Advanced Materials Research Vol. 1023

Abstract: The steel matrix composites with 5CrNiMo mold steel as substrate and WC particles as hard phase, were prepared by electroslag melting and casting. The composite material’s properties such as friction factor, wear volume and wear mechanism were investigated by scanning electron microscope (SEM) and friction wear test equipment. The results demonstrate that the sample’s abrasive resistance improved greatly after heat treatment. In the condition of dry sliding wear, surface peeling caused by adhesive wear and adrasive wear caused by wear debris as the third body are the main wear mechanism.

Abstract: This experiment was on the basis of the argon-arc clad injection technology, Ni60 self-fluxed alloy powder was coated on the surface of Q235 steel plate, then TiC, TiN, MoC and Co powder were sprayed by the modificated injection device, and at the same time the powder was vibrated by the ultrasonic-assisted vibration device self-designed. So the sprayed powder particles were smaller, shape was more regular, and distribution more uniform. The results show that the microhardness of composite coating was more than 5 times than that of the matrix, and the wear volume was about 1/5 than the matrix. The good combination, high strength and high wear resistance composite coating was obtained.

Abstract: A traditional III-V GaAs/AlGaAs based semiconductor solar cell heterojunction structure, i.e. n-GaAs/n-AlGaAs/n-GaAs/i-GaAs/p-GaAs is used in this study to investigate the surface polymer passivation on this kind of solar cell. For GaAs/AlGaAs solar cell, the top n-GaAs/n-AlGaAs structure is responsible for the selective etching stop layer. The selective etched surface barriers associated with polymer gratings with different aspect ratios, i.e. grating period (gp) to depth (d), are produced on solar cell surface by using the photolithography and Micro Electro Mechanical Systems (MEMS) techniques. A reflective-type diffraction optical grating is fabricated on the surface of the solar cell to redirect the incident light reflected from the solar cell back onto the solar cell surface. The experimental results show that the addition of the surface optical gratings reduce the light reflectivity value as high as 25%. From inspection of surface reflectivity , the average reflectivity is found to be decreased from 12.1% down to 7.9 %.

Abstract: The adsorption mechanisms of silicone rubber (SR)-stainless steel (SS) interfacial system and silicone rubber-HMX interfacial system were studied by molecular simulation method in the present paper. The molecular simulation results revealed that silicone rubber-stainless steel interface has obvious adsorption effect, while silicone rubber-HMX interface has certain adsorption effect. The systematic potential energy calculation results revealed that coulomb interaction and van de waals interaction might be the major microscopic adsorption mechanism for silicone rubber-stainless steel interfacial system and silicone rubber-HMX interfacial system.

Abstract: For more accurate evaluation of the static contact angle, the height-width method and circle fitting algorithm are investigated, the comparison of some factors on the two algorithms are analyzed, including difficulties of programming, computational complexity, influence of dimensionless drop volume, contact angle and edge noise on accuracy. The critical dimensionless drop volumes corresponding to a contact angle error of 3° are given. The results indicate that: the programming of height-width method is more difficult than that of the circle fitting algorithm, the computational complexity of the height-width method is less than that of the circle fitting algorithm. The errors of the two algorithms increase with the drop volume and contact angle, the height-width method is more accurate than that of the circle fitting algorithm, the errors acceleration decrease/increase with the drop volume/contact angle. The critical dimensionless drop volumes of the two algorithms decrease as the contact angle increases, and them will tend to saturation. The noise-resistant capacity of the circle fitting algorithm is better that the height-width method. Therefore, the circle fitting algorithm should be selected in the condition of high noise level. Otherwise the height-width method should be selected.

Abstract: Through the introduction of the application situation and basic properties of recycled concrete,the author analyzes its application value and and research direction in engineering application,and then puts forward to the application prospect of recycled concrete in road engineering.

Abstract: With the constant increasing of traffic flow and axle load, the early failure of semi-rigid base asphalt pavement is increasingly serious in China. The bad durability and short service life of pavement have become main obstacles in road construction development. Based on the experience of successful application, the early failure of semi-rigid base asphalt pavement is solved, and the service life of pavement is increased by using of the composite asphalt pavement. To solve the design problem of the composite asphalt pavement , its mechanical properties influence results of are obtained by the factors, such as shear strain, shear stress, compression strain on top of subgrade, etc, by a lot of calculation using Shell pavement design software. These provide theoretical basis for durable asphalt pavement design based on rut-resistance property.

Abstract: Consideration on the traditional experiment was time-consuming and required a major investment in human and material resource, even leaded to a great level of error in the process of experiment. The new test method of thermal conductivity of cement concrete based on discrete element method was presented. The cylinder-shaped specimen was created via the mass graduation of the cement concrete, and make sure the numerical model was identical to the truth experiment. The thermal micro-properties composed of density,specific heat, coefficient of linear thermal expansion and thermal resistance were conducted. The applied constant heat flux and constant temperature as the boundaries were investigated via the herein developed model. The results testified that the virtual test data was nearly identical with the analytical values for both different boundaries, and it confirmed that the new numerical model using discrete element method is feasible and reliable. It also supplied a new method on thermal properties study.

Abstract: The authors report a deferential scanning calorimetric study of MgO–Al₂O₃–SiO₂ glasses which possess low melting temperature due to introduction of some quantity of B₂O₃, Li₂O and CaF₂. It is shown that the content of Li₂O has a strong impact on the overlapping extent of the rates of nucleation and crystal growth. High-quartz tends to precipitate at low temperature (~1173 K) for the studied glasses, irrespective of Li₂O content. With increasing annealing temperature, spodumene and cordierite form as main crystalline phase for the samples with high and low Li₂O content, respectively, and then cristobalite crystals occur for both glass compositions. Microhardness firstly increases and then decreases, depending on crystalline phase sequence, and a maximum microhardness value is obtained to be 10.5 GPa.