Si₃N₄ ceramics exhibit excellent mechanical properties due to their strong covalent bonding characteristics, however, this characteristic makes them difficult to secondary process, severely limiting their widespread industrial applications. In this study, dynamic hot forging (DHF) technology was employed to process commercial Si₃N₄ ceramics, the effects of hot forging temperature on the microstructure and mechanical properties of materials were studied. The results indicate that under a dynamic pressure of (60±5) MPa and a hot forging temperature of 1 800 ℃, the Si₃N₄ ceramics exhibit optimal mechanical properties, with a hardness of 13.84 GPa, a fracture toughness of 6.88 MPa·m^1/2, and a bending strength reaching 925 MPa. All performance metrics significantly surpassing those of the original samples. This performance enhancement is primarily attributed to two key factors: firstly, the elimination of defects such as pores during the hot forging process, and secondly, the structural texturing effect induced by dynamic pressure. The DHF technology developed in this study provides an effective new method for the secondary processing and strengthening of high-performance difficult-to-machine ceramic materials.

In the harsh service environment, spacecraft must withstand long-term exposure to aerobic environments, extreme aerodynamic heating, high temperatures, and high pressures. Thermal protection materials show excellent thermal insulation, protection, compression resistance, and impact resistance under the dual action of high temperature and strong airflow, and can maintain stable chemical and physical characteristics. As an anti-thermal insulation materials, its low thermal conductivity can significantly reduce heat transfer while retaining the necessary mechanical properties, which has important application value in the aerospace field, and can ensure the stable operation of internal equipment in high temperature environment. This paper systematically discusses the basic principles and key properties of two typical anti-thermal insulation materials (ceramic thermal protection materials and metal thermal protection materials), analyzes their preparation technology and practical applications, summarizes the existing main problems, and puts forward the future development direction, providing a new perspective and reference for the research in this field.

Rare earth tantalate/niobate (RE(Ta/Nb)O₄) materials have attracted significant attention as promising candidates for next-generation thermal barrier coatings due to their excellent properties. The machine learning was used to analyze the thermal conductivity of RE(Ta/Nb)O₄ (RE=Sc, Y, Yb, Dy, Gd, Sm, Ho, La, Lu, Tm, Er, Ce, Eu) materials, and combined a greedy algorithm to identify materials with lower thermal conductivity for thermal barrier coatings in this study. Using feature parameters such as element composition, atomic properties and parameters, crystal structure information, and thermodynamic data, the gradient boosting decision tree model was employed for material screening and validated through experiments. The results show that the experimental values of (Y_2/7Yb_5/7)(Ta_1/2Nb_1/2)O₄ align well with the predicted model, and gradient boosting decision tree proves to be an effective machine learning model for future thermal conductivity predictions. Several low thermal conductivity RE(Ta_1/2Nb_1/2)O₄ thermal barrier coating materials are successfully identified. Co-doping with multiple rare earth elements and high-entropy RE(Ta/Nb)O₄ exhibit superior thermal performance compared to certain single- component RE(Ta/Nb)O₄ materials, making them promising new materials for thermal barrier coatings.

Two nickel-based single crystal superalloys, CSUSX-Os-1 and CSUSX-Os-2, with Os mass fraction of 3% and different Co/Cr mass ratios (6.5∶9.6, 9.6∶6.5), were prepared using vacuum induction melting and rapid solidification techniques. After solution and aging treatment, the alloys were thermal exposed at 1 100, 1 150, and 1 200 ℃ for different time to investigate the effects of thermal exposure time and temperature on the microstructure of the alloys. The precipitation tendency of TCP phases was predicted using the electron vacancy method and the d-orbital electron energy level prediction method. The results show that the γ′ phases in both alloys coarsen with the increase of thermal exposure temperature and the extension of thermal exposure time, and the area fraction of γ' phase of CSUSX-Os-1 alloy is smaller than that of CSUSX-Os-2 alloy at the same thermal exposure temperature. The CSUSX-Os-1 alloy exhibits greater tendency for TCP phase precipitation than the CSUSX-Os-2 alloy. Moreover, the compositions of the TCP phases precipitated in the two alloys are different, the TCP phases in the CSUSX-Os-1 alloy enrich in Cr, W, Os, and Ni, and the size of the lath-shaped TCP phases gradually increases with the increase of thermal exposure time; the TCP phases in the CSUSX-Os-2 alloy enrich in Ta, Ti, and W, and also has a lath-shaped morphology.

