Applied Mechanics and Materials Vols. 117-119

Abstract: In this paper, self-characteristics (the room-temperature characteristics and the high-temperature characteristic) of iron ores used in sintering, such as chemical composition, size distribution, assimilation, liquid phase fluidity, self-strength of bonding phase, etc, were studied. Then, the principles of ore-proportioning optimization basing on self-characteristics of iron ore during sintering were proposed. Schemes of ore-proportioning optimization were designed and sinter pot test were carried out．Results of sinter pot confirmed the method of optimizing ore proportioning based on iron ore self-characteristics. This work provides good countermeasure for improving sinter quality and reducing sinter cost as soon as possible, under the condition of making full use of the existing iron ore resources.

Abstract: Production of aluminium-clad copper has been performed using vacuum roll bonding, hundreds nm of intermetallic compounds are formed on the bond interface. On the tensile testing, it is broken from the base metal of aluminium and high bond tensile strength is available. In this study, heat treatment has been taken to aluminium-clad copper produced by vacuum roll bonding. Microstructure observation, EPMA, EDS and XRD have been carried to the investigation of the formation of intermetallic compounds. As a result, 3 types of intermetallic compounds such as CuAl₂, CuAl and Cu₉Al₄ were formed at the bond interface of aluminium-clad copper. And it was clarified that the apparent activation energy for growth behavior of CuAl and Cu₉Al₄ is lower than CuAl₂. The effect of intermetallic phases on bond strength has also been investigated with the growth of intermetallic compounds. The decrease of tensile strength has been clarified. The broken position is near the interface between CuAl₂ and CuAl. Furthermore, the bond strength of aluminum-clad copper is seriously affected by the thickness of CuAl₂.

Abstract: Exposed to 650°C air, TP304H stainless steel with two different grain size was oxidized at this temperature. At the meantime, comparison of their oxidation was through the oxidation kinetics curves and analysis of the morphology and composition of oxide scale which conducted by SEM and X-ray. The results showed that the oxidation rate of TP304H stainless steel was slowed down by grain refinement and oxide scale of fine-grained TP304H steel was thinner than that of coarse-grained steel. The nucleation and the growth of nuclei of coarse-grained oxide scale were more rapid. In addition, the grain refinement of austenitic stainless steel accelerated the diffusivity of Cr and made for the formation of dense and continuous oxide scale, so that the oxidation of stainless steel can be effectively inhabited.

Abstract: GRP (Glass fiber reinforced plastics) jacking pipe has many advantages, such as lightweight, high strength, corrosion resistance, long life, good hydraulic and so on. The key of GRP jacking pipe is the joints problem. There are two different joints material in GRP jacking pipe: GRP ring and steel ring. The effect of different joints material on the GRP jacking pipe is analyzed by ABAQUS. When the jacking pipe with jacking force, the deflection angle of the pipeline has significant effect on joints force, even if the 0.05° of deflection, the pipe axial compression stress will double. When the jacking pipe without jacking force, joints force related to free deflection angle of the joints. Through comparison the steel ring and GRP ring shows that GRP ring better than steel ring on the ability to withstand deflection.

Abstract: The accelerated corrosion action of sulfur for carbon steel in wet H₂S environment was studied by simulating the actual serviced environment. The weight-loss method, SEM, EDS and X-ray diffraction techniques are used to analyze the corrosion rate, the structure and the composition of the corrosion production formed in the environments. The results show that sulfur aggravated the corrosion sharply in wet H₂S environment.

Abstract: The effects of deformation temperature on microstructure and mechanical properties of AZ80 magnesium alloy were investigated. The mechanical properties and microstructure were carried out in Gleeble-1500 thermal simulation experiment and optical microscope. The extrusion deformation, dynamic recrystallization had taken place in all the deformation samples, grains were thinner than before deformation.The reasonable deformation process can make the dynamic recrystallization organization of grain smaller and obtain higher strength. The best deformation temperature was about 360°C to 390 °C.

