Papers by Keyword: Fe

Abstract: This study was undertaken to investigate the effect of carburization of metallic Fe by (20%,v/v) carbon monoxide (CO). Carburization of Fe by carbon monoxide was examined by using temperature-programmed reduction (TPR), X-Ray powder diffractometry (XRD) and Carbon Hydrogen Nitrogen Sulfur (CHNS) technique. Based on a thermodynamic calculation, the free energy Gibb’s value to produce carbon is-8.08 kcal/mol which are favorable. However, production of iron carbide from the same reaction, the free energy Gibb’s value is +9.24 kcal/mol which is not feasible. From the XRD results, shows that after carburization of Fe, the peak appears only for Fe but there is a broad peak between 20 – 30°. The peak might be indicated as carbon in amorphous form. This finding is supported by the percent of carbon content in CHNS analysis which are increasing when the temperature is increased. This shows that after carburization the carbon content is increasing with increasing in temperature due to carbon deposited on metallic iron. In this research, three different temperatures were used which are 300°C, 500°C and 700°C.

Abstract: This paper presents the novel microstructure design, called Harmonic Structure, which gives structural metallic materials outstanding mechanical properties through an innovative powder metallurgy process. Homogeneous and ultra-fine grain (UFG) structure enables the materials high strength. However, such a “Homo-“ and “UFG” microstructure does not, usually, satisfy the need to be both strong and ductile, due to the plastic instability in the early stage of the deformation. As opposed to such a “Homo-and UFG“ microstructure, “Harmonic Structure” has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the harmonic structure is heterogeneous on micro-but homogeneous on macro-scales. In the present work, the harmonic structure design has been applied to pure metals and alloys via a powder metallurgy route consisting of controlled severe plastic deformation of the corresponding powders by mechanical milling or high pressure gas milling, and subsequent consolidation by SPS. At a macro-scale, the harmonic structure materials exhibited superior combination of strength and ductility as compared to their homogeneous microstructure counterparts. This behavior was essentially related to the ability of the harmonic structure to promote the uniform distribution of strain during plastic deformation, leading to improved mechanical properties by avoiding or delaying localized plastic instability.

Abstract: The grinding hardening workpiece deformation caused by high temperature leads to the variation of the grinding force. Grinding force of dynamic variation affects the grinding depth of hardened layer distribution. So it is necessary to study the variation rule of grinding hardening force. Through grinding arc temperature analysis and deformation analysis, the influence factor for grinding arc temperature and workpiece deformation on grinding force is analyzed. The analysis results are compared with the experimental results.

Abstract: The feasibility of using the ultrasonic melt treatment to prepare billets for thixocasting process of hypoeutectic Al-7%Si alloys was studied in this paper. The work covered the billet preparation, soaking treatments and thixocasting process, with focus on the microstructural features in each case. The results showed that the use of ultrasonic treatment in billet preparation resulted in highly uniform, fine and non-dendritic microstructures. Billets with globule sizes as small as 58 µm, and roundness of more than 0.7 were obtained by ultrasonic melt treatment. Different soaking conditions before thixocasting were done and the optimum from which was the soaking for 5 min at 580°C, which resulted in thixocast parts with excellent combination of fine globules of 80 µm and roundness of 0.7 - 0.81. The eutectic Si, as well, was greatly refined by the ultrasonic thixocasting process. Furthermore, high-Fe ultrasonic treated billets, which were thixocasted successfully, exhibited Fe-intermetallic particles in highly desirable fine compacted form. These results reveal the feasibility and competence of UST as a potential route for feedstock production.

