The multi-component ceramics of BaO-SrO-CaO-MgO-Al2O3-2SiO2(BSCMAS) with different molar ratio of Ba,Sr,Ca,Mg were prepared by a conventional solid-state reaction. The fabrication procedure, CMAS corrosion resistance, and microstructures of BSCMAS were investigated. The results show that the multi-component ceramics of Ba0.3Sr0.3Ca0.35Mg0.05Al2Si2O8 (B0.3S0.3C0.35M0.05AS) can form a single-phase solid solution by adjusting the concentration of MgO. The CMAS corrosion of B0.3S0.3C0.35M0.05AS were carried out at 1 250, 1 300 ℃ and 1 350 ℃. The B0.3S0.3C0.35M0.05AS showed better CMAS corrosion resistance than Ba0.5Sr0.5Al2Si2O8. The sluggish diffusion of multi-component cations in B0.3S0.3C0.35M0.05AS leads to suppressing the interdiffusion of Ba—Sr with Ca—Mg, combined with the quick formation of anorthite to block the out-diffusion of Ba and Sr, resulting in the improved CMAS corrosion resistance of B0.3S0.3C0.35M0.05AS material.

To explore the application prospects of high-entropy carbide ceramics as wear-resistant parts, a high-entropy (TiVTaMoW)C ceramic with a uniform distribution of elements was prepared via ball milling and subsequent two-step sintering with metal carbides as raw materials. The friction and wear properties of (TiVTaMoW)C ceramic at room temperature and 800 ℃ sliding against Al2O3, SiC, and Si3N4 balls were investigated, respectively. The results show that (TiVTaMoW)C ceramic exhibits superior tribological properties with low friction coefficients and wear rates at room temperature. Especially for sliding against SiC ball, the friction coefficient and wear rate are (0.38±0.01) and (1.52±0.36)×10-7 mm3/(N·m). The surface of (TiVTaMoW)C ceramic is severely oxidized during sliding and accompanied by aggravated wear when the temperature is 800 ℃. The wear rates of high-entropy carbide ceramic sliding against all of the friction pair balls can increase to 10-4 mm3/Nm. The oxidation products of MoO3 and V2O5 with low shear stress characteristics form self-lubricating and transferring films between the friction pairs, which made the friction coefficients maintain the same level as that at room temperature. In addition, SiC friction pair presents better tribological compatibility with (TiVTaMoW)C ceramic with a low friction coefficient and wear rate at room temperature and 800 ℃.

High-entropy oxides with complex compositions can be designed as novel ferroelectric materials with interesting physical consequences. A single-phase (K0.5Bi0.5)0.2Ba0.2Sr0.2Ca0.2Mg0.2TiO3 high-entropy ceramic with a perovskite structure was synthesized by a conventional high-temperature solid-state method, and the dielectric and ferroelectric properties of the ceramic were investigated. The results show that there are no relaxation peaks in the test temperature range because of the multi-element doping. The dielectric constant of ceramic has a high-temperature stability at < 300 ℃. The maximum dielectric constant of 8 887 is obtained at 100 Hz and 650 ℃. The introduction of high-entropy oxide in the ceramic can have high-entropy ferroelectrics in complex materials, and modify the properties of electronic ceramic.

The function of thermal barrier coating is to protect the hot components of advanced aero-engines from hot corrosion and ensures the hot components service in high-temperature environment safely. In general, a low thermal conductivity and a high fracture toughness are the key performance indexes for the selection of novel thermal barrier coating materials. In this work, a high-entropy rare-earth tantalate ceramic of (Y0.2Dy0.2Sm0.2Yb0.2Er0.2)TaO4 (i.e. (5RE0.2)TaO4) with the superior properties was synthesized via solid-state reaction. The results indicate that (5RE0.2)TaO4 exhibits a low thermal conductivity (i.e., 1.68 W·m-1·K-1 @ 900 ℃) and a high thermal expansion coefficient (i.e., 10.0×10-6 K-1 @ 1 200 ℃). (5RE0.2)TaO4 shows a high fracture toughness (i.e., 2.6 MPa·m1/2) and a low brittleness index (i.e., 2.1 μm-1/2) because of the unique ferroelastic toughening effect. In addition, (5RE0.2)TaO4 also has a promising application prospect as one of thermal barrier coating materials.

