Analysis of Melting in a Mixed Metal Powder Bed With Finite Thickness Subjected to Constant Heat Flux Heating

2003 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Selective Laser Sintering ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Constant Heat Flux ◽  
Metal Powders ◽  
Powder Bed ◽  
Solid Foundation ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Liquid And Solid Phases

Melting of a subcooled powder bed with the finite thickness that contains a mixture of two metal powders with significantly different melting points is investigated analytically. Shrinkage induced by melting is taken into account in the physical model. The temperature distributions in the liquid and solid phases were obtained using an exact solution and an integral approximate solution, respectively. The effects of porosity, Stefan number, and subcooling on the surface temperature and solid-liquid interface are also investigated. The present work built solid foundation to investigate the complex three-dimensional selective laser sintering (SLS) process.

Analysis and modeling of direct selective laser sintering of two-component metal powders

2005 ◽  
Author(s):  
◽  
Tiebing Chen
Keyword(s):  
Laser Beam ◽  
Selective Laser Sintering ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Gaussian Laser Beam ◽  
Scanning Velocity ◽  
Two Component

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Direct Selective Laser Sintering (SLS) is an emerging technology of Solid Freeform Fabrication (SFF) that 3-D parts are built from the metal-based powder bed with CAD data. A one-dimensional analytical model of melting in a two-component powder layer with finite thickness subjected to a constant heat flux heating and a two-dimensional numerical model of SLS of a two-component powder layer with a moving laser beam scanning were developed consecutively. Three-dimensional modeling of laser sintering of a two-component metal powder mixture under a moving Gaussian laser beam was investigated numerically at last. The effects of the moving heat source intensity, the scanning velocity, the thickness of the powder layer and the number of existing sintered layers underneath on the sintering depth, the configuration of the heat affected zone (HAZ) and the temperature distribution are discussed.

Segregation Patterns and the Phase-Field 3D-Model for Adiabatic Phase Transition in Al-Cu Alloys

2013 ◽  
Vol 668 ◽  
pp. 870-874
Author(s):  
Heng Min Ding ◽  
Tie Qiao Zhang ◽  
Lv Chun Pu
Keyword(s):  
Dendritic Growth ◽  
3D Model ◽  
Three Dimensional ◽  
Cartesian Grid ◽  
Solute Diffusion ◽  
Solute Redistribution ◽  
Cu Alloys ◽  
Solid Phases ◽  
Solid Liquid ◽  
Liquid And Solid Phases

In the paper, a model basing on solute conservative in every unit is developed for solving the solute diffusion equation during solidification. The model includes time-dependent calculations for temperature distribution, solute redistribution in the liquid and solid phases. Three-dimensional computations are performed for Al-Cu dendritic growth into an adiabatic and highly supersaturated liquid phase. A numerical algorithm was developed to explicitly track the sharp solid/liquid (S/L) interface on a fixed Cartesian grid. Three-dimensional mesoscopic calculations were performed to simulate the evolution of equiaxed dendritic morphologies.

Experimental and Numerical Analysis of Droplet Cooling

2010 ◽  
Author(s):  
Paolo Tartarini ◽  
Mauro A. Corticelli ◽  
Paolo E. Santangelo
Keyword(s):  
Three Dimensional ◽  
Numerical Approach ◽  
Solid Substrate ◽  
Liquid Interface ◽  
Temperature Trend ◽  
Numerical Code ◽  
Uniform Mesh ◽  
Thermal Transient ◽  
Solid Liquid Interface ◽  
Solid Liquid

Dropwise cooling represents a major subject of interest for both academic and industrial researches. The present work is focused on investigating the thermal transient occurring as two water droplets are gently released (We < 30) onto a heated solid surface. This latter has been kept at initial temperature lower than 373.15 K to analyze the single-phase-evaporation regime. To the purpose, both an experimental and a numerical approach have conveniently been employed. Infrared thermography has been used to evaluate the temperature trend at the solid-liquid interface: an experimental facility has been built to carry out measurements from below, thus realizing a fully non-intrusive approach. A transparent-crystal disk has been inserted to serve as the solid substrate; its upper surface has been painted by a black coating, thus providing a black-body surface as the solid-liquid interface. The infrared thermocamera has been placed below and perpendicular to that surface; temperature has been thereby measured, being emissivity a known parameter. A numerical code has been developed to predict the involved physical phenomena: temperature trend, evaporation time and evaporated flux result from discretizing the three-dimensional energy-diffusion equation by the finite-volume method. Moreover, the model is based on structured non-uniform mesh to adapt to the occurring temperature gradients. Very good agreement is shown between experimental and numerical outcomes in terms of thermal transient and recovery.

