Papers by Keyword: Molten Metal

Abstract: Currently, mathematical modeling applying numerical methods is widely used in the study of metallurgical processes, including metal casting processes in continuous-casting machines. The authors developed a new technology and device for casting metal into a continuous-casting machine mold and metal mixing using the effect of a rotating closed-bottom submerged nozzle with eccentric holes. The theoretical study of processes of mold filling with molten metal was carried out applying a proven numerical method and a special software package. A calculation program was developed based on the numerical schemes and algorithms. The results of calculating metal casting into a rectangular mold are presented as an example. The calculation results are provided in the form of molten metal flow patterns in various sections of the mold.

Abstract: Formation of nanostructure states on the surface of materials exposed to concentrated flows of energy is one of the relevant problems of modern materials processing. In the paper the authors describe the mechanism of the micro-scale droplets formation based on the study and modeling of the physical processes and technological aspects of the interaction between the heterogenic plasma flows and the molten substance at the electrode tip. The authors show new physical mechanisms and criteria for micro-and nanoparticles origination, develop a physical-mathematical model of the interaction between the molten metal and the plasma discharge with imposed high-frequency pulse action.

Abstract: The spout at the connection of the pipe and the chamber is easily clogged when a large amount of molten metal is conveyed to the chamber in squeeze casting for large parts. In order to reduce the chances of clogging and clean up quickly when clogged, a quickly removable pipe is designed. The pipe is heated through thermal conduction by resistance wire, and thermal equilibrium is used to derive the power of heating element. Solid-state regulator is applied to control the heating power. Molten aluminum is conveyed from furnace to chamber using electromagnetic pump. The experiment shows that the molten metal flowing through the pipe is smooth, and the temperature of molten metal can be maintained stability.

Abstract: Continuous metallothermic reduction of TiCl₄ in a molten salt medium is affected by the low solubility of TiCl₄ in appropriate molten salts, the solubilities of suitable reducing metals in the salts and the vapour pressures of the different chemicals in the system. The purpose of the study is to compare quantitatively how the physical properties of the different suitable reducing agents will affect the development and design of a process to continuously produce titanium powder from TiCl₄ in molten salt. In the study Li, Na, Mg and Ca are compared with respect to the mass transfer rate requirements of TiCl4 absorption and metal dissolution.

Abstract: Electromagnetic metallurgy is an advanced subject of the production technological research in metallurgical industry. Magnetic floating smelting has already been successfully applied to producing hyperpure metal. No report on using magnetic floating method to continuously cast molten metal into near net shape waste heat processing billet along horizontal direction by one step on line. This article discusses the research and development state and the application prospect of the new technology.

Abstract: In the present study the analysis of 5 different mechanisms of porosity formation during laser melt injection (LMI) technology were performed. Experiments were supported by thermodynamic and fluid-flow analysis. Special attention should be paid to i. clean the surface of the substrate, ii. use inert shielding gas, iii. use proper particle size and gas velocity, iv. use proper laser power and laser beam velocity to control bath temperature and v. deoxidize the surface of the added particles.

Abstract: Silicon nitrides are often used as ladles, stalks, heater element protection tubes, etc., in the metal casting industry. A low wettability for molten metals is required for these purposes since wetting by molten metals leads to adhesion of solidified metals, which causes several problems. Surface structure is known to affect wettability. Thus, the present study attempts to fabricate silicon nitrides with controlled surface structures. Silicon nitrides, whose surfaces were covered with ordered hemispherical protrusions, were fabricated by the slip-casting technique. The cast bodies were sintered, and subjected to wettability tests using molten metals. For comparison, silicon nitrides with as-sintered and polished surfaces were also prepared. The surface with protrusions exhibited a lower contact angle compared to the as-sintered and polished surfaces. The contact angle depended on the diameter of the hemisphere; it was the largest at a diameter of 0.3 mm.

Abstract: It is well known that the main failure mechanisms in die-casting mould are heat checking due to thermal fatigue and melt-out caused by chemical reaction between die and molten alloys. Thermal fatigue tests were carried out using the thermal cycle simulator to establish the proper method to estimate the thermal fatigue resistance of hot die steel. In this study, the thermal shock tester consisted of induction heating and water spray cooling unit was constructed to evaluate thermal crack propagation resistance and the sum of crack length per unit specimen length, Lm is proposed as the index representing the susceptibility to crack initiation and propagation. Also, new concept of measurement for the melt-out behavior was suggested. AISI H13 hot work tool steel was solution treated and tempered at various temperatures, to control the hardness and toughness that have effect on the behavior of thermal crack propagation. The result of thermal fatigue test showed that there is optimum value of hardness and impact energy to maximize the thermal crack propagation resistance. The influence of nitriding on melt-out resistance was also investigated. The dissolution rate due to melt-out phenomenon tended to be smaller for thicker compound layer. Furthermore, the resistance to melt-out was affected by the compound layer thickness rather than that of diffusion layer. The results of the both tests properly reflect the effect of materials properties on failure modes of die-casting mould and it means those test methods are suitable to evaluate the durability of hot work tool steel for die-casting.

Abstract: This paper presents a method aimed at controlling free surface flow and stirring melt via a magnetic field induced by the permanent magnets. The rotating magnetic field (RMF) can realize the free surface shape control and the melt stirring simultaneously. Numerical model was built to analyse the magnetic field distribution. Two drivers that have the same structure were analysed and optimised. Quasi-steady-state free surface was obtained by regulating the rotating velocity of the magnetic drivers, which is proportional to the magnetic force. Solidification experiment was preformed on a platform of a mini-continuous caster. The solidifying front was observed via addition of a small quantity of Sn-wt.43%Pb into the continuous casting alloy Sn-wt.3.5%Pb, it was found that the solidifying shell grows uniformly under the condition of a proper imposition of the double-permanent-magnet-driver.