Induction Crucible Furnace Research Articles

Confinement and aspiration of dust and gas in the production of atomized copper powders

A system for the confinement and aspiration of dust and gas emissions is developed. A movable casing installed on an induction crucible furnace prevents air contamination when melt is prepared and atomized to produce copper powders and alloys. The content of harmful admixtures in air at workplaces does not exceed the threshold limit value. The research has provided input data to develop aspiration and dust separation systems for the production of copper powders and alloys.

Formation of MHD processes in induction crucible furnace at single-phase supply of inductor

The article discusses some technical approaches that enable one to obtain the single-loop circulation of metal in induction crucible furnace without the application of complicated and special multiphase power supply sources (multiphase inverters). The results of investigations into electromagnetic and hydrodynamic processes in a furnace with liquid metal charges are presented at different variants of the power supply of multisection inductors of crucible furnaces from a single-phase inverter.

Optimization of Heat Treatment Conditions of Magnesium Cast Alloys

In this paper there are presented results of the optimization of heat treatment conditions, which are temperature and heating time during solution heat treatment or ageing as well the cooling rate after solution treatment for MCMgAl12Zn1, MCMgAl9Zn1, MCMgAl6Zn1, MCMgAl3Zn1 cast magnesium alloys. A casting cycle of alloys has been carried out in an induction crucible furnace using a protective salt bath Flux 12 equipped with two ceramic filters at the melting temperature of 750±10°C, suitable for the manufactured material. The heat treatment involve the solution heat treatment and cooling in different cooling mediums as well water, air and furnace. The improvement of the manufacturing technique and chemical composition as well as of heat treatment and cooling methods leads to the development of a material designing process for the optimal physical and mechanical properties of a new developed alloy.

Numerical modelling of free surface dynamics of conductive melt in induction crucible furnace

Numerical modelling of free surface dynamics of conductive melt in induction crucible furnace

Development of a lining made from Karelian quartzites for crucible induction furnaces

Factors are considered that increase the service life of a lining for a crucible induction furnace. Results are provided for laboratory studies and industrial tests of Karelian quartzites of Jotnian age of the Shokshinsk for- mation and Jatulian age of the Metchang'yarvinsk formation. The effect of impurities is quartzites on crucible induction furnace lining wear resistance is studied. Brief characteristics of quartzites are provided. The possi- bility is established of using waste materials from quarry production of Shokshinsk quartzites for preparing quartzite mixes. Crucible melting of cast iron, steel and non-ferrous met- als relates to the main requirements of casting-metallurgical technology and also exhibits economic advantages over cu- pola melting of cast iron, and it has a cheap and rapidly re- placeable acid lining. The economics of operating melting furnaces and the quality of melted metal depend on the qual- ity and service life of the lining. Specifications laid down for lining materials relate to refractories based on quartzite. A quartzite lining is favorably distinguished from magnesite and alumina materials by cheapness and the fact that shrink- age is balanced by growth of quartz during allotropic trans- formations. Domestically produced furnaces for melting cast iron, steel and alloys based on copper mainly operate on a quartz lining. This lining is also most widespread abroad. For exam- ple, in Germany about 90% of induction furnaces use it. Quartzites that during quartz inversion retain adequate strength and density are suitable for lining induction furnaces (1). In crucible induction furnaces (Fig. 1) metal has a ther- mal, chemical, and erosion effect on the lining. High metal- and slag-resistance of the lining is provided by minimum po- rosity of the sintered layer of the lining, for example of the Swedish lining mix Radanit (Fig. 2). An acid lining of a quartz mix has a constant volume or little growth within the limits of 1% during service. Between the sintered part of the lining and the inductor during crucible firing and its opera- tion a lightly-sintered (buffer) layer is created that prevents the spread of cracks deeper into the lining towards the induc- tor. Lining expansion gives rise to slow sintering of the rammed walls of the crucible due to which a powder buffer layer is retained for a long time. The safety of operating a furnace with an acid lining is provided by the fact that the buffer layer prevents breakthrough of molten metal to the in- ductor. An acid lining is quite inert with respect to molten cast iron and slag, and it exhibits the required refractoriness.

