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Porous fiber-based ceramics have been widely applied in various fields because of their excellent thermal insulation property and high thermal stability property. However, designing porous fibrous ceramics with enhanced comprehensive performances, such as low density, low thermal conductivity, and high mechanical properties at both room temperature and high temperature, is still a challenge and the future development trend. Hence, based on the lightweight cuttlefish bone that possesses a “wall-septa” structure with excellent mechanical performance, we design and fabricate a novel porous fibrous ceramic with the unique fiber-based dual structure of lamellas by the directional freeze-casting method and systematically investigate the effects of lamellar components on the microstructure and mechanical performances of the product. For the desired cuttlefish-bone-structure-like lamellar porous fiber-based ceramics (CLPFCs), the porous framework formed by the overlapping of transversely arranged fibers helps to reduce the density and thermal conductivity of the product, and the longitudinally arranged lamellar structure replaces traditional binders and plays an important role in improving the mechanical properties in the direction parallel to the X–Zplane. Compared with traditional porous fibrous materials reported in the literature, the CLPFCs with an Al2O3/SiO2molar ratio of 1:2 in the lamellar component exhibits prominent comprehensive performances, such as low density, excellent thermal insulation property, and outstanding mechanical performances at both room temperature and high temperature (3.46 MPa at 1300 °C), indicating that the CLPFCs are a promising candidate for applications in high-temperature thermal insulation systems.

As a type of titanate, the pseudobrookite (MTi2O5/M2TiO5) exhibits a low thermal expansion coefficient and thermal conductivity, as well as excellent dielectric and solar spectrum absorption properties. However, the pseudobrookite is unstable and prone to decomposing below 1200 °C, which limits the practical application of the pseudobrookite. In this paper, the high-entropy pseudobrookite ceramic is synthesized for the first time. The pure high-entropy (Mg,Co,Ni,Zn)Ti2O5with the pseudobrookite structure and the biphasic high-entropy ceramic composed of the high-entropy pseudobrookite (Cr,Mn,Fe,Al,Ga)2TiO5and the high-entropy spinel (Cr,Mn,Fe,Al,Ga,Ti)3O4are successfully prepared by the in-situsolid-phase reaction method. The comparison between the theoretical crystal structure of the pseudobrookite and the aberration-corrected scanning transmission electron microscopy (AC-STEM) images of high-entropy (Mg,Co,Ni,Zn)Ti2O5shows that the metal ions (M and Ti ions) are disorderly distributed at the A site and the B site in high-entropy (Mg,Co,Ni,Zn)Ti2O5, leading to an unprecedentedly high configurational entropy of high-entropy (Mg,Co,Ni,Zn)Ti2O5. The bulk high-entropy (Mg,Co,Ni,Zn)Ti2O5ceramics exhibit a low thermal expansion coefficient of 6.35×10−6K−1in the temperature range of 25–1400 °C and thermal conductivity of 1.840 W·m−1·K−1at room temperature, as well as the excellent thermal stability at 200, 600, and 1400 °C. Owing to these outstanding properties, high-entropy (Mg,Co,Ni,Zn)Ti2O5is expected to be the promising candidate for high-temperature thermal insulation. This work has further extended the family of different crystal structures of high-entropy ceramics reported to date.

Uniform and dense carbon nanotubes (CNTs) were grown on the surface of the graphite film (GF) by a plasma-enhanced chemical vapor deposition process. The synthesized CNTs can act as a bridge between GF and Al matrix to enhance the interface performance and improve thermal properties of the GF/Al laminated composite simultaneously. A layer-by-layer CNTs–GF/Al composite with both increased mechanical property and thermal management capability was fabricated through an optimized pressure infiltration process, which was time- and energy-saving. The results show that the interface of the laminated composite is well bonded and no interface product such as Al4C3is generated. Additional investigations reveal that the growth of CNTs is an effective way to improve the thermal conductivity and reduce the coefficient of thermal expansion of the GF reinforced Al composites. Overall, the best-performing CNTs–GF/Al composites with a CNTs–GF volume fraction of 51.42% show an increase of 47.99% in thermal conductivity and 26.44% in interlaminar shear strength, making them promising thermal management laminated materials.