Based on the in-depth study of high-entropy alloys, a concept of configuration entropy stable single phase is introduced into inorganic non-metallic materials, thus developing high-entropy ceramics. The advantage of high-entropy ceramics is the diversity of composition and structure, which makes them have an application potential as functional materials. In this paper, high-entropy multiphase ceramics with a spinel structure and a perovskite structure were synthesized by a simple solid-state sintering method. The phase composition, microstructure, element content and valence state, and electromagnetic wave absorption properties were investigated. The microwave absorption properties of high-entropy multiphase ceramics sintered at different temperatures were analyzed. The results show that the high-entropy multiphase ceramics can be prepared, and two crystal structures (i.e., spinel structure and perovskite structure) can be formed due to the high-entropy effect. At 1 300 ℃, there exists a maximum dielectric constant. The high-entropy multiphase ceramics prepared have the optimum electromagnetic wave absorption performance when the frequency range is 8.2-12.4 GHz.

Silicon nitride (Si3N4) ceramics have a wide potential application in industrial processes, but high fracture toughness and hardness are always difficult to be handled, thus affecting the application of Si3N4 ceramics. In this paper, silicon nitride ceramics were fabricated via spark plasma sintering at 1 600 ℃ with high-entropy boride phase (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2 as sintering aids. The effect of (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2 on the phase assemblage, densification, microstructure and mechanical properties was investigated. Compared with (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2-free Si3N4 ceramic, the addition of only 1.0% (in volume fraction) (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2 in the ceramic can increase the mass fraction of β-Si3N4 from 38% to 53% at 1 600 ℃, showing a bimodal microstructure. As a consequence, the fracture toughness of Si3N4-based ceramic increases from (5.4±0.3) MPa·m1/2 to (6.9±0.2) MPa·m1/2, and the hardness maintains (20.2±0.2) GPa. The relative density of Si3N4-based ceramics decreases and the phase transformation enhances with increasing the high-entropy boride fraction to 2.5% and 5.0%, thus leading to a decrease in the hardness.

Transition metal carbide ceramics are typical representatives of ultra-high temperature ceramics with extremely high melting point and hardness. However, the toughness and wear resistance need to be improved. Based on the high-entropy theory, a multi-carbides solid solution, i.e., high-entropy carbides, has a higher melting point, a good toughness and superior friction/wear characteristics. In this paper, (Ti1/6V1/6Nb1/6Ta1/6Mo1/3)C high-entropy ceramics were prepared via spark plasma sintering (SPS) at 1?600-2 100 ℃, and the densification behavior, phase composition, microstructure, mechanical properties and wear resistance were investigated. The results show that (Ti1/6V1/6Nb1/6Ta1/6Mo1/3)C high-entropy ceramics with a single-phase face-centered cubic structure can be obtained by sintering at 1 700 ℃. The relative density of the high-entropy ceramics is greater than 98% at ≥1 900 ℃. The grain size increases and the elemental distribution becomes uniform as the sintering temperature increases from 1 700 ℃ to 2?100 ℃. The grain boundary sliding and oxide impurities (TiO2) aggregation occur at grain boundaries. The dislocations appear in grains. The optimal mechanical properties of the high-entropy ceramics prepared by sintering at 2 100 ℃ can be obtained, i.e., the Vickers hardness of 20 GPa, elastic modulus of 431 GPa and fracture toughness of 4.46 MPa?m1/2, respectively, and the average specific wear rate is 5×10-7 mm3/(N·m), showing a superior wear resistance.

