Advanced Materials Research Vol. 815

Abstract: The TiC-Cu composites with different mass fraction were prepared by powder metallurgy method. The effect of ball milling time and sintering temperature on the morphology, relative density and electrical conductivity of TiC/Cu composites has been investigated. As-milled sintered compacts were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and conductivity measurements. The results demonstrate that under laboratory conditions with the milling time increasing grains are remarkable refined. Mechanical milling can bring about changes of lattice parameters, the grain size first decrease and then increase as milling time increasing. Relative density showed strong dependency on the milling time. The effect of the grain being refined by ball milling is helpless to improve electrical conductivity of composites. For the composites with TiC content<50wt.%, as milling time prolonging the electric conductivity decreases while for the 50%TiC-Cu the conductivity are not be impacted.

Abstract: Red clay is normally used in the area of Guangxi for roadbed filling and slope overburden. The engineering properties of red clay are closely related with the hydraulic characteristics. A new rapid method is adopted for measuring the soil-water retention curve of the red clay based on the dynamic multi-step outflow tests. The static soil-water retention curve is obtained through the non-equilibrium changes of soil-water under each step of matric suction. Compared with the traditional measured methods, the new method can save much time for determining the hydraulic characteristic functions, especially for clay soils. Several experiments are done under different suction steps and load time on the same red clay sample for verifying the effectiveness of the new rapid method. The experimental results show that the static soil-water data are largely dependent on the initial several suction steps and load time in the dynamic multi-step outflow tests. If the suitable loading scheme is adopted in the dynamic multi-step outflow method, the time can be saved greatly for obtaining the soil-water characteristic curve and hydraulic conductivity function of red clay. The significance of the rapid method will great for the engineering design and evaluation related with unsaturated red clay.

Abstract: In order to search for new bioactive substances containing 1,3,4-oxadiazole, some 5-aryl-l,3,4-oxadiazole-2-ylsulfanyl derivatives were synthesized from the active intermediate 5-aryl-l,3,4-oxadiazole-2-thiones, obtained from the condensation of aromatic carboxylic acid hydrazides and carbon disulfide at triethylamine alkaline solution catalyzed by propylphosphonic anhydride, followed by reaction with ethyl chloroacetate in alkaline media under ultrasound irradiation in the presence of PEG-400. The structural features were confirmed by IR, 1HNMR spectra and elemental analysis. These compounds have been screened for their good antibacterial activities against Escherichia coli, Staphyhcoccus aureus and Bacillus Subtilis.

Abstract: The atomization mechanism here makes full use of the comprehensive effects of the centrifugal atomization, the oscillating atomization and the impact breakage atomization, synthesizing the superiorities of the three as an organic and powerfully efficient whole, and making their mutual reactions stronger step by step. The impact breakage atomization is a new auxiliary mechanism among the three, which can improve the atomizing process of droplets considerably after the centrifugal and the oscillating atomization, producing much better an atomizing result. It is very convenient, simple and direct to fulfill the three-in-one.

Abstract: A three-dimensional physical and mathematical models of the heat transfer in the furnace specimen with an internal defect were established. Combined with the theory of infrared thermographic temperature measurement, using the L-M method, the inverse heat transfer problem of the boiler furnace wall bricks with crack was investigated. The size of defect was accurately estimated. Conclusions can be drawn by computational analysis, firebrick played a major role in the furnace thermal insulation effect. When firebrick fails, the inspection surface temperature is abnormal, and the temperature difference between the outer surface of the defect and that of the normal wall is an exponential relationship with the increase of defect depth.

Abstract: Shipping auxiliary swing test Platform is a kind of test device which can complete performance tests of the ship auxiliary equipment by simulating the motion of ships in the laboratory environment. This article presented a swing test-bed with high torque dynamic load of three-degree of freedom (3-DOF), simulated mainly the motion of rolling, pitching and heaving in a specific sea state. Put forward some comparison and design of the structure schemes against the requirement of high torque load, choose the best scheme according to the test requirement, and introduce some key accessories design of the made reliability accounting on the key mechanical structure of the swing test-bed.

Abstract: In order to improve the tensile strength and crack resistance of carbon fiber reinforced concrete, enhance the bond strength of carbon fiber and concrete, and improve the durability of concrete component, this article describes the basic methods and study progress of carbon fiber surface treatment. At the same time, the advantages and disadvantages of various methods are analyzed. The effect of oxidation is more obvious than its of non-oxidation, but the method of the oxidation require more complex conditions, and it is suitable for industrial production of sound equipment, and it need for strict control conditions; the method non-oxidation is used after the oxidation of carbon fiber, then the effect will be more better than the effect of without oxidation. Increasing the surface roughness of carbon fiber and improving the toughness of concrete lay a theoretical foundation for practical application of carbon fiber.

Abstract: In order to study the raw material sources and their identification methods of blue and white porcelain made in Jingdezhen Jiajing official kiln (J-O-kiln) and Dehua Housuo kiln (D-H-kiln), 22 blue and white porcelain samples of J-O-kiln and D-H-kiln were analyzed for their body and glaze chemical compositions by Proton Induced X-Ray Emission (PIXE). A set of fingerprint chemical components among them were selected for distribution analysis. Our results show that the raw material sources the porcelain bodies of J-O-kiln are relatively concentrated, and those of D-H-kiln porcelain bodies are relatively scattered, and the raw material sources of porcelain bodies made in the two kilns are quite different, and the raw material sources, recipes of the transparent glazes and blue and white glazes made in these two kilns are also quite different. Therefore, blue and white porcelain samples from J-O-kiln and D-H-kiln can be better easily differentiated by PIXE and fingerprint chemical components distribution analysis.

Abstract: The ettringite results from alunite/bauxite and gypsum which has the characteristic of fast setting and volume expansion, so the main properties and microscopic structure of grouting material modified with alunite/bauxite and gypsum at different proportion were investigated. The results have shown that the grouting mortar modified with 7-20% content of bauxite/alunite/gypsum had the properties such as the setting time could be controlled below 1 hour, long-term expansion rate stabilized basically as 0.2%, compressive strength of 1, 3 and 14 days were more than 17 MPa, 31 MPa and 50 MPa, respectively; the pullout force of 1 meter sample at 14 days reached 87 kN. The micro-analyzing by using MIP, SEM and XRD showed that there were plenty of expansive crystals and tiny pore structures in harded paste which can exist steadily for a long term. The achievements will provide an important basis to application of cement-based grouting material as first-aid repairing.

Abstract: The La_1-xSr_xCoO₃ (x =0.0, 0.1, 0.2 and 0.3) samples were prepared by solid-state reaction method. The X-ray diffraction patterns show that the samples are of R-3c spacegroup and the relative intensity of (024) plane diffraction peak increases with the increase of Sr concentration. The x-ray absorption fine structure data of Co ions can be fitted with 2 and 3 different scattering paths for the samples with x=0, 0.1 and for x=0.2 and 0.3, respectively. A new peak arises in x-ray absorption spectra of O ions. These results suggest a relationship between the variations of electron densities and local structure distortion. Both the valence band photoemission and x-ray absorption spectra indicate the existence of possible phase separation scenario that comes from the different types of Co-O bonds which coexist in one sample.