PUBLICATIONS IN THE SOLIDIFICATION / MATERIALS PROCESSING / MANUFACTURING AREA BY E.F. MATTHYS AS OF 10/96

(Full abstracts for some of these papers can be found below.)



Journal and Proceedings Articles

Wang G. and E.F. Matthys. 1996. Heat Transfer Modelling of the Planar Flow Casting Process. To appear in Heat and Mass Transfer in Manufacturing Technologies. Washington, DC: Hemisphere Pub.

Wang S.P., G.X. Wang, and E.F. Matthys. 1996. Substrate Melting and Resolidification in Metal Deposition and Casting Processes. To appear in the Proceedings of the 1997 NSF DDM Conference, Seattle, WA.

Wang G.X., V. Prasad, and E.F. Matthys. 1996. Solute distribution during rapid solidification into an undercooled melt. To appear in Journal of Crystal growth.

Wang G.X. and E.F. Matthys. 1996. Modeling of Non-equilibrium Surface Melting and Resolidification for Pure Metals and Binary Alloys. To appear in Journal of Heat Transfer.

Wang, G.X. and E.F. Matthys. 1996. On the Heat Transfer at the Interface Between A Solidifying Metal and a Solid Substrate. In Melt-spinning, Strip Casting, and Slab Casting, pp. 205-236, TMS Pub., Warrendale, PA.

Wang, G.X. and E.F. Matthys. 1996. Study of Interfacial Thermal Contact During Solidification on a Substrate (II). In Proceedings of the 1996 NSF Design and Manufacturing Conference, pp. 449-450, SME Pub., Dearborn MI.

Wang G.X. and E.F. Matthys. 1996. Experimental investigation of interfacial thermal conductance for molten metal solidification on a substrate. Journal of Heat Transfer, Vol. 118, No. 1, pp. 157-163.

Wang G.X. and E.F. Matthys. 1995. Modeling of Surface Melting and Resolidification for Pure Metals and Binary Alloys : Effect of Non-equilibrium Kinetics. In Transport phenomena in materials processing; vol. HTD- 317-2, pp. 349-359.

Wang G.X. and E.F. Matthys. 1995. Experimental investigation of interfacial heat transfer for molten metal solidification on a substrate. In Transport phenomena in Manufacturing and Materials Processing, Vol. HTD-306, pp. 171-179, ASME Pub.

Liu W., G.X. Wang, and E.F. Matthys. 1995. Thermal analysis and measurements for a molten metal drop impacting on a substrate: cooling, solidification, and heat transfer coefficient. International Journal of Heat and Mass Transfer. vol. 38, No. 8, pp. 1387-1395.

Wang, G.X. and E.F. Matthys. 1995. Study of Interfacial Thermal Contact During Solidification on a Substrate. In Proceedings of the 1995 NSF Design and Manufacturing Conference, pp. 451-452, SME Pub., Dearbon MI.

Liu W., Wang G.X. and E.F. Matthys. 1994. Spallation of a Substrate by Thermal Shock and Thermal Expansion Differential after Molten Metal Droplet Deposition. In Thermal Processing of Materials (ed: V. Prasad et al.), Vol. HTD-289, pp. 21-29, ASME Pub, Washington D.C.

Wang, G.X. and E.F. Matthys. 1994. Interfacial Thermal Contact during Rapid Solidification on a Substrate. In Heat Transfer 1994 (ed: G. Hewitt), IChemE Pub., Rugby UK, Vol. 4, pp. 169-174 (1994).

Wang G. and E.F. Matthys. 1993. Modeling of rapid planar solidification of a binary alloy. In Heat and Mass Transfer in Materials Processing and Manufacturing, Vol. HTD-261, pp. 35-44, ASME Pub.

Liu W., G. Wang, and E.F. Matthys. 1992. Determination of the thermal contact coefficient for a molten metal droplet impinging on a substrate. In Transport Phenomena in Materials Processing and Manufacturing, vol. HTD-196, pp. 111-118, ASME, New York.

