- 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)
Intelligent material is a new type of smart multifunctional material that can spontaneously sense the change of external environment and judge, handle and properly make the response. At the same time, it's also the fourth generation material after natural material, synthetic polymer and artificial design material, triggering a new revolution in material science. Starting from the historical origin of shape memory composite, this paper details the latest development of shape memory alloy and shape memory polymer from aspects of shape memory mechanism and engineering application. The discussions of recent technological problems are also included, such as the weak biocompatibility, small deformation, slow actuation velocity and brief fatigue life of SMA as well as the complex manufacture of 3D printing, small strength and stiffness of SMP, etc. The possible near development directions are finally forecasted.
Silk fibroin is a natural polymer with biocompatibility, biodegradability and other excellent properties, which is a promising material in the fields of medicine, food and cosmetics, etc. In this work, the preparation techniques, material structure, properties and development trend for silk fibroin and its composites with natural biological protein, inorganic material, synthetic polymer, carbon nanotube and graphene oxide were introduced, respectively. The preparation principles of materials were explained, with an emphasis on the relationship between preparation methods and properties. The interaction mechanism between individual composites was analyzed, and the application on tissue engineering, drug application, anticoagulant materials and other aspects were also summarized. According to the key factors which restrict the research and development of silk fibroin and its composites, the promising future development ways were proposed, for example, realizing the scale production, developing the intelligent materials and restructuring modification of silk fibroin from the gene aspect.
The petrochemical equipment is subjected to electrochemical corrosion under the circumstance of which there are many chemical substances such as acid, alkali and salt. For the above electrochemical corrosion problems, using conductive polymer composite coating to resist corrosion of steel was put forward in this paper. The three kinds of anti-corrosion mechanism of the polyaniline coating in details were discussed, including metal oxide passivation, shielding effect and corrosion inhibition effect.A range of polyaniline and polyaniline composite coating and the application of the anticorrosion on steel were summarized, the application of polyaniline/inorganic composite coating was emphasized and the research trend of polyaniline coating was prospected. Polyaniline composite coating, especially binary and multi-components composite coating and the corrosion mechanism of composite coating will be the trend of future research and development.The preparation of polyaniline composite coating and corrosion protection study in complex environment will provide the reference to the application of that in a complex environment.
CaBi2Nb2-xCoxO9 ceramics were prepared by a solid-state reaction method. The effect of Co doping on their piezoelectric, dielectric and conductive properties was studied. The results show that the structure of Co doped CBN ceramics is the orthorhombic symmetry and CaBi2Nb1.95Co0.05O9 ceramics are found with impurity phase. All of the CBNCo ceramics have compact structures and are in good sinter condition. The density and the piezoelectric activity of CBN ceramics are obviously improved with Co doping contents. Co dopant greatly decreases the dielectric loss values and slightly increases the Curie-temperature of CBN ceramics. Meanwhile, the introduction of Co dopant increases the number of defects and thus changes the conductive mechanism.
The TiO2/reduced graphene oxide composite, synthesized by a facile one-pot hydrothermal method, was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectrum, and ultraviolet-visible (UV-Vis) spectroscopy to observe the crystal structure, intensity of functional group, microstructure and optical property. The composite material was synthesized by using glucose, sodium dodecyl sulfate (SDS), polyvinylpyrrolidone (PVP) as inducing agents, respectively. The structure and photocatalytic activity for degradation of methyl orange (MO) of the composite were investigated. The results reveal that the composite induced by glucose and SDS shows the highest activity, whose degradation rate can be up to 92% in 30min. However, 120 minutes is necessary for the commercial P25 to remove 90% methyl orange (MO). Compared with the composite prepared by self-assembly with no inducing agent, there are no obvious difference existing in the one induced by polyvinylpyrrolidone (PVP) in terms of photocatalytic reactivity.
