Abstract:Carbon Fiber Reinforced Polymer （CFRP） exhibits anisotropic mechanical properties and inherently low interlaminar bonding strength，which collectively lead to machining defects during conventional processing，consequently limiting its broader industrial application.Ultrasonic machining，which superimposes high-frequency vibrations onto conventional mechanical processes，has been widely adopted due to its proven capability to reduce cutting forces/temperatures while mitigating machining defects in CFRP composites.This study provides a systematic review of ultrasonic machining technology for CFRP，beginning with an overview of key system components：ultrasonic vibration tool holders，wireless power transmission systems，and ultrasonic power supply units.The material removal mechanisms and defect formation dynamics are analyzed through multiple perspectives，including kinematic characteristics，cutting force fluctuations，and chip formation patterns.Special attention is devoted to the investigation of the root causes，detection methodologies，and ultrasonic suppression mechanisms of typical processing defects such as delamination，burr formation，and tearing.Furthermore，the review systematically summarizes the technical advantages，operational paradigms，and process parameter-effect correlation mechanisms in ultrasonic machining，while projecting future development trajectories.

Abstract:Laser cladding technology is an excellent surface modification method，which can generate dense ceramic coatings on the surface of the substrate and also achieve on-site repair of wear，corrosion and other damages，so that the parts can be kept in service without replacement，which greatly reduces the maintenance cost.This paper first introduces the classification of laser cladding technology and the laser cladding ceramic coatings，then elaborates on the numerical simulation and the performance optimization method of laser cladding ceramic coating，finally summarizes the research direction of laser cladding ceramic coating and looks forward to the problems and improvement measures in research and development and industrial production.

Abstract:To investigate the grain growth behavior and its mathematical model of 45Cr14Ni14W2Mo heat-resistant stainless steel，grain growth experiments were conducted.A qualitative analysis of the microstructure morphology was performed，revealing that the grains of the heat-resistant stainless steel exhibited an equiaxed grain structure within the temperature range of 1 100 to 1 200 K，whereas the grains exhibited a mixed grain structure within the temperature range of 1 300 to 1 400 K. Additionally，a quantitative analysis of the average grain size was conducted， and the specific effects of holding time and temperature on the grain growth behavior of the heat-resistant stainless steel was thorough discussed.Based on the traditional Sellar and Beck model，a modified mathematical model for grain growth was proposed and calculated to characterize and predict the grain growth behavior of the heat-resistant stainless steel.The results show that the modified model exhibites significant advantages in prediction accuracy compared to the traditional model.

Abstract:The effects of tributyl phosphite （TBP） content on the process performance，thermal stability and mechanical properties of frontal polymerization dicyclopentadiene （DCPD） resins were systematically investigated using TBP as an inhibitor.The results show that when the molar ratio of DCPD to Grubbs Ⅱ catalyst （GC2） is 10，000：1，the TBP molar ratio increases from 1 to 5，the pot life is extended from 1，876 s to 8，104 s by three times；the glass transition temperature increases from 121.2 ℃ to 134.5 ℃，an increase of 11%；the rate of frontal polymerization decreases from 7.14 cm/min to 3.96 cm/min，a decrease of 44%；the frontal temperature decreases from 203 ℃ to 173 ℃，a decrease of 15%.When the molar ratio of DCPD and TBP is same，and the molar ratio of GC2 increases from 1 to 2，the gel temperature and time of the resin system decrease dramatically，and the glass transition temperature decreases by more than 30 ℃，but the frontal polymerization rate increases by about two times.In addition，regardless of the GC2 content，the thermal decomposition temperature and mechanical properties of the frontal polymerization DCPD resin are basically unaffected by the inhibitor content.

Abstract:The gelcasting and reaction sintered Si₃N₄ based ceramics is applied to critical component in nonferrous metal smelting and casting industries due to its excellent properties，However，it still had disadvantages of gas tight，antioxidation and toughness.In this study，Si powders and clay are used as raw materials to prepare gelcasting and reaction sintered Si₃N₄-O''-Sialon multi-phase ceramics.The results show that the clay can improve the processing properties of slurry，green body and sintering.The closed pores sealing effect caused by the high temperature liquid phase of clay and the sintering densification effect can significantly reduce the apparent porosity and increase the bending strength.Dissolution and nitridation of high temperature liquid phase can promote crystallization of β-Si₃N₄ and O''-Sialon from liquid phase.With the nitridation temperature increasing，the morphologies of O''-Sialon change from amorphous and granules into matured crystalline of needle-like，columnar-like and polyhedron-like grains with larger scale，leading to a toughening effect.The appropriate range of Si content and nitridation temperature are 70% to 80% and 1 500 to 1 600 ℃，respectively.For the sample of 80% Si and 1 600 ℃，the apparent porosity，bulk density，bending strength，work of fracture and critical stress intensity factor are 14.15%，2.22 g/cm³，114.0 MPa，450.3 J/m² and 1.88 MPa·m^1/2，respectively.