Wang G. and E.F. Matthys. 1992. Two-dimensional boundary-layer modeling of Planar Flow Melt-Spinning with Undercooling. In Melt-Spinning and Strip Casting, pp. 263-282, Warrendale, PA: TMS Pub.

Matthys E.F. 1992. Heat transfer and fluid mechanics in materials processing. In Proceedings of the 1992 NSF Design and Manufacturing System Conference, Atlanta, January 8-10; Pub: Society of Manufacturing Engineers, Dearborn; pp. 135-138.

G. Trapaga, E.F. Matthys, J. Valencia, and J. Szekely. 1992. Fluid Flow, Heat Transfer, and Solidification of Molten Metal Droplets Impinging on Substrates: Comparison of Numerical and Experimental Results. Metallurgical Transactions, vol. 23B, No. 6, pp. 701-718.

Wang G. and E.F. Matthys. 1992. An improved boundary-layer model for the Planar Flow Melt-spinning process. Advanced Sensing, Modelling, and Control of Materials Processing; pp. 231-252. Warrendale, PA: TMS Pub.

Wilde P. and E.F. Matthys. 1992. Experimental Investigation of the Planar Flow Casting Process: Development and Free Surface Characteristics of the Solidification Puddle. Materials Science and Engineering, vol. 150, No. 2, pp. 237-247.

Wang G. and E.F. Matthys. 1992. Numerical modelling of phase change and heat transfer during rapid solidification processes: use of control volume integrals with element subdivision. International Journal of Heat and Mass Transfer, 35, No. 1, pp. 141-153.

Wang G. and E.F. Matthys. 1992. Modelling of splat cooling: effect of heat transfer and undercooling on solidification characteristics. "Advanced Sensing, Modelling, and Control of Materials Processing"; pp. 59-80. Warrendale, PA: TMS Pub.

Wang G. and E.F. Matthys. 1991. Heat Transfer Modelling of Rapid Solidification on a Substrate : A Parametric Investigation for Large Undercooling. International Journal of Rapid Solidification, vol. 6, No. 3-4, pp. 297-324.

Wang G. and E.F. Matthys. 1991. Modelling of heat transfer and solidification during splat cooling: effect of the splat thickness and splat / substrate thermal contact. International Journal of Rapid Solidification, vol. 6, No. 2, pp. 141-174.

Wang G. and E.F. Matthys. 1991. Modelling of Rapid Solidification by Melt-spinning: Effect of Heat Transfer in the Cooling Substrate. Materials Science and Engineering, vol. A136, pp. 85-97.

Gong Z., P. Wilde, and E.F. Matthys. 1991. Numerical Modelling of the Planar Flow Melt-Spinning Process, and Experimental Investigation of the solidification puddle dynamics. International Journal of Rapid Solidification, vol. 6, No. 1, pp. 1-28.

Gong Z., P. Wilde, and E.F. Matthys. 1990. Planar Flow Casting : Fluid Flow, Heat Transfer, and Solidification Puddle Dynamics. In Intelligent Processing of Materials, (Eds: H. Wadley and W.E. Eckhart), pp. 149-161. Warrendale, PA: TMS Pub.


Technical Reports

Wang G.X. and E.F. Matthys. 1991. Two-dimensional modelling of planar flow melt-pinning. Report No. UCSB-ME-91-2 (27 p.), College of Engineering, University of California, Santa Barbara.

Valencia J.J., E.F. Matthys, G. Trapaga, and J. Szekely. 1990. The impingement of molten metal drops on a substrate: comparison of experimental and numerical modelling results. Report No. UCSB-ME-90-12 (37 p.), College of Engineering, University of California, Santa Barbara.

Wang G. and E.F. Matthys. 1990. Modeling of planar flow casting and splat cooling: effect of process parameters on solidification characteristics. Report No. UCSB-ME-90-11 (38 p.), College of Engineering, University of California, Santa Barbara.

