composite

摘要： Hybrid materials collected from organic and inorganic sources,which are traditionally used as brake lining materials,generally include fly ash,cashew shell powder,phenolic resins,aluminium wool,barites,lime powder,carbon powder and copper powder.The present research focuses on the specific effects produced by fly ash and aims to provide useful indications for the replacement of asbestos due to the health hazards caused by the related fibers.Furthermore,the financial implications related to the use of large-volume use of fly ash,lime stone and cashew shell powder,readily available in most countries in the world,are also discussed.It is shown that many manufacturing and automotive industries,which are currently experiencing difficulties in meeting the increasing demand for brake lining material,may take advantage from the proposed solution.

摘要： The initial geometric imperfection is one of the primary factors affecting the buckling behaviors of composite cylindrical shells under hydrostatic pressure.In this study,ovality and thickness variations as two representative types of the geometric imperfections are considered.After measuring the geometric imperfections,a typical carbon fiber reinforced polymers(CFRP)cylindrical shell is tested to obtain the buckling pressure.The buckling behaviors of the shell sample are analyzed in combination with the strain responses.By using the nonlinear numerical analysis,the buckling shapes of the CFRP cylinder shells with different combinations of ovality and thickness variation are firstly discussed.The rules of influence of such imperfections on the buckling pressure are then obtained by nonlinear regression method.Finally,an empirical formula is proposed to predict the buckling pressure of the composite cylinder shells,and the calculated results from the formula are in good agreement with the numerical results.

摘要： A flexible anode composite,carbon cloth@SiO_(2)composite(CC@SiO_(2)),was synthesized by a one-step solution method using tetraethyl orthosilicate(TEOS)as the silica source.CC@SiO_(2)can be directly used as the negative electrode material for lithium-ion battery,and its initial reversible deintercalation capacity reaches 1358.7 mA·h·g^(-1).The electrode shows a capacity of 863.8 mA·h·g^(-1)up to 130 cycles at 0.5 A·g^(-1),displaying excellent rate performance and cycle stability.

摘要： The fabrication of boron carbide reinforced aluminum matrix composites(Al-B_(4)C)with various contents of B_(4)C(1wt%,6wt%,15wt%,and 30wt%)was performed by powder metallurgy,and the influence of the content of B_(4)C on their mechanical and tribological behavior was examined.The Al-30B_(4)C composites recorded the highest density(~2.54 g/cm^(3)),lowest porosity(4%),maximum Vickers hardness(HV~75),lowest weight loss(0.4 mg),and lowest specific wear rate(0.00042 mm^(3)/(N·m))under a load of 7 N,with an enhancement of 167%in hardness,a decrease of 75.8%in weight loss,and a decrease of 76.7%in the specific wear rate compared with pure aluminum.In addition,the scanning electron microscope images of the worn surface revealed that the Al-B_(4)C composite has the narrowest wear groove of 0.85 mm at a load of 7 N,and the main wear mechanism was observed as an abrasive wear mechanism.According to the friction analysis,the coefficient of friction between surfaces increased with increasing boron carbide content and with decreasing applied load.In conclusion,B_(4)C is an effective reinforcement material in terms of tribological and mechanical performance of the Al-B_(4)C composites.

摘要： The hydropower sector is currently experiencing several technological developments.New technologies and practices are emerging to make hydropower more flexible and more sustainable.Novel materials have also been recently developed to increase performance,durability,and reliability;however,no systematic discussions can be found in the literature.Therefore,in this paper,novel materials for hydropower applications are presented,and their performance,advantages,and limitations are discussed.For example,composites can reduce the weight of steel equipment by 50%to 80%,polymers and superhydrophobic materials can reduce head losses by 4%to 20%,and novel bearing materials can reduce bearing wear by 6%.These improvements determine higher efficiencies,longer life span,waste reduction,and maintenance needs,although the initial cost of some materials is not yet competitive with respect to the costs of traditional materials.The novel materials are described here based on the following categories:novel materials for turbines,dams and waterways,bearings,seals,and ocean hydropower.

摘要： A Zn-38Al-3.5Cu-1.2Mg composite reinforced with nano-SiC_(p) was fabricated via stirring-assisted ultrasonic vibration.To improve the abrasive resistance of the Zn-38Al-3.5Cu-1.2Mg/SiC_(p) composite,several stabilization treatments with distinct solid solutions and aging temperatures were designed.The results indicated that the optimal stabilization treatment for the Zn-38Al-3.5Cu-1.2Mg/SiC_(p) composite comprised solution treatment at 380°Cfor 6 h and aging at 170°Cfor 48 h.The stabilization treatment led to the formation of dispersive and homogeneous nano-SiC_(p).During the friction wear condition,the nano-SiC_(p) limited the microstructure evolution from the hardα(Al,Zn)phase to the softβ(Al,Zn)phase.Moreover,the increased amount of nano-SiC_(p) improved the grain dimension and contributed to the composite abrasive resistance.Furthermore,the stabilization treatment suppressed the crack initiation and propagation in the friction wear process,thereby improving the abrasive resistance of the Zn-38Al-3.5Cu-1.2Mg/SiC_(p) composite.

