Applied Mechanics and Materials Vol. 442

Abstract: In this paper, the bottom pouring vacuum suction casting is used, and the TiAl-based alloy blade with good face quality was obtained. Bottom pouring vacuum suction casting obtained Ti-47Al-5Nb-0.5Si alloy fine structure, the average grain size is 20um or less. Metal permanent forced cooling effect increases the undercooling degree, and the formation of Ti5Si3 can hinder the grain growth and the formation of nucleation particles, and Nb elements are conducive to the formation of B2 phase, and these three reasons refined the grain size.

Abstract: The paper summarized the causes of influencing the gilding quality of electric connector contact bodies made by copper alloy.We put forward realiable and effective ways to solve the problems of the gilding quality,Chosing the optimum technological parametars of gold plating bath,achieving optimum structure desig of contact bodies ,improving the process of gilding are the best solutions.

Abstract: The paper presents an experimental study on the relationship betweenprocess parametersand surface integrity of powder-metallurgy high-speed steel S390 in ultraprecision grinding. The optimal machining parametershave been obtained based on the Taguchi quality design method.The affected layerinduced by ultraprecision grinding has a uniform white layerand an inconspicuous dark layer; there are some carbides in the white layer of some samples; a compressive residual stress field exists on the ground surface. In addition, experiments confirm that lapping can remove the white layer effectively and increase the compressive residual stresses with a growth rate of 65%.The derived results satisfy the real requirements in practice.

Abstract: A series of simulated continuum annealing experiments were done on 0.4mm Ti-IF by Gleeble-3800 thermal simulation machine at 700, 730, 760, 790, 820 and 850 degree. The optical microstructures of the specimens were characterized. Transmission electron microscopy analysis was carried out to investigate the second phase particles shape, size and distribution. The mechanical properties of the specimens were measured. The results showed that the yield strength and the tension strength of the steel decreased when the annealing temperature increased, the elongation increased when the annealing temperature increased, expect a maximum elongation value at 760 degree. Based on the microstructure and the second phase, the reason why there was a maximum value was discussed.

Abstract: Z11A3M, Z6A3M, Z1.6A1.6M, Z1A1M and Z1M coating samples were prepared in HDPS by traditional continuous hot dipping method. The microstructure, element distribution and phase was analyzed by SEM, EPMA and XRD. The corrosion resistance was checked in SST. The result was, MgZn₂ and eutectic could be found in all ZAM coating. The ZAM coatings showed excellent corrosion resistance in SST than GI. The corrosion resistance was 4.1 to 11 times of GI. There was no strong relativity between alloy composition and corrosion resistance due to Mg enrichment on the surface of coating. Edge-unsealed ZAM samples showed good corrosion resistance than edge-sealed sample.

Abstract: The absorbing performance have been tested and analyzed by taking cement as matrix, blending material graphite and carbon fibers for absorbing agent trial Sample, in the 8 ~ 18 GHz frequency band, the results indicate that graphite and carbon fibers and composite cement which made of absorbing material has good absorbing property. Blending material absorbing properties of cement-based materials, the impact must be considered together, not the more the better, when blending material exceeding a certain threshold, enhance its ability of wave-transparent enhance while absorbing property will be reduced finally.

Abstract: The aluminum (Al) tube beam was reinforced by CFRP, and the low speed impact test was performed with five different lay-up sequences and two different laminate thicknesses. Stable symmetric crushing mode accompanying one or two layers of lobes with plastic hinge were observed in all specimens. Each direction of carbon fibers, parallel, perpendicular, and oblique to the loading direction, offers respective crashworthiness characteristics in the bi-material tube beam, and the characteristics from each direction were mixed when stacked together. The specific energy absorbed (SEA) and crush force efficiency (CFE) were improved simultaneously up to 38% and 30%, respectively in the Al / CFRP bi-material rectangular tube beam with a [0^o/90^o]_2n lay-up sequence compared to the pure Al tube beam.

Abstract: The absorbing performance have been tested and analyzed by taking cement as matrix, blending material nanoTiO₂ and steel fibers for absorbing agent trial Sample, in the 8 ~ 18 GHz frequency band, the results indicate that nanoTiO₂ and steel fibers and composite cement which made of absorbing material has good absorbing property. Blending material absorbing properties of cement-based materials, the impact must be considered together, not the more the better, when blending material exceeding 6wt%, its ability of wave-transparent enhance while absorbing property will be reduced finally. By using ANSYS software for computer simulation of the specimen to test experimental data and found the computer simulation algorithm not only can verify the correctness of the conclusion but also auxiliary correction deviation appeared in the course of the real data and the error value.

Abstract: The BaTiO₃ precursor was prepared by alkoxide method, in which barium hydroxide octahydrate and butyl titanate were chosen as the Ba and Ti sources, and diethanolamine (DEA) as the polymerizing agent respectively. In order to determine the synthesis parameters of the target product, the phase transition process of the precursor with temperature increasing was investigated by TG-DTA. The effect of calcination temperature, the dosage of DEA and calcination time on the phase compositions and crystal structure of the synthesized samples were investigated by XRD. The results indicate that DEA can promote the formation of tetragonal BaTiO₃ effectively, and the high-purity tetragonal BaTiO₃ was obtained by heat treatment of the precursor at 1100°C for 3h with 1mL DEA dosage.

Abstract: Monomer casting polyamide 6 (MCPA6) was modified by zeolite whose microstructure owns nanoscale holes which has excellent interfacial compatibility with MCPA6. The zeolite / MCPA6 composites were prepared by anionic in-situ polymerization. FTIR indicated that the addition of zeolite did not cause adverse reaction in the reaction system. The results also showed that zeolite / MCPA6 composites had two melting peaks; MCPA6 transformed from α crystal to γ crystal structure partly. The zeolite played a role of heterogeneous nucleation agent which improved the crystallinity of MC nylon 6. When the addition of zeolite was 5 phr, the zeolite / MCPA6 composite crystallization temperature increased over MCPA6 6.8 °C.