In the aerospace field， welding serves as the primary joining process for TA3 alloy components，and the microstructure and mechanical properties of its welded joints have a significant impact on the service safety of welded components. This study compares the tensile properties of the base metal and welded specimens and studies the deformation morphology before and after tension using scanning electron microscopy combined with electron backscatter diffraction. The results show that the microstructure of TA3 alloy is equiaxed α grains before welding， and massive， acicular and serrated α grains appear after welding. The yield strength （378 MPa） and tensile strength （458 MPa） of welded specimens are higher than that of base material specimens， but the elongation is lower. The reason is that after the base meterial sample is welded， the welding temperature has the effect of aging treatment on the sample. There exists aging hardening， and the grain size inside the weld area becomes smaller， which will increase the tensile strength. Because the microhardness of the weld zone is obviously higher than that of the base metal zone， the fracture of the welded joint is located in the base meterial zone. The deformation mechanism of the weld zone is stress-induced deformation twin （\mathrm{2}\overline{\mathrm{1}}\overline{\mathrm{1}}2）［\mathrm{2}\overline{\mathrm{1}}\overline{\mathrm{1}}3］ and （\overline{\mathrm{2}}\mathrm{1}12）［\overline{\mathrm{2}}\mathrm{1}13］， with a Schmid factor of 0.038， exhibiting high shear stress and strong coordination of grain deformation. Deformation twins （\overline{\mathrm{2}}\mathrm{11}2）［\mathrm{2}\overline{\mathrm{1}}\overline{\mathrm{1}}3］ also appear in the base material region， but the Schmid factor is 0.078， indicating a relatively high degree of stress concentration.

The β titanium alloy Ti-1300 is fabricated utilizing laser engineered net shaping （LENS） technology. This study systematically examine the microstructural evolution of the alloy along the deposition direction during the LENS process， and elucidate the intrinsic relationship between its mechanical properties and microstructure. The results indicate that the thermal cycling of each deposited layer in the LENS process has a profound impact on the microstructural evolution. Initially， columnar crystals are formed with a thickness of （15.6±1.2） mm， comprising approximately 20% of the total deposited thickness. Subsequently， these grains transform into equiaxed grains. Within the as-deposited grains， the microstructure undergo a transition from a basket-weave structure to a lamellar structure， and the discontinuous grain boundary α phase changes to a continuous grain boundary α phase along the deposition direction. Notably， the basket-weave microstructure imparts exceptional strength to the alloy. However， the continuous grain boundary α phase tends to promote intergranular fracture， resulting in reduced ductility.

With the widespread application of carbon fiber reinforced polymer （CFRP） in the aerospace field， studying the friction performance at the interface of CFRP and aluminum alloy connections has become increasingly important. This study experimentally investigates the influence of surface microtexture parameters on the friction performance at the aluminum alloy-CFRP interface. The results indicate that both contact pressure and microgroove geometric parameters significantly affect the interface friction performance. As the contact pressure increases from 7.5 MPa to 30 MPa， the sliding friction coefficient significantly decreases， primarily due to the formation and enhancement of a self-lubricating film. Under high contact pressure， the microstructures on the aluminum alloy surface embed into the CFRP plate， creating a plowing effect. The micro-cutting action generates epoxy resin debris that fills the microstructure grooves， forming a stable lubricating film. The groove depth has the most significant impact on friction performance， with a groove depth of 31.8 μm significantly reducing the sliding friction coefficient to 0.197. The synergistic effect of contact pressure and microtexture geometric parameters markedly improves the interface friction performance and connection strength. This study provides theoretical basis and practical guidance for optimizing composite material connection technology.