Carbon fiber (CF)-reinforced ceramic composites show the attractive potential for next generation thermal protection materials because of their outstanding reliability and excellent high-temperature resistance but are facing great challenges in the combination of the engineering practicality and versatility. Herein, it is demonstrated that silicon carbide nanowires can be grown on the surface of CF to create a multifunctional thermal barrier application composite. The embedding of the silicon carbide nanowires in the interface of CF and ceramic matrix significantly increased the structural health monitoring sensitivity and interface strength of the composites. Compared to the conventional CF/ZrC composites, the structural health monitoring sensitivity of the composites with SiC nanowires is greatly elevated with a 14-fold improvement. Additional investigations revealed that the multifunctional SiCnws–CF/ZrC nanocomposites enjoyed a low thermal conductivity of 0.49 W/(m·K), a light weight (0.76–1.85 g/cm3), and a relative high compressive strength of 23.64 MPa, which is favorite in applying as a thermal barrier material. Furthermore, the interface design strategy could be extended as a universal method in fabricating various fiber-reinforced composites for a wide range of other applications.

Carbon nanofibers (CNFs) were grown around the carbon fiber architecture through a plasma enhanced chemical vapor deposition method to enhance the interface performance between CF architecture substrate and ZrC preceramic matrix. The synthesized 3D CF hierarchical architectures (CNFs-CF) are coated with zirconium carbide (ZrC) ceramic to enhance their antioxidant property and high temperature resistance. The composition and the crystalline phase structure of the composite were detected with the X-ray photoelectron spectroscopy and X-ray diffraction. The results of scanning electron microscopy show that, the as-prepared CNFs and consistent ZrC ceramic coating are uniformly covered on the surface of carbon fiber architecture substrate. The ZrC ceramic products with excellent crystallinity were got from the pyrolysis of preceramic polymer at 1600 °C in inert atmosphere. Comparing with the untreated CF, the loading of ZrC ceramics around the CNFs-CF architecture surface are significantly increased. The thermal stability and mechanical property of CNFs-CF/ZrC nanocomposites have been promoted obviously compared with the CF/ZrC ceramic nanocomposite. The prepared CNFs-CF/ZrC ceramic nanocomposite is one of the potential candidate materials for the thermal protection application.

Large-scale core–sheath heterostructural SiC nanowires were facilely grown on the surface of carbon fibers using a one-step chemical vapor infiltration process. The as-synthesized SiC nanowires consist of single crystalline SiC cores with a diameter of ∼30 nm and polycrystalline SiC sheaths with an average thickness of ∼60 nm. The formation mechanisms of core–sheath heterostructural SiC nanowires (SiCnws) were discussed in detail. The SiCnws-CF shows strong electromagnetic (EM) wave absorption performance with a maximum reflection loss value of −45.98 dB at 4.4 GHz. Moreover, being coated with conductive polymer polypyrrole (PPy) by a simple chemical polymerization method, the SiCnws-CF/PPy nanocomposites exhibited superior EM absorption abilities with maximum RL value of −50.19 dB at 14.2 GHz and the effective bandwidth of 6.2 GHz. The SiCnws-CF/PPy nanocomposites in this study are very promising as absorber materials with strong electromagnetic wave absorption performance.