K2SiF6:Mn4+ phosphor was prepared by wet chemical etching, and the effect of the raw material molar ratio of K/Mn of different materials and different reaction time on the structure and properties of phosphor was studied, the surface of K2SiF6:Mn4+ was coated with SiO2 to improve the thermal stability of K2SiF6:Mn4+ phosphor by sol-gel method. The structure, morphology, excitation spectrum and emission spectrum of phosphor powder were characterized by X-ray diffraction, scanning electron microscope and fluorescence spectrometer. The results show that the change of K/Mn ratio does not change the crystal structure of K2SiF6:Mn4+, the sample has cubic structure. At 460nm excitation, the strongest narrowband emission peak is located at 630nm (2Eg → 4A2). The crystal structure of K2SiF6:Mn4+ phosphor coated with SiO2 has not been changed. The results show that the thermal stability of the K2SiF6:Mn4+ phosphor coated with SiO2 is improved.
Chitosan, extenders anointed and in-situ synthesis method were used to synthesize anode-composite lead-carbon batteries.SEM, EDS, BET and RM were used to characterize and analyze the morphology of carbon materials.The results show that chitosan-carbon has non-crystal structures.Its pore size distribution is between 5-10nm.Specific surface area reaches to 487.4m2/g.The negative composite material electrode is mixed with a conductive agent to produce pastel.Pb-C analog battery was assembled.Electrochemical workstation is used to test chronoamperometry curves, electrochemical impedance spectroscopy so as to evaluate the possibility of in-situ synthesis anode composite material and its potential value of practical application.Electrochemical testing results show that the Pb-C negative plate, which is made by anode composite carbon material as the carbon source of in-situ synthesis of chitosan, possessing better electrochemical performance and smaller resistance.Its specific capacitance of cyclic voltammogram test is 162.9F/g with longer first discharge platform, the ultimate capacity reaches to 108.722mAh·g-1 when chitosan as carbon source, the specific capicity is 98% of the theoretical capacity. After 1000times of cycle there is almost no decay in capacity.
Nanosized FeNi particles were loaded along multiwalled carbon nanotubes (MWCNT) to achieve high performance to attenuate electromagnetic (EM) waves of 2-18GHz and power frequency (50Hz). The MWCNT/Ni was produced through the electroless plating method, then followed by a polyol approach to produce MWCNT/FeNi composite nanowires. The microstructure of MWCNT/FeNi composite nanowires was characterized by transmission electron microscopy, scanning electron microscope, X-ray diffraction and vector network analysis. The results show that the multi-component structure endows MWCNT/FeNi composite nanowires with effective EM absorption band (RL < -10dB) covering the frequency range of 3.5-13.5GHz. Meanwhile, 76% electric field and 58% magnetic field are produced with the attenuation of 50Hz power frequency electromagnetic (EM) wave.
The FexNi1-x (0 < x < 1) alloy powders with different compositions were prepared by an oxalate precipitation-precursor thermal decomposition process. The phase structure and morphology of the precursor and FexNi1-x powder were characterized by XRD and SEM, respectively. With the increase of Ni content, the phase structure of precursor was gradually changed from FeC2O4·2H2O to NiC2O4·2H2O, and the morphology was changed from short rod to cube and polyhedron. The FexNi1-x powders show porous structure and its geometric shape is similar to the corresponding precursor and the particle size becomes smaller. The phase structure of FexNi1-x powders is changed with the composition from iron-rich bcc to nickel-rich fcc structure. The electromagnetic parameters of the composites of FexNi1-x powders and paraffin were measured and the microwave absorbing properties were calculated. The results reveal that Fe0.5Ni0.5 sample shows a best electromagnetic loss, and when the composite thickness is 3.0mm, the minimum RL reaches -52.58dB at 6.82GHz. Fe0.6Ni0.4 sample with a thickness of 1.5mm shows a maximum effective bandwidth (RL < -10dB), which reaches up to 4.02GHz.