Abstract: New Al-Mg alloys have been developed for super-plastic forming (SPF) based on commercial AA5083/AA5086 alloys, but with an increased Mn content from 0.5 to 1.5 wt.% and a decreased impurity Fe level from 0.25 to 0.05 wt.%.The effects of Mn and Fe levels on super-plasticity have been investigated by high temperature tensile testing of cold rolled H18 sheets at 425 to 525°C with a strain rate of 2×10^-3 s^-1. The microstructure evolution during different processing stages, grain size and grain size stability were investigated by optical microscopy and scanning electron microscopy. Both Mn and Fe showed a similar and significant contribution to grain size control in recrystallization, but their effect on high temperature sheet formability was different. An increase in Mn level led to an improvement in high temperature tensile elongation, while an increase in Fe content reduced the sheet formability. A new alloy with 1.5 wt.% Mn and 0.05 wt.% Fe, when processed to H18 temper, was able to reach more than 400% tensile elongation at 450 - 500°C with a strain rate of 2×10^-3 s^-1.

Abstract: Arc spraying (AS) is a thermal spraying method. The spraying distance represents one of the main technological parameters. EDAX analysis, performed on the sprayed layers (SDA and SDS), have shown differences between the initial chemical composition of the filler material and of the obtained layers. The quantitative variations determined for Ni, Fe and Cr can be explained by: the volatilization process of the chemical elements from the electric arc area; losses increase with increasing the length of the spraying jet.

Abstract: Since external loads affect the sealing performance of bolted flanged joints, this paper calculated external loads of bolted flanged joints by using CAESAR II software and evaluated the effects of external loads on the sealing performance from the viewpoint of changes in contact gasket stress and flange rotation by using ANSYS software. The FE results showed that the contact gasket stress decreases a lot at the tension side and increases a little at the compression side. The paper also evaluated the stress distribution in bolted flanged joints subjected to external loads. The results suggested that the flange rotation and the overall stress increased compared with that of flange without external loads. External loads can induce unexpected leakage and strength failure of the bolted flanged joints during operation.

Abstract: Iron is indispensable to make hemoglobin and other iron material elements, is also necessary to exchange and oxygen in the blood of an element, many organisms in REDOX system cannot leave it. Most of the iron distribution in special cells in the body. Using the high pressure nitrifying pot method and wet method and treatment of samples were determined in Comb Mushroom samples Fe element content, the determination results are shown in table 2. High pressure nitrifying pot method relative standard deviation of Fe element is 3.689%; Wet method to determine the relative standard deviation of Fe elementt is 5.473%. Visible high pressure nitrifying pot method and treatment of samples of precision of the measuring precision and wet processing samples are relatively good, the measuring precision of the former better. By comparison, high pressure nitrifying pot method specific humidity method to deal with the sample good measuring precision, higher accuracy, and the measurement process to save time.

Abstract: Smelting slag from mineral process and blast furnace process to vanadium titanium magnetite is a kind of precious secondary resource in which TiO₂ content is higher than 20%. Taking titanium-bearing blast furnace slag in Panzhihua region as research object, this paper analyzes four factors that affect the leaching rate of Al and Fe. The four factors are reaction temperature, reaction time, acid concentration, and the ratio of acid and slag. The conclusion drawn from hydrochloric acid leaching experiment is the factor that causes greatest effect to leaching rate of Al and Fe is reaction temperature, then reaction time follows. Acid concentration and the ratio of acid and slag cause insignificant affect. Appropriate leaching condition is 5h reaction time, 5mol/L hydrochloric acid concentration, 90°C~100°C reaction temperature and 1.2 the ratio of acid and slag. Max leaching rate of Al and Fe is 78.5% and 65.8% respectively.

Abstract: In this paper, the effects of contents of Fe and P on the microstructures and properties of Cu-Cr-Zr resistance spot welding electrode alloys have been studied by means of electrical conductivity and hardness measurements and optical microscopy. By the addition of 2.5%Fe and 0.03P%, after being aged for 6h, the Cu-Cr-Zr-Fe-P alloy has the highest hardness of 125HV. At this time, the electrical conductivity of alloy is 60%IACS. The addition of 0.1%Zn contributes very little to hardness and electrical changes.