To satisfy the eagerness for mullite fiber-based porous ceramics (Muf-based porous ceramics) with complex geometries in high-temperature thermal insulation fields, vat photopolymerization three-dimensional (3D) printing was first employed to prepare the highly complex Muf-based porous ceramics. Herein, a photosensitive hydroxysiloxane HPMS-KH570 was employed as the resin matrix, which not only prevented the fiber agglomeration and improved the rheological properties of the slurries but also acted as a high-temperature binder to fix the fiber cross points after sintering and consequently improved the structural stability of the 3D-Muf-based porous ceramics. The effects of mullite fiber (Muf) aspect ratio and content on the performance of Mufslurries, microstructure and physical properties of the 3D-Muf-based porous ceramics were investigated. When the fiber aspect ratio was 45 and the fiber content was 6.67 vol%, the Mufslurry exhibited the most suitable properties for vat photopolymerization 3D printing, and the corresponding 3D-Muf-based porous ceramics exhibited a well-defined 3D printed lattice structure with struts consisting of randomly crisscrossing Muf. This unique 3D skeleton structure endowed the 3D-Muf-based porous ceramics with low density (0.47 g/cm3) and low room temperature thermal conductivity (0.11 W/(m·K)), enabling it a promising candidate for high-temperature (1000–1400 ℃) insulation materials. Furthermore, this printing strategy provided references for vat photopolymerization 3D printing of other fiber-based materials.

Suspended particulate matter plays a significant role in the studies of sediment fluxes, phytoplankton dynamics, and water optical properties. This study focuses on the relationships between particle size distribution (PSD), water’s inherent optical properties (IOPs), and water constituents. We investigated the complex waters of Poyang Lake, the largest freshwater lake in China, in wet and dry seasons during 2008–2011. Because of the distinct temporal–spatial variation of Poyang Lake, these parameters and relationships also demonstrate seasonal and regional variability. The variation range of the concentration of suspended particulate matter is 0.32–69.08  mg/l, with a mean value of 22.21  mg/l. The median particle size in the dry season is much larger than that of the wet season. The Junge distribution fits the PSD of Poyang Lake very well in the scope of 6.21–331 μm. Furthermore, the slopes of the PSD range from 3.54 to 4.69, with a mean value of 4.11, with the steepest slopes (>4.5) occurring in the waters around Songmen Mountain Island and the northern waterway. A negative correlation was found between median particle size (D_v50) and the mass-specific absorption coefficient at 443 nm [apm(443)] for both wet and dry seasons. Identical to analogous waters, the spectral slopes of the PSD correlate well with the spectral slopes of the attenuation coefficient, but with different fitted formulas. In the dry season, the particle size can better explain the variability of the scattering coefficient, while the mass-specific scattering coefficient is better explained by the apparent density. However, no similar results were found for the wet season. In addition, the spectral slopes of the backscattering coefficient correlated well with the PSD slope, and the bulk refractive index calculated from the backscattering ratio and PSD slope can indicate the particle composition of Poyang Lake. Overall, the knowledge on the PSD and IOPs gained in this study broadens our understanding of water optics in highly turbid water columns.

Background: With the development of high-speed and high-precision rotating machinery, the rotor usually needs to work at very high speeds and the huge unbalancing vibration of rotor may be caused by a tiny unbalancing mass. To reduce the unbalance of rotor, a suitable dynamic balancing method should be designed for different rotor systems. In this article, various patents have been discussed. Objective: The typical dynamic balancing methods and technologies are summarized and analyzed so as to provide some references for dynamic balancing design and application. Method: To make it easier to design the proper balancing measure for actual rotating mechanical system, the dynamic balancing methods for rotor are classified as workpiece dynamic balance, assembling dynamic balance, field dynamic balance and online dynamic balance according to the balancing time of rotor. Results: The principle of all kinds of dynamic balancing method is given firstly, and then advantages, disadvantages and future developments about each balancing method are reviewed in the paper. Conclusion: Corresponding to these balancing methods, the online dynamic balancing method is recommended.

Background: With the development of high-speed and high-precision rotating machinery, the patents of dynamic balance mechanism have been increasingly applied on rigid rotor system. Objective: To analyze the unbalance vibration characteristics and design the suitable dynamic balance method for rigid rotor system, the method of modeling and simulation is utilized in the paper. Method: Based on the principle of rotor dynamics, the mathematic model is built firstly between the vibration response and unbalance excitation. According to double-face dynamic balance principle, the correction of correcting face is made equivalent to the unbalance excitation of the rotor system, and then the mathematic model is developed with double-face correcting function. The matlab language is applied to design the simulation program for the dynamic balance model. Results: Based on simulation analysis, the relations are analyzed between unbalance vibration response and rotating frequency, influence coefficient and rotating frequency, influence coefficient and axial positions of correcting face in the paper. The analysis results prove that the modeling method for double-face dynamic balance of rigid rotor system is reasonable. Conclusion: The mathematic model provides a theoretic foundation for further patent technology on the rotor dynamic balance.