In this paper, DyF₃ and Dy₂O₃ powders were used as diffusion sources to prepare high Ce content (Pr,Nd)₂₀Ce₁₁Fe_bal(Cu,Ga,Zr)_1.0B_0.97 (mass fraction) sintered magnets. The effects of DyF₃/Dy₂O₃ co-diffusion on the magnetic properties and microstructure of the magnets were investigated using ultra-high coercivity permanent magnet pulsed field magnetometer, X-ray diffractometer, differential scanning calorimeter, and electron probe microanalyzer. The results show that after DyF₃/Dy₂O₃ diffusion, the coercivity increases from 913.01 kA/m to 1 237.78 kA/m, representing an enhancement of 324.77 kA/m (35.6%). Additionally, the thermal stability is improved as the temperature coefficient of coercivity increasing from -0.606 %/℃ to -0.567 %/℃ in 20-120 ℃. The variation in remanence is minimal, with a change of only -0.01 T. After diffusion, the surface layer of the magnet predominantly consisted of the tetragonal (Nd,Ce,Dy)₂Fe₁₄B primary phase, along with a small proportion of cubic RE-O-F secondary phase. In the DyF₃/Dy₂O₃ system, Dy₂O₃ reduces the decomposition temperature of DyF₃ (<600 ℃), thereby providing a driving force for the diffusion of Dy atoms. Dy diffusion depth in DyF₃/Dy₂O₃ co-diffusion reaches up to 800 μm, the content of Dy gradually decreases with the increase of diffusion depth. Enriched regions of Dy and F elements are observed in the surface layer (0-60 μm). Ce is primarily enriched in the 0-60 μm range and at the triangular grain boundaries inside the bulk of the magnet. At a depth of 50-400 μm from the surface, Dy elements form a continuous network-like (Nd,Ce,Dy)₂Fe₁₄B shell structure around the main phase grains, which can effectively enhance the magnetocrystalline anisotropy field at the main phase grain surfaces, suppress the nucleation of reverse magnetization domains at the grain surfaces, and consequently improve the coercivity.

Polycarbosilane commonly used precursor for SiC fibers is prohibitively expensive. To mitigate production expenses, this study employs polysiloxane as the silicon source and polyacrylonitrile as the carbon source to prepare a modified precursor. Polymer precursor fibers were fabricated via precursor-derived ceramic technology combined with electrostatic spining. The fibers underwent stabilization through ultraviolet irradiation and air-stabilization followed by pyrolysis in a N₂ atmosphere to produce SiC(O) fibers, then the microstructures and oxidation resistance of the SiC(O) fibers were investigated. The results show that the SiC(O) fibers exhibit a diameter of 200-300 nm, excellent uniformity, and pore-free surface. Moreover, their oxidation resistance at 600 ℃ surpasses that of carbon fibers.

The microstructure of the Ti-Al alloys fabricated by laser-directed energy deposition (LDED) often exhibits coarse columnar grains through several melten pools, which makes it difficult to obtain uniform mechanical properties. In this paper, Nb was selected as an additive element of Ti-Al binary alloys, and a series of Ti-6Al-xNb (x=5, 6.5, 7.5; mass fraction) ternary alloys were fabricated by LDED. The microstructure, room temperature tensile properties, and deformation mechanism of the alloys were characterized by optical microscope, X-ray diffractometer, scanning electron microscope, and electron backscattering diffractometer. The effects of Nb content on the microstructure and tensile properties of LDED Ti alloys were investigated. The results show that the microstructures of the alloys with different Nb contents are similar, which are mainly composed of elongated acicular or lamellar α/α′ phase, and there are a small amount of residual β phase. The alloy has the highest ultimate tensile strength ((902±35) MPa) and yield strength ((849±20) MPa) when the mass fraction of Nb is 6.5%, which is mainly attributed to the reduction in grain size. In addition, the elongation of these alloys decrease gradually with increasing Nb content. The lowest elongation of (10.2±1.4)% can be observed when the mass fraction of Nb is 7.5%.