摘要： Fe_(2)O_(3)was synthesized by the solvothermal method,and the synthesized Fe_(2)O_(3)was added in the process of preparing BiOCl by hydrolysis,and then Fe_(2)O_(3)/BiOCl photocatalytic materials with different composite ratios were prepared.The optimal Fe_(2)O_(3)/BiOCl(1Fe/50Bi)sample showed a highest photocatalytic efficiency for cationic dyes(Rhodamine B)and anionic dye(methyl orange)degradation irradiated with visible light,as compared with that of a bare BiOCl catalyst.Meanwhile,radical capturing experiments indicated that the photo-induced holes(h^(+)) is the main active species.X-ray powder diffraction and ultraviolet-visible diffuse reflectance spectroscopy were used to characterize the structural and optical properties,which proved that Fe_(2)O_(3)was successfully composited to the BiOCl surface and effectively reduced the bandgap of BiOCl.More importantly,the optimal 1Fe/50Bi sample shows the highest photocatalytic efficiency for tetracycline(TC)degradation(98%)irradiated with visible light,as compared with that of a bare BiOCl catalyst.Consequently,the Fe_(2)O_(3)/BiOCl photocatalyst have potential applications in environmental purification.

摘要： The most common process to manufacture advanced composites is the costly autoclave.One of the out-of-autoclave alternatives is the low-cost vacuum assisted resin infusion(VARI)which produces quality parts with less pollution.Epoxy resin is a widely used composite matrix resin,but its high flammability limits its use as interior composite parts for vehicles.The usual flame retardant for epoxy involves halogen,which is effective but has high smoke toxicity.As a result,halogen-free flame retardant epoxy resin systems become dominant.In this paper,phosphorus flame retardant was combined with benzoxazine(BOZ)to produce synergistic effect and achieve satisfactory flame retardance,as well as mechanical improvement for the epoxy resin.Differential scanning calorimetry(DSC),dynamic mechanical analysis(DMA),thermal gravitational analysis(TGA),the cone calorimeter(CC),and limiting oxygen index(LOI)were used to characterize the resins.The results showed significant improvement on the flame retardance of the synergistically modified resins.Specifically,the carbon residue increased by 113.6%,and the char thickness increased by 6 to 7 times,compared to those of the flammable benchmark resin.The LOI reached 33 and passed the UL94 V-0 vertical burn rating.The modified resins also exhibited adequate stability and viscosity suitable for VARI processes.

摘要： A large part of the energy savings in the building sector comes from the choice of materials used and their structures. We are interested, through a numerical study, in establishing the link between the thermal performance of composite materials and their microstructures. The work begins with the generation of a two-phase 3D composite structure, the application of the Random Sequential Addition (RSA) algorithm, and then the finite element method (FE) is used to evaluate, in steady-state, the effective thermal conductivity of these composites. The result of the effective thermal conductivity of composite building material based on clay and olive waste at a volume fraction of 10% obtained by simulation is 0.573 W·m?1·K?1, this result differs by 3.6% from the value measured experimentally using modern metrology methods. The calculated value is also compared to those of existing analytical models in the literature. It can be noticed also that the effective thermal conductivity is not only related to the volume fraction of the inclusions but also to other parameters such as the shape of the inclusions and their distribution. The small difference between the numerical and experimental thermal conductivity results shows the performance of the code used and its validation for random heterogeneous materials. The homogenization technique remains a reliable way of evaluating the effective thermal properties of clay-based building materials and exploring new composite material designs.

摘要： Down to the road of miniaturization and high power density,the heat dissipation is becoming one of the critical factors restricting further development of advanced microelectronic devices.Traditional polymer-based thermal interface materials(TIMs) are not competitive for the high efficiency thermal management,mainly due to their low intrinsic thermal conductivity and high interface thermal resistance.Solder-based TIM is one of the best candidates for the next generation of thermal interface materials.This paper conducts a perspective review of the state of the art of solder TIM,including low melting alloy solder TIM,composite solder TIM and nanostructured solder TIM.The microstructure,process parameters,thermal performance and reliability of different TIMs are summarized and analyzed.The future trends of advanced TIMs are discussed.