Advanced Materials Research Vols. 652-654

Abstract: Monoethanolamine (MEA) was investigated as corrosion inhibitors of a 6063 aluminum alloy in 3.5 % solution using polarization and electrochemical impedance spectroscopy techniques and weight loss. The polarization curves show that monoethanolamine (MEA) can increase corrosion potential (Ecorr) and pitting corrosion potential (Epit), and decrease corrosion current density (icorr) of the 6063 aluminum alloy. EIS results indicate that monoethanolamine (MEA) can increase impedance of the 6063 aluminum alloy. The results show that monoethanolamine exhibits better inhibitor properties for the 6063 aluminum alloy. Electrochemical test results show monoethanolamine (MEA) can improve corrosion resistance and the inhibition action depends on the concentration of the inhibitor. The weight-loss experiment also proves that monoethanolamine (MEA) can improve the corrosion resistance of the 6063 Al alloy.

Abstract: Solvent refining of silicon from Al-Si melts assisted by a centrifugation was investigated for three alloys in the Al-Si system. Silicon was successfully separated from aluminum-rich phase in the form of a foam by centrifugation. As the silicon content increased, the recovery decreased because less aluminum-rich phases remained in the silicon foam. The weight ratio before and after acid leaching of the silicon foam was inversely related to its apparent density before acid leaching. The purity of the extracted silicon decreased slightly with increased silicon content. The purity of the silicon flakes obtained from the Al - 30% Si alloy was 4N, except aluminum. Boron and phosphorus in the silicon flakes could be lowered effectively by decreasing the silicon content in the Al-Si alloys

Abstract: This paper researches the material erosion mechanisms of high silicon- aluminum (Si-Al) alloy in micro electrical discharge machining (Micro-EDM). By using Quanta 200F environment scanning electron microscope, the microstructure of Al-50wt%Si alloy by spray forming was observed. And a simplified model of high Si-Al alloy was set up. The Al-50wt%Si alloy was machined by using copper electrode and tungsten electrode respectively. And the differences of surface morphologies and element energy spectrum were compared. The process and the material erosion mechanisms of high Si-Al alloy in Micro-EDM were analyzed in detail. The results may provide theoretical basis for Micro-EDM of high Si-Al alloy.

Abstract: The raw materials used for manufacturing copper foams are the metal and a carbonate in powder form. Copper foams are fabricated by mixing metal and carbonate powder, sintering, and removing carbonate processing. The effect of Cu particle size, compacting pressure on the porosity of porous samples are analyzed. With SEM and EDS, particles binding and microstructure evolution during sintering are studied, and the mechanical properties of porous samples are measured. Results show that copper foams with the porosity of 60 % ~85 % are successfully prepared, pore size 50~1000㎛.The porosity of copper foams decreases with the pressure increasing and copper particle size decreasing at same volume fraction of copper powder . The compressive strength of copper foams decreases with the porosity raising, for the copper foam of 80% porosity, the compressive strength up to 20-30Mpa.The electrical conductivity of copper foams decreases with porosity increasing. Thermal expansion coefficient α of copper foams increases from 17 to 19*10-6 .K-1 when temperature rising from 50°C to 100°C.

Abstract: The thermally insulating compound AeroTherm appeared on the market in recent times. The manufacturer determines its thermal insulating properties. The aim of this article is to verify thermal-technical properties of AeroThermu on the lining from YTONG (autoclaved aerated concrete blocks) that serves as the supporting base.

Abstract: Large amounts of waste clay brick generated in the city expansion process, which formed serious harm on the city environment, and resulted in the waste to the aggregate resources. The waste clay brick was processed the recycled aggregate, which can be used for preparing the recycled concrete. The pretreatment method to recycled aggregate have certain influence on the compressive strength of recycled concrete, through the experiment, we can get that different pretreatment methods can improve accordingly the compressive strength of recycled concrete, and has certain reference significance to the reuse of recycled aggregate.

Abstract: In order to study the dynamic response of the reinforced concrete column which is under the high speed impact of different diameter projectile, LS-DYNA finite element calculation software was used to, designing four kinds of solutions, calculate and analyse the reinforced concrete column under the situations. Projectile velocity curve、projectile acceleration curve and the results of reinforced concrete column damage of different α value(the ratio of projectile diameter and reinforced concrete column side length) in the conditions of the same impact parts(1/2 of the column high) and initial velocity(800m/s)were obtained. Based on the analysis of the numerical simulation results, we get the influence rule of the dynamic response of reinforced concrete column which is under the impact of different diameter projectile.

Abstract: The influence of admixture of super-fine limestone powder and low-quality fly ash in different proportions on the fluidity and strength of cement mortar is studied. The test results show that the mortar fluidity increases with the increase of the super-fine limestone powder (the mixing amount of fly ash reduces), and the strength of cement mortar can improve when limestone powder and low-quality fly ash are combined admixed to a certain ratio. The maximum flexural strength of the 28d mortar is 9.8MPa and its maximum compressive strength is 42.2MPa, and at this time, the limestone powder accounts for 33.3% of the mineral admixtures. However, when the mixing amount of super-fine limestone powder is over a certain range, the strength of 28d cement mortar will reduce.

Abstract: This paper describes study of temperature variation in the gelling and hardening, thermal baking and pouring stage of foaming gypsum mold. The temperature difference curve in the gelling and hardening process shows an rapid decline, tending to the placid downward eventually after a clipping rise. During the thermal baking stage, owing to the low heat conduction coefficient of the foaming gypsum mold, the actual temperature of each thermocouple lags behind the craft temperature, lag degree increases gradually with the extension of baking temperature and holding time. At the initial period of pouring process for molten aluminum, the temperature of center position in the mold increases fast by absorbing lots of heat in the solidification process, whereas, slower temperature rising curve occurs in the edge and intersection position. Coupled with the ongoing of air convection heat transfer, resulting in a continuous falling of temperature, therefore the temperature difference curve of each point inside the mold shows a successive upward trend with the solidification process of molten aluminum alloy.

Abstract: In this investigation, waste polystyrene boxes were collected and treated before mixed with common concrete in especial dies to produce new brick called poly-brick. The main tests performed these tests include the measurement of thermal conductivity, overall heat transfer coefficient and the compression stress. It can be seen that the thermal conductivity of the poly-brick increased with increasing the percentage of waste polystyrene and vary from 0.78 (W/mk) at 0% Polystyrene to 0.227 (W/mk) at 50% and the overall heat transfer coefficient reduced from 7.85 to 2.77 W/m2k. Comparisons between common building structure versus the new Poly-Brick was made and it indicates that the heat transfer rate reduced from 1413 to 498.6 Watt at 50% ratio of the mixture which means 64.7% of energy saving. On the other hand, the compression stress found to be less than that for the common brick. Reduction in energy consumption, which means that low cost of heating and cooling needs, safer, clean and comfortable environment achieved. It is also leads to getting rid of the waste material and has resolved numerous design challenges such as mould.