When liquid steel is tapped from a basic oxygen furnace (BOF), it is essential to minimize the quantity of slag carry-over, because the high level slag may result in the oxidation and the phosphorus reversion during the secondary metallurgy process. The system with the infrared thermal camera is widely used to detect the slag. However, two problems still exist. The first problem is the tracking of tapping stream. The second problem is to automatically discriminate between the slag and the steel according to their different infrared emissivities. In this paper, a system used to inspect the slag content is designed. A method that can quickly identify and track the tapping stream is proposed to only measure slag from the area identified as the stream. This reduces any errors caused by background heat sources in the field of view. A method to discriminate between the slag and steel is also proposed. Experimental results prove that the quantity of slag carry-over is decreased with using the system.

A series of nano-titanium carbide doped polyimide (nano-TiC/PI) composite films were successfully prepared via in situ polymerization. The microstructure of the obtained composite films was characterized by the scanning electron microscopy (SEM). The effects of different TiC contents on the mechanical and thermal properties of composite films were investigated. Dielectric properties of the nano-TiC/PI composite films were analyzed in detail with respect to different experimental parameters including frequency and filler concentration. Results indicated that the TiC particles dispersed homogeneously in PI matrix when its' content was below 15 vol.%. The addition of TiC particles could effectively improved the thermal stability of composite films. In comparison with pure polyimide film, the dielectric constant of the composite films with 5 vol.% TiC was significantly increased by thirteen times while the loss tangent only increased a little. Moreover, the composite films exhibited good dielectric stability over a wide range of frequency. The development of these novel polyimide composite films with favorable dielectric properties are potential for embedded capacitor applications.

Based on 481-year records of historical dust storm (DS) and Dryness-Wetness Index (DWI) at 120 sites, spatial distribution characteristics of dryness-wetness (DW) in typical dust storm years (DS years) and in non-dust storm years (non-DS years) were derived for continental China. In DS years, most of the sites were drier than in normal years while in non-DS years wetter than normal, and the variation of DWI in DS years was larger than that in non-DS years. The relative instability and increased regional difference of atmospheric circulation in DS years might have induced more frequent DS events and dry-wet abnormality in continental China. In DS years the latitudinal (north-south) dry-wet difference was larger than that in non-DS years, that is, north China was even much drier than south China. This might be attributed to increased latitudinal differences of thermal and pressure gradients in DS years, resulting in the southward withdrawal of precipitation and increase of DS events.

Continuous liquid interface production (CLIP) strategy is a promising fast shaping additive manufacturing method due to its continuous UV-polymerization process. However, the large-scale extension of CLIP technology, especially for the printing of ceramics, is far from maturity. Herein, a highly cost-effective desktop top-down CLIP strategy was employed for the shaping of polymer-derived ceramics at a fast speed (100mm/h in height). The deliberate shaping direction of the top-down CLIP strategy not only improved the printing speed, but also enabled full utilization of the natural oxygen in the air to generate the liquid interface on the top of the photocurable resin, ensuring that the printing process can be carried out continuously. These printed 3D-polysiloxane components can be further converted into dense and crack-free 3D-SiOC ceramics with a smooth surface upon a heat treatment. The strategy of top-down CLIP printing SiOC ceramics can be applied to the fast fabrications of other polymer-derived ceramics.

•A novel liquid photosensitive epoxy-acrylic siloxane was synthesized.•Non-photosensitive liquid siloxane was employed to promote gases release.•SiOC components with strut thickness of 500 μm was fabricated without defamation.•Sample with the addition of inert siloxane exhibited better compressive strength.