- Ei，ESCI收录期刊
- 中国科学引文数据库(CSCD)核心期刊
- 中文核心期刊
- 文摘与引文数据库(Scopus)
- 剑桥科学文摘(CSA)
Continuous fiber reinforced and toughened ceramic matrix composites (CMCs) are key thermal structural materials in aerospace and other fields. Mechanical connectivity, as one of the most reliable connectivity methods, is an essential method to achieve connectivity of large and complex CMCs components. At present, research on CMCs joints is rapidly developing, but there is few comprehensive review literature on CMCs joints. Based on the research work in the field of CMCs joints in recent years, the preparation and mechanical property characterization methods of CMCs fasteners were summarized in this paper, the damage and failure mechanism of CMCs fasteners were systematically stored and discussed, and focusing on the influencing factors and laws of mechanical properties of CMCs fasteners from the perspective of material properties and external environment. The research work on CMCs mechanical joints was presented, and the damage law, failure mechanism, finite element simulation and reliability of CMCs connectors were prospected.
Owing to the feature of ultrahigh power density, the dielectric capacitors play an increasingly important role in the field of industrial production, basic scientific research, aerospace, and military industry in recent years. However, the relatively low energy storage density of the dielectric capacitors generally leads to their big sizes, which is difficult to meet the miniaturization requirements of future devices. Polymer-ceramic nanocomposites can combine high permittivity of the ceramic fillers and the excellent breakdown strength of the polymer matrix, thus achieving excellent energy storage performance. At present, developing the polymer-ceramic nanocomposites with high energy storage density is the key to realize the miniaturization goal of dielectric capacitors in the future. The current research progress of polymer-ceramic nanocomposites for energy storage capacitor applications from three perspectives was systematically summarized, including regulation of the nanofillers, optimization of the interfaces, and design of the multilayer composite structure. Notably, the influences of the dimension, size, species, hierarchical structure of the nanofillers, interface optimization methods such as surface modification and core-shell structure construction, as well as multilayer structure design such as sandwich structure and gradient structure on the permittivity, breakdown strength and the energy storage density of the nanocomposites were introduced in detail. Meanwhile, the structure-activity relationships between the microstructure of nanocomposites and their energy storage properties were further analyzed and discussed. Finally, based on the challenges and shortcomings of the current research, the important development directions of this field in the future were proposed, including selecting the new 2D nanofillers, enhancing the energy storage efficiency, employing multimode combined optimization strategy, and constructing the corresponding dielectric capacitors.
SiC fiber-bonded ceramics (FBCs), as a new thermal-structural material obtained by hot-pressing sintering of SiC fiber, has low porosity, high fiber volume fraction, high temperature resistance, oxidation resistance and high strength. It is an excellent candidate material for high temperature components such as turbine blades and rotors of aero-engine. The research progresses of FBCs were systematically reviewed in this paper. The structural characteristics and preparation methods of two types of FBCs (Tyranohex and SA Tyranohex) were introduced, the relationships among the composition, structure and performance of FBCs were discussed. It was noted that the interface carbon layer plays a crucial role in the performance of FBCs. The mechanical properties of SA-Tyranohex at room temperature and high temperature were highlighted, and the reasons for its excellent high temperature performance were analysed. The examination, verification and application development were summarized. The difficulties of FBCs in forming complex components were pointed out, and the future development trends and research directions were prospected. Finally, it was proposed that conducting research on SiC fiber-bonded ceramics is of great significance for the development of new materials for high-temperature resistant components in China.
