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In order to solve the complex load transfer and structural design of the joint structures including skin, longeron and frame in the composite fuselage, the adhesively bonded integrated composite joint was designed. Static tensile test was performed and the strain-load curves and damage modes were obtained. Then the numerical simulation model of integrated composite joint was built. The damage initiation, propagation and failure process of integrated composite joint under tensile load were simulated and analyzed. Results show that: the first load drop and the ultimate failure load of the joint are 120.82 kN and 168.11 kN respectively; the initial damage occurs at the corner bend region of the lower-left corner-shaped preform, and extends across the radius bend region among short flange, long flange and web, and leads to the interface debonding of the upper and lower corner-shaped preform and the delamination of corner-shaped preform and L-shaped preform. Compared with the experimental results, the errors of the first load drop and the ultimate failure load from numerical calculated results are 6.68% and 2.61% respectively, which agree with each other very well.

Quasi-liquid solid electrolytes are a promising alternative for next-generation Li batteries. These systems combine the safety of solid electrolytes with the desired properties of liquids and are typically formed by solutions of Li salts in ionic liquids incorporated into solid matrices. Here, we present a fundamental understanding of the transport properties in solutions of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]), either in bulk form or incorporated in a boron nitride (BN) matrix. We performed a series of quasi-elastic neutron scattering experiments that, given the high incoherent neutron scattering cross section of hydrogen, allowed us to focus on the Emim+ dynamics. First, [Emim][TFSI]/LiTFSI solutions (0.5 and 2.5 mol·kg-1) were investigated and we show how the increase in the concentration reduces the Emim+ mobility and increases the activation energy of their long-range motions. Then, the 0.5 mol·kg-1 solution was incorporated into the BN matrix and we report that the diffusivities of the Emim+ cations that remain mobile under confinement are highly accelerated in comparison with the bulk sample and the activation energy of these motions is drastically reduced. We present the experimental evidence that this effect is related to the content of the Emim+ cations immobilized near the surfaces of the BN pores.

This research uses nanotechnology and molecular assembly technology, using biocompatible hydroxyapatite material as the inorganic filler, organically compound and assemble with the organic resin matrix to achieve the performance shear of the composite material, thus developing strength High-resistance, easy-to-process and good biocompatibility composite resin dental restoration materials, and the nano-composite resin material flexural strength, compressive strength and water absorption value were characterized in laboratory stage, the performance fully reached the current clinical use Various indicators of imported composite resin. This study analyzed the differences in the effects and friction properties of different prosthetic materials in oral repair. In order to better simulate the friction and wear performance of dental restoration materials in the oral environment, this paper studied under two conditions of oil lubrication and artificial saliva lubrication, and the wear mechanism from the macro aspects of friction coefficient, wear rate, wear resistance, etc. The research results show that the abrasion performance of the nanocomposite resin is closely related to its surface morphology and characteristics. The comparison with the performance of ceramic and composite resin restoration materials shows that nanocomposite resin materials have better mechanical properties and resistance than other dental restoration wear performance.

Al-60wt.%Si composites were successfully prepared by semi-solid squeezing powder mixture of Al and Si at 700 °C. The appearance of about 50wt.% Al-Si metal liquid results that less than 4–5 MPa pressure can squeeze the Al-Si powder mixture to near full density at vacuum condition. The effects of Si particle size on the microstructure and properties of Al-60wt.%Si were investigated. The results show that the composites are consisted of only Si and Al. Si particles distribute evenly in aluminum matrix. Al matrix exhibits a certain preferred orientation under the condition of directional solidification. Si particles with 5 μm size tend to be aggregated into locally interconnected particles and can be effectively passivated. As Si particle size ranges from 10 to 20 μm, the corner passivation effect for Si particles is gradually suppressed. The fracture morphology of Al-60wt.%Si is composed of cleavage platforms of Si grains and fine tearing ridges of Al which tightly wraps Si grains. With the increase of Si particle size from 5 to 20 μm, the flexural strength of Al-60wt.%Si decreases from 270 MPa to 223 MPa, the thermal conductivity increase from 128 to 136 W·m−1·°C−1, and the average coefficient of thermal expansion from ambient temperature to 400 °C ranges from 9.49 to 9.97 × 10−6 °C−1.