Simulation of flank induction rotator of liquid metal

A laboratory model of a liquid metal electromagnetic rotator, which is a unit of a melting facility based on induction crucible furnaces, and mathematical models constructed using the COSMOL Multiphysics system by the technique of detailed equivalent circuits are described. The results of mathematical and physical simulation are compared.

Technological practicability of the numericalmodeling of induction heating process in steel pieces

This paper presents the numerical modeling (using the Finite Difference Method-FDM, and Finite Element Method- FEM) of the electromagnetic and thermal fields in a steel piece heated up inside an induction crucible furnace, and the experimental validations. Both modelings have been validated experimentally, so they can be used in designing the equipments and in the numerical control of induction heating process. The program based on FDM can be used in the first stage of designing due to the reduced CPU time. In this stage the inductor parameters and heating time can be estimated, and a study of the influence of diverse factors upon the heating process can be achieved. The FLUX 2D program can be used in the optimization stage, because it allows a more thorough analysis of the phenomena.

Effects of mixture composition on the lining stability of a crucible induction furnace

Research results are reported on the effects of components on the resistance of acid lining for the crucible induction furnace. To raise the lining resistance, one needs to eliminate components that react with the silica crucible. The extent of silicon reduction from the lining is dependent on the heating of the metal and the contents of carbon and silicon in the liquid. Increasing the carbon content and reducing the silicon concentration in the metal favor wear on the crucible. The slag components most actively influencing the resistance of the lining are magnesium and calcium oxides, which are produced on modifying cast iron, ferrous oxide, and manganese on account of reduction in the viscosity of the slag, increase in its wetting power, and penetration into the pores and unevenness in the walls of the crucible.

Turbulent flow dynamics, heat transfer and mass exchange in the melt of induction furnaces

Experimental investigations of the turbulent flow velocities measured in the melt of experimental induction furnaces show, that beside the intensive local turbulence pulsations, macroscopic low‐frequency oscillations of the recirculated toroidal main flow eddies play an important role in the heat and mass exchange processes. Traditional numerical calculations of the flow and transfer processes, based on wide spread commercial codes using various modifications of the k‐ε turbulence model show that these models do not take into account the low‐frequency oscillations of the melt flow and the calculated temperature and concentration distributions in the melt essentially differs from experimental results. Therefore, the melt flow dynamics in an induction crucible furnace was numerically simulated with help of transient three‐dimensional calculations using the large eddy simulation turbulence model. This leads to a good agreement between calculated and measured periods of low‐frequency oscillations and heat and mass transfer between the toroidal flow eddies.

A method of further purification of zone-refined aluminum by cold-crucible levitation melting in ultra-high vacuum

We have found that impurity elements with a solid/liquid distribution coefficient k less than unit are removed efficiently by levitation melting in ultra-high vacuum. Therefore, this method was applied to the purification of the tail part of zone-refined aluminum, because in this part the impurity elements with k less than unit are accumulated. The tail part of zone- refined aluminum with residual resistance ratio RRR = R (300K)/ R (4. 2K) = 1 500 to 15 000, was melted in ultra-high vacuum (about 10–8 Pa) in a cold crucible induction furnace. By this way, the RRR of the sample was improved to 20000.

A sensitivity approach for the optimization of loss efficiencies

This paper presents the optimization of the loss efficiency of inductive heating devices by the application of a sensitivity approach. Based on a mixed potential FE skin effect problem a new sensitivity formulation is derived and extended to the adjoint variable method. Through this the time for the calculation of the cost function and its gradient is minimized. The algorithm is applied to the positioning of the field turns of a simple inductive heating device. Finally the optimization of a crucible induction furnace is shown.

