ingress into concrete to cause the process of steel corrosion is one of the main reasons to the durability failure of reinforced concrete structures, particularly exposed to marine cyclic drying-wetting zones. It is thus of great significance for the development of durability theory to conduct the chloride ingress resistance analysis of AAC under drying-wetting cycles. Compared with concrete C50, the effects of cyclic drying-wetting time ratio (i.e. 3.0∶1.0, 11.0∶1.0 and 85.4∶1.0) and exposure time (i.e. 30, 90 and 180 d) on the chloride ingress properties of AAC were investigated via a designed automatic experimental set-up of cyclic drying-wetting test. A theoretical model of chloride ingress into AAC under drying- wetting cycles was proposed for numerical calculation. The results show that the chloride content within AAC is obviously less than that in concrete C50. This is because AAC has a smaller porosity and a denser pore microstructure rather than concrete C50, thus exhibiting a better resistance to chloride ingress. The surface chloride concentration and apparent chloride diffusion coefficient of AAC first increase and then decrease as the cyclic drying-wetting time ratio increases. It is indicated that the numerical data of chloride profiles calculated by the proposed model of chloride transport into unsaturated concrete under various conditions of the drying-wetting cycles are in reasonable agreement with the experimental results.

To investigate the influence of hardened cement paste on the calcination and properties of Portland clinker, the calcination characteristics of hardened cement paste at 1 000 - 1 450 ℃ were investigated. The effects of hardened cement paste content (i.e., 0%, 10%, 20%, and 30%) and calcination temperature (i.e., 1 350, 1 400 ℃ and 1 450 ℃) on the sintering and properties of Portland cement clinker at the same target values were also studied. The results show that C₃S phase is formed again after the calcination of hardened cement paste at 1 300 ℃. For a partial replacement of raw cement material with harden cement paste, the temperature of a liquid phase appears and the apparent activation energy decreases. Its optimal dosage is 20%. The raw cement material with a higher content of harden cement paste can stabilize the crystal formation of C₂S, resulting in a difficulty of C₃S formation. Also, the crystal formation of C₃S changes from R form to M form. The incorporation of an appropriate amount of hardened cement paste (i.e., 20%) improves the mechanical properties of clinker in later stage, which may be related to the difference in C₃S crystal form, C₂S activity and the development quality of cement clinker.

Nano-sized C-S-H crystal seed nucleating agent can effectively promote the hydration process of cement and improve the early strength of cementitious composites via providing some nucleation sites for cement hydration products. The calcium-silica molar ratio can affect the early strength effect of nano-sized C-S-H crystalline seeds on cement, but the specific influence law is still controversial. In this paper, the effect of calcium-silica molar ratio on the size and morphology of nano-sized C-S-H crystalline species and their early strength effects on cement was investigated by X-ray fluorescence spectroscopy, multiple light scattering analysis, dynamic light scattering analysis, X-ray diffraction, transmission electron microscopy, cement hydration exotherm and strength tests, and the mechanism of calcium-silica molar ratio affecting the early strength of nano-sized C-S-H crystalline species on cement was elucidated. The results show that the nucleation efficiency of C-S-H nano-crystals can be improved as calcium and silicon molarity is increased.The size of C-S-H nano-crystals gradually becomes smaller and the dispersion stability of suspension improves when calcium-silica molar ratio increases from 1.0 to 1.7. Also, the morphology of C-S-H nano-crystals changes from spherical to tin foil, and the stacking between the crystals decreases and the layer thickness becomes thinner when calcium-silica molar ratio increases. The C-S-H nano-crystals can promote the development of cement hydration exothermic rate and early strength, especially within the age of 1 d. The higher the calcium-silica molar ratio is, the greater the acceleration of cement hydration exothermic rate by C-S-H nano-crystals and the higher the early compressive strength enhancement will be.

Carbon sponge can be used as a carrier for phase-change materials due to its advantages of low density, large pore volume, and high thermal conductivity. A carbon sponge with certain graphitization characteristics and a porosity of 96.30% was synthesized as a carrier with absorbent cotton and MgO as raw materials, and a composite phase-change material encapsulated by a porous carbon sponge was prepared with Na₂SO₄·10H₂O/Na₂HPO₄·12H₂O as a phase-change medium. The results show that the adsorption amount of carbon sponges prepared at 700, 800 ℃ and 900 ℃ to the phase-change materials is 60, 75 and 102 times greater than their weights, respectively. Also, the solid-liquid phase-change cycle performance of the carbon sponge-encapsulated materials prepared at different temperatures was discussed at 5-60 ℃. After 5 000 cycles, the latent heat of the phase-change material is still > 200 J·g^-1, which is reduced by 13%, and the thermal conductivity increasing rate is > 50%. The composite phase-change material encapsulated by porous carbon sponge has promising application prospects in the field of solar energy storage.