SiC fiber is one of the common reinforcements for ceramic matrix composite (CMC) due to its superior characteristics such as low density, high tensile strength, excellent high temperature resistance and oxidation resistance. The preparation of coating on the surface of SiC fiber can not only improve the mechanical properties, high temperature resistance, oxidation resistance and electromagnetic functional properties of the fiber itself, but also effectively improve the bonding properties of the interface between the fiber and the matrix to promote the fracture toughness and mechanical properties of the composite. The preparation methods of surface coatings on SiC fiber were firstly reviewed in this paper by elaborating on the basic processes and related research progress of etching, deposition, chemical vapor infiltration, and precursor derived methods, and the advantages and disadvantages of different preparation methods were compared. Then the effects of coatings on SiC fibers and their reinforced composite materials were reviewed. Finally, the development trend of surface coating on SiC fibers was briefly summarized. The combination of experimental research and computational simulation can be used to simulate the real service environment of SiC fibers coatings, and the performance of fibers under extreme service conditions can be improved by preparing thermal barrier composite coatings.
As one kind of advanced high temperature structural and functional materials, it is necessary for fiber reinforced silicon carbide matrix composites (SiC CMCs) in the field of thermal management (TM) to combine the efficient heat transfer and high temperature heat resistance. Common fibers reinforced SiC CMCs, such as carbon fibers reinforced SiC CMCs (Cf/SiC or Cf/C-SiC), silicon carbide based fiber reinforced SiC CMCs (SiCf/SiC), etc., have a low degree of graphitization of the reinforcing fiber and are difficult to form an effective heat transport network. The latest research progress on the preparation and properties of fiber reinforced SiC CMCs with highly thermal conductivity was reviewed in this paper. The heat transport ability of fiber reinforced SiC CMCs can be improved by introducing highly thermal conductive phase, optimizing interfacial structure, making silicon carbide crystal coarse-grained, and designing preform structure. Moreover, the development of the fiber reinforced SiC CMCs with highly thermal conductivities was prospected, that is, comprehensively considering the factors that affect the performance of SiC CMCs, flexibly using the structure-activity relationship between the microstructure and properties of the composites, in order to prepare fiber reinforced SiC CMCs with stable size, excellent properties.
W-Zr alloy has the advantages of high density, high strength and high reaction potential, which can not only exert the excellent penetration ability of tungsten-based alloy, but also provide additional damage by using the oxidation reaction of zirconium. W-Zr alloys have shown great application potential in reactive fragment, armor-piercing projectiles, and small caliber projectiles, and have attracted attention both domestically and internationally. The preparation methods, mechanical properties, and reaction characteristics of W-Zr alloy reactive structural materials were summarized in this paper, especially focusing on the penetration ability and energy release characteristics. On the basis, it was proposed that the future development of W-Zr alloys should focus on the regulation of combustion characteristics of W and the improvement of plasticity. Additionally, there is still a lack of systematic research on the synergistic mechanism between the microstructure, mechanical properties, dynamic fracture, and reaction energy release of W-Zr alloys, which requires further improvement through a combination of experimental research and simulation calculations.
Reversible metal electrodeposition device (RMED) is a new type of electrochromic device, which has excellent spectrum regulation ability in visible and infrared regions, and has unique advantages such as simple structure, low energy consumption, multi-color state regulation. It shows great application potential in intelligent window, thermal management, information display and other fields. In recent years, the performance of RMED has been improved through structural design and electrolyte composition optimization, but there are still some problems such as poor open circuit stability, short cycle life and limited size, which seriously hinder the development and application of RMED. From the perspectives of spectral tuning range and performance optimization, the research progress of spectrum regulation devices based on reversible metal electrodeposition was summarized in this article. The spectral tuning range mainly includes visible and infrared bands. The current development status of RMED in the visible light region using different metal deposition systems was briefly introduced, which is also the most widely studied direction at present. The electrode innovation for achieving infrared spectral tuning was the focus of the discussion. The research methods for improving device performance such as open-circuit stability and cycling stability were discussed. Finally, it was pointed out that RMED still faces some development difficulties, and in the future, in-depth and systematic research can be carried out on device performance and theoretical mechanism, among other aspects.