Abstract: Properties of thermoplastic starch (TPS) produced from commercial-grade modified cassava starches were investigated in a pilot scale for future practical production in plastic industry. Five types of commercial cassava starches including native, oxidized, acetylated, octenyl succinate and pregelatinized starches were transformed into TPS by extrusion. The morphology implied that degree of destructuration could be manipulated by adjusting amount of glycerol of the starch melt. All types of TPS exhibited strong water sensitivity especially when exposed to humid atmosphere (>0.75 water activity). Compared among these selected five commercial cassava starches, there were no significant differences in sorption properties. Tensile strength of the thermoplastic starches increased with increasing starch content, and a drastic gain was recorded for 80% starch content for all types of starches. The elongation at break seemed to reach a maximum value for native TPS and pregelatinized TPS when composition of starch was 70%. The concavity of elongation at break of both TPS’s could arise from greater mobility of starch molecules during deformation due to the presence of glycerol and water, so that the properties shifted from glassy to more fluid-like. When compared among the types of modification, pregelatinized starch produced a highly elongated TPS with lowest strength due to its complete destructuration of starch granules, and the octenyl succinate starch yielded the highest strength and most brittle TPS. This study proved that cassava starch had a considerable potential to further developed for biodegradable applications but higher degree of modification than these of common commercial grade was required to improve water resistance of its thermoplastic starch.

Abstract: In recent years, the reservoir sediments have been a disturbance to Taiwan government, and are getting worse due to the climate change. Consequently, it becomes an urgent issue for the authority to dredge and dispose reservoir sludge effectively. Material researchers in civil engineering and environmental engineering, cooperating with microbiologists and geochemists, have recently attempted the solidification of sludge granules into sandstone-like materials employing microorganisms. The aim of this study is to investigate the approach to solidify sludge or soil particle rapidly to attain strength through the growth of bacteria and apply the technique in practical. In this research, we used Bacillus pasteurii in the solidification of reservoir sludge. The sludge used in the experiment has a moisture content of 40%. The change of bacteria broth culture concentration (0%, 25%, 50%, 75%, and 100%) and CaCl₂ ratio in the culturing Urea-CaCl₂ medium (10%, 30% and 70%) were used as the experimental variables. The culture broth was mixed directly with reservoir sludge to form a cubic specimen (50 mm x 50 mm x 50 mm), which was then used in compressive strength, XRD and SEM test. The test results showed that being cultured in 70%-CaCl₂ medium, the specimen blended with 100% bacteria broth had the highest compressive strength. Compared with the blank samples (0% bacteria broth), the compressive strength was enhanced by approximately 13.48%. Also, it was suggested that the solidification by bacteria can indeed enhance the compressive strength of the cube. The sludge solidified with bacteria cultured in 70%-CaCl₂ medium has the highest compressive strength. The result also showed that the higher the content of CaCl₂ used in the culturing medium is, the more CaCO₃ deposit is induced by the bacteria.

Abstract: The flow behavior and associated structural changes of an Inconel 600 superalloy were analyzed by using hot compression tests in the temperature and strain rate ranges of 850–1200 °C and 0.001 to 10 s^–1, respectively. The stress–strain curves exhibited the trend typical of materials in which deformation is recovery-controlled at high strain rates and low temperatures, while at low strain rates and high temperatures, the flow curves exhibited a softening typical of recrystallization phenomena. Constitutive analysis was carried out to investigate the hot deformation mechanism using the hyperbolic sine law.

Abstract: Factors affecting microwave-assisted extraction of garlic essential oil from garlic were investigated experimentally. Suitable conditions for such extraction process were studied by single factor approach to improve the product yield. The product yield under the resultant suitable conditions can reach to 0.478% based on raw garlic cloves. The product yield for microwave-assisted extraction method is as 2.5 times as that for conventional solvent extraction approach.