To address the problem that low thermal conductivity and high thermal expansion coefficient of substrate materials for electronic packaging, the layered porous TiC-Ni frameworks were prepared by ice template method, and then layered TiC-Ni/EP composites were prepared through infiltrating epoxy (EP) into the pores of porous frameworks via vacuum impregnation method in this paper. Scanning electron microscope, universal mechanical testing machine, and thermodilatometer were used to study the effects of Ni content on the pore morphology, laminar structure characteristics of the layered porous TiC-Ni frameworks and the microstructure, mechanical, and thermal properties of the composites. The results show that the interlayer spacing and wall thickness of porous frameworks increase, the compressive strength and bending strength of the composites decrease with the increase of Ni content, while the thermal conductivity and thermal expansion coefficient of composites increase. The porous frameworks and the composite with φ(Ni)=2% have the best laminar structure characteristics, the thermal conductivity of the composite is 2.24 W/(m·K), and the thermal expansion coefficient is 30.23×10^-6 K^-1.

As a new additive manufacturing technology, photocuring printing technology provides a new way for battery manufacturing. This paper introduces the current research status of photocuring technology in the battery field, describes the application of photocuring technology in battery materials such as conductive polymers, carbon-based materials, metal oxides, solid electrolyte materials, and separator materials, puts forward suggestions and prospects for the development of photocuring printing batteries, in order to provide reference for scientific researchers and technical personnel in related fields.

In this study, the most recently reported thermodynamic parameters for the Ni-Cr, Ni-W, and Cr-W binary systems were integrated with experimental data from the Ni-Cr-W ternary system. A thermodynamic assessment and optimization were conducted using the calculation of phase diagram (CALPHAD) method, resulting in a self-consistent set of thermodynamic parameters. The σ phase in the system was modeled using a sublattice model: (Cr,Ni,W)_0.533(Cr,Ni,W)_0.333(Cr,Ni,W)_0.134. The calculated isothermal sections of the Ni-Cr-W system at 1 273, 1 473, 1 673, and 1 813 K, as well as the liquidus projection, demonstrate excellent agreement with experimental data, indicating that the thermodynamic database of this work can accurately reproduce experimental observations and provide critical insights for the design of advanced multicomponent alloys within this system.

Copper and copper alloy have excellent electrical conduction, heat conduction and other characteristics, the development of 3D printing makes the importance of bronze alloy precision components increasingly prominent in the high-end manufacturing. Bronze alloys were prepared by laser powder bed fusion technique with different scanning speed (200, 400, 600 mm/s) in this paper, the microstructures, mechanical properties, and tribological properties were studied by optical microscopic observation, hardness test, friction experiment, three-dimensional morphology analysis, SEM and EDS characterization analysis. The results indicate that with the increase of scanning speed, the porosity of 3D printed bronze alloy cladding layer increases, the grain size of molten pool decreases, the grain structure becomes more dense, the hardness increases; tribological property of 3D printed bronze alloy increases and the friction loss decreases. Moreover, the wear mechanism of 3D printed bronze alloy is mainly adhesion wear and abrasive wear, and oxidation wear is more serious under the condition of low scanning speed.

The thermodynamic properties of alloy solutions are crucial for evaluating phase stability and calculating phase diagrams. Accurate prediction of these data is of great significance for the development of new alloy materials, optimization of metallurgical processes, improvement of product quality, and reduction of production costs. In this study, the unified extrapolation model (UEM) was employed to calculate the enthalpy of mixing of the Ag-Bi-Cu, In-Li-Sn, and Al-Sn-Zn ternary alloy systems at various compositions. The results were compared with those obtained from several commonly used extrapolation models, including the Kohler, Muggianu, Toop, and general solution models, as well as experimental data reported in the literatures. The findings indicate that UEM provides overall superior predictions compared to other models, demonstrating higher accuracy and applicability in the prediction of thermodynamic properties.

