Amino-terminated polyethers and amino-terminated polyurethane were used as curing agent to cure the epoxy resin together and get a series of cured products. The damping properties of the composites were studied by DMA...
详细信息
Amino-terminated polyethers and amino-terminated polyurethane were used as curing agent to cure the epoxy resin together and get a series of cured products. The damping properties of the composites were studied by DMA test at different measurement frequencies. Damping mechanical tests show that the flexible epoxy resin has higher loss factor than common epoxy. The highest loss factor reaches 1.57. Also the height and position of loss factor peak of the flexible epoxy resin varies by changing the content of amino-terminated polyethers. Results shows that the flexible epoxy resin can be used as damping polymer materials at room temperature or in common frequency range.
Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene (CLPS) as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysila...
详细信息
Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene (CLPS) as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysilane (VTES), vinyl trimethoxysilane (VTMS) and γ-methacryloylpropyl trimethoxysilane (MPS). The treated glass fibers were analyzed by fourier transform infrared spectroscopy (FTIR). Dynamic mechanical thermal analysis (DMTA) and thermo-gravimetric analysis (TGA) were employed to investigate the effect of glass fibers surface modification on viscoelastic behavior and thermal properties. The morphology of fracture surfaces of various composites was observed by scanning electron microscopy (SEM). The results revealed that these coupling agents were connected to the surfaces of the fibers by chemical bonding. Dynamic mechanical properties as well as thermal stability of the composites were improved considerablely, but to varying degrees depending on the fiber modification. The diversities of improvement of properties were attributed to the different interfacial adhesion between CLPS matrix and the glass fibers.
As pore-forming materials, the coated polyop-hydroxybenzoate(short for PHB) and h-BN can be applied in the preparation of abradable seal coatings at high temperature. The characteristics of coating such as morpholog...
详细信息
As pore-forming materials, the coated polyop-hydroxybenzoate(short for PHB) and h-BN can be applied in the preparation of abradable seal coatings at high temperature. The characteristics of coating such as morphology, thermal stability and composition were studied by SEM, EDS and FTIR. The results show that the modified PHB will change the remained carbon amount, porosity and pore morphology of the coating, which can affect the properties of coatings. If the pore is small enough in uniform distribution, the coating with 5 MPa bond strength, 30-55 HR45Y superficial hardness and certain of carbon can be suitable to well abradability.
Most inorganic thermoelectric semiconductors are intrinsically brittle,restricting the application of ther-moelectric ***,developing ductile thermoelectric materials is crucial to thermoelectric technology *** this wo...
详细信息
Most inorganic thermoelectric semiconductors are intrinsically brittle,restricting the application of ther-moelectric ***,developing ductile thermoelectric materials is crucial to thermoelectric technology *** this work,single-phase SnTe bulks with dense dislocations were prepared by melting quenching combined with spark plasma *** resulting SnTe thermoelectric materials exhibited a large compressive strain of∼7.5%at room temperature,originating from high-density pre-existing mobile *** initiation of localized slip bands and preferred slip system were also identified by first-principles *** microstructural characterizations reveal that the thermal activated dislocation emission and migration lead to higher compressive strains at intermediate *** 673 K,the deformation mechanism changed from dislocation mediated to grain boundary mediated plasticity,resulting in an ultra-high compressive strain of∼42%.In sum,new insights into the mechanical behavior of SnTe thermoelectric material over a wide range of temperatures were *** work offers the dislocation engineering strategy to design ductile thermoelectric materials for flexi-ble electronics and energy systems.
Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power *** fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions *** and ...
详细信息
Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power *** fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions *** and Ti5Si3 were two important intermediate phases during the whole *** microstructure characteristics of the Ti3SiC2/TiB2 composites were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The experimental results show that the grains of Ti3SiC2/TiB2 composite are structured in a layered form,and the formation of TiB2 particles as reinforcements with elongated or equiaxed shape distributes in Ti3SiC2 matrix.
Using high aluminum refractory material as substrate at 1400℃, we studied the connections between several oxides such as Fe203, MnOv CuO, and the formation of defects such as coating crack, exfoliation, blistering, e...
详细信息
Using high aluminum refractory material as substrate at 1400℃, we studied the connections between several oxides such as Fe203, MnOv CuO, and the formation of defects such as coating crack, exfoliation, blistering, erosion, and fading away appeared in the application of high temperature infrared radiation coating. Analyses showed that thermal stress formed during the heating process due to the thermal expansion coefficient differential between the coating and the substrate, and volume effect caused by the crystal transferred when the temperature changed, which resulted in the coating crack and exfoliation. The gas produced by the reactions between components and binder or the components themselves during the heating process caused the coating blistering. The EMPA and XRD analyses show that oxides with low melting point in the penetrating area of the substrate may form eutectic with low melting point and produced thermal defects, which leads to the erosion by penetrating to the substrate. The valent changes of Fe2O3 and MnO2 during the heating process cause the volatilization of the oxides or the pulverization of the coatings, resulting in the coating fades away easily at high temperature for a long time.