A kind of alumina ceramic was prepared by atmospheric pressure sintering under air atmosphere using MgO-CuO-TiO2-Eu2O3 as sintering additive. The effect of Eu2O3 doping amount and sintering temperature on the phase composition, microstructure as well as dielectric properties of Al2O3-based microwave ceramic samples was studied by XRD, SEM and EDS. The results show that the Al2Eu2O9 secondary crystalline phase is present in all Al2O3 ceramics with Eu2O3 addition, and the Al2Eu2O9 phase is enhanced with the increase of Eu2O3 content. With higher Eu2O3 content, the density of Al2O3 ceramics increases first and then decreases. As sintering temperature increases, the dielectric constant and quality factor Q·f of Al2O3 ceramics increase first and then decrease. When the sintering temperature rises up to 1450℃ and the content of Eu2O3 is 0.25%(mass fraction), the relative density of the sintered body reaches to the maximum of 98.21%, and the dielectric properties of the Al2O3 ceramics are superior with the dielectric constant 10.05 and the quality factor Q·f 37984GHz.
The Al-TiO2-C grain refiners with the mass fraction of 0.3% La2O3 were synthesized by the exothermic dispersion method using Al, TiO2, C, and La2O3 powders as raw materials, The refiners were fabricated by different compacting pressures, including 80, 85, 88, 90kN and 92kN respectively. Effect of Al-TiO2-C refiners prepared by different compacting pressures on refinement performance of ZL101 alloy was studied. The effects of compacting pressures on the phase morphology and microstructure of Al-TiO2-C refiners were investigated by using XRD, SEM and EDS analysis. The refinement capability of Al-TiO2-C refiners on ZL101 alloy was evaluated by using extracting characteristic values from thermal analysis cooling curves of ZL101 alloy, which comes from MATLAB software. The results show that the optimal compacting pressure is 90kN, Al3Ti exhibiting round block obviously increases and the size is uniformly distributed in the microstructure of refiners; moreover, the number of nucleation particles TiC as well as Al2O3 is increased. Al-TiO2-C has the best refinement performance on ZL101 alloy.
The AlCoCuFeMnNi high-entropy alloy cladding layer with CeO2 was prepared by plasma cladding technology on 45 steel. The microstructure and phase composition of the cladding layer were investigated by XRD, SEM and EDS, and its microhardness and wear property were also tested. The results show that the phase structure of the cladding layer is mainly composed of BCC dendrites and FCC interdendrites. Thermodynamic calculation shows a small amount of AlCoNi phase exists in the cladding layer without CeO2, and a large number of Fe-rich precipitated particles in the dendrites is observed, the hardness value exhibits gradient changes from 260HV0.2 to 420HV0.2, and their friction coefficient is between 0.16 and 0.57. After adding 1%(mass fraction) CeO2, the Fe diffusion decreases into cladding layer, and a 32μm Fe-rich peritectic transition layer is formed on the bottom of the cladding layer. The average hardness value is about 400HV0.2, and their friction coefficient is relatively stable (0.28-0.31). The mass loss of the layer with CeO2 is 74.4% of that without CeO2. The grain refinement strengthening is the main reason of the improvement of wear properties.
Different sizes and graded mixed WC particles reinforced iron matrix composites were prepared by powder metallurgy, in which Fe30A self-fluxing alloy was used as the matrix, and the cast WC and the WC-Co as the reinforcement. Microstructure and phase of the composites were analyzed. The results show that the cast WC particles are dissolved from the edge of the particles and react with the matrix to generate the flocculent Fe6W6C interlayer and disperse Ni17W3 small particles, and part of the WC-Co particles are transformed into Ni17W3 particles. The microstructural morphology of the mixed particle reinforced composite materials presents that small particles are uniformly distributed between large particles, and the small particles can be the primary particles or the Ni17W3 particles. The hardness and wear properties tests of the composite materials show that the graded mixed reinforced composite has higher hardness and better wear resistance.