Superoleophobic refers to the phenomenon that the contact angle (CA) of the oil droplet with low surface tension on the solid surface is greater than 150° as well as the sliding angle (SA) is less than 10°. However, due to the low surface tension of organic liquids, the construction of superoleophobic surfaces was relatively difficult. Inspired by springtail, re-entrant structure has become a breakthrough to solve this problem.Together with surface chemical composition modification and surface roughness, it has been introduced into the design and manufacturing system of superoleophobic surface. Several classical wetting models such as Young model, Wenzel model, Cassie-Baxter model were introduced, the design methods of superoleophobic surfaces were elaborated from the structural structure and chemical composition, and the research progress of superoleophobic surface preparation technologies such as electrospinning, sol-gel method, deposition method, etching method and laser processing was discussed, the oleophobic properties of various surfaces under test liquids with different surface tension were summarized. Finally, the research direction of superoleophobic surface was prospected, that is, low cost, simple operation, environmental friendly and excellent physical and chemical properties of the obtained surfaces. The preparation technology of superoleophobic surfaces would be further explored.
Polymer ionic gel is a new type of gel system composed of ionic liquid (IL) and polymer matrix, which has excellent extensibility, high conductivity and good stability. It has broad application space in the field of flexible electronic products, and has attracted the attention of researchers at home and abroad. Based on the investigation of the research progress in related fields in recent years, the matrix classification of polymer ionic gel materials was summarized, the modification methods of conductive hydrogels were discussed, the application of ionic gel in related fields was expounded, and on this basis, the challenges faced by polymer ionic gel and its future development direction were summarized and prospected. It was pointed out that the development of ionic gel with excellent mechanical properties, high conductivity and degradability is the focus of future research. At the same time, improving the environmental stability of ionic gel and reducing the preparation cost of ionic gel are urgent problems to be solved in practical applications. The preparation and application of ionic gel will promote the rapid development of flexible electronic materials.
The ZrC-SiC multiphase ceramic precursor of PZCS with abundant active cross-linking sites was prepared by a dehydrocoupling reaction between polyzrocarbonane (PZC) and polycarbosilane (PCS). The ceramization mechanism of PZCS and the composition and structure of the final ceramic were studied. The results reveal that the ceramic yield of PZCS (71.84%, mass fraction, the same below) is significantly higher than that of PZC (51.40%) or PCS (53.46%) precursor at 850 ℃, due to the promoted crosslinking of active groups during the ceramization process. Meanwhile, under the catalysis of Zr-Cp, the short-range carbon and Zr, Si elements are directly converted to carbide ceramics through the synergistic transformation of two polymers in PZCS, avoiding the adverse effects of carbon thermal reduction to the ceramics, and effectively reducing the sintering temperature. The ZrC-SiC nanocomposite ceramic with both high temperature resistance and oxidation resistance components is prepared after pyrolysis of PZCS. The generation of ZrC and SiC phases could inhibit crystallization and refine the grain size, of which the ZrC grain size is 25.4 nm. Moreover, the generation of ZrC-SiC nanocomposite structure would be beneficial for improving the comprehensive performance of ultra-high temperature ceramics.
Continuous alumina fiber-reinforced ceramic matrix composites are one of the ideal thermal structural materials for aerospace applications. Mechanical properties of composites in different environments depend on the mechanical properties of continuous alumina fibers, but effect of different heat treatment environments on mechanical properties and microstructure of alumina fibers has rarely been reported. In this study, mechanical properties and microstructure of Nextel 610 fibers from different heat treatment atmosphere, heat treatment temperature and heat treatment time were characterized in detail. It is found that when heat treatment temperature is increased from 1000 ℃ to 1400 ℃, tensile strength of N610 fibers is decreased from 2.58 GPa to 0.94 GPa and surface grain size increased from 97.3 nm to 184.1 nm in air; tensile strength of N610 fibers is decreased from 2.18 GPa to 0.95 GPa and surface grain size is increased from 91.3 nm to 171.7 nm in steam. Many internal defects in N610 fibers because of H2O molecules diffuse into fibers at high temperature. At the same process of heat treatment, tensile strength and growth rate of surface grains of N610 fibers in steam are lower than those in air.