Copper based composites with high graphite contents for pantograph sliders have been manufactured via an inexpensive powder metallurgy method. Large size cluster graphite is added into the matrix as solid lubricant to optimize the mechanical and wear performance of the composites. The mechanical performance and microstructure of graphite cluster/ copper-based (GC/Cu) composites are investigated. The highest graphite content in GC/Cu composites can reach up to 5 wt%. The graphite cluster/copper-based composites show an outstanding mechanical performance, in which the impact toughness can reach 4.8 J/cm2 with 5 wt% graphite cluster. The matrix is constituted with single α-phase Cu10Sn3with second phase particles CuNi2Sn. Moreover, friction and wear behavior with or without electric currency have been explored systematically, which indicates that the friction coefficient with 5 wt% graphite composites reached a minimum of 0.184 at a load of 25 N. It also exhibits the excellent friction performance under the effect of electric current. The smallest wear rate of 4.2×10−3 mg/m occurs in the sample with 2 wt% graphite at 30 A. Meanwhile, the interaction between pantographs and contact wire has been investigated based on elemental analysis and surface morphology. Oxidation and material transfer is found on the worn surface.

Co-Cu composite powders with different Cu contents were synthesized via an ultra-rapid solution combustion synthesis (SCS) method and WC-10(Co/Cu) cemented carbides with an ultrafine grain size were prepared by microwave sintering the compacts of powder mixes of WC and the Co-Cu composite powders. The effects of Cu addition on the microstructure and properties of the microwave-sintered WC-Co cemented carbides were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), field emission transmission electron microscopy (FE-TEM) and mechanical properties tests. The results showed that the addition of a small amount of Cu instead of Co in the WC-Co cemented carbides enhances the sintering, restrains the WC grain growth and improves the mechanical properties. The average WC grain size decreases as Cu is added, and the grain size distribution narrows. The Rockwell hardness and fracture toughness of the WC-10(Co/Cu) alloys with a 0.5 wt% Cu addition reach 90.7 HRA and 14.3 MPa m−1/2, respectively. In addition, the transverse rupture strength (TRS) reaches 2544.7 MPa with a 1 wt% Cu content. The present results show that Cu-doped WC-Co cemented carbides have excellent comprehensive performances.

In this paper, high-Si reinforced Al matrix composites (H-Si/Al) with Si mass ratio 50–70% were successfully fabricated from the powder mixture of Si and Al by a novel route called as powder semi-solid squeeze. It is found that no Al–Si lamellar eutectic in the composites. As the Si content increases, fine Si particles in the H-Si/Al are reduced and the coarse Si particles may increase in size, or gather together to form twisted large particles and even form a space network structure. With the Si content ranging from 50% to 70%, The flexural strength varies between 248 and 179 MPa, the mean coefficient of thermal expansion from ambient temperature to 100 °C can be regulated between 11.32 and 7.55 × 10 −6 °C −1 , and the thermal conductivity varies between 140 and 120 W m −1 °C −1 , showing that H-Si/Al prepared by powder semi-solid squeeze have excellent mechanical and thermal properties.

Commercial F500 SiC powder and 6061 Al powder were chosen to fabricate the 50 vol.-% SiCp/6061Al composites via pressureless sintering. Effects of pre-treatment of the SiC powder and sintering temperature on the microstructures and properties of the composites were studied. Densification mechanism and interfacial reaction of the composites were also investigated. The results show that the composites have a high sintering ability and a low interfacial reaction activity. The density, bending strength and thermal conductivity of the composites are all sensitive to the sintering temperature. The composites sintered at 680°C are nearly fully dense and have the following optimal properties: the relative density of 98.5%, the bending strength of 495 MPa, the TC of 153 W/(m K) and the coefficient of thermal expansion of 8.1 × 10−6/°C (50–100°C), which are superior to most of the SiCp/Al composites of the similar composition reported previously.

