Thermal Modeling of Deposit Solidification in Uniform Droplet Spray Forming

1997 ◽  
Vol 119 (3) ◽  
pp. 332-340 ◽  
Author(s):  
P. Acquaviva ◽  
Chen-An Chen ◽  
Jung-Hoon Chun ◽  
Teiichi Ando
Keyword(s):  
Thermal State ◽  
Liquid Fraction ◽  
Solidification Process ◽  
Spray Forming ◽  
Forming Process ◽  
Material Microstructure ◽  
Precise Control ◽  
Uniform Droplet Spray ◽  
Droplet Spray ◽  
Uniform Droplet

In spray forming, the deposit thermal state is a key parameter which influences the microstructural evolution upon and after droplet impact onto the deposit. The uniform droplet spray (UDS) forming process has been developed to enable precise control of the droplet and deposit thermal state and the resultant material microstructure. By having a uniform droplet size throughout the spray, all the droplets deposited onto the substrate will have the same thermal state upon impact, allowing for precise control of the solidification process. This paper describes a one-dimensional, finite difference model that predicts the temperature and liquid fraction of the deposit during the UDS process. The model employs an explicit temperature-enthalpy method to incorporate a variety of solidification models. Experiments were conducted using Sn-15 wt percent Pb binary alloy. Temperatures were measured in the deposit and acceptable agreement with the simulation was obtained. Modeling has shown that the deposit thermal state is highly dependent on variations in spray conditions, which are predicted using droplet trajectory and droplet thermal models. Using the droplet and deposit models, the relationship between UDS process parameters and material microstructure can be understood.

Numerical Simulation of Molten Metal Droplet Impinging in Uniform Droplet Spray Rapid Prototyping

2011 ◽  
Vol 704-705 ◽  
pp. 680-684 ◽  
Author(s):  
Feng Liang Yin ◽  
Sheng Zhu ◽  
Jian Liu ◽  
Yuan Yuan Liang
Keyword(s):  
Numerical Simulation ◽  
Surface Tension ◽  
Rapid Prototyping ◽  
Solidification Process ◽  
Solid Substrate ◽  
The Body ◽  
Molten Droplet ◽  
Uniform Droplet Spray ◽  
Droplet Spray ◽  
Uniform Droplet

A two-dimensional mathematical model has been developed to simulate the impinging and solidification process of a single droplet onto substrate in uniform droplet spray rapid prototyping. Droplet free surface is tracked by volume-of-fluid (VOF) algorithm. The effect of surface tension on the droplet is taken into consideration by means of considering surface tension to be a component of the body force. The governing equations are solved using a finite volume formulation. The calculation results predicted the final shape of a molten droplet impacting onto a solid substrate, and revealed that the solidification process began at the leading edge with the spread process of droplet. The simulation results provide insight and information not easy available from experimental. Keywords: numerical simulation, droplet, rapid prototyping

scholarly journals Uniform-droplet spray forming

1997 ◽  
Author(s):  
C A Blue ◽  
V K Sikka ◽  
Jung-Hoon Chun ◽  
T Ando
Keyword(s):  
Spray Forming ◽  
Uniform Droplet Spray ◽  
Droplet Spray ◽  
Uniform Droplet

sPreparation of ZrO 2 beads by an improved micro‐droplet spray forming process

2021 ◽  
Author(s):  
Jun Chen ◽  
Wan‐Qing Xue ◽  
Chang‐Ming Xu ◽  
Pai‐Feng Luo ◽  
Ji‐Gui Cheng ◽  
...  
Keyword(s):  
Spray Forming ◽  
Forming Process ◽  
Droplet Spray

Optimisation of Spray Forming Ni Superalloys via Process Modelling and On-Line Monitoring

2007 ◽  
Vol 546-549 ◽  
pp. 1327-1332 ◽  
Author(s):  
Jia Wei Mi ◽  
Patrick S. Grant
Keyword(s):  
Numerical Model ◽  
Liquid Fraction ◽  
Metal Flow ◽  
Internal Heat ◽  
Spray Forming ◽  
Forming Process ◽  
Substrate Heating ◽  
University Of Oxford ◽  
Thermal Boundary Conditions ◽  
On Line

The optimisation of spray forming IN718 alloy rings for aeroengine applications was investigated using both modelling and experimental approaches. A multiphysics numerical model has been developed and implemented to assist in the optimisation of the spray forming process. IN718 alloy ring preforms were spray formed at University of Oxford (UK) and The University of Bremen (Germany). A variety of on-line monitoring facilities were integrated onto spray forming units to (1) investigate the dynamics of alloy melt atomisation and droplet deposition at a sprayed surface; and (2) acquire ring preform thermal history and various thermal boundary conditions for the numerical model. Modelling and experiments were performed iteratively to investigate the effects of key spray forming parameters including gas metal flow ratio, atomiser scan, substrate heating schemes on the resulting ring preform shape, internal heat flow and solidification. It was found that preform top surface temperature and alloy liquid fraction inside the preform during spray forming were critical factors in governing the formation of macro/microporosity and the grain size of as-sprayed preforms. In the optimised conditions, IN718 alloy ring preforms were characterised by a microporosity of less than 1.5% and randomly oriented equaxied grains of 20-50 μm.

Numerical Simulation of Thermal History in a Novel Spray Forming Process

2007 ◽  
Vol 539-543 ◽  
pp. 1171-1176 ◽  
Author(s):  
Yun Zhong Liu ◽  
Yuan Yuan Li
Keyword(s):  
Liquid Fraction ◽  
Spray Forming ◽  
Heat Extraction ◽  
Spray Distance ◽  
Forming Process ◽  
Cooling Rates ◽  
Deposit Surface ◽  
Wide Range ◽  
New Process ◽  
Forced Cooling

A novel spray forming process was developed to produce large billets, wide plates or thick tubes with excellent microstructures and high cooling rates. Its uniqueness lies in a combination of the wide-range reciprocating movement and the swing scan of a gas atomizer, and the externally forced cooling of substrate during this spray deposition procedure. Its basic concept is that both good sticking and rapid solidification can be achieved if droplets with high liquid fractions impact a cold substrate, spread fully and then deposit on the surface. In order to control and optimize this new process, the thermal histories of droplets and deposits for spray forming of aluminum alloy billets were simulated with a set of new numerical models. Through shortening spray distance and raising melt superheat properly, the liquid fraction of droplets before deposition will increase and their spread on the deposit surface can improve for good sticking. Simulation results show that the optimal liquid fraction of droplets for deposition is about 0.2 higher than that in the conventional Osprey process. Its optimum spray distance is about 0.25m, which is nearly half as that in the Osprey process. In addition, this new process increases the mushy layer area and the specific surface area of heat extraction during deposition. Together with the forced cooling of substrate, it results in higher cooling rates. A high-quality large billet can be obtained by controlling the atomizer movement, the droplet liquid fraction and the deposit surface temperature properly in this new process.

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