Advanced Materials Research Vols. 512-515

Abstract: The higher damping capacity and hardness Li₆La₂SrBi₂O₁₂ceramic particles at room temperature were added into the cement to form the composite materials. The maximum damping capacity of the 25 wt% Li₆La₂SrBi₂O₁₂ceramic/cement composites is as high as 0.015 at 310 K and 9 Hz, corresponding to a vibration energy dissipation of about 10% in each vibration cycle. The flexural strength of the the 10 wt% Li₆La₂SrBi₂O₁₂ceramic/cement composite is about 50% higher than that of the pure cement sample

Abstract: The purpose of this study is to develop a non-contact deburring method and optimize its operation parameters. A deburring method using enhanced ultrasonic cavitation without abrasives is proposed and its work conditions were optimized. In additional, aging changes on the microhardness and surface roughness of specimens were studied experimentally in the process. The aging microhardness went through two stages. In the first stage, the work hardening characteristic of aluminum induced the increase in microhardness of specimen. After the microhardness reached an extreme, it went down. The surface roughness increased with treatment time. These time-dependent changes indicated that parts should be treated discontinuously during the ultrasonic deburring process to avoid being eroded by cavitation bubbles. Deburring experiments indicated that the burrs can be effectively removed by these enhanced cavitation bubbles.

Abstract: The effect of annealing treatment on the structure, gaseous hydrogen characteristics and electrochemical properties of the La _0.67 Mg _0.33 Ni _2.5 Co _0.5 alloys was investigated. Alloy structure analyses show that all of the alloys consisted of complex phases such as (La,Mg)₂(Ni,Co)₇ phase, (La,Mg)(Ni,Co)₃ phase and La(Ni,Co)₅ phase. The homogenization of composition was improved by annealing treatment. Gaseous hydrogen characteristics were also improved after annealing. The pulverization of the alloy particles was reduced after annealing treatment, which could improve the cycling stability. Electrochemical experiments show that all of the alloy electrodes exhibited good activation characteristics, that annealing treatment improved the maximum discharge capacities of the alloy electrodes from 371.1 mAh/g (as-cast) to 387.7 mAh/g (1173K). The cyclic stability of alloy electrodes was also improved after annealing. However, the high rate dischargeability characteristics were deteriorated.

Abstract: The influence of cetane number improver on emission characteristics of diesel engine fueled with methanol/diesel blend fuel was investigated. Methanol/diesel blend fuel was prepared, in which the methanol content is 10%, different mass fraction (0%，0.5%) of cetane number improver were added to the blend fuel. Load characteristic experiments at maximum torque speed of the engine were carried out on 4B26 direct injection diesel engine. The results show that, compared with the engine fueled with diesel, the CO emission increases under low loads and reduces under medium and high loads, the HC emission increases, the NOx emission decreases under medium and low loads and increases under high loads, the soot emission reduces significantly when the diesel engine fueled with blends. When cetane number improver was added to blends, the CO and NOx emission reduces, the HC emission decreases, the soot emission increases to some extent compared with the methanol/dieselblend fuel without cetane number improver.

Abstract: In the present work, effect of vanadium on mechanical and thermal fatigue resistance of Cr5 deposited metal is investigated. It is found that hard phases with rich vanadium are mainly distributed at grain boundaries. Vanadium affects the high temperature tensile strength and thermal fatigue cracking obviously. With the increase of vanadium content, high temperature tensile strength of deposited metals shows a initial rise up, then drop for more than 0.54 wt.% V. Toughness and high temperature plasticity are increased up to 0.26 wt.% V, then drop up to 0.89 wt.% V, then toughness and plasticity increase again. Moreover, the thermal fatigue crack length shows a initial decrease up to 0.26 wt. % V, then slightly rise up for 0.89 wt.% V, then crack length shorten again. It is expected that the optimal vanadium content is in a range of 0.18~0.26 wt.% for resisting the thermal crack growth. Fractographic observation shows that the thermal fatigue cracks mainly are transgranular growth. It is felt that the crack length is closely related to microstructure, oxidation resistance, toughness and high temperature plasticity of the deposited alloy

Abstract: With the growing importation of liquefied natural gas (LNG), the interchangeabilities issues of pipeline natural gas (PNG) and LNG are becoming increasingly serious in China. In this paper, some sampled domestic appliances were selected to experimentally investigate the interchangeability of multi-source natural gases including PNG and LNG in Guangdong province. Performances including heat Load, thermal efficiency, CO emission and NOx emission were examined. Through the testing result it can conclude that the heat load of domestic appliances changes consistently with Wobbe Index of gases; well-adjusted domestic appliances can interchange within the different source gases and without materially increasing in CO and NOx emissions, but the efficiency of gas appliance will be largely affected.

Abstract: Temperature significantly influences the engineering properties of clayey soil and this temperature effect usually depends on soil type. In this investigation, laboratorial experiments were conducted on three soils to evaluate the adsorbed water content, Atterberg limits, swelling, shear strength and permeability under different temperatures (5-50°C). The results indicate that liquid limit decreases, swelling increases, permeability increases with increasing temperature. It is fundamentally due to the change of adsorbed water content. Hydrophilic minerals, which contain large amounts of adsorbed water, play an important role in the temperature effect. With the increase of hydrophilic minerals, the temperature effect on liquid limit increases and the effect on swelling ratio decreases. The hydrophilic minerals content also has significant impact on the temperature effect of permeability. With increasing temperature, the adsorbed water is transformed to free water, and then the permeability may increase significantly. The shear strength of clayey soils with higher content of hydrophilic mineral is more sensitive to temperature variation. The cohesive force mainly changes linearly with the temperature. Different phenomena, i.e. thermal-hardening or thermal-softening, was observed on strength behaviour due to different hydrophilic mineral content, moisture content and dry density of sample.

Abstract: In order to find the corrosion cause of petroleum casing premium connection material, the fixture was design to simulate material enduring compressive stress, and the fixture was put in high temperature autoclave, and the corrosion rate of two kind casing material(carbon steel and stainless steel) enduring compressive stress were test in H2S and CO2 and Cl- water solution. The result was that compressive stress accelerated the corrosion of petroleum casing steel, and when compressive stress was greater than the value half as the yield strength the corrosion rate increased quickly.

Abstract: Environmental protection is a growing concern for many industries today. This paper shows manufacturing environmental performance improvement for free cutting steel products. Inclusions have the characteristics of sulfur and bismuth in free cutting austenitic stainless steels without lead addition. Machinable additives lead to improved chip breakage, and thus reduced tool wear. The machinability of free cutting austenitic stainless steels without lead addition is much better than that of conventional austenitic stainless steel. Bismuth can replace lead because lead is a harmful factor for environment and machine operators' health. The reduction of environmentally harmful substances such as lead was performed. A feasible combination of free-cutting additives should yield a stainless steel product with acceptable machining and mechanical properties.

Abstract: The TiO₂ microcrystal was prepared under low temperature using tetrabutyl titanate as raw material. The TiO₂ catalyst was characterized by XRD, SEM, TEM, FITR, and PL. At the same time, the degradation performance of TiO₂ microcrystal on methyl orange was studied in ordinary sunlight conditions. The experiments show that TiO₂ microcrystal at 85°C with 50 mL nitric acid as a crystal control agent can be obtained. Meanwhile, the light absorption of catalyst can be extended to the visible light; the methyl orange can be degraded within 100 min under visible radiation.