Three-dimensional hotspots in evaporating nanoparticle sols for ultrahigh Raman scattering: solid–liquid interface effects

Nanoscale ◽  
2015 ◽  
Vol 7 (15) ◽  
pp. 6619-6626 ◽  
Author(s):  
Yudie Sun ◽  
Zhenzhen Han ◽  
Honglin Liu ◽  
Shengnan He ◽  
Liangbao Yang ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Capillary Force ◽  
Three Dimensional ◽  
Liquid Interface ◽  
Sers Enhancement ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Interface Effects

Decreasing interface adsorbing and increasing capillary-force packing of nanoparticles in an evaporating Ag-sol droplet is responsible for much higher SERS enhancement.

Three-Dimensional Modeling of Selective Laser Sintering of Two-Component Metal Powder Layers

2005 ◽  
Vol 128 (1) ◽  
pp. 299-306 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Metal Powder ◽  
Continuous Wave ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Gaussian Laser Beam ◽  
Scanning Velocity ◽  
Three Dimensional Modeling

Laser sintering of a metal powder mixture that contains two kinds of metal powders with significantly different melting points under a moving Gaussian laser beam is investigated numerically. The continuous-wave laser-induced melting accompanied by shrinkage and resolidification of the metal powder layer are modeled using a temperature-transforming model. The liquid flow of the melted low-melting-point metal driven by capillary and gravity forces is also included in the physical model. The numerical results are validated by experimental results, and a detailed parametric study is performed. The effects of the moving heat source intensity, the scanning velocity, and the thickness of the powder layer on the sintering depth, the configuration of the heat affected zone, and the temperature distribution are discussed.

scholarly journals Application of cellular automata and Lattice Boltzmann methods for modelling of additive layer manufacturing

2018 ◽  
Vol 28 (1) ◽  
pp. 31-46 ◽  
Author(s):  
Dmytro Svyetlichnyy ◽  
Michal Krzyzanowski ◽  
Robert Straka ◽  
Lukasz Lach ◽  
W. Mark Rainforth
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Cellular Automata ◽  
Integrated Modelling ◽  
Holistic Model ◽  
Content Type ◽  
Powder Bed ◽  
Physical Mechanisms ◽  
Solid Liquid Interface ◽  
Solid Liquid

Purpose The holistic numerical model based on cellular automata (CA) and lattice Boltzmann method (LBM) are being developed as part of an integrated modelling approach applied to study the interaction of different physical mechanisms in laser-assisted additive layer manufacturing (ALM) of orthopaedic implants. Several physical events occurring in sequence or simultaneously are considered in the holistic model. They include a powder bed deposition, laser energy absorption and heating of the powder bed by the moving laser beam, leading to powder melting or sintering, fluid flow in the melted pool and flow through partly or not melted material, and solidification. The purpose of this study is to develop a structure of the holistic numerical model based on CA and LBM applicable for studying the interaction of the different physical mechanisms in ALM of orthopaedic implants. The model supposed to be compatible with the earlier developed CA-based model for the generation of the powder bed. Design/methodology/approach The mentioned physical events are accompanied by heat transfer in solid and liquid phases including interface heat transfer at the boundaries. The sintering/melting model is being developed using LBM as an independent numerical method for hydrodynamic simulations originated from lattice gas cellular automata. It is going to be coupled with the CA-based model of powder bed generation. Findings The entire laser-assisted ALM process has been analysed and divided on several stages considering the relevant physical phenomena. The entire holistic model consisting of four interrelated submodels has currently been developed to a different extent. The submodels include the CA-based model of powder bed generation, the LBM-CA-based model of heat exchange and transfer, the thermal solid-liquid interface model and the mechanical solid-liquid interface model for continuous liquid flow. Practical implications The results obtained can be used to explain the interaction of the different physical mechanisms in ALM, which is an intensively developing field of advanced manufacturing of metal, non-metal and composite structural parts, for instance, in bio-engineering. The proposed holistic model is considered to be a part of the integrated modelling approach being developed as a numerical tool for investigation of the co-operative relationships between multiphysical phenomena occurring in sequence or simultaneously during heating of the powder bed by the moving high energy heat source, leading to selective powder sintering or melting, fluid flow in the melted pool and through partly (or not) melted material, as well as solidification. The model is compatible with the earlier developed CA-based model for the generation of the powder bed, allowing for decrease in the numerical noise. Originality/value The present results are original and new for the study of the complex relationships between multiphysical phenomena occurring during ALM process based on selective laser sintering or melting, including fluid flow and heat transfer, identified as crucial for obtaining the desirable properties.