To solve the problem of the shortened cycle life of phase-change latent heat storage due to the large subcooling degree and serious phase stratification of mirabilite phase-change materials, a graphene oxide/mirabilite composite phase-change material (GO-MCPCM) was prepared with Na₂SO₄·10H₂O-Na₂CO₃·10H₂O-NaCl phase-change composite as a matrix and graphene oxide (GO) as additives. The microstructure and properties of GO and GO-MCPCMs were characterized by scanning electron microscopy, transmission electron microscopy Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetry-Differential scanning calorimetry, respectively. The results show that the O/C ratio in oxidized graphene oxide is increased by 65.75%, the structural defect level is increased from 0.224 to 1.088, indicating that the oxidation-treated graphene has no agglomeration phenomenon and has good hydrophilicity and compatibility. The crystalline phase transition temperature of GO-MCPCMs is 23 ℃, the degree of subcooling reduces to 0 ℃, only sodium sulfate decahydrate releases heat, and the crystalline hydrate is Na₂SO₄·10H₂O with a grain length of approximately 2 cm. The maximum latent heat of GO-MCPCMs crystallization at a mass fraction of 0.075% is 156.7 J/g, and the attenuation rate of the latent heat of GO-MCPCMs crystallization at a mass fraction of 0.075% is 4.3% after 500 solid-liquid cycles. Therefore, the addition of GO can improve the thermal stability of the mirabilite composite phase-change material, and graphene oxide/mirabilite composite phase-change material prepared has a good thermal cycle stability and a long service life.

Fatty acids as phase change materials (PCMs) are extensively used to alleviate the energy crisis of buildings. The PCM of lauric acid-myristic acid-stearic acid (LA-MA-SA) was synthesized. LA-MA-SA/EG/DE stabilized composite PCMs were synthesized via melting impregnation with an expanded graphite (EG) and a diatomaceous earth (DE). The microstructures and thermal physical properties of the stabilized composite PCMs were determined. The results show that LA-MA-SA is physically adsorbed with EG and DE and has a good adsorption effect. The steady-state tests of thermal conductivity indicate that EG can effectively improve the thermal conductivity of PCM, and the addition of 2%-10% EG can enhance the thermal conductivity by 29.7%-708.2%. The addition of DE can play an active role in shaping for compound and prevents the leakage of PCM. After 100 DSC cycles of the stabilized composite PCM, there is little difference from the phase change temperature and latent heat of the PCMs. According to the results of the heating and cooling tests, the gypsum board of LA-MA-SA/10% EG/10/% DE shows a good heat storage and release performance and a relative thermal comfort time for 0.82 h.

The development of high-performance anode-supported solid oxide fuel cells (SOFCs) contributes to reducing the working temperature of SOFCs, and the preparation process and structural parameters of cells have a significant impact on the performance. Tape casting is a cheap and mass-produced cell fabrication method. In this paper, anode-supported SOFCs were prepared by a tape casting technique. The effects of pore-former type in anode support, the thickness and porosity of the anode functional layer and the thickness of the electrolyte on the SOFC performances were investigated. An anode functional layer with the thickness of about 12 μm was prepared when PMMA was used as a pore-former of the anode support, thus obtaining a preferred anode structure. Reducing the thickness of the electrolyte can reduce the ohmic resistance, but a too thin electrolyte can lead to the insufficient strength of electrolyte, affecting the stable operation of SOFCs. An anode-supported SOFC with the optimized anode and an electrolyte thickness of 8 μm has a peak power density of 1.2 W·cm^-2 at 800 ℃.

To develop novel environmental-friendly photo-Fenton catalysts, hercynite (FeAl₂O₄) was prepared via reaction sintering. The catalytic performance in photo-Fenton and the degradation of hercynite for rhodamine B dye was investigated. The results show that the phase composition in the samples is a high-purity hercynite with Fe²⁺ and Fe³⁺ complex valence states. The optimal degradation efficiency and TOC removal efficiency are 90.71% and 76.46%, respectively at pH value of 3.14, FeAl₂O₄ of 1.0 g/L and H₂O₂ of 2% (in volume fraction). After four cycles, hercynite still maintains a good stability. The synthesized hercynite as an optical photo-Fenton catalyst can be recycled and reused for times, The synthesized hercynite which has a potential application prospect in dye wastewater treatment.