The photocatalytic reduction of CO_(2) is a promising strategy to generate chemical ***,this reaction usually suf-fers from low photoactivity because of insuffi cient light absorption and rapid charge *** engineering ...
详细信息
The photocatalytic reduction of CO_(2) is a promising strategy to generate chemical ***,this reaction usually suf-fers from low photoactivity because of insuffi cient light absorption and rapid charge *** engineering has become an eff ective approach to improve the photocatalytic ***,ultra-thin(~4.1 nm)carbon-doped Bi_(2)WO_(6) nanosheets were prepared via hydrothermal treatment followed by *** ultra-thin nanosheet structure of the cata-lyst not only provides more active sites but also shortens the diff usion distance of charge carriers,thereby suppressing charge ***,carbon doping could successfully extend the light absorption range of the catalyst and remarkably promote charge separation,thus inhibiting *** a result,the as-prepared Bi_(2)WO_(6) photocatalyst with ultra-thin nanosheet structure and carbon doping exhibits enhanced photocatalytic CO_(2) reduction performance,which is twice that of pristine ultra-thin Bi_(2)WO_(6) *** study highlights the importance of defect engineering in photocatalytic energy conversion and provides new insights for fabricating effi cient photocatalysts.
Designing high cost-effective catalysts has been one of the core topics in energy conversion and *** to unique electronic structure and excellent comprehensive properties,Pt-group metal(PGM)based-materials occupy the ...
详细信息
Designing high cost-effective catalysts has been one of the core topics in energy conversion and *** to unique electronic structure and excellent comprehensive properties,Pt-group metal(PGM)based-materials occupy the top region of numerous volcanic curves and are currently difficult to be replaced by abundant tran-sition metal ***,we pay attention to the osmium(Os),as the cheapest and the least noticed PGM in the field of electrocatalysis,with promising application ***,the three main modification strategies(anion modulation,heterostructure construction,substrate engineering)of Os-based catalysts in hydrogen evolution reaction(HER),the structural advantages provided in oxygen evolution reaction(OER),and other energy-related electrocatalysis applications are discussed one by *** addition,we discuss the key problems and countermeasures faced in their further breakthroughs,and look forward to future development trends and ***,the insights in this work will promote the understanding and designation of Os-based catalysts.
With industrial grade Al(OH)3 as raw materials, the self dispersion nanosized AlOOH crystal powder were prepared by the sol-hydrothermal method. The results of XRD and TEM show that the nanosized AlOOH could automat...
详细信息
With industrial grade Al(OH)3 as raw materials, the self dispersion nanosized AlOOH crystal powder were prepared by the sol-hydrothermal method. The results of XRD and TEM show that the nanosized AlOOH could automatically disperse to a single-dispersing state in water without surface modification, dispersant, additive and accessional conditions (ultrasonic wave dispersing, ball-mill dispersing). The application results of the product indicate that the nanosized AlOOH can be composed into a toughened nanocomposites without surface modification. Accordingly, the self dispersion characteristic and mechanism of hydrothermal crystallization and charging composite dispersion of nanosized AIOOH are found, and a new technique of preparing polymer/inorganic nanocomposites is proposed, which is called blending compositing new techniques of sol even dispersing at auasi-homogeneous phase.
It is still a great challenge for semiconductor based-devices to obtain a large magnetoresistance(MR) effect under a low magnetic field at room temperature. In this paper, the photoinduced MR effects under different...
详细信息
It is still a great challenge for semiconductor based-devices to obtain a large magnetoresistance(MR) effect under a low magnetic field at room temperature. In this paper, the photoinduced MR effects under different intensities of illumination at room temperature are investigated in a semi-insulating gallium arsenide(SI-Ga As)-based Ag/SI–Ga As/Ag device. The device is subjected to the irradiation of light which is supplied by light-emitting diode(LED) lamp beads with a wavelength in a range of about 395 nm–405 nm and the working power of each LED lamp bead is about 33 mW. The photoinduced MR shows no saturation under magnetic fields(B) up to 1 T and the MR sensitivity S(S = MR/B) at low magnetic field(B = 0.001 T) can reach 15 T^(-1). It is found that the recombination of photoinduced electron and hole results in a positive photoinduced MR effect. This work implies that a high photoinduced S under a low magnetic field may be obtained in a non-magnetic semiconductor device with a very low intrinsic carrier concentration.
暂无评论