Carbon nanotube (CNT) with carboxyl functional groups and flake Cu-Cr powder were used as raw materials.The surface of flake Cu-Cr powder was treated by hydrophilic functional groups,and the CNT/Cu-Cr matrix composites were prepared by wet dispersion and powder metallurgy process,realizing the uniform dispersion of carbon nanotube in the Cu-Cr matrix.The microstructure of the composite block was observed by field emission scanning electron microscope,and the effects of CNT and Cr content on the mechanical and electrical properties of the composites were studied.The results showed that the optimal system was the composites containing CNT with a volume fraction of 2% and Cr with a mass fraction of 3% in the alloy powder (2% CNT/Cu-3Cr).In comparison with the Cu-3Cr bulk,the yield strength increased by about 12%,the tensile strength increased by about 13%,the friction coefficient decreased by about 19% and the electrical conductivity decreased by about 23%.

Cu/SiO₂ catalysts were prepared by deposition precipitation,sol-gel and ammonia evaporation method,respectively.The physicochemical structure properties of the catalyst were characterized by N₂ adsorption-desorption,N₂O titration,XRD,FT-IR,H₂-TPR and NH₃-TPD,and the performance of hydrogenation of dimethyl adipate (DMA) to 1,6-hexanediol (HDO) was investigated.The results showed that although the sol-gel and ammonia evaporation method had high copper dispersion and surface acidity due to the the presence of copper phyllosilicate structure,they are restricted by the smaller pore structure.Instead,the Cu/SiO₂ catalyst prepared by the traditional deposition precipitation method had higher reaction activitydue to the larger pore.Under the conditions of reaction temperature 200 ℃,reaction pressure of 50 MPa,liquid hourly space velocity of 0.6 h^-1 and molar ratio of H₂ to ester of 175,the reaction could be run stably for 50 h.The conversion rate of dimethyl adipate can reach 99.8%,and the 1,6-hexanediol selectivity can reach 98.2%.

Perovskite,a proton conducting ceramic material with high proton conductivity,became one of the preferred materials for energy conversion and storage devices.Due to the characteristics of fire resistance and easy cracking,the processing technology of this kind of material was complicated and limited.One of the keys to realize the wide application of energy devices based on this kind of materials was to solve its low-cost,fast,efficient and non-destructive preparation process.This work enabled fast,efficient and cost-effective fabrication of high energy density integrated devices by developing a novel laser 3D printing technology that integrates micro-extrusion-based 3D printing with accurate and rapid laser machining(sintering,drying,cutting and polishing)and applying it to proton conductor energy devices.The self-developed proton ceramic slurry was printed layer by layer according to the designed model through 3D printing.Rapid drying and in-situ reaction sintering of the printing layer were carried out by CO₂ laser.Picosecond laser was used for micro-nano processing of the machining layer,such as polishing and cutting.Through the experiment,the method successfully 3D printed the proton conductor energy device;the original powder was sintered by laser reaction and the perovskite crystal structure proton ceramics were obtained;the microchannel energy device was rapidly and accurately machined by picosecond laser;the fuel cells were fabricated and the fabricated devices had the same performance as the reported traditional processes,such as the electrolyte conductivity of ~6.95×10^-3 S/cm.The results showed that the technology platform proposed in this work can not only efficiently and accurately manufacture proton ceramic materials and energy devices,but also realized the device with complex structure that cannot be fabricated by the traditional process.At the same time,it created the possibility for the future practical application of energy devices based on proton conductor materials.

In order to explore the effect of pre-treatment on the corrosion performance and corrosion mechanism of different aluminum alloys,domestic sheets AA1060,AA2024,AA3003,AA5052,and AA6061 were selected as the research objects.Through neutral salt spray experiment and electrochemical test,different aluminum alloys before and after polishing treatment were tested and characterized.The results show that after 24 h of neutral salt spray test,the surface of the polished and unpolished aluminum alloys has different degrees of corrosion.The electrochemical test results show that the self-corrosion potential of AA1060,AA2024,AA3003,and AA5052 aluminum alloys decreases to varying degrees.And the polarization resistance of AA1060,AA3003,and AA5052 aluminum alloys al increases to varying degrees.The comparison shows that AA2024 is the most severely corroded.