Wilde P.D. and E.F. Matthys. 1990. "An experimental investigation of planar flow melt-spinning: puddle and ribbon dynamics." Report No. UCSB-ME-90-7 (146 p.), College of Engineering, University of California, Santa Barbara.

Wang G., Z. Gong, P. Wilde, and E.F. Matthys. 1990. "Modelling of Planar Flow Casting and Splat cooling: Temperature Profiles, Interface velocities, and cooling rates." Report No. UCSB-ME-90-3 (51

Eskenazi M.I., P. Wilde, and E.F. Matthys. 1989. "Planar Flow Casting: Flow Visualization and Numerical Modeling." Report No. UCSB-ME-89-2 (50 p.), College of Engineering, University of California, Santa Barbara.

Matthys E.F., M. Eskenazi, P. Lermant, and P. Wilde. 1988. "Heat transfer and fluid dynamics during solidification: planar flow casting and levitation melting." Report No. UCSB-ME-88-5 (39 p.), College of Engineering, University of California, Santa Barbara.

Eskenazi M.I. and E.F. Matthys. 1988. "Modelling of planar flow melt spinning using the boundary layer equations." Report No. UCSB-ME-88-4 (87 p.), College of Engineering, University of California, Santa Barbara.



SOME ABSTRACTS


(Please note that abstracts for several papers published since mid-95 will be added shortly. Thank you for your patience.)


MODELING OF SURFACE MELTING AND RESOLIDIFICATION FOR PURE METALS AND BINARY ALLOYS: EFFECT OF NON-EQUILIBRIUM KINETICS

Wang G.-X. and E.F. Matthys. 1995

To appear in Transport Phenomena in Manufacturing and Materials Processing (Proceedings of the 1995 ICME), ASME Pub, Washington D.C.

Abstract
A one-dimensional model including non-equilibrium phenomena was developed for surface melting and resolidification of both pure metals and binary alloys substrates. Non- equilibrium kinetics from crystal growth theory are introduced in the model to treat both non- equilibrium melting and resolidification. The modelled problem involves a moving boundary with both heat and solute diffusions and is solved by an implicit control volume integral method with solid / liquid interface immobilization by coordinate transformation. For illustration of the model applicability, we have analyzed laser surface melting of pure metals (Al, Cu, Ni, Ti) and dilute Al-Cu alloys, and some typical results are presented. The computation results show large solid overheating and melt undercooling which result from the high heat flux and the slow kinetics. The melt undercooling is maintained during most of the resolidification process and so is the high solidification rate. Complex interface velocity variations during the earlier stages of resolidification were obtained and result from interactions between various physical mechanisms. A strong effect of the solute on the interface velocity was also predicted.


Experimental Investigation of Interfacial Thermal Resistance for Molten Metal Solidification on a Substrate

Wang G.-X. and E.F. Matthys, 1995

To appear in Transport Phenomena in Net-Shape Manufacturing (Proceedings of the 1995 National Heat Transfer Conference), ASME Pub.

Abstract
Experiments have been conducted to quantify the interfacial heat transfer between molten copper and a cold metallic substrate, and in particular to investigate the heat transfer variation as the initial liquid / solid contact becomes a solid / solid contact after nucleation. A high heat transfer coefficient (ranging from 104 to 105 W/m2K) during the earlier liquid cooling phase and a lower heat transfer coefficient (from 103 to 104 W/m2K) during the subsequent solid splat cooling phase were estimated through matching of model calculations and the measured temperature history of the sample. The dynamic variations in the interfacial heat transfer resulting from the solidification process were quantified for splat cooling and were found to be affected by the melt superheat, the substrate material, and the substrate surface finish.


Thermal Analysis and Measurements for a Molten Metal Drop Impacting on a Substrate: Cooling, Solidification, and Heat Transfer Coefficient

Liu W., G.-X. Wang, and E.F. Matthys. 1995.