As a kind of high-entropy ceramics, high-entropy boride ceramics have attracted more and more attention because of their excellent high temperature comprehensive mechanical properties and stability. However, there is no review on the research of high entropy boride ceramics. Therefore, the definition of high-entropy ceramics and the preparation methods of high-entropy borides were introduced. The application of first-principles calculations in the study of high entropy borides, the prediction of synthesis of high-entropy borides and the prediction and understanding of properties are summarized. The advantages and disadvantages of various preparation methods of high-entropy boride ceramic powders and bulks were comprehensively evaluated. Taking mechanical properties as the focus, various physical and chemical properties of high-entropy boride ceramics and their influencing factors and mechanisms were analyzed. At the same time, the shortcomings of high-entropy borides in theoretical calculation, preparation and exploration of material properties are summarized, and the possible future research directions were analyzed and prospected.

Low-temperature hot pressed Si3N4 ceramics show a greater Vickers hardness and a lower fracture toughness, while high-temperature hot pressed Si3N4 ceramics show a lower Vickers hardness and a higher fracture toughness. To prepare Si3N4 ceramics with a great Vickers hardness and a high fracture toughness, a low-temperature hot pressed Si3N4 ceramic was prepared via sintering at 1 500 ℃ with 20% SiC whisker (SiCw, in volume fraction) and 2.5% ZrB2. The phase composition, relative density, microstructure and mechanical properties of low-temperature hot pressed Si3N4 ceramic were investigated, compared with high-temperature hot pressed Si3N4 ceramics at 1 800 ℃. The results show that the addition of SiCw inhibits the densification of Si3N4 ceramics sintered at 1 500 ℃, and the relative density decreases from 97.9% to 92.9%, the Vickers hardness decreases from 20.5 GPa to 16.4 GPa, and the fracture toughness increases from 2.9 MPa·m1/2 to 3.4 MPa·m1/2. However, the addition of SiCw and ZrB2 promotes the phase transition from α-Si3N4 to β-Si3N4. The relative density of Si3N4-SiCw-ZrB2 reaches 97.5%, and the Vickers hardness and fracture toughness are 20.7 GPa and 5.1 MPa·m1/2, respectively. Compared with low-temperature hot pressed Si3N4 ceramic, the fracture toughness of Si3N4-SiCw-ZrB2 ceramic is improved without reducing the Vickers hardness. Compared with high-temperature hot pressed Si3N4 ceramic, the hardness is greatly improved. The Si3N4-based ceramic with high hardness and toughness prepared via a low-temperature hot pressing with SiCw and ZrB2 can have a promising application in ceramic structural parts.

(1-x)BiFeO3-xBaTiO3(BF-xBT, x=0.28,0.29,0.30,0.31) piezoelectric ceramics were prepared by a conventional sintering technology. The relationship between the phase structure and dielectric, ferroelectric and piezoelectric properties of the ceramics near the phase boundary was investigated. Based on the results by X-ray diffraction, all the samples present a pure perovskite phase structure without any impurity phase, and all the ceramics are located around the rhombohedral-pseudocubic phase boundary. The phase structure gradually transforms from rhombohedral to pseudocubic phase as x increases, and the content of R and pC phase tends to be equal when x=0.30, showing the optimum electrical properties (i.e., piezoelectric coefficient (d33) =165 pC/N, remanent polarization (Pr) = 26.80 μC/cm2, and the Curie temperature (TC) = 465 ℃). In addition, the changes of Raman vibration mode and diffuseness factor of the samples after quenching indicate that the quenching process can effectively improve the long range order degree and the temperature stability of ferroelectric phase of the samples, resulting in a further increase in the Curie temperature of BF-xBT ceramics. For a ceramic BF-0.30BT, the enhanced dielectric and ferroelectric properties are obtained due to its more proper R/pC phase ratio and quenching process. Also, the relationship between the phase structure evolution and piezoelectric properties of BF-xBT ceramics was revealed, and the electrical properties of BF-xBT ceramics were further optimized by quenching process, so as to provide a reference for broadening the application temperature range of the BF-BT system materials.