Extension of the k-ε model for the numerical simulation of the melt flow in induction crucible furnaces

Checking the calculations of turbulent melt flow in induction crucible furnaces that were carried out with various modifications of the two-dimensional (2-D)k-e model using experimental findings has shown basic differences in the distributions of the specific generation of the turbulent energy and the kinetic energy of the turbulence. The discrepancies are explained by the distinctive three-dimensional (3-D) character of the pulsations and the low-frequency fluctuations of the macroscopic toroidal eddy; these are not taken into account in the numerical methods mentioned. With the aid of this 3-D model, the additional component of turbulent kinetic energy involved is estimated, and an approximation formula for the low-frequency component of the specific generation of turbulence is given. This results in an extension of the 2-Dk-e model for a recirculated flow with several toroidal eddies, leading to good qualitative agreement of the characteristics of turbulent flow with the experimental findings. Since the numerical simulation—in agreement with industrial practice and the experiments carried out—demonstrates good effective mixing of the entire flow region, there is thus a possibility for the simulation of aterial transport in the melt of induction crucible furnaces as part of the widespread 2-D computation methods.

ＴｉＡｌの脱酸

The deoxidation of TiAl is one of the key technologies to recycle the scrap contaminated through the casting processes. Fairy high amount of aluminum, more than 30%, enables the few deoxidation methods such as evaporation of aluminum oxide or Ca addition, while they are inapplicable to conventional Ti-alloys containing lower aluminum.The TiAl with 0.21% oxygen was successfully deoxidized by the electron beam melting to the range of 0.02∼0.03% with the 10% loss of aluminum which is ready to estimate by Langumuir's evaporation equation.It is also revealed that the calcium works as the effective deoxidizer for TiAl. The TiAl with 0.16% oxygen was remelted in the cold crucible induction furnace and was deoxidized by calcium to the 0.01% to a minimum. The product of [%Ca] and [%O] was about 0.008 in this case. Deoxidation products, coherent to the side surface of the ingot, were identified as the CaO by the EPMA.

Features of service of the lining of a crucible induction furnace in melting of cast iron

It has been established that a feature of lining service at the metal-slag-lining-gaseous atmosphere interface of a furnace is overgrowth of it with the products of reaction of the refractory with the molten metal and slag.

A dry rammed lining of crucible induction furnaces for low-temperature alloys

The production tests confirmed the desirability of replacement of concrete linings of induction furnaces for melting of aluminum by dry ramming compounds providing a significant reduction in the length of repairs and an increase in furnace productivity

A boundary element method to predict the shape of a molten metal free surface in EM confinement field

An iterative procedure to predict the equilibrium shape of a molten-metal free surface in an electromagnetic confinement field is developed. An impedance boundary condition (IBC) formulation forms the computational core of the procedure, in which a balance of electromagnetic and gravitational pressures is sought. The method is used to predict the shape of the molten-metal free surface in a crucible induction furnace. The formulation is described, and results showing the very close agreement with measured free surface contours are presented. The effects of supply frequency, mass density, and free level within the furnace and considered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Quartzites for crucibles and methods of lining crucible induction furnaces (Review)

With observation of the requirements of chemical and grain-size compositions, progressive methods of lining work, and sintering of the crucible, domestic quartzites provide a long lining life of induction crucible furnaces in melting of iron and sufficient life in melting of carbon steel.

Modelling the temperature cycle of induction furnace linings with laboratory equipment

A study of the temperature cycle in the lining of a laboratory rig reproducing the thermal conditions of the operation of the lining in crucible induction furnaces allowed the tracing of the nature of the change in the temperature as a function of the distance to the source of heat, the rate of change in its temperature, the heating or cooling time, and the influence of the cooler. Determinations were made of the highest rates of change in temperature during the switching-off of the heater from the energy source, which in the heater zone (in the layer up to 10 mm thick) reached 65–110 deg/min. Cooling at the same rate, especially for small furnaces, cannot be prevented during the metal pouring period. The developing thermal stresses should cause cracking of the working layer, in connection with which the presence of the nonsintered, metal-impermeable buffer layer in the crucible is essential. This equipment allows a model to be constructed without complicated calculations, and investigations to be made of the temperature cycle for the single-sided heated lining with outside cooling. The results obtained can be used for other cylindrical heating units with rammed linings.