Int. J. Heat Mass Transfer, Vol. 38, No. 8, pp. 1387-1395.

Abstract
The behavior of a molten metal droplet impinging, spreading and solidifying on a solid substrate is relevant to many processes such as splat cooling and spray deposition. In this study, we have conducted experiments aiming at the study of the cooling and solidification of a molten metal droplet after impact. Temperature measurements were conducted during and after solidification. Some results are presented to illustrate the effect of superheat and substrate material on cooling rate. We have also estimated the thermal contact coefficient between splat and substrate by matching for a number of conditions the experimental data to predictions of a heat transfer and phase change model. The results suggest that this coefficient can decrease during solidification by an order of magnitude during solidification for the case of a splat on metal substrates. For splats on quartz where there is good bonding, the thermal contact coefficient appears to stay the same before and after solidification.


Study of Interfacial Thermal Contact During Solidification on a Substrate

Wang, G.X. and E.F. Matthys. 1995.

In Proceedings of the 1995 NSF Design and Manufacturing Conference, pp. 451-452, SME Pub., Dearbon MI.


Spallation of a Substrate by Thermal Shock and Thermal Expansion Differential during Splat Cooling

Liu W., G.-X. Wang, E.F. Matthys. 1994.

In Thermal Processing of Materials, Vol. HTD-289, pp. 21-29, ASME, New York.

Abstract
The manufacture of metal matrix composite materials by spray deposition is a very attractive process, but impaired by the spallation that may take place after impact of molten metal droplets on the fibers. In this work, the spallation of a quartz substrate was investigated through video and acoustic measurements, and through temperature measurements of the splat surface. The time scales pertaining to the fracture mechanisms are examined from acoustic measurements of the spallation. The spall formation mechanism was quantified by analyzing the geometric configuration of the splats and spalls under varying conditions of droplet superheat, droplet size, and droplet or substrate material. Furthermore, the thermal contact resistance between the splat and the substrate was evaluated by matching the measured temperatures of the top or bottom surface of the splat with numerical results from a heat conduction model with phase change.


Interfacial Thermal Contact during Rapid Solidification on a Substrate

Wang G.-X. and E.F. Matthys. 1994.

In Heat Transfer 1994, (Proceedings of the 10th international heat transfer conference), IChemE Pub., Rugby, UK. Vol. 4, pp. 169-174.

Abstract
In processes such as strip casting, a thin layer of molten metal is brought in contact with a colder substrate. The metal/substrate interface heat transfer may then determine the melt cooling rate and solidification velocity, and therefore affects strongly the material properties of the solidified product. As a first step in the systematic study of the interface heat transfer phenomena in those processes, we have performed experiments to quantify the interface heat transfer coefficient when molten metal is solidified on a substrate. The temperature of the solidifying metal is measured at various locations, and an inverse heat transfer model is then used to estimate the variation in interface heat transfer coefficient as a function of time. This coefficient is calculated for a range of superheats and two substrate materials. It is found that large variations in heat transfer coefficient take place before and around nucleation time, but that this coefficient remains about constant starting shortly thereafter.


Modeling of Rapid Planar Solidification of a Binary Alloy

Wang G.-X. and E.F. Matthys. 1993.

In Heat and Mass Transfer in Materials Processing and Manufacturing, Vol. HTD-261, pp. 35-44, ASME, New York.

Abstract
Many manufacturing systems involving fast-moving substrates or material to be processed are intended to achieve conditions that would result in rapid solidification with undercooling. A general one-dimensional model for planar solidification of binary alloys and which includes non-equilibrium solidification with melt undercooling has been developed to investigate these processes. Solidification kinetics relationships for binary alloys are introduced to supplement the heat and solute diffusion equations in order to provide a more complete description of this moving boundary problem. We use an implicit finite difference method with solid/liquid interface immobilization by coordinate transformation. An efficient iteration scheme was developed to calculate the varying temperature and solute concentrations at the moving solid/liquid interface. As an example, splat cooling of a dilute binary nickel alloy is analyzed and some typical results are presented.