The full Cu3Sn solder joint has been widely used in 3D packaging gradually. 270℃ and 1N were chosen as soldering temperature and pressure respectively to fabricate solder joints under different soldering time in order to analyze the process of microstructural evolution.Cu6Sn5 morphology with different soldering temperatures and time was also observed respectively to investigate the growth law of Cu6Sn5 and the effect of soldering temperature on the Cu6Sn5 morphology. The results show that scallop-like Cu6Sn5 is formed along the Cu substrate after 30min soldering, and a thin layer of Cu3Sn is generated between Cu6Sn5 and Cu substrate.When the soldering time is increased to 60min, liquid Sn is totally consumed and Cu6Sn5 becomes a cohesive whole. With the increase of soldering time, Cu3Sn grows at the expense of Cu6Sn5. Cu6Sn5 is totally transformed into Cu3Sn up to 480min. The growing process of Cu6Sn5 includes nucleation, growth, fusion and covering up the big grain. With the increase of soldering temperature, the morphology of Cu6Sn5 changes from polyhedron shape to procumbent.
The influence of quenching temperature and holding time in dual-phase region on microstructure and mechanical properties of 7Ni steel was studied by X-ray diffractometer, scanning electron microscopy and thermal dilatometer. Based on the thermal expansion curve, the production and transformation rate of reversed austenite of 7Ni steel under each stage of the QLT treatment was quantitatively measured, and the transformation process of reversed austenite was revealed. The results indicate that the transformation of reversed austenite during QLT treatment successively goes through four stages:quenching temperature holding, quenching cooling, tempering temperature holding and tempering cooling. Appropriately improving the quenching temperature in dual-phase region and extending the holding time is beneficial to the transformation of reversed austenite during tempering, and also promotes its uniform distribution, which consequently reduces the strength and enhances the ductility as well as toughness of 7Ni steel. Under the quenching in dual-phase region treatment at 660℃ for 30min, the comprehensive mechanical properties of the 7Ni steel are the best, which completely meet the mechanical property requirements of 9Ni steel stipulated by ASTM A553.
The Zr-1Nb alloy was treated by laser melting and vacuum annealing in order to improve the high temperature corrosion resistance. The morphology of the melting layer was observed by scanning electron microscopy, phase compositions and quantities were determined by X-ray diffraction and Raman; surface roughness was determined by profile meter; and hardness was measured by the micro-hardness tester. In order to characterize the corrosion resistance, autoclave experiments were conducted for 70 days in an aqueous steam condition of 360℃ under 18.6MPa in 0.01mol/L LiOH solutions. The results show that the surface roughness of Zr-1Nb cladding tubes is improved by laser melting; the laser melted layer is mainly composed of α-Zr phase and a small amount of m-ZrO2, and the phase composition of laser melted layer does not change after heat-treatment; under high power condition, laser melting can reduce the high temperature corrosion resistance of Zr-1Nb alloy. However, the high temperature corrosion resistance of Zr-1Nb alloy can be improved significantly under the condition of low power laser melting and auxiliary heat treatment process. By laser melting treatment, microhardness of zirconium alloy can be increased by 50-80HV0.1. And after heat treatment, microhardness of zirconium alloy is decreased compared with the laser melted sample, but it is still higher than the origin sample.
TC4 alloy samples were built by selective laser melting (SLM). The microstructure was observed, and electrochemical measurements were performed to investigate the corrosion resistance of SLMed TC4 alloy in different forming surface and roughness. The traditional rolled sample was introduced as a reference. Results show that processing method, forming surface and roughness act a significant role in influencing the corrosion resistance. The microstructure of SLMed TC4 on vertical section consists of the primitive columnar β grains filled with a large number of acicular α' martensites oriented at approximately ±45° with building direction. Unlike the typical α+β phase of traditional rolled sample, a chessboard pattern is observed on cross-section of SLMed TC4. The electrochemical results suggest that the corrosion resistance of traditional rolled sample is superior to that of SLMed sample. SLMed TC4 sample exhibits a better corrosion resistance on the vertical section, compared with the cross-section. Besides, the SLMed sample with rougher surface exhibits poorer corrosion resistance. Obvious etch pit is found on the surface of SLMed sample and the corrosion morphology is pitting.