A series of Ca2+-doped cordierite ((Mg1-xCax)2Al4Si5O18) ceramic powders were prepared by a sol-gel method. The effect of the substitution of Ca2+ for Mg2+ of cordierite ceramics on the sintering properties, structural characteristics, microwave dielectric properties and fracture toughness was investigated. The results show that the introduction of Ca2+ can improve the sintering activity of the powder, thus improving the density of the sample and the sintering densification. The single α-cordierite phase is obtained in the range of 0<x≤0.1 because Ca2+ is doped into the cordierite structure to form the solid solution. When the x value is larger than 0.1, an anorthite phase appears. The dielectric constant of cordierite ceramic decreases, and the quality factor, the temperature coefficient of frequency and fracture toughness improve when Mg2+ substitutes for Ca2+. The optimum performance of (Mg1-xCax)2Al4Si5O18 ceramic is obtained when the x value is 0.1, i.e., the dielectric constant of 4.61, the quality factor of 9949GHz and the temperature coefficient of frequency of -26×10-6/℃, and the fracture toughness of 4.76MPa·m1/2.

Although engineering ceramics are widely used in industry, its high brittleness is one of the main factors restricting its popularization. This paper was to synergistically improve the strength and toughness of engineering structural ceramics. A wood tree ring-like Si3N4/Ni composite was prepared with micron-sized powder of Si3N4 and high purity nickel wire via hot pressing sintering. The interface bonding between Si3N4 matrix and Ni wire in Si3N4/Ni composite was investigated, and the physical and mechanical properties of the composite were characterized. The results show that the interface between Si3N4 matrix and Ni wire in the composite is well bonded, and the wood tree ring-like material structure contributes to the strengthening and toughening of ceramic materials. The bending strength and fracture toughness of the composite are (989±87) MPa and (8.12±0.8) MPa·m1/2, respectively. Compared with single-phase Si3N4, the physical and mechanical properties of Si3N4 ceramics are improved.

The rich transition metal elements in stainless steelmaking dust, such as Fe, Cr, Ni, and Mn, can be used to prepare black ceramic pigments. The stainless steelmaking dust can be ultilized to prepare cobalt-free black ceramic pigments. According to the color mechanism of Fe-Cr-Ni-Mn black pigment, an appropriate amount of chemical reagents Fe2O3, Cr2O3, MnO and NiO was added into stainless steel making dust in a mixed mass ratio of 6:1:1:1. The chromaticity value vibration rules of black ceramic pigments prepared under different conditions were investigated, and the coloring mechanism of the pigments was discussed as well. The results show that a high firing temperature or a long holding time causes the decomposition of Cr-containing spinel phase, adversely affecting the coloring properties of the pigment. The optimum firing process of the pigment is the firing temperature of 1 175 ℃, the holding time of 30 min, and the furnace cooling method. The L*, a* and b* values of the prepared pigment are 37.20, 0.13 and 0.02, respectively, and the main phases in the pigment are Fe2O3 and mixed spinels. The absorbance of the pigment to each visible light wavelength band is basically the same, and the bandgap of the pigment is 0.88 eV. The color of the pigment is black. The average grain size of spinels is only 26.795 nm, and the pigment has a superior thermal stability at 20-1 100 ℃. The ceramic has a good color performance when the pigment is used to prepare the ceramic. It is indicated that the prepared black ceramic pigment with the superior coloring property has a promising application potential.