Determination of the thermal contact coefficient for a molten metal droplet impinging on a substrate.

Liu W., G.-X. Wang, and E.F. Matthys. 1992.

In Transport Phenomena in Materials Processing and Manufacturing, vol. HTD-196, pp. 111-118, ASME, New York.

Abstract
The behavior of a molten metal droplet impinging, spreading and solidifying on a solid substrate is relevant to many processes such as splat cooling and spray deposition. In this work, we have conducted experiments aiming at the study of the cooling and solidification of a molten metal droplet after impact. Measurements of temperature and of acoustic emissions, together with high-speed visualization were conducted during and after spreading. Some results are presented to illustrate the effect of superheat and substrate material on cooling rate. We have also evaluated the value of the thermal contact coefficient by matching the experimental data to predictions of a heat transfer and phase change model. The results suggest that the value of the heat transfer coefficient decreases during solidification by up to an order of magnitude for the case of a splat on metal substrates. For splats on quartz or glass where there is good bonding, the thermal contact coefficient appears to stay constant throughout the process.


Two-dimensional boundary-layer modeling of Planar Flow Melt-Spinning with Undercooling.

Wang G.-X. and E.F. Matthys. 1992.

In Melt-Spinning and Strip Casting, pp. 263-282, Warrendale, PA: TMS Pub.

Abstract
This paper describes a two-dimensional model of fluid flow and heat transfer with phase change for the planar flow melt-spinning process. Boundary layer theory is used to model fluid flow and heat transfer in the solidification puddle, and a semi-implicit finite difference scheme is used to solve the corresponding governing equations. In order to take into account non-equilibrium solidification with melt undercooling, a growth kinetics relationship between the solidification interface velocity and the interface undercooling is incorporated in the model. The location of the interface and its temperature are calculated using an interface tracking technique based on control volume integrals with element subdivision. Besides the interface velocity and temperature, and melt cooling (or heating) rate, the model predicts also the shape of the downstream meniscus formed between the crucible and the moving wheel. Some results for the planar flow melt- spinning of an aluminum melt with undercooling are presented, including predictions of the streamlines and isotherms in the puddle. The effect of the interface kinetics and melt undercooling on the solidification characteristics is quantified through a comparison with an equilibrium solidification model. The results show the effect of recalescence on the solidification of the ribbon, and in particular allow us to quantify the fraction of the ribbon affected by this recalescence. In this lower region, a much higher interface velocity is predicted than in the upper part of the ribbon which is solidified under quasi- equilibrium conditions.


Heat transfer and fluid mechanics in materials processing.

Matthys E.F. 1992.

In Proceedings of the 1992 NSF Design and Manufacturing Systems Conference, Atlanta, January 8-10; Pub: Society of Manufacturing Engineers, Dearborn; pp. 135-138.


Fluid Flow, Heat Transfer, and Solidification of Molten Metal Droplets Impinging on Substrates: Comparison of Numerical and Experimental Results.

Trapaga G., E.F. Matthys, J. Valencia, and J. Szekely. 1992.

Metallurgical Transactions, vol. 23B, No. 6, pp. 701-718.


An improved boundary-layer model for the Planar Flow Melt-spinning process.

Wang G.-X. and E.F. Matthys. 1992.

In Advanced Sensing, Modelling, and Control of Materials Processing; pp. 231-252. Warrendale, PA: TMS Pub.

Abstract
A two-dimensional boundary-layer fluid flow and heat transfer model has been used to analyze solidification during the planar flow melt-spinning process. An interface-tracking technique is also implemented in this model to predict the solid/liquid interface motion and therefore to calculate more accurately its velocity and the melt cooling rate at that location. Heat conduction in the chill wheel has also been taken into account. The influence of the fluid flow in the puddle on the solidification behavior during planar flow melt-spinning has been quantified by comparing the results of this two-dimensional boundary-layer model with two simpler one-dimensional heat conduction models. It is seen that these one-dimensional models either overestimated or underestimated the interface velocity when compared with the two-dimensional boundary model. This two- dimensional model also predicts a sharp increase in solidification rate after detachment of the fluid from the crucible.