Alumina fiber reinforced alumina ceramic matrix composites possess high temperature resistance, high strength and oxidation resistance, etc, and have a considerable application prospects in the field of thermal structural materials used in aerospace. Using NextelTM 610 fabric as the reinforcement, alumina ceramic matrix composites were prepared by Slurry Infiltration-molding process and sintered in a muffle furnace at high temperature for one time. The temperature range suitable for the preparation of composites was determined by the effects of heat treatment temperature on the crystalline phase, mechanical strength and other properties of fiber and matrix. The effects of solid content on the mechanical properties and microstructure of the composites were studied. The results show that the bending strength of NextelTM 610/Al2O3 ceramic matrix composite increases first and then decreases with the increase of solid content. When the solid content of the slurry is 60% (mass fraction, the same below), the bending strength is the largest, up to 370.68 MPa. When the solid content is less than 60%, the reason why the flexural strength of the composite is low is that the matrix in the fiber bundles is not filled enough. When the solid content increases to 65%, the degradation of the flexural strength of the composite is due to the formation of too many matrix defects and the strengthening of the fiber-matrix interface, which hinders the fiber debonding, pull-out and other toughening mechanisms.
BaTiO3 has advantages of high permittivity, low dielectric loss, low cost and environment friendly. However, due to the nonlinear dielectric behavior occurred around the phase transition temperature of BaTiO3 ceramic, its availability in the field of temperature-stable capacitor is limited. To modify the dielectric-temperature properties of BaTiO3, a series of BaTi1-xCexO3 (x=0-0.20) ceramics was synthesized by solid-state reaction method. Ce dopant was introduced into the B-site (Ti-site) of BaTiO3. The effects of Ce dopant on the phase evolution, defect state, microstructure and dielectric properties were investigated. The modifying mechanism was also discussed with the help of first-principles calculation method. In all ceramic samples, it is revealed that Ce element completely enters the B-site of BaTiO3 in the form of Ce4+ ion. With the increase of Ce doping concentration, the room temperature structure of BaTi1-xCexO3 ceramics transforms from tetragonal/pseudo-cubic structure into orthorhombic/tetragonal structure, then into pseudo-cubic structure. Owing to the radius difference between Ce4+ and Ti4+ ions, Ce doping will lead to the rising of lattice parameters, accompanied by the appearance of local distortion and the decrease of long-range ferroelectric order, the variation of band structure, density of states and charge density configuration, as well as the generation of Ba and Ti vacancies. Compared with pure BaTiO3 ceramic, the average grain size of Ce-doped ceramics decreases first and then increases with the increase of Ce content, while the relative density of ceramics increases gradually. The peak dielectric constant of BaTi1-xCexO3 ceramic increases first and then decreases as the Ce concentration increasing. The corresponding temperature is slowly reduced from 122 ℃ to 112 ℃ in the x value range of 0-0.08, then rapidly declines to -3 ℃ in the x value range of 0.08-0.20. BaTi1-xCexO3 ceramics with x≥0.06 have the dielectric behavior of diffused phase transition (DPT). And the x=0.20 ceramic exhibits the typical characteristic of relaxor ferroelectric, with the room temperature dielectric constant of 3258.38, and the |Δεr/εr25 ℃|≤22% temperature range of -60-87 ℃, which matches the requirement of EIA X5S standard. Therefore, it can be concluded that B-site Ce doping will effectively enhance the permittivity stability of BaTiO3 in a variable temperature environment. This will provide some new ideas to develop dielectric materials with stable dielectric properties in wide temperature range.