Abstract:The surface metallized liquid crystalline polyarylate conductive fiber can meet the requirements of aviation harness cables for weight reduction，radiation resistance，chemical corrosion resistance and other characteristics.However，its surface chemical inertia hinder the pretreatment coarsening of metallized preparation.The coarsening effect of sodium hydroxide and "Sodium hydroxide-ammonia alcohol derivative" on polyarylate fiber was studied by SEM and FTIR，and then the appropriate coarsening process parameters were obtained.On this basis，nickel electroless plating was carried out and the surface morphology，composition and crystallization of the coating were characterized by SEM，EDS and XRD.The results show that when the temperature is 50 ℃，the polyarylate fiber has a good coarsening and etching effect after being treated with 40% NaOH and 20% ethanolamine derivative for 10 min.The surface structure of the nickel plated fiber is compact and flat，the whole fiber is evenly wrapped without cracking and peeling，and average unit length resistance of the fiber is 10.8 Ω/cm.

Abstract:In order to explore the low-velocity impact resistance of 2.5D interleaved laminated structure composites，2.5D interleaved laminated structure test panels，conventional interleaved laminated structure test panels and same laminate laminate test panels were prepared.The performance of two interleaved laminated composite structures and laminated composites under low-velocity impact damage was investigated by drop weight test and post-impact compression.The results show that under the impact of the falling weight，compared with the laminated structure，the surface impact deformation area of the 2.5D interleaved laminated structure is reduced by 73.79%，the internal damage projection area is reduced by 21.66%，and the compressive strength after impact is increased by 10.53%.The 2.5D interleaved laminated structure exhibits excellent resistance to low-speed impact deformation and damage.

Abstract:Al-Zn-Mg-Cu （7050） alloy has been selected as a model system for the investigation of precipitate stability，subject to proton irradiation during solar flare events.10 MeV Cl³⁺ heavy-ions were used as surrogate，for accelerated simulation experiment at room temperature，up to a fluence of 5.0×10¹⁸ ions/m².The dimensional and structural stability of strengthening precipitates η′-MgZn₂ and η-MgZn₂ were analyzed，and their impacts upon nanohardness were evaluated.Characterizations based on transmission electron microscopy confirmed that：（1） nano-scale dispersed η′-MgZn₂ demonstrated high dimensional stability，however partly prone to ballistic mixing and vacancy-induced dissolution，thereby reducing the total precipitate population；（2） equilibrium phase η-MgZn₂ were distributed at grain boundaries and within grain interiors，exhibited pronounced coarsening due to radiation-enhanced diffusion，but the precipitate population remained almost constant.Nanohardness evaluation indicated negligible irradiation hardening，probably associated with the contribution of irradiation-induced defect clusters，which hindered dislocation motion，and compensated the softening caused by the partial loss of η′-MgZn₂.The current study shows that it is crucial to focus on the dissolution of η′-MgZn₂ and the coarsening of η-MgZn₂，and mitigate the effects by enhanced precipitate/matrix interface stability and increased defect sink densities，so as to enhance the radiation tolerance of materials.

Abstract:Nickel-based elastic alloy had excellent corrosion resistance and high temperature mechanical properties.The inclusion defects in the alloy seriously affect the yield of wire in the preparation process.The inclusions in NiCrWCo alloy were studied by scanning electron microscopy and energy spectrum analysis，and the sources，types and formation mechanism of inclusions were analyzed.The results show that there are granular or chain-like Al₂O₃，TiCN，TiC，WC，Cr₂O₃，Al₂O₃ and other inclusions in the NiCrWCo alloy.The particle size is 1.5-3.5 μm，and the chain length is 3-15 μm.The causes of inclusions are mainly due to the low purity of metallurgical raw materials，insufficient gas protection in smelting process and solidification segregation in cooling process.Finally，the inclusion control scheme is discussed from the perspectives of raw materials for smelting，furnace lining contamination，and vacuum control during smelting.

Abstract:Through visual inspection， macro/microscopic fracture morphology examination，microstructural characterization，and hardness testing of fractured bolts from a high-pressure oil filter subjected to 61 200 cycles of high-temperature pressure shock，this study investigated the abnormal fracture mechanism of GH4169 bolts connecting the outlet check valve and upper housing.The results indicate that the bolt fracture is fatigue-induced.Continuous chain-like Laves phases precipitated along grain boundaries significantly reduces material plasticity and abnormally increases notch sensitivity，ultimately triggering fatigue crack initiation.Additionally，stress concentration causes by small root radii at thread grooves and potential uneven assembly loads exacerbate fatigue crack propagation.This engineering failure case directly demonstrates the detrimental effects of grain boundary chain-like Laves phases on fatigue failure processes，providing critical insights to enhance researchers'' and engineers'' awareness of Laves phase-related hazards.