Experimental Investigation of the Planar Flow Casting Process: Development and Free Surface Characteristics of the Solidification Puddle.

Wilde P. and E.F. Matthys. 1992.

Materials Science and Engineering, vol. 150, No. 2, pp. 237-247.

Abstract
Planar Flow Casting (PFC) is one of the most promising processes for the manufacture of thin metal sheets and high-performance rapidly-solidified alloys, but very little experimental information is available about this process. We have therefore developed an experimental installation that enables us to study the dynamic behavior of the PFC solidification puddle. We have in particular used high-speed video recordings to analyze casting runs conducted for various values of the most important parameters. The size and shape of the puddle have been quantified, and the effect of variations in flow rate, gap, and wheel speed on the puddle shape has been studied. We have also investigated the dynamics of the development of the puddle immediately after melt ejection. Both digitized results and high-speed photographic sequences of solidification puddles are shown and discussed in this article.


Heat Transfer Modelling of the Planar Flow Casting Process.

Wang G. and E.F. Matthys. 1992.

Accepted for publication in Heat and Mass Transfer in Manufacturing Technologies. Washington, DC: Hemisphere Pub. (Printing cancelled.)


Numerical modelling of phase change and heat transfer during rapid solidification processes: use of control volume integrals with element subdivision.

Wang G.-X. and E.F. Matthys. 1992.

International Journal of Heat and Mass Transfer, 35, No. 1, pp. 141-153.

Abstract
An effective interface-tracking scheme has been developed for the numerical modelling of heat transfer and phase change during rapid solidification. This technique is based on Control Volume Integrals, and achieves high-resolution tracking of the solid / liquid interface by element subdivision. It is particularly well-suited for rapid solidification with undercooling, for which the accurate prediction of the interface temperature during recalescence is very important. This approach has been used to model the Planar Flow Casting and Splat Cooling processes. Some results on temperature profiles and on interface velocity, location, undercooling, and cooling rate are shown for both processes.


Modelling of splat cooling: effect of heat transfer and undercooling on solidification characteristics.

Wang G.-X. and E.F. Matthys. 1992.

In Advanced Sensing, Modelling, and Control of Materials Processing; pp. 59-80. Warrendale, PA: TMS Pub.

Abstract
A non-equilibrium numerical model has been developed to study the heat transfer and phase change during splat cooling with undercooling. This model allows the interface temperature to vary during solidification, and a kinetics relationship is introduced to enable us to calculate this temperature as well as the interface velocity. We are presenting some results that illustrate the difference in results predicted by an equilibrium model and by linear and exponential undercooling models. Some results on interface velocity and temperature are shown for various nucleation temperatures and for various external heat transfer coefficients. It is seen that these parameters affect considerably the solidification characteristics, in particular the variation of interface velocity through the splat and the size of the recalescence region. Interestingly, it is shown that a lower external heat transfer may result indirectly in a higher interface velocity during recalescence, all other parameters being equal.


Heat Transfer Modelling of Rapid Solidification on a Substrate : A Parametric Investigation for Large Undercooling.

Wang G.-X. and E.F. Matthys. 1991.

International Journal of Rapid Solidification, vol. 6, No. 3-4, pp. 297-324.

