Abstract: Electropulsing treatment was applied to high carbon pearlitic steel to assess the effects of the treatment on microstructure and properties. Ferrite recrystallisation and cementite spheroidisation were induced in samples treated at pulse duration and frequency greater than 40μs and 50Hz, respectively. Ferrite grain size of electropulsed samples was refined compared to similarly annealed samples. The results are explained through a combination of heating and athermal dislocation and atomic mobility effects. With optimisation, electropulsing may offer an improved annealing processing method.
Abstract: The thermal reactions of mechanically milled wolframite and thermal coal mixtures have been investigated using Differential thermal analysis /thermogravimetry (DTA-TG), X-ray dffraction (XRD) and Scanning electron microscope (SEM). Mixtures were prepared according to stoichiometry and also with a 30% excess of coal. Samples were milled with a planetary ball mill for 4 h, then heated at 1000°C and 1100°C for 1 h in a tube furnace under Ar gas. Phase identification was performed by XRD and morphology of the milled powders by SEM. A large difference in thermal reactions between stoichiometric and 30% excess coal containing samples was observed. In the stoichiometric mixture, the product was dominated by Fe6W6C with only a small amount of W2C, WO3 and Fe2WO6. The mixture with excess coal consisted of only Fe3W3C phase without any traces of other phases in the XRD. Homogeneity of composition with the excess amount coal was higher than stoichiometric mixture. It does not appear possible to form WC by this route.
Abstract: The grain size effect on surface morphology, microstructure and mechanical properties of commercial purity titanium specimens subjected to ultrasonic impact treatment was studied. It was found by atomic force microscope that ultrasonic impact treatment of titanium specimens resulted in surface corrugation happens due to their severe plastic deformation. The profile height of the corrugated surface depends on the grain size of specimens and varies in a wide range. The thicknesses of a modified surface layer of fine-and coarse grained titanium specimens were studied. Electron backscatter diffraction (EBSD) analysis revealed that the plastic deformation was accompanied by twin and low angle boundary formation in the surface layer of titanium specimens. The effect of ultrasonic impact treatment on the microhardness of the surface layer of the specimens under study was investigated.
Abstract: The influence of the salt quantity on the recovery yield of aluminium scrap was studied considering an heterogeneous charge. The analysed heterogeneous charge was composed by different types of scrap such as turning, shredded materials and dross. The amount of salt was related to the scrap quality using the salt factor, which is defined as the ratio between the non-aluminium content in the scrap and the quantity of salt required. Two levels of salt factor were considered, 1.2 and 1.8. The analysis of variance was then implemented to verify the influence of the salt quantity on the recovery yield. The results were statistically confirmed using the Anderson-Darling test, the Dixon’s outliers test and the coefficient of variance. An increment of the recovery yield from 95% to 97% was revealed by increasing the salt factor from 1.2 to 1.8.
Abstract: The present work describes a methodology to implement microstructural data obtained from TEM tomography into finite element (FE) simulation software. In this first approach the tomographic reconstruction is treated with different software to create a 3D realistic model of the microstructure of the composite. This realistic model is compared against 2D image-based models via FE simulations in order to compare the mechanical behavior achieved with both procedures. After this first study the results obtained with both types of model are similar. These results are a promising starting point for the development of this novel methodology for obtaining nanocomposite FE models from TEM tomography with realistic results.
Abstract: Efflorescences formed on the surface of air (ambient) and elevated (70°C) temperatures cured high calcium fly ash based geopolymer type concretes have been characterized by the XRD, SEM-EDX and FTIR techniques. The mineralogical composition of the efflorescence depends on curing temperature. At ambient temperature the main phase of efflorescence consists of atmospheric carbonation product of sodium hydroxide such as thermonatrite (Na2(CO3)·H2O, PDF 8--448), while in the 70°C cured concrete it represents sodium calcium carbonates gaylussite (Na2Ca (CO3)2·5H2O, PDF 21-343). Mineralogical composition difference between the ambient and 70°C cured concrete’s efflolorescences is related to chemical reaction of alkaline liquid with fly ash constituents.
Abstract: The aim of this report is to introduce a simulation model of the process of obtaining second-generation bioethanol from waste food industry (rice husk and whey), using Aspen HYSYS simulator in stationary state. The objective is to add value to this waste for the production of sustainable biofuels, helping to solve two problems shortages of oil and the generation of effluent dairies. The model includes the steps of hydrolysis, fermentation and separation of bioethanol generated from lignocellulosic waste (rice husk) in combination with whey, achieving the equipment design and operating conditions to reach a production of bioethanol of 7.57 t/h with a purity of 91.9% w/w from 28.89 t/h of pretreated biomass and 88 t/h whey.
Abstract: The objective in this study was to conduct a technical-economic study of the esterification process of used vegetable oils (UVOs) for the production of biodiesel from the point of view of energy savings achieved by implementing heat exchange networks (HENs). Used vegetable oils (UVOs) can be employed as an input in the production of biodiesel by catalytic transesterification. But, previously it is necessary to reduce its level of free fat acids (FFA) by the acid-catalyzed esterification process in order to prevent undesirable saponification reaction. To carrying out an optimal design of the technology required in the process, simulation tools have an important role for process engineering and optimization of resources. Computer programs such as Aspen PlusTM and Aspen Energy AnalyzerTM provide an environment to perform process modeling and network design optimal heat exchange. In this paper, from the Aspen PlusTM simulation of the process of catalytic esterification in acid medium of UVOs, the technical-economic evaluation process was conducted with and without network of heat exchange in order to analyze the different investment options. The comparison of the two projects (with and without the implementation of HENs) was performed by determining the net present value (NPV). On the scale set for the project, the total cost of the equipment of heat exchange for the esterification process designed with HENs was US$ 4,782.50 higher than the corresponding to the process without HENs application. However, it should be noted that the cost of services decreased by 30% annually, and on the other hand, comparing the process, it was observed that the NPV of the HENs process was 29.5% higher, which leads to the conclusion that the project which includes heat exchange networks is technically and economically feasible.
Abstract: Vegetable extracts have become important as an environmentally acceptable, readily available and renewable source for wide range of inhibitors. They are the rich sources of ingredients which have very high inhibition efficiency. The aim of the present work is to study the corrosion inhibition characteristics of aqueous extract of USINHIB (the abbreviation attributed to garlic extract, derived from romanian language, which was used as vegetable inhibitor), which have been studied as an eco-friendly green inhibitor for corrosion control of carbon steel in 0.5 M hydrochloric acid. The inhibitive effect of naturally available vegetable extract USINHIB toward the corrosion of carbon steel in 0.5 M HCl solution has been investigated by electrochemical techniques. Open circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy and cyclic voltammetry in presence and absence of vegetable inhibitor were used to provide detailed information about the corrosion of steel surface which occurs in acidic environment. The three electrode electrolytic cell was used. The obtained results showed the increase in the inhibition efficiency.