Search results for "Crucible"

Über die struktur aus 2,4,6-tri(dihydroxymethyl-amino)-1,3,5-triazin (hexamethylolmelamin) erhaltener polykondensate

1960

Die Polykondensation von Hexamethylolmelamin bei 110°C bis 150°C in Platintiegeln und im Stickstoffstrom erfolgt ohne ein Schmelzen der weisen, pulverigen Proben. Es wird hierbei der Gewichtsverlust, sowie quantitativ der abgespaltene Formaldehyd und das abgespaltene Wasser bestimmt. Aus den Elementaranalysen der Polykondensate einerseits, sowie dem Gewichtsverlust und den Spaltprodukten andererseits, lassen sich fur den durchschnittlichen Grundbaustein der Polykondensate innerhalb einer gewissen Streuung ubereinstimmende Summenformeln ableiten. Aus den Summenformeln und dem quantitativ verfolgten Polykondensationsverlauf schlieslich ergeben sich die Konstitutionsformeln der durchschnittlic…

Numerical 3D modelling of turbulent melt flow in a large CZ system with horizontal DC magnetic field. II. Comparison with measurements

2004

This paper presents a comparison between numerically calculated and measured temperature distributions in turbulent flow in a laboratory model for a CZ large silicon single crystal industrial growth system with a horizontal DC magnetic field. The laboratory model consists of an electrically heated 20” crucible with low-temperature InGaSn melt, a water-cooled metallic crystal model, and a magnet system creating a horizontal magnetic field in the range 0–. Distributions of time-averaged temperature values in various cross sections in the melt are obtained from measurements by a multichannel thermocouple system. A 3D numerical model for the scalar potential induced in the melt by the velocity …

Controlling melt convection—an innovation potential for concerted microstructure evolution of Nd-Fe-B alloys

2005

The solidification process and the resulting microstructure of Nd-Fe-B alloys in consideration of melt convection has been investigated experimentally with a specially designed forced crucible rotation technique. Samples were subjected to well-defined forced rotation and vibration, respectively, during induction heating and solidification. A concerted microstructure evolution is possible by enhancement or suppression of the melt convection. As a result, the microstructure pattern, mainly the volume fraction of the soft magnetic a-Fe phase, vary strongly with the strength of the internal flow motion. A distinct reduction of the a-Fe volume fraction in samples with strong melt rotation was ob…

Application of dynamic and combined magnetic fields in the 300mm silicon single-crystal growth

2002

Abstract The increase of diameter in the silicon single crystal growth from 200 to 300 mm for industrial application, and to 400 or 450 mm for research, respectively, has triggered off the development of numerous new technologies like crystal-growth-supporting systems, low-power hot zones, high strength of static magnetic fields and new quartzglas qualities. At Wacker Siltronic, new kinds of magnetic fields have been developed for 300 mm CZ growth. In this paper, the results of dynamic and combined (static and alternating) magnetic fields are discussed. Instead of buoyancy-driven convection, a magnetic-field-controlled melt flow has been obtained in large melt volumes. The crucible wall tem…

Numerical 2D modelling of turbulent melt flow in CZ system with dynamic magnetic fields

2004

Abstract The paper presents results of 2D axisymmetric mathematical modelling of laboratory CZ model facility that corresponds well to a large industrial silicon CZ growth system. The purpose of the investigation is to examine turbulent melt flow features that develop in the model crucible, when various dynamic magnetic fields (travelling, alternating) are applied, and to test the applicability of the modified low Re k–e turbulence model for the calculation of flows in these cases by extensive comparisons between calculated and measured data. The electromagnetic field is calculated with a self-developed program, and the calculations of the melt motion are carried out with the user modified …

Experimental investigations and numerical modelling of the melting process in the cold crucible

2005

PurposeAims to present recent activities in experimental investigations and numerical modelling of the induction cold crucible installation.Design/methodology/approachTemperature and velocity measurements using thermocouples and electromagnetic velocity probes were performed in aluminium melt which was used as a model melt. Measured temperature field and flow pattern were compared with transient 3D calculations based on large eddy simulation (LES) turbulence modelling scheme. Numerical results are in good coincidence with the experimental data.FindingsThe modelling results show that only 3D transient LES is able to model correctly these heat and mass transfer processes.Originality/valueIt i…

Numerical studies of the melting process in the induction furnace with cold crucible

2008

PurposeAims to present recent activities in numerical modeling of cold crucible melting process.Design/methodology/approach3D numerical analysis was used for electromagnetic problem and 3D large eddy simulation (LES) method was applied for fluid flow modeling.FindingsThe comparative modeling shows, that higher H/D ratio of the melt is more efficient when total power consumption is considered, but this advantage is held back by higher heat losses through the crucible walls. Also, calculations reveal that lower frequencies, which are energetically less effective, provide better mixing of the melt.Originality/value3D electromagnetic model, which allows to take into account non‐symmetrical dist…

Thermal and Hydrodynamic Analysis of the Melting Process in the Cold Crucible Using 3D Modeling

2008

Is the Crucible Reproducible? Reconciling Melting Experiments with Thermodynamic Calculations

2011

Experimental studies and thermodynamic modelling have advanced our understanding of partial melting in the crust and have provided a frame-work for the interpretation of migmatites, residual granulites and granites. Each approach has advantages and pitfalls, and each is more appropriate than the other for investigating particular aspects of the melting process. A comparison of these two approaches may be useful because, together, they potentially give more information. A comparison of a small number of experiments with model calculations using equivalent bulk compositions shows important consistencies between the results, especially regarding the overall topologies of key melting equilibria…

Analysis and Design of Induction Liquid Metal Processes Using Advanced Numerical Modelling

2019

Comprehensive knowledge of the turbulent flows, heat and mass transfer processes in the melt of induction applications is required to realize efficient metallurgical processes. Therefore, the process oriented development, design and optimization of induction furnaces for melting and casting of metals require praxis oriented simulation and analysis of the complex in-stationary turbulent melt flows and temperature distributions as well as the heat and mass transfer processes in the liquid metal. The studies, presented in this paper, demonstrate the possibilities of using advanced three-dimensional transient numerical modelling for successful simulation of the melt flow as well as heat and mas…