Abstract
A parametric investigation of the heat transfer and phase change during splat cooling has been conducted with a non-equilibrium numerical model. This model is able to track the solid / liquid interface motion for rapid solidification with large undercooling. Some results are shown to illustrate the level of uncertainty introduced by the use of linearized kinetics models. The influence of various parameters (such as nucleation temperature, splat / substrate thermal contact, melt and substrate materials, kinetics coefficients, initial substrate temperature, and initial melt temperature) on the solidification interface temperature and velocity has also been investigated. The related physical mechanisms are discussed in terms of heat transfers and temperature distributions. One important effect quantified in this study is the fact that both the interface velocity during recalescence and the fraction of the splat affected by recalescence depend not only on the nucleation temperature but also (and very strongly) on the undercooling distribution across the splat upon nucleation. For instance, a relatively high nucleation temperature with small temperature gradients in the splat may well result in a higher solidification rate over a larger fraction of the splat than a very low nucleation temperature with large temperature gradients in the splat. Interestingly (and somewhat counterintuitively) one might then achieve higher solidification rates in the splat for poor thermal contact between the splat and the substrate than for good thermal contact, all other parameters (including nucleation temperature) being equal.


Modelling of heat transfer and solidification during splat cooling: effect of the splat thickness and splat / substrate thermal contact.

Wang G.-X. and E.F. Matthys. 1991.

International Journal of Rapid Solidification, vol. 6, No. 2, pp. 141-174.

Abstract We have developed an improved Control Volume Integral method for the numerical modelling of rapid solidification processes. This technique provides high-resolution tracking of the solidification interface with and without undercooling. We have conducted a study of the splat cooling process and of the effect of various parameters on the local interface velocity, cooling rate, and temperature in the splats. In particular, the effect of the heat transfer coefficient at the splat / substrate interface and of the splat thickness on the solidification characteristics has been investigated over a range of conditions. Among other observations, the region over which recalescence takes place has been quantified, with the recalesced splat fraction found to be proportionally much larger for a thin splat than for a thick splat. Rather sharp differences are seen to exist between this domain and the rest of the splat in terms of interface velocity, cooling rate, and temperature. The comparison of results with and without undercooling indicates that large errors in interface velocity and cooling rate in the bottom part of the splat would result from the use of models that do not take into account the undercooling phenomenon.


Modelling of Rapid Solidification by Melt-spinning: Effect of Heat Transfer in the Cooling Substrate.

Wang G.-X. and E.F. Matthys. 1991.

Materials Science and Engineering, vol. A136, pp. 85-97.

Abstract
An improved Control Volume Integral method has been developed for the numerical modelling of heat transfer during the melt-spinning process. The heat transfers both inside the melt and in the substrate are incorporated directly in the numerical models. Several parametric studies have been conducted to investigate the effect of the heat transfer in the wheel, of the wheel material, of the melt material, and of the superheat level on the solidification characteristics, and in particular on the interface velocity and on the cooling rate at the interface. The calculations show also that the local substrate surface temperature may increase under the solidification puddle by several hundred Kelvins, even for a copper wheel, and this surface temperature increase is found to have a significant impact on the solidification process. We believe that it is essential to include the surface heating factor in numerical models of melt-spinning and other rapid solidification processes relying on direct contact with a solid substrate.


Numerical Modelling of the Planar Flow Melt- Spinning Process, and Experimental Investigation of the solidification puddle dynamics.

Gong Z., P. Wilde, and E.F. Matthys. 1991.

International Journal of Rapid Solidification, vol. 6, No. 1, pp. 1-28.

Abstract
A numerical model based on two-dimensional boundary layer equations has been developed for the Planar Flow Melt-Spinning process. The coupled continuity, momentum, energy, and phase change equations are solved simultaneously. The velocity and temperature distributions in the puddle and ribbon, the cooling rate at any location, and the shape and location of both the solid / liquid interface and the downstream meniscus can then all be evaluated numerically. Parametric studies have been conducted, and some examples of isotherm and streamline maps are shown for several values of the main process parameters. We have also conducted an experimental investigation of the dynamics of the solidification puddle by high- speed video recordings, and some results such as photographs of high-frequency surface waves and of the establishment of a typical solidification puddle are shown. The experimental results were used to obtain estimates of the thermal contact resistance at the substrate by matching the measured detachment point and meniscus shape with numerical modelling results.



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