High-performance copper-based pantograph slide materials play a crucial role in the rapid development of modern urban rail transit urgently. Herein, a full density graphite/copper-alloy matrix composite for pantograph slide has been successfully obtained by the hot powder forging process. The composite exhibits the full density when forging energy density is 307.6 J cm−3. In addition, the influence of different aging treatments on microstructure and mechanical performances of the composite has been studied in detail. The hardness and resistivity of the forged materials are greatly improved after an optimum aging treatment. Simultaneously, the friction and wear performances with or without currency current have been investigated, which demonstrates the friction coefficient can reach the minimum of 0.109 under 35 N. In current-carrying friction, the wear rate of the composite is an extremely small value of 5.5 × 10–5 mg m−1 after the aging treatment, indicating the outstanding anti-friction and self-lubricating performance. All the comprehensive analyses illustrate the full density graphite/copper-alloy matrix composite with excellent mechanical shows an enormous potential for pantograph slide.

SiC/Al composites with uniformly distributed SiC particles were fabricated by pressureless infiltration of liquid AlSi7Mg alloy into SiC preforms with different porosity derived from SiC powders. The linear expansion of SiC preforms without any deformation was about 4% due to the oxidation of SiC powders during the sintering process. SiC preforms had no change in both shape and dimensions after infiltration so that near-net-shape composites were achieved. As SiC volume fraction varies from 39% to 62%, the thermal conductivity of SiC/Al composites with bending strength beyond 360 MPa and elastic modulus beyond 140 GPa varies from 146 to 118 W m−1 K−1 at room temperature, and the mean linear coefficient of thermal expansion from room temperature to 373 K varies from 10 × 10−6 to 7.69 × 10−6 K−1, agreeing better with the Turner's model.

The nanocrystalline β-SiC powder was successfully synthesized by ball milling the Si-50%C elemental powder. During ball milling, a solid solution of C in Si, Si(C), firstly forms, followed by SiC. The formation of SiC is controlled by the mixing mechanism of the gradual diffusion reaction(GDR) and the mechanically induced self-propagating reaction(MSR). The amount of β-SiC increases with milling time increasing. After 40 h milling, there exists only β-SiC in the milled powder. The grain size of β-SiC is about 6.4 nm after the powder is milled for 60 h. After the 60 h-milled Si-50%C elemental powder is heat treated at 1 100 °C for 1 h, the grain size of β-SiC does not change, but the lattice ordering degree of β-SiC increases.

The TiC and TiB 2 powders were successfully synthesized by ball milling the Ti 50 C 50 and Ti 33 B 67 elemental powders, respectively. During ball milling the Ti 50 C 50 powder, a solid solution of C in Ti, Ti(C), was first formed, followed by TiC. After milling for 80 h, the powder was composed of TiC with grain size of 6 nm and a small amount of Ti(C) which was finally completely transformed to TiC after heat treatment. During ball milling the Ti 33 B 67 powder, a solid solution of B in Ti, Ti(B), was first formed followed by the formation of an amorphous structure which transformed into a hexagonal phase of TiB 2 with grain size of about 10 nm.

TiB2 nanocrystalline powder was synthesized by mechanical alloying of Ti-67B elemental powder. X-ray diffraction(XRD) and transmission electron microscopy(TEM) were used to study the structural evolution of the powder during ball milling. The effects of heat treatment on the structural evolution and thermal stability of the mechanically alloyed(MAed) Ti-67B powder were also discussed. During ball milling the Ti-67B powder, a solid solution of B in Ti, Ti(B) is firstly formed. When the powder is milled for 10 h, the amorphous transition of Ti(B) from the crystalline to the amorphous phase occurs. When the powder is milled for 20 h, nanocrystalline TiB2 is formed from the amorphous Ti(B). When the powder is milled for 60 h, only TiB2 is detected with grain size of 10 nm. The formation of TiB2 nanocrystalline is controlled by the gradual diffusion reaction mechanism. During heat-treatment of the MAed Ti-67B powder, the structural changes of TiB2, including grain growth and lattice ordering degree increasing may occur.