Using carbon fiber cloth with different areal densities and tow sizes, two kinds of carbon fiber preforms with same carbon cloth laminated structure were produced through different z-direction stitching methods. Then, C/C-SiC composites were prepared by combining chemical vapor infiltration (CVI) with gas silicon infiltration (GSI). The influence of carbon fiber preform structure on the microstructure and mechanical properties of CVI-GSI C/C-SiC composites was studied. The results show that the density, phase composition, structure, and properties of the two composites prepared from preforms with the same fiber volume fraction and C/C preform density are significantly different. The smaller carbon fiber tow (1K) and carbon cloth surface density (92 g/m2), as well as the larger voids left by lock stitching, provide more sufficient channels for the infiltration of Si vapor in the GSI reaction process. Thus T1 composite finally prepared has low porosity, uniform structure, and higher performance, with bending strength, modulus, and fracture toughness of 300.97 MPa, 51.75 GPa, and 11.32 MPa·m1/2, respectively. The comprehensive control of the initial preform structure and the C/C intermediate structure is the key to the preparation of high performance C/C-SiC composites by the CVI-GSI process.
As the source of intense electron beam, the cathodes have an important effect on the performance of high power microwave source. Graphite is a common material for explosive emission cathodes of high power microwave source, which have the advantages of stable operation and long life under high pressure and repetition frequency. The carbon fiber with high aspect ratio and low emission threshold was chosen to be composited with the graphite cathode, and the field emission and high power microwave test platforms were adopted to analyse field emission properties, intense electron emission performances and output microwave characteristics of pure graphite cathodes and carbon fiber composited graphite cathodes. Meanwhile the effect of carbon fiber on the electron emission properties of graphite cathodes was studied combined with the microstructure characterization of the cathodes. The results show that compared with the flake graphite cathodes, the field emission threshold of 40%(mass fraction) carbon fiber composited graphite cathodes decreases from 143 kV/cm to 119 kV/cm, a reduction of about 16.8%, and the output pulse width and peak of 480 kV increase by 13.5% and 5.7%, respectively. Considering the structural stability of carbon-fiber in the process of explosive electron emission, the carbon-fiber is also beneficial for improving the service life of the cathodes.
Based on the self-made Zr0.5Hf0.5C precursor and commercial liquid polycarbosilane, C/Zr0.5Hf0.5C-SiC composite was successfully prepared by the precursor impregnation and pyrolysis(PIP) process. The influence of the thickness of pyrolytic C coating on the structure and bending properties of composite materials was studied. The results show that the self-made Zr0.5Hf0.5C precursor can be converted into Zr0.5Hf0.5C solid solution at a relatively low temperature of 1400 ℃. Because of its good permeability, the transformed Zr0.5Hf0.5C matrix exists in both the inter-bundle and intra-bundle regions of the C/Zr0.5Hf0.5C-SiC composite, which presents as a layered structure on SiC matrix. The phase composition of C/Zr0.5Hf0.5C-SiC composite mainly includes C, SiC and Zr0.5Hf0.5C. The densities of three groups of composites with different thicknesses of pyrolytic C coating (0.67, 0.84, 1.36 μm) are 2.07, 1.99, 1.98 g/cm3, respectively. SiC content in the composite decreases with the increase of the thickness of pyrolytic C coating. The three groups of composites with different thicknesses show pseudoplastic fracture mode during bending loading tests, bending strength, bending modulus and fracture toughness are above 410 MPa, 60 GPa and 15.6 MPa·m1/2, respectively. Good interface bonding and pre-introduced SiC matrix are the keys to obtaining excellent bending properties of C/Zr0.5Hf0.5C-SiC composites.
Carbon fiber reinforced silicone resin derived SiOC ceramic (C/SiOC) composite is a high-temperature structural material with good application prospect due to its performance/cost ratio. In order to further reduce the cost, carbon fiber needled felt with low price was selected as the reinforcement, and C/SiOC composites were prepared by precursor impregnation pyrolysis (PIP) process. The hot molding process was introduced in the first cycle of PIP route. By optimizing the concentration of precursor solution, molding temperature and pressure, the fiber volume fraction and matrix content in the first cycle were effectively improved without damaging the structure of needled felt. Accordingly, the bending strength at room temperature and fracture toughness of C/SiOC composites were increased to 331 MPa and 16.0 MPa·m1/2, respectively. Then the microstructure evolution during the fabrication of C/SiOC composites was evaluated. The results show that SiOC matrix grows in the carbon fiber bundle firstly, then grows from inside to outside of carbon fiber bundle during fabrication. The pores are distributed around Z direction fibers. Porosity of the composites is decreased gradually and pores of the composites transformed from connected ones into isolated ones as the fabrication cycles is increased. When the fabrication cycles reach 8, the porosity of the composites is unchanged basically. At the same time, the densification of composites is completed.