Silicon carbide and 2024 aluminum alloy powders with average particle sizes of 14 μm and 15 μm are selected as the reinforcement phase and matrix alloy， respectively. SiC_p/2024Al composites with volume fractions of 35%， 45%， and 55% are fabricated by hot isostatic pressing. The influence of aging treatment on the mechanical properties of the composites is investigated. The results show that aging treatment significantly enhances the hardness of the composites. Increasing the aging temperature and the volume fraction of SiC both shorten the peak aging time of the composites. When the aging temperature is increased from 160 ℃ to 190 ℃， the peak aging time of the composite with a 35% volume fraction is reduced from 9.5 h to 2 h. At 190 ℃， the peak aging time of all three volume fraction composites is shortened to 2 h. The precipitation strengthening of the matrix alloy during the heat treatment process results in higher flexural strength in the aged composites compared to the as-sintered composites with the same volume fraction. The higher the matrix alloy content， the more significant the strengthening effect. Among them， the peak-aged composite with a 35% volume fraction exhibits the highest flexural strength， reaching 901 MPa at 170 ℃. With the increase of volume fraction， the matrix alloy content decreases， reducing the ability of the material to alleviate local stress concentration through plastic deformation. Moreover， defects in the composites gradually increase. Therefore， both the as-sintered and heat-treated composites with a 55% volume fraction exhibit lower flexural strength. However， the micro-yield strength of the aged composites is higher than that of the as-sintered composites. The aged composite with a 45% volume fraction generally has the highest micro-yield strength， fluctuating in the range of 361-380 MPa， while the aged composite with a 55% volume fraction has the lowest micro-yield strength. The micro-yield strength of the composite with a 35% volume fraction initially increases and then decreases with increasing temperature， reaching its highest value （368 MPa） at 180 ℃， slightly higher than that of the composite with a 45% volume fraction under the same conditions.

Based on the current status and requirements of wear in zirconia ceramics， in response to the problem friction reduction performance of single-textured specimens， different texture types are combined to extract biomimetic contours from biological surfaces and design various novel composite biomimetic textures. The numerical simulation and the experimental investigation methods are used to analyze the friction reduction performance of composite biomimetic textures，solving the Reynolds equation numerically， studying the influence of composite texture types on oil film load capacity， pressure distribution area， and maximum static pressure， and conducting experimental exploration of the tribological performance using a friction and wear testing machine. The results indicate that composite biomimetic textures exhibit higher oil film load capacity， wider pressure distribution areas， and lower friction coefficients compared to other texture types， among them， the comprehensive anti-friction effect of the scale + feather composite texture is the best； the friction reduction mechanism of composite biomimetic textures can be mainly attributed to changes in contact stress points， the asymmetric distribution of pressure and abrasive storage properties， and the form of pressure distribution of composite texture is highly dependent on a single texture type.

8%（mass fraction）Y₂O₃ partially stabilized zirconia （8YSZ） is a currently commonly-used top-coat material for thermal barrier coatings （TBCs） applied to turbine blades in aero-engines. However， its volume change induced by high-temperature phase transitions above 1200 ℃ can easily lead to cracking and failure of TBCs. Sc₂O₃ is employed as an alternative stabilizer to fabricate 8%Sc₂O₃-92%ZrO₂（mole fraction） ceramics （8SSZ） via a solid-state synthesis method. The thermophysical properties of 8SSZ and conventional 8YSZ， including thermal expansion coefficient （CTE）， thermal conductivity， and high-temperature phase/grain stability， are systematically compared. The results show that after heat treatment at 1400 ℃ in a muffle furnace， the CTE of 8SSZ measured by a dilatometer ranges from 8.91×10^-6 K^-1 to 10.7×10^-6 K^-1， which is comparable to that of 8YSZ. Thermal conductivity tests reveal that 8SSZ exhibits a thermal conductivity of 2.59 W/（m·K）， approximately 20% lower than that of 8YSZ. X-ray diffraction （XRD） and scanning electron microscopy （SEM） results demonstrate that 8SSZ maintains phase stability without phase transitions after 500 h at 1400 ℃， outperforming 8YSZ in high-temperature phase stability. However， 8SSZ still exhibits the issue of excessive grain growth.

Interlayer crack is a significant obstacle to the wide-scale implementation of light-cured additive manufacturing in industrial applications. The formation mechanism of crack defects during the forming and debinding stages of the process is investigated and their effects on the properties of light-cured ZrO₂ ceramics are analyzed. Furthermore， the study compares and analyzes the influence of exposure time and debinding rate on the distribution of cracks in ZrO₂ ceramics. The research analyzes and compares the influence of exposure time and debinding rate on the distribution of cracks in ZrO₂ ceramics. The results indicate that it is easier to obtain defect-free ceramic green bodies when the slice thickness matches the exposure layer thickness. Moreover， the study observes that the green body exhibits the least number of surface cracks when the debinding rate is set at 0.1 ℃/min. Consequently， the research achieves the successful production of ceramic parts with a density of 99% and a flexural strength of 450 MPa.These findings establish a solid scientific foundation and provide valuable technical guidance for the manufacturing and application of defect-free ZrO₂ ceramics using light-cured additive manufacturing.

