Study on the Bonding Mechanism of Copper-Low Carbon Steel for Casting Compounding Process

The casting compounding process for copper-steel composite material has broad prospects of application, but due to the lack of supporting theories (especially the bonding mechanism of copper-steel at high temperatures), it is developing slowly. In this research, copper-steel composite materials for different casting temperatures have been prepared by the casting compound process. The results show that, for the casting compound process, the stable copper-steel transition layer can be formed in a short time, and the bonding of copper and low carbon steel is the result of both the diffusion of Cu in low carbon steel and the dissolution of Fe in molten copper. The diffusion coefficient of Cu in the low carbon steel is mainly concentrated in the range of 4.0 × 10−15–8.0 × 10−14 m2/s. However, for casting compound process of copper-steel, as the temperature rises the thickness of the copper-steel transition layer gradually decreases, while the Fe content in the copper layer gradually increases. At the same time, the analysis of the glow discharge results shows that, during the solid-liquid composite process of copper-steel, the element C in steel has a great influence. As the temperature rises, the segregation of C intensifies seriously; the peak of the C content moves toward the copper side and its value is gradually increases. The segregation of C would reduce the melting point of the steel and cause irregular fluctuations of the diffusion of Cu in low carbon steel. Therefore, a relatively lower molten copper temperature is more conducive to the preparation of copper-steel composite materials.

Immobilization of fluorides from spent carbon cathode in a copper smelting slag

The fluorides from spent carbon cathodes could be effectively solidified in a molten copper smelting slag (FeO-Fe3O4-SiO2-CaO-Al2O3) in forms of CaF2 and Ca4Si2F2O7. The results of thermodynamic analysis, chemical analysis, and XRD and EPMA analyses showed that the F solidification efficiency increased with the CaO amount and decreased with the addition of Al2O3 and SiO2. In addition, it was noteworthy that the F solidification efficiency decreased with an excessive CaO amount, which could be ascribed to the consumption of SiO2 through forming CaSiO3 and Ca3Si2O7. It restricted the solidification of the fluoride into Ca4Si2F2O7. Under the conditions of melting temperature of 1300?C, residence time of 60 min and N2 flow rate of 40 ml/min, the optimum CaO and NaF amounts were found to be 20 wt.% and 6 wt.% respectively, in which the F solidification efficiency in the copper smelting slag of FeO-Fe3O4-SiO2-CaO-Al2O3 obtained 98.35%.

Bubble Nucleation in Core-Shell Structure Molten Oxide-Based Membranes with Combined Diffusion-Bubbling Oxygen Mass Transfer: Experiment and Theory

Oxygen-selective membranes are likely to play a leading part in the future separation processes relevant to the energy engineering. A newly developed molten copper and vanadium oxide-based diffusion-bubbling membrane with...

Ground stone tools from the copper production site Al-Khashbah, Sultanate of Oman

Archaeological research at Al-Khashbah, Sultanate of Oman, conducted by the University of Tübingen, revealed a large Early Bronze Age (3rd millennium BCE) site. During the intensive surface survey and excavations, several ground stone tools were found. Most of them came from the vicinity of monumental stone and mud-brick structures, so-called towers, and are clearly connected to copper-processing waste such as slag, furnace fragments and prills, i.e., droplets of molten copper. Therefore, it is assumed that these ground stone tools were used within the operational procedures of copper-processing. Interestingly, only the monumental towers from the first half of the 3rd millennium BCE, i.e., the Hafit period, feature larger quantities of ground stone tools as well as copper processing waste. Towers from the second half of the 3rd millennium BCE, i.e., the Umm an-Nar period, have none. Within the scope of this paper, the distribution of the different types of ground stone tools in Al-Khashbah as well as their find context will be presented. They are illustrated with drawings generated from 3D models created using digital photography processed with the software Agisoft Photoscan. Comparisons with other 3rd millennium BCE sites in Eastern Arabia show that there as well, copper-processing remains are often associated with ground stone tools. The overall variety of types seems to be rather homogeneous in the region.