Hot corrosion behavior of a new cobalt-base superalloy at 900℃ in the molten NaCl was investigated by salt-leaching method. The results show that the selective oxidation occurs at the initial stage of corrosion, and the oxidation films including Al2O3, Cr2O3 and a small amount of TiO2 are formed on the surface of the superalloy. However, the protective Cr2O3 and Al2O3 are corroded by the molten NaCl and then the substrate is exposed to the corrosive substances, so that the corrosion rate is accelerated. During the corrosion, rod Al2O3 is formed in inner corrosion layer, and then Co3W is easily formed around Al2O3 owing to the depletion of Al element in the matrix. As a result, a fast path for O diffusion is formed in the interface between Co3W and rod Al2O3 phase, resulting in the increase of hot corrosion rate after 80h.
The surface of 20CrMnTi steel was strengthened by the square-spot laser shock peening(LSP) with 25J and 30J pulse energy. The layered style morphology, roughness, micro-hardness and residual compressive stress of the strengthened sample surface by LSP were test. The polarization curve and the corrosion morphology were investigated. The results show that, plastic deformation occurs in the surface after square-spot LSP, the surface roughness Ra of the specimens reduces to 0.433μm, and micro-hardness improves, great residual compressive stress is formed. The appropriate laser power density of LSP increases the density of the strengthened layer and passive film on the surface, and the transverse residual compressive stress makes the passive film more stable, and improves the corrosion resistance of materials. But the too large laser power density will cause the generation of pit defects in the material surface and the ablation of Al foil. Thus the Cl- is accumulated at the pit defects, the local tensile stress is generate on the surface of the material, and the surface passive film on the material is destroyed, and degrade the performance of corrosion resistance of the material.
Fully end-capped silicon-containing arylacetylene (FEC-PSA) terminated with phenylacetylene was prepared in terms of Grignard route. A low viscosity PSA resin for resin-transfer molding (RTM) process was prepared by blending FEC-PSA and PSA. A silane coupling agent triethoxy(acetenyl)silane (TEOAS) was synthesized as a quartz fiber (QF) surface modifier. RTM process was used to fabricate the quartz fabrics reinforced blended PSA composites. The processing performance and thermal properties of the blended PSA, surface of the quartz fibers and the mechanical properties of the composites were investigated. The results show that the blended PSA resin has not only highly heat-resistance, but also good processing performance. XPS analyses indicate that the surface of QF is grafted by ethynyl groups. The interfacial strength between the surface of QF treated by TEOAS and the blended PSA resin is improved. The flexural strength and interlayer shear strength (ILSS) of the interfacial strengthening composites are increased by 28.8% and 25.4%, respectively, compared to the pristine composite without TEOAS-treated QF.
The threshold value of stress intensity factor range was acquired according the study of fatigue crack propagation property of directional PMMA (YB-DM-10). It was found that the plot of fatigue crack propagation rate is accordance with Pairs Law and Walker Law. The effect of angles in plane, frequency and stress ratio on the fatigue crack propagation was studied. According the comparison of coefficient in Pairs Law, Walker Law and morphology SEM in fracture surface under test conditions with different parameters, the effect of different parameters on fatigue crack propagation rate was analysed. Results show that the fatigue crack propagation rates of test specimens with different cutting angle in XY plane of PMMA sheet are nearly the same. The frequency has slight effect on the fatigue crack propagation, except that data become separate in the third region of da/dN-△K plot. On the condition of same stress intensity factor range, the fatigue crack propagation rate accelerates as the stress ration increases. The result of the study established foundation for the application of directional PMMA and the research on the damage tolerance of transparent materials used in aircraft cockpit canopies.
The aging behavior of silicone rubber seals during long-term storage was studied by scanning electron microscope, attenuated total reflection-Fourier transform infrared spectroscopy, pyrolysis gas chromatography-mass spectrometry, thermogravimetric analysis and compression set test. The results show that the mechanical properties of silicone rubber seals stored in natural storehouses and sheds are seriously degraded. The grease plays a protective role in silicone rubber samples stored in natural storehouses. The degradation reactions mainly occur in the aging process. The phenyl isocyanate is migrating from inner to surface of silicone rubber samples in the long-term storage aging process. The aging mechanism of silicone rubber samples stored in natural storehouses and sheds is basically identical, and the external environment has an important impact on the microstructures and thermal stabilities of the silicone rubber seals.
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