Lithium (Li) metal is a potential anode material for high energy density batteries. However, issues such as lithium dendrite growth, interface instability, poor cycling stability and large volume expansion limit the application of lithium metal anode. Aiming at the problem of dendritic growth and volume expansion, a semi-confined hierarchical porous carbon (HPC) material with a large specific surface area was prepared by template method. The high specific area of HPC electrode can reduce the local current density of Li deposition, and the rich pore structure can restrict the Li deposition in it, thus inhibiting the dendritic growth and alleviating the volume expansion. Li‖HPC battery can cycle for more than 250 cycles at a current density of 1.0 mA/cm2 and a deposition capacity of 1.0 mAh/cm2, maintaining a Coulombic efficiency of 97.6%. Li@HPC‖lithium iron phosphate a deposition capacity of (LiFePO4) full cell has a specific capacity of 93.6 mAh/g after 100 cycles at 0.5 C, which is higher than that of Li@Cu‖LiFePO4 full cell (60.8 mAh/g) with an increase of by 32.8 mAh/g.
One of the key problems restricting the commercial application of controllable nuclear fusion reactors is plasma facing materials (PFMs). As the most promising PFMs, there are still many problems in the applications of tungsten and tungsten alloys. Due to their high strength at elevated temperatures, high melting point and good irradiation resistance, refractory multi-principal-element alloys are expected to meet the needs of PFMs. In the present study, (TiVTa)95X5(X=Cr, Zr, W) was designed and manufactured by using arc-melting. The effects of the addition of Cr, Zr and W on the microstructure and phase stability at 900 ℃ of TiVTa-based alloys were investigated by XRD, SEM and EDS. The results show that as-cast TiVTa-based alloys are simple solid solutions with BCC structure. After homogenization treatment at 1200 ℃, phase decomposition occurs in the (TiVTa)95Cr5 alloy, and a small amount of second phase C15_Laves appears in the matrix. At 900 ℃, TiVTa-based alloys are all decomposed into a BCC main phase and a C15_Laves second phase which mainly distributed along the grain boundaries, and the volume fraction of the second phase in TiVTa and (TiVTa)95W5 alloys is small whereas the addition of Cr and Zr intensifies the phase decomposition. After phase structure and elemental analysis, the lattice constant and elemental composition of the precipitated C15_Laves phases in (TiVTa)95X5(X=Cr, Zr, W) alloys are inconsistent with the possible Laves phase in the binary alloy system, and the difference is mainly attributed to the elemental composition of the Laves phase.
Ti-Zr-Ta refractory alloy has excellent mechanical properties and impact-initiated energy release characteristics, and shows good application prospects in the field of energetic structural materials. At present, Ti-Zr-Ta alloy is mainly prepared by melting process. However, its components are all refractory metals, so it is difficult to fabricate large parts with uniform structure by melting and casting. Based on this, the Ti-Zr-Ta refractory alloy powder was prepared by hydrogenation-dehydrogenation, and then sintered by vacuum hot-pressing process. On this basis, the microstructure, mechanical properties and shock-induced energy release characteristics of the sintered Ti-Zr-Ta alloy were studied. The results show that the average particle size of Ti-Zr-Ta alloy powder prepared by hydrogenation-dehydrogenation is 9.4 μm, and it is composed of three phases of BCC1, BCC2 and HCP. The density of Ti-Zr-Ta alloy sintered at 1300 ℃ is 7.34 g/cm3, which roughly achieves full densification, and the alloy is mainly composed of two phases of BCC1 and BCC2. The quasi-static compressive strength and fracture deformation are 1637 MPa and 6.4%, respectively, showing brittle fracture characteristics. In the ballistic gun experiment, the peak overpressure generated by 5.6 g of as-sintered Ti-Zr-Ta alloy breaking through the target plate at a speed of 1493 m/s in the 27 L closed target box reaches 0.195 MPa, showing excellent impact energy release characteristics, and the energy release is mainly derived from the oxidation reaction of small fragments generated by high-speed impact of alloy projectiles.