In this study, α-Al₂O₃ was selected as a mineralizer for the preparation of silica based ceramic cores used in precision casting. Techniques such as X-ray diffractometer, field emission scanning electron microscope, energy dispersive spectroscopy, and the three-point bending testing were employed to investigate the effects of mineralizer amount and silica sol strengthening treatment on the phase composition, microstructures, shrinkage rate, open porosity, density, and bending strength of the ceramic cores. The results indicate that α-Al₂O₃ exerts a dual effect on the ceramic cores. On one hand, it acts as a reinforcing phase that hinders the viscous flow of fused quartz and enhances the strength of the cores; on the other hand, its excellent high-temperature stability reduces the sintering density of the ceramic cores, leading to decreased shrinkage rates and strength. However, silica sol strengthening treatment effectively seals the pores and promotes sintering of the cores. After silica sol strengthening treatment, cores with w(α-Al₂O₃)=2% exhibit an increase in room temperature bending strength to 16.6 MPa and high-temperature bending strength to 37.5 MPa, meeting the application standards for ceramic cores in the precision casting industry.

Ti-Al alloys have indispensable application value in the aerospace field because they can effectively enhance the performance of aircraft engines. However, during the processing of heating and pressurization, the alloy may undergo multiple ordered-disordered phase transitions, which will significantly affect its mechanical properties. X-ray diffraction is widely used in material analysis, but it is difficult to distinguish ordered and disordered phases with the same lattice structure (such as α₂ and α phases). In contrast, neutron diffraction generate diffraction through the interaction between the incident beam and the atomic nuclei of the substance, and have stronger penetrating ability than traditional laboratory X-rays. Moreover, neutron diffraction and X-ray diffraction show differences in the distribution of diffraction peak intensities, which enables neutron diffraction not only to assist in distinguishing the ordered and disordered phases of Ti-Al alloys, but also to further measure the degree of order of the phases. Therefore, the complementary characteristic of neutron diffraction technology and X-ray diffraction technology in diffraction patterns provides a powerful support for in-depth research on the ordered-disordered phase transitions of Ti-Al alloys. This paper systematically elaborates on the methods for calculating the diffraction peak intensities and degree of order of Ti-Al alloys based on neutron diffraction and X-ray diffraction technologies. It also introduces the experimental methods of the two diffraction technologies and their applications in the study of phase transitions of Ti-Al alloys, and looks forward to their application and development prospects in related fields.

In order to investigate the wear and protection on the rail surface of electromagnetic launch under extreme electromagnetic thermal coupling field, based on COMSOL and ABAQUS finite element software, the electromagnetic thermal model and the thermal-mechanical coupling wear model for Mo, Ni, W wear-resistant and conductive coatings were established, and the influences of different wear-resistant and conductive coatings on the electromagnetic thermal distribution of electromagnetic launch and wear resistance of the rail were explored. The results show that the coating surface alters the distribution of current density on the rails, reducing the thermal effects and lowering the overall temperature. During electromagnetic launching, mechanical wear on the rails is primarily concentrated on the front of the section, and the rail wear is significantly reduced after applying the coatings. For uncoated rails, the maximum wear depth is 1.142 μm, and the wear volume is 2.170 mm³; after applying the Mo, Ni, and W coatings, the maximum wear depths of the rail are 0.070, 0.095, and 0.042 μm respectively, and the wear volume ranges from 0.030 to 0.069 mm³. Among them, the W coating exhibits the lowest maximum wear depth and wear volume due to its superior thermal conductivity, excellent electrical conductivity, high hardness, and outstanding wear resistance.

The conversion of CO₂ into chemicals with added value through electrocatalysis is an effective solution for reducing atmospheric CO₂ concentration and alleviating the energy crisis. In this paper, the effects of adding phosphoric acid on the microscopic morphology and electrocatalytic CO₂ reduction properties of CuS micro/nano-tubes were investigated by X-ray diffractometer, scanning electron microscope, transmission electron microscope, and electrochemical experiments. The results show that the addition of phosphoric acid leads to shorter lengths, smaller outer diameters, and thinner constituent unit nanosheets of micro/nano-tubes. The reduced micro/nano-tube size helps to expose more active sites, which improves the electrocatalytic CO₂ reduction properties with a Faraday efficiency of the liquid-phase product formic acid up to 68% at -1.0 V. This work is expected to provide guidance for the design and preparation of catalysts for electrocatalytic CO₂ reduction.