The preparation of carbon paper used phenolic resin as matrix carbon， and different heat treatment temperatures （1400-2700 ℃） are used to obtain matrix carbon with different structures. At the same time， the effect of matrix carbon content and structure on carbon paper for proton exchange membrane fuel cell is studied. The results show that the matrix carbon in carbon paper is more prone to graphitization transformation than carbon fiber. As the content of the matrix carbon increases， the d₀₀₂ diffraction peak of the carbon paper becomes sharper. When the heat treatment temperature increases from 2100 ℃ to 2400 ℃， the graphitization of the carbon paper increases by 45.2%， which is the largest increase. With the increase of heat treatment temperature， the carbon papers， with different matrix carbon ratios， show differences in performance trends. When the carbon content of the matrix is 60%（mass fraction， the same below） and 120%， the thickness of the carbon paper gradually decreases with the increase of the graphitization temperature， and the tensile strength of the carbon paper has a slight change； when the carbon content of the matrix is 200% and 350%， with the increase of graphitization temperature， the thickness of carbon paper decreases slightly and then increases， and the tensile strength of carbon paper decreases rapidly. The surface resistivity of carbon paper shows a downward trend with the increase of heat treatment temperature， and its change trend is basically consistent with the change trend of thickness. Therefore， when preparing carbon papers with different properties， it is necessary to consider the synergistic effect of matrix carbon content and structure.

This study utilizes mushroom stalks as a biological template and melamine as a precursor for carbon nitride to synthesize g-C₃N₄/C，via thermal polymerization method. Copper sulfate pentahydrate （CuSO₄·5H₂O），ammonium molybdate tetrahydrate （（NH₄）₆Mo₇O₂₄·4H₂O），and thiourea （CH₄N₂S） are selected as the sources for Cu，Mo，and S，respectively. A two-step hydrothermal process is employed to prepare CuS/MoS₂ composites with different mass ratios. Then CuS/MoS₂ is anchored on the surface of g-C₃N₄/C to obtain CuS/MoS₂-g-C₃N₄/C composite electrode materials. The composite electrode materials are characterized by their phase structure，microstructure，pore structure，and capacitance performance. The results indicate that the CuS/MoS₂-g-C₃N₄/C composite electrode materials exhibit high purity，good crystallinity，good phase contact interface， and abundant porous structure. In electrochemical performance testing，the CuS/MoS₂ composite material with a mass ratio of MoS₂ to CuS at 1∶2 demonstrates optimal electrochemical performance，achieving a specific capacitance of 230 F·g^-1 at a current density of 1 A·g^-1. When the mass ratio of CuS/MoS₂ to g-C₃N₄/C is 1∶1，the CuS/MoS₂-g-C₃N₄/C composite material exhibits the best electrochemical performance，with a specific capacitance of 434.7 F·g^-1. Moreover，after 1000 cycles，the capacitance retention rate is 89.2%，showing good stability.

The MnO₂ and VB₂ co-doped NiCr₂O₄ coatings（MV） with different ratios of moles are prepared by atmospheric plasma spraying（APS）， and the phase composition， microstructure， infrared emissivity and thermal shock resistance of the coatings are investigated. The results show that the co-doping of NiCr₂O₄ with MnO₂ and VB₂ can more effectively improve the infrared emissivity of the coatings than the doping of MnO₂ or VB₂， thus the coating with MnO₂ and VB₂ doping ratio of 1∶1 （MV11） has the highest emissivity. In the 0.75-2.5 μm wavelength ranges， the room temperature band emissivity of the MV11 coating is 0.928， and in the 2.5-25 μm， the infrared emissivity of the coating increases from 0.884 at room temperature to 0.918 at 1000 ℃. It is mainly attributed to the transition metal ions and B ions enter the spinel lattice， increasing the concentration of oxygen vacancy in the lattice， introducing partial energy levels into the bandgap， and causing lattice distortions， enhancing free carrier transition absorption and infrared lattice vibration absorption. In addition， after 30 thermal cycles of water cooling at 25-750 ℃， microcracks appear in the coating， but the phase structure did not change significantly， and the emissivity decreases slightly， indicating that the coating has good thermal shock resistance.