The base application of porous ceramic membrane is ceramic support. For conventional ceramic supports (such as alumina), the expensive raw materials and high sintering cost both restrict their applications. Therefore, the low-cost preparation of ceramic support with natural minerals has attracted more attention. In this paper, a series of porous ceramic supports were fabricated with kaolin clay, talc and calcium carbonate as raw materials. The sintering characteristic of the green body was analyzed by thermal expansion instrument. The phase composition, micro-structure, pore size distribution and bending strength were characterized by X-ray diffractometer, scanning electron microscope, mercury porosimeter and universal testing machine. The acid and alkali corrosion resistances of the supports were also investigated. The results indicate that the obtained green body exhibits a superior low-temperature sintering characteristic. The porous supports were prepared via chemical reaction sintering. The suitable sintering temperatures of the supports are in the range of 1 000-1 200 ℃. The obtained supports have a homogeneous micro-structure and a unimodal pore size distribution. The porous supports prepared at 1 000-1 200 ℃ have the open porosities of 49.8%-49.4%, the average pore sizes of 1.09-1.83 μm, the bending strengths of 40.57-28.85 MPa, the nitrogen gas flux of 119-340 m3·m-2·h-1 under a trans-membrane pressure of 0.1 MPa and a superior alkali resistance as well.

Silicon carbide ceramic membranes can be used in various water and wastewater treatments due to their high hydrophility, and superior chemical and thermal resistances. However, their applications are restricted due to some corresponding problems like high sintering temperature and then the high production cost. In this work, a low-temperature aid (LTA) bonded SiC ceramic symmetric membrane was sintered at 1 000 ℃. The results show that LTA bonded SiC particles to form a skeleton of the symmetric membrane. The porosity of the membrane decreases from 42% to 35% and the average pore size decreases from 3.5 μm to 2.1 μm with the increase of LTA content from 10%(mass fraction) to 30%. Based on the results of the separation test on oil-in-water emulsion, the oil rejection and flow flux are 93.3% and 123 L/(m2·h) at the trans-membrane pressure of 0.2 bar, respectively. This study provides a low sintering temperature and energy saving strategy for the preparation of SiC ceramic membrane.

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.

Silico-manganese slag is a main solid waste produced from production of silicon-manganese alloy, which affects the environment. It is thus necessary to explore the corresponding disposal methods since the exsiting processing technology restricts the absorbing capacity. A microcrystalline cast stone was fabricated by the Petrurgic firing method with silico-manganese slag as a raw material. The bulk density, microhardness, flexural and compressive strength of the samples were determined. The influences of crystallization temperature and time on the phase structure and properties of the finished product were invesigated. The results show that a hot molten slag is cooled to 950 ℃ for 60 min and then annealed at 760 ℃, obtaing a microcrystalline cast stone with the superior properties. The microcrystalline cast stone has a compact structure, and the precipitated crystal phases are mainly clinopyroxene, diopside and aluminum diopside, as well as anorthite and wollastonite. The bulk density of the cast stone can reach 3.11×103 kg·m-3, the microhardness is 8.77×103 MPa, and the flexural strength and the compressive strength are 86 MPa and 222.9?MPa, respectively.

To solve the problems of thermal shock resistance and radiation efficiency attenuation due to the high-temperature oxidation of silicon carbide porous ceramics used in high-temperature combustion of porous media, a silicon carbide billet was prepared by an organic foam impregnation method. Also，porous silicon carbide ceramics containing cordierite infrared radiation coating were fabricated on the surface of silicon carbide skeleton via in-situ reaction sintering. The results show that the vacuum impregnation slurry can coat the skeleton surface and completely fill up the triangular holes of the silicon carbide skeleton. The three-layered porous silicon carbide ceramics with a cordierite coating, the central layer of the silicon carbide skeleton and the cordierite filling layer were prepared by sintering at 1 350 ℃. The mechanical properties, thermal shock resistance and high-temperature wet oxidation resistance of porous silicon carbide ceramics are improved due to the formation of the three-layered structure. The compressive strength of porous silicon carbide ceramics is 1.18 MPa after heat-treatment at 1 350 ℃, and the residual strength retention rate is 67%. According to the results of porous media combustion experiments, the three-layered structure of silicon carbide porous ceramic with a surface reinforcement by cordierite infrared radiation coating can reinforce silicon carbide porous media burner radiation heat transfer process and increase the combustion efficiency, thus increasing the burner surface temperature by 140 ℃ and reducing the emissions of CO and NOx pollutants in the burner.