In this paper, carbon fiber paper (CFP) was used as the carrier to prepare low-loading IrO₂-RuO₂/Co₃O₄@CFP catalysts with different Ir/Ru atomic ratios through hydrothermal, in-situ electrochemical displacement reaction, and high-temperature calcination. The microstructure and electrochemical performance of the catalysts were characterized by scanning electron microscope, high-resolution transmission electron microscope, X-ray diffractometer, X-ray photoelectron spectrometer, and electrochemical measurements. The results show that the catalyst with an Ir/Ru atomic ratio of 4∶1 exhibits the optimal oxygen evolution reaction catalytic activity and stability in acidic media. It achieves an oxygen evolution overpotential of 225 mV at a current density of 10 mA/cm² and a Tafel slope of 45.97 mV/dec. Moreover, no obvious performance degradation is observed after continuous reaction for 50 h at a current density of 100 mA/cm². This study can provide design ideas and feasible strategies for the synthesis of low-cost and high-performance acidic oxygen evolution catalysts.

This study used heterogeneous precipitation and heat treatment methods to coat ZnO on the surface of YCo powder particles, and introduced FeSiAl powders to fabricate FeSiAl/ZnO@YCo composites. The microwave absorption properties and electromagnetic loss mechanisms of various YCo-based composite systems were comparatively investigated. The results reveal that the FeSiAl/ZnO@YCo composites exhibit significantly improved absorption property compared to pristine YCo. At 4.6 GHz, the reflection loss of pure YCo is less than -3.00 dB, while the FeSiAl/ZnO@YCo composites achieve a maximum reflection loss of -16.50 dB with an effective absorption bandwidth of approximately 1.9 GHz, indicating remarkable improvement in low-frequency absorption property. In the high-frequency range, FeSiAl/ZnO@YCo composites maintain excellent property, reaching a reflection loss of -24.80 dB at 16.8 GHz with an effective absorption of 2.1 GHz. The enhanced microwave absorption property of the FeSiAl/ZnO@YCo composites are attributed to multiple loss mechanisms (interfacial polarization, resonance loss, and eddy current loss), along with significantly optimized electromagnetic parameters and attenuation constants.

To optimize the structure of the coarse-grained regions in hot-deformed Nd-Fe-B magnets and enhance their structural uniformity. In this paper, Nd-Fe-B magnets with different Cr contents were prepared using fast-quenched magnetic powder and Cr powder as raw materials through hot pressing and hot deformation processes. The effects of Cr content on the microstructure and magnetic properties of the magnets were studied by scanning electron microscope, energy spectrometer, X-ray diffractometer, and the mechanism of its magnetic property changes was revealed. The results indicate that an appropriate addition of Cr can significantly enhance the remanence and maximum magnetic energy product of Nd-Fe-B magnets. When w(Cr) is 0.5%, the remanence and magnetic energy product can reach 1.39 T and 353 kJ/m³, respectively. Cr exists as single particles, and the rare-earth-rich phase enriches around the Cr particles, forming a coating layer, which effectively reduces the inhomogeneous distribution of rare-earth-rich phases, optimizes the overall width and distribution of the coarse-grained regions. Thus, the texture of the magnet is optimized, leading to the improvement of comprehensive magnetic properties.

The weight reduction design of supersonic aircraft urgently requires lightweight and high-strength Al matrix materials for service above 300 ℃. In this study, an in-situ nano-Al₂O₃ reinforced Al matrix composites were fabricated via powder hot extrusion, and their microstructure and high-temperature mechanical properties were investigated by X-ray diffractometer, field emission scanning electron microscope, transmission electron microscope, and tensile property test. The results show that in-situ generated nano-Al₂O₃ particles (approximately 115 nm) are uniformly dispersed within the Al matrix, which exhibits an average grain size of approximately 640 nm, and yielding a composite hardness (HV) of 148. After thermal exposure at 500 ℃ for 100 h, the composites maintain nearly unchanged hardness and average grain size. The composites achieves a room-temperature tensile strength of 482 MPa with an elongation of 5.9%, while maintaining a tensile strength of 240 MPa at 300 ℃. This enhancement is primarily attributed to the effective pinning of grain boundaries and hindrance of dislocation motion by the in-situ nanoparticles, maintaining the thermal stability of the structure, which significantly improves the high-temperature mechanical performance of the composites.