A series of In_xFe_y-a MOF materials were successfully prepared by one-step hydrothermal method using foreign metal ion induction strategy,and their potential as oxygen evolution reaction(OER)electrocatalysts was demonstrated.XRD,TEM and N₂ adsorption results manifest that the introduction of Fe³⁺ makes the original In-MOF lose long-range ordering.Such disordered nanostructures have high specific surface area and abundant exposed metal active sites,which is in favor of the electrocatalytic performance.Specially,Fe-aMOF exhibits superior OER activity,only requiring an overpotential of 258.2 mV to deliver the current density of 0.01 A/cm²,along with a low Tafel slope of 45.4 mV/dec.Moreover,Fe-aMOF also has outstanding durability and can run continuously for at least 110 h at 0.01 A/cm².This work will further bring unique insights for the rational design and construction of next-generation high-efficience electrocatalysts.

In this paper,the expandable graphite was used as raw material,and the graphene /HDPE composites were successfully prepared by microwave heating and melt blending.The properties were characterized by scanning electron microscopy(SEM),differential scanning calorimetry(DSC),X-ray diffractometry(XRD)and tensile test.The results show that thick graphene(TSG)has good compatibility with HDPE matrix.At the same time,graphene with lamellar structure provides heterogeneous nucleating agent for HDPE crystallization,which improves its crystallinity.When the mass fraction of TSG content was 0.3%,the HDPE tensile strength increased from 22.5 MPa to 24.9 MPa,increased by 10.5%,the bending modulus increased from 443.5 MPa to 510.4 MPa,increased by 15.1%,and the impact strength increased from 55.3 kJ/m² to 56.0 kJ/m²,increased by 1.3%.The mechanical properties of the composites are obviously improved.

When core-shell magnetic nanowires are used as high-density magnetic storage units,the upper limit of magnetic storage rate is limited by the resonant frequency of the system.In order to investigate the effect of antiferromagnetic interfacial exchange interaction on the resonance behavior of core-shell magnetic nanowires,the dynamic behavior of the system was studied by means of micromagnetic simulation.In this study,two systems were considered,namely the system with ferromagnetic interfacial exchange interaction and the system with antiferromagnetic interfacial exchange interaction.Firstly,the effect of interfacial exchange interactionon the magnetic resonance behavior of the system was discussed.It was found that the magnetic resonance frequency of the system with antiferromagnetic interfacial exchange interactionwas slightly higher than that of the ferromagnetic system.Then the influence of the external DC magneticfield on the resonance frequency and resonance linewidth of the system was discussed.It was found that the resonance linewidth of the system with antiferromagnetic interfacialexchangeinteractionwas nonlinear to the intensity of the external DC magneticfield.Finally,the influence of temperature on the magnetic resonance behavior of the systems was discussed.It was found that the thermal stability of ferromagnetic system was stronger than that of the system with antiferromagnetic interfacial exchange interaction.

Periodic operation of chemical reaction is a technology to improve system performance by using reaction nonlinearity.Its evaluation and optimization are still the key problems to be solved in industrial application.The nonlinear output frequency response functions method based on synchronous periodic operation of inlet concentration and inlet temperature is proposed for a typical nonlinear continuous stirred tank reactor.Firstly,the individual contribution of each periodic operation input to the system performance index is derived and analyzed;Secondly,the optimal phase difference to maximize the conversion is selected;Finally,the contribution of each order cross term of synchronous periodic modulation of inlet concentration and inlet temperature is determined.The simulation results show that the proposed method is better than the traditional NFR method and single variable NOFRFs method,and improves the accuracy of cycle operation evaluation.At the same time,the optimal design was carried out under the allowable process constraints,which significantly improved the conversion of reactants,and provided a reference for other types of chemical reaction process cycle operation evaluation and optimization.

Ferromagnetic metal/alloy particles can effectively regulate the electromagnetic properties,but the eddy current effect induced by the local agglomeration of particles limits the further improvement of the material′s electromagnetic absorbing properties.In this work,Co microspheres,microflakes and dendritic crystals were fabricated by a simple solvothermal method.The Co microflakes exhibits strong,broad,and thin wave-absorbing properties from the C～Ku(4~18 GHz)bands.SEM characterization results show that the diameter of Co microflakes is 12~78 μm and the thickness of Co microflakes is 0.1~0.5 μm.VSM measurement shows that the Co microflakes have excellent static magnetic properties,with a saturation magnetization of 148.6 A·m²/kg and a coercivity of 0.96 A/m.Electromagnetic performance tests show that Co microflakes have strong dielectric loss and magnetic loss capabilities.When it is used as filler,the strongest reflection loss(RL_max)is as high as 62.77 dB at 5.0 GHz,the effective absorption bandwidth is 1.2 GHz,and the thickness is only 2.37 mm.Co microflakes have a wide absorption frequency(completely cover C,X and Ku bands),strong reflection loss and thin thickness,providing a good model material for rationally designing thin,light,wide and strong electromagnetic wave absorbers.