Solute Field in Liquid Ahead of the Solid-Liquid Interface during Dendritic Solidification Incorporating Relaxation Effect

2014 ◽  
Vol 981 ◽  
pp. 867-870
Author(s):  
Xiang Zhong Jin ◽  
Hong Yang Wang ◽  
Ning Wang ◽  
Xiao Guang Lan ◽  
Shu Li
Keyword(s):  
Finite Thickness ◽  
Relaxation Effect ◽  
Diffuse Interface ◽  
Bulk Liquid ◽  
Interfacial Region ◽  
Dendritic Solidification ◽  
Paraboloid Of Revolution ◽  
Model Predictions ◽  
Solid Liquid Interface ◽  
Solid Liquid

Through solving an extended Fick’s diffusion equation for the solidification front of a paraboloid of revolution, a generalized Ivantsov function is obtained. The relaxation effect of nonequilibrium liquid diffusion is taken into account. The solute profile in the interfacial region and in the bulk liquid during steady-state dendritic solidification is uniquely determined. It is concluded that the consideration of the relaxation effect and the diffuse interface of finite thickness which decreases with increasing of velocities are necessary for achieving the good model predictions.

scholarly journals Electron microscopy of nanoparticle superlattice formation at a solid-liquid interface in nonpolar liquids

2020 ◽  
Vol 6 (20) ◽  
pp. eaba1404
Author(s):  
E. Cepeda-Perez ◽  
D. Doblas ◽  
T. Kraus ◽  
N. de Jonge
Keyword(s):  
Electron Microscopy ◽  
Three Dimensional ◽  
Honeycomb Structure ◽  
Liquid Interface ◽  
Thin Layers ◽  
Fine Tuning ◽  
Particle Layer ◽  
Dense Packings ◽  
Solid Liquid Interface ◽  
Solid Liquid

Nanoparticle superlattice films form at the solid-liquid interface and are important for mesoscale materials, but are notoriously difficult to analyze before they are fully dried. Here, the early stages of nanoparticle assembly were studied at solid-liquid interfaces using liquid-phase electron microscopy. Oleylamine-stabilized gold nanoparticles spontaneously formed thin layers on a silicon nitride (SiN) membrane window of the liquid enclosure. Dense packings of hexagonal symmetry were obtained for the first monolayer independent of the nonpolar solvent type. The second layer, however, exhibited geometries ranging from dense packing in a hexagonal honeycomb structure to quasi-crystalline particle arrangements depending on the dielectric constant of the liquid. The complex structures formed by the weaker interactions in the second particle layer were preserved, while the surface remained immersed in liquid. Fine-tuning the properties of the involved materials can thus be used to control the three-dimensional geometry of a superlattice including quasi-crystals.

scholarly journals 3D Numerical Analysis of the Asymmetric Three-Phase Line of Floating Zone for Silicon Crystal Growth

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 121 ◽  
Author(s):  
Xue-Feng Han ◽  
Xin Liu ◽  
Satoshi Nakano ◽  
Hirofumi Harada ◽  
Yoshiji Miyamura ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Silicon Crystal ◽  
Three Dimensional ◽  
Heat Transfer Fluid ◽  
Floating Zone ◽  
Phase Line ◽  
Three Phase ◽  
Em Field ◽  
Solid Liquid Interface ◽  
Solid Liquid

A numerical simulation has been carried out to study the asymmetric heat transfer, fluid flow, and three-phase line to explain the phenomenon of the spillage of the melt in floating zone (FZ) silicon growth. A three-dimensional high-frequency electromagnetic (EM) field is coupled with the heat transfer in the melt and crystal calculation domains. The current density along the three-phase line is investigated to demonstrate the inhomogeneous heating along the three-phase line. The asymmetric heating is found to affect the flow pattern and temperature distribution of the melt. The three-dimensional solid–liquid interface results show that, below the current supplies, the interface is deflected due to strong heating below the current supplies. The calculated asymmetric three-phase line shows a similar trend as the experimentally observed results. The results indicate that the re-melting and spillage phenomenon could occur below the current supplies.

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