Abstract:To solve the problems of poor quality consistency and low reliability of traditional pneumatic hammering interference sealing riveting，the research on the process parameters of electromagnetic sealing riveting was carried out.Taking ZL114A cast aluminum alloy as a typical material，the orthogonal test method was adopted with hole-making accuracy，notch form，and head form as variables and the performance of test pieces was tested based on the sealing performance after riveting.The results show that the leakage rate of the specimen is the lowest and the sealing performance is the best under the conditions of H8 bottom hole accuracy，convex head and double-angle notches，and the north form had the greatest impact on the sealing performance.Further analysis of leakage rate and interference amount measurements shows that test specimens still meet sealing requirements even when the interference amount does not meet the self-sealing riveting standard requirements.Therefore，from an engineering application perspective，the interference amount requirement can be relaxed to 0.4% under specific conditions.

Abstract:Aiming at the problem of warping deformation of the insulating base of the slender-type connector with a large number of cores，the warping mechanism of the glass fiber reinforced polyphenylene sulfide （GFRPPS） insulating base during the molding process was analyzed.The optimal gate position and size were determined through Moldflow simulation analysis.Based on the range analysis of the orthogonal test of the molding process parameters，the influences of process parameters such as barrel temperature，mold temperature and injection pressure on warping deformation were determined.Through production verification，the theoretically superior combination parameters of the molding process were obtained.The results show that when designing the mold，the feeding method of one end and a single gate should be adopted，which can effectively avoid warping deformation.During the molding process，the barrel temperature and injection pressure have a significant impact on warping deformation.In the production process，the optimal molding process parameters should be determined in combination with the warping deformation and surface appearance state of the product.The mold is heated by oil temperature.By adjusting the temperature difference between the static mold and the moving mold，the shrinkage caused by uneven wall thickness is offset，thereby reducing warping deformation.

Abstract:As a typical difficult-to-machine material， cemented carbide YG10 was prone to cause severe tool wear when common cutting method was used.In response to this problem，laser-assisted cutting method was proposed for machining.By comparing the tool wear conditions under the two machining methods of ordinary cutting and laser-assisted cutting，it was demonstrated that laser-assisted cutting could effectively reduce cutting force and tool wear.The support vector regression model （SVR） and cross-validation-support vector regression model（CV-SVR）were established，and the amount of flank wear under specific cutting conditions were predicted.The result shows that the prediction results of the two models have a small error with the actual values，in particular，the CV-SVR model has higher fitting accuracy，compared with the SVR model，the average relative error is reduces by about 10%.The CV-optimized SVR model can effectively simulate the nonlinear relationship in tool wear，and it can provide a basis for the judgment of tool wear in actual machining.

Abstract:Shape memory alloys have been widely used in U.S.military aircraft and Airbus/Boeing civil aircraft models，and were first successfully applied in the domestic Yun12F aircraft with airworthiness certification approval.To break through the airworthiness verification technical barriers of imported pipe joints and establish independent airworthiness certification standards，this study conducted systematic tests on domestic shape memory alloy pipe joints for the first time，based on airworthiness verification experience with imported products from the Yun12F.Results demonstrate that domestic joints have reached imported product levels in core performance metrics：flame resistance （5min exposure without failure），burst strength （critical value 35 MPa），pressure stability（21 MPa pressure maintenance qualified），and repeated assembly performance （maintained sealing after 8 disassemblies），all complying with international airworthiness standards.The research identified primary failure modes of domestic memory alloy pipe joints and applicable compliance methods，preliminarily establishing airworthiness verification methodologies.This lays the foundation for developing domestic airworthiness certification methods and standards for shape memory alloy pipe joints.

Abstract:A micro pressure automatic inflation system was designed to address the issue of missed detection under atmospheric pressure for three-stage diaphragm tanks.The system achieved automatic inflation and overpressure control in the gas and liquid chambers under micro pressure conditions，and solved the problem of missed detection helium gas leak detection under atmospheric pressure.Comparing and analyzing the micro pressure automatic inflation system with traditional manual inflation operation，the results show that the flow design of the micro-pressure automatic inflation system can reduce the high-pressure helium gas to micro-pressure levels of 10 kPa，120 kPa，the overpressure reversal of the diaphragm can be effectively avoided through the setting of the system''s back pressure valve，the missed detection effect is significantly better than that of normal pressure helium mass spectrometer missed detection.This research ensures the safety of the helium leak testing process for diaphragms within the tanks，enhances the reliability of the quality of three-level diaphragm tanks，and can be applied to subsequent micro-pressure inflation tests for other products.