Sewage sludge and household garbage are used as an alternative fuel in recent production of cement. However, the alternative fuel causes serious alkali attack and spalling of bauxite-SiC refractories for cement kiln lining, thus having an impact on the operation of the cement kiln. In this paper, the alkali vapor exposure was used to evaluate alkali attack on some raw materials like bauxite, mullite (M60) and molochite, which were used to prepare mullite-SiC composite refractory as a lining of cement kiln. The results show that the alkali attack resistance of these raw materials is closely related to their chemical composition, phase composition and microstructures. Bauxite with corundum and mullite as main phases is attacked by alkali to form a kaliophilite phase and induce cracks and loose structure, further enhancing gaseous alkali penetration and serious damage. Mullite (M60) with mullite as a main phase is attacked by alkali to form leucite and transient liquid phase. The resultant liquid phase prevents from the penetration of alkali, and the attack only occurs on the surface layer, so mullite (M60) exhibits a superior alkali attack resistance. Molochite with mullite and glass (the content of 46%) reacts with alkali vapor to form more liquid phase and leucite. As alkali vapor is dissolved in the glass phase of molochilte, the integrity of molochite is destroyed by alkali attack.

Aluminum nitrides are considered as high-performance thermal conductive substrate and packaging materials due to the remarkable properties, including high thermal conductivity, high electrical resistivity, low thermal expansion coefficient, low dielectric loss and excellent mechanical properties. This review represented the preparation techniques, properties and applications of AlN powders and ceramics. The challenges and implications for aerospace application were discussed. In addition, their potential applications for spacecraft electronics were also prospected.

Optoelectronic functional films and devices are widely used for applications in flat display, solid-state lighting, information transmission and storage, new energy and photochemistry. The research highlights in this field rely on developing protocols for further improving their performance. Additive manufacture, that is 3D printing as a simple, high-precision, no mold-required, material-saving, personalized and batch-oriented intelligent fabrication technology, has attracted recent attention. This review reported the major additive manufacture techniques for developing optoelectronic functional films and devices and their research progress via highlighting inkjet printing, electrohydrodynamic printing and direct writing capable of printing optoelectronic functional films with three-dimensional structures and deliberating the challenges in realizing complex shape and in-situ multiscale modulation in microstructure. Aerosol jet printing was emphasized with great potential for simultaneously controlling the nano-and micro-structures during printing optoelectronic functional films via exploiting the microreactor capabilities of aerosols. Carbon-based materials and MXene were taken as examples for demonstrating the functionality and applicability of additive manufacture techniques in printing optoelectronic functional films and devices. Recent studies on the additive manufacturing of advanced optoelectronic functional materials and devices were summarized, i.e., developing new material and ink formulation, printing process control and new additive manufacturing processes. In addition, the future development was also prospected for next-generation additive manufacture protocols endowing the functionality of in-situ multiscale modulation of microstructures during the printing process, thus favoring the development of high-performance optoelectronic functional materials and devices in the future.

Cement hydration is a key process to determine most properties of cementitious materials. Clarifying the mechanisms of cement hydration intersects both academic and practical interests. Recent research work on Portland cement hydration kinetic models was reviewed. The hydration simulation models, such as GEMS thermodynamic calculation, HymoStruc3D and CEMHY3D and other hydration simulation models and their limitations were discussed. The application of quasi-elastic neutron scattering and nuclear magnetic resonance methods in the evolution of water states and the development of pore structure during cement hydration process were summarized. In addition, this review also gave the future developemt and challenges in this field.

Refractory castables are green materials for the development of refractory industry due to their advantages of low energy consumption, simple process and convenient mechanized construction. However, water-containing castables are prone to structural damage and even explosive spalling during the heating process of drying, so as to shorten the service life of components and cause economic and resource losses under the combined action of thermal stress caused by temperature gradient and internal pressure caused by water vapor. From the perspective of the anti-spalling of castables, this review represented the basic mechanism of explosive spalling, the microstructure and spalling resistance of typical bonding systems, anti-spalling means, test methods and numerical simulation, and gave the future related research aspects.