Advanced Materials Research Vols. 287-290

Abstract: Ca₃Co₄O₉ and Ca_3-xLa_xCo₄O9 powders were prepared by sol-gel process. The Ca-Co-O thermoelectric material ceramics were prepared. The ceramics materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructure and thermoelectric properties of ceramics were researched. The results indicate that the crystal of Ca_3-xLa_xCo₄O₉ with La adding growth ideally, the material had high density and low pore rate. The Ca_3-xLa_xCo₄O₉ ceramics contain directional array plate-shaped grains with layered structure. The thermoelectric properties of Ca_3-xLa_xCo₄O ceramics were excellent. There were high Seebeck coefficient and high electrical conductivity for Ca_3-xLa_xCo₄O₉ ceramics. The power factor increased with temperature increasing.

Abstract: 171 propellant is a new type of energetic material, extensive research indicates that the traditional methods evaluating the stability of this propellant are unsuitable. So in this article, the stability of this material was studied by aging test, methyl-violet test and gas phase chromatography test. The results show that gas phase chromatography test is feasible for evaluating the stability of this material, but methyl-violet test is unsuitable.

Abstract: According to cargo flow, the strength of the logistics supply need could be predicted. Improving predicting accuracy can provide a scientific basis for the construction and operation on the logistics park. Generalized regression neural network model of logistics park is introduced under the impact of supply chain management, and designing steps about the prediction model is given. And the prediction model predicts Jinan Gaijiagou Logistics Park well.

Abstract: Comb-shaped hyper-branched polycarboxylate admixture polymers, both the water-reducing-type JS and slump-retaining-type BT, were prepared, and their adsorption characteristics with Ca²⁺ ions were studied by conductivity loss experiments. The results indicated that, both the water-reducing-type JS and slump-retaining-type BT, would generate certain electrical conductivity loss in CaCl₂ aqueous solutions, suggesting that there was some close adsorption between the polymer and Ca²⁺ ions, the adsorption was closely related with the pH value of the polymers, the neutral and alkaline samples neutralized by NaOH show an higher adsorption than that non-neutralized. The adsorption was achieved by the strong interaction between carboxylic acid groups in the polymer backbones and Ca²⁺ ions (rather than Cl^- ions)

Abstract: As we know , the materials will swell and contract when it is heated or cooled . A kind of method for mastery the real contractive rate of alloy was bring forward through researching the contractive rate of alloy. Using the method a inspecting testing mould of alloy was designed , and the real contractive rate was mastered by the mould . And this provides the reliable contract date for the design of mould cavity dimension , and reduces the work of mould repair , and also save a lot of money and labor.

Abstract: By summarizing the research and development status in recent years, this thesis especially introduces the preparation method and enhancement mechanism of the functionally gradient material of Mo-MoSi₂. Results of experiments show that: alloying and compounding can significantly improve the room-temperature brittleness and high temperature strength；and the application of Chemical Vapor Deposition (CVD) method in the preparation of Mo-MoSi₂ multiphase anti-oxidation coating, has obvious advantages in that it reduces cracking and improves the coating quality. Finally, the developing trend of Mo-MoSi₂ and its prospected difficulties and hot issues are also pointed out.

Abstract: Mg-1.5%Zr-x%Cd alloys (x=0, 0.5, 1.0, 1.5, mass%) were prepared by PM (powder metallurgy) technology, and the microstructure, mechanical properties and damping capacities of the alloys were researched by OM, three-point bending test and DMA, etc. The results show that the microstructure becomes into strip or block shaped morphology, granular particles Zr appear at grain boundaries or inside grains, and the grains are more refined with the increase of Cd additions. Micro-hardness(HV) and bending strength(σbb) of the alloys increase with increasing addition of Cd. Damping capacities of the Mg-1.5%Zr-x%Cd alloys improves with Cd additions, and increase with the temperature. The damping peak temperature increases with increasing frequencies, showing the characteristic of relaxation damping.

Abstract: Comprehensive study is performed for the one-dimensional phononic crystals with locally resonant structures mechanism and Bragg scattering mechanism. Found locally resonant mechanism is same as Bragg scattering mechanism on one-dimension phononic crystal. The reasons of producing lower frequency band gap are still stiffness decrease and quality increase. So the theory that locally resonant structure is better than Bragg scattering in low frequency vibration reduction is inexact.

Abstract: In the present work, a ester of glucose (a) with 4-(4-(ethoxybenzoyloxy) phenoxy) -6-oxohexanoic acid side–arms has been synthesized. Compared with b and c, reported previously, a had the same side-arms but different chiral core. The phase behaviors of three star-shaped liquid crystals (a, b, c) have been compared and studied, and the effect of the different structure of chiral core on the phase behaviors of the star-shaped liquid crystals has been discussed. a, b and c displayed cholesteric phase, unlike the nematic side arm. a, b and c were all laevo-rotationary, unlike their parent cores. The melting temperature of a, b and c decreased with the increase of the sugar ring of the chiral core. The mesomorphic region of a on cooling cycle was wider than that on heating cycle. For b and c, the case was similar.

Abstract: SiCp/Al composites were fabricated by ceramic mold freedom infiltration and pressureless infiltration, respectively. The microstructure and phases are analyzed by metallurgical microscope and coefficient of thermal expansion of SiCp/Al composites were tested by thermal dilatometer. The results show that SiCp/Al composites are compact and uniform. SiC particles were dispersed uniformly in Al matrix, and SiCp segregation was not found in composites. Under a certain SiCp size range, space between SiCp decreases with decreasing of SiCp size, and CTE of SiCp/Al composites also decreases with decreasing of particles size. Compared with CTE of composite with pure aluminum as matrix, CTE of composite with ZL101 as matrix is less. Under the annealing process, CTE of SiCp/Al composites with ZL101 as matrix is less than that with the solution and aging, which indicated that its dimensional stability of resisting to temperature fluctuation is better, and thermal expansion behavior and characteristic of SiCp/Al composites are also better.