In order to improve the reaction efficiency and rate of Al powder with seawater, highly active Al base powder (Al-Mg-Sn-Bi alloy powder, AMSB) was prepared by adding low melting metal (Sn and Bi) by atomizing. The hydrogen generation rate and open circuit potential of AMSB alloy powder were measured by hydrogen generation test and electrochemical test, and the hydrolysis mechanism was characterized. The hydrogen generation test results show that the hydrogen generation rate of AMSB alloy powder in 3.5%(mass fraction) NaCl solution can reach 214.80 mL·min-1·g-1, and the hydrogen generation efficiency can reach 80.45%. The results of electrochemical experiments show that the addition of Sn and Bi can reduce the open circuit potential of AMSB alloy powder and promote the negative shift of the electrode potential of Al powder. The phase composition and microstructure of AMSB alloy powder before and after the reaction were characterized by XRD, XPS and SEM-EDS. Low melting point elements Sn and Bi can destroy the densification of oxide film, effectively improve the reaction efficiency of Al with water and promote the reaction process of Al and water. Moreover, the galvanic cell effect formed between Al, Sn and Bi elements is an important reason for the improvement of the hydrolysis performance of AMSB alloy powder. Therefore, the highly active Al based powder prepared has a certain application value in the field of high energy water reaction metal fuel.
In order to meet the needs of large area thermal protection(≥1500 ℃)for high-speed aircraft, the high temperature resistant alumina fiber reinforced aerogel composite was used as the thermal insulation layer, and the carbon fiber fabric was used as the panel layer preform. Through the normal needle puncture process and the precursor impregnation pyrolysis process, the integrated TPS material for thermal protection was prepared, and the high temperature resistance performance tests were carried out to provide theoretical and technical support for the engineering application of materials. The results show that the integrated TPS material with good integrity and no obvious defects can be prepared by needle puncture suture technology and PIP process, and the density is only 0.6 g/cm3. When C/SiC composites are used in high-temperature oxidation environment, the oxidizing atmosphere diffuses into the material through defects such as pores and cracks, and oxidizes with carbon fibers, resulting in the degradation of composite properties. The material has excellent high temperature resistance, with mass ablation rate of 0.051 g/s and linear ablation rate of 0.077 mm/s; There is no obvious gap structure, and there is no obvious shrinkage on the whole, showing good high temperature resistance.
Indium tin oxide (ITO) nanocrystals with different shapes and sizes were synthesized by one-pot method, and ITO nanocrystal films were prepared by spin-coating process. The near-infrared spectrum regulation properties of the films prepared by ITO nanocrystals with different morphologies and sizes were studied. The results show that the visible light transmittance of ITO nanocrystal film is 89.2%, and the resistivity is 54 Ω·cm after 5 spin coatings. The films prepared by uniform spherical ITO nanocrystals with an average diameter of (6.88±1.53) nm exhibit the best near-infrared spectrum regulation ability. After applying a voltage of ±2.5 V, the spectrum regulation at 2000 nm is 39.3%, and the optical density change is 0.43. The ITO nanocrystal film maintains high visible light transmittance before and after electrochromism. The electrochromism of ITO nanocrystals is caused by change of frequency and intensity of localized surface plasmon resonance(LSPR) caused by electron injection/extraction, and its electrochromic process is realized by capacitor charging and discharging.
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