Design on Transfer Piping of Molten Metallic Materials for Squeeze Casting

2013 ◽  
Vol 675 ◽  
pp. 93-97
Author(s):  
Hao Nian Min ◽  
Ming Shao ◽  
Wen Zhang
Keyword(s):  
Solid State ◽  
Molten Metal ◽  
Thermal Equilibrium ◽  
Thermal Conduction ◽  
Molten Aluminum ◽  
Squeeze Casting ◽  
Heating Power ◽  
Metallic Materials ◽  
Electromagnetic Pump ◽  
State Regulator

The spout at the connection of the pipe and the chamber is easily clogged when a large amount of molten metal is conveyed to the chamber in squeeze casting for large parts. In order to reduce the chances of clogging and clean up quickly when clogged, a quickly removable pipe is designed. The pipe is heated through thermal conduction by resistance wire, and thermal equilibrium is used to derive the power of heating element. Solid-state regulator is applied to control the heating power. Molten aluminum is conveyed from furnace to chamber using electromagnetic pump. The experiment shows that the molten metal flowing through the pipe is smooth, and the temperature of molten metal can be maintained stability.

scholarly journals Floquet-state cooling

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Onno R. Diermann ◽  
Martin Holthaus
Keyword(s):  
Solid State ◽  
Ground State ◽  
Thermal Equilibrium ◽  
Transition Matrix ◽  
Fourier Spectrum ◽  
Dissipative System ◽  
Quasistationary State ◽  
Matrix Elements ◽  
Periodically Driven ◽  
Transition Matrix Elements

AbstractWe demonstrate that a periodically driven quantum system can adopt a quasistationary state which is effectively much colder than a thermal reservoir it is coupled to, in the sense that certain Floquet states of the driven-dissipative system can carry much higher population than the ground state of the corresponding undriven system in thermal equilibrium. This is made possible by a rich Fourier spectrum of the system’s Floquet transition matrix elements, the components of which are addressed individually by a suitably peaked reservoir density of states. The effect is expected to be important for driven solid-state systems interacting with a phonon bath predominantly at well-defined frequencies.

scholarly journals Cutting Properties of Austenitic Stainless Steel by Using Laser Cutting Process without Assist Gas

2012 ◽  
Vol 2012 ◽  
pp. 1-8
Author(s):  
Hitoshi Ozaki ◽  
Yosuke Koike ◽  
Hiroshi Kawakami ◽  
Jippei Suzuki
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Molten Metal ◽  
Laser Power ◽  
Laser Cutting ◽  
Cutting Speed ◽  
Cutting Process ◽  
Metallic Materials ◽  
Bottom Side ◽  
Gas Nozzle

Recently, laser cutting is used in many industries. Generally, in laser cutting of metallic materials, suitable assist gas and its nozzle are needed to remove the molten metal. However, because of the gas nozzle should be set closer to the surface of a workpiece, existence of the nozzle seems to prevent laser cutting from being used flexible. Therefore, the new cutting process, Assist Gas Free laser cutting or AGF laser cutting, has been developed. In this process, the pressure at the bottom side of a workpiece is reduced by a vacuum pump, and the molten metal can be removed by the air flow caused by the pressure difference between both sides of the specimen. In this study, cutting properties of austenitic stainless steel by using AGF laser cutting with 2 kW CO2 laser were investigated. Laser power and cutting speed were varied in order to study the effect of these parameters on cutting properties. As a result, austenitic stainless steel could be cut with dross-free by AGF laser cutting. When laser power was 2.0 kW, cutting speed could be increased up to 100 mm/s, and kerf width at specimen surface was 0.28 mm.

Electric Potential Drop Method for Evaluating Crack Initiation and Crack Propagation: The Help of FE Simulation

2019 ◽  
Author(s):  
Patrick Le Delliou
Keyword(s):  
Electrical Resistivity ◽  
Plastic Strain ◽  
Electric Potential ◽  
Thermal Conduction ◽  
Voltage Drop ◽  
Potential Drop ◽  
Metallic Materials ◽  
Ductile Tearing ◽  
Practical Applications ◽  
Plastic Case

Abstract The electric potential drop (EPD) method is a laboratory technique to monitor the initiation and the propagation of a crack, mainly in the field of fatigue research. It can also be used in fracture experiments, involving plasticity and large deformations. The size of a crack in a metallic member is predicted by applying a constant d.c. (direct current) or a.c. (alternating current) to the member and by measuring an increase in electric resistance due to the crack. Practically, several pairs of probes are attached to the specimen crossing over the crack and the voltage drop is measured periodically along the test. The main difficulty is to correlate the EPD changes to the crack extension. Thanks to the analogy between the thermal conduction problem and the electrical conduction problem, a classical thermo-mechanical finite element solver can be used to predict the EPD along a crack, given the electrical resistivity of the material, the current intensity and the geometry of the structure and of the crack. This technique works well for fatigue studies, where the structure remains elastic and whose shape is unchanged. However, in fracture experiments, the change in geometry and the possible effect of the plastic strain on electrical resistivity make the problem much more complex. The paper presents the principle of the EPD method, a work on the effect of the plastic strain on the electrical resistivity, FE computations for the elastic case (for fatigue pre-cracking) and for the plastic case (for ductile tearing experiments). Several practical applications will be presented on various metallic materials.

Filling Characteristics of Magnesium Alloy Molten Metal in Squeeze Casting

2012 ◽  
Vol 502 ◽  
pp. 335-341
Author(s):  
Yun Chen ◽  
Ding Fang Chen ◽  
Juan Du ◽  
Ji Xiang Luo
Keyword(s):  
Magnesium Alloy ◽  
Fluid Mechanics ◽  
Molten Metal ◽  
Wall Thickness ◽  
Squeeze Casting ◽  
Air Entrainment ◽  
Filling Process ◽  
Fluid Level ◽  
Filling Characteristics

Based on fluid mechanics, the filling process of magnesium alloy step-plate casting molten metal was analyzed, and the filling characteristics were studied by numerical simulating. The results show the filling velocity and the wall thickness of casting have a great effect on the filling characteristics of magnesium alloy. When the filling velocity is less than 0.3 m/s, the liquid frontier of molten metal and the fluid level of thick upper surface fluctuate greatly, and the defects of air entrainment and oxide impurities will appear. When the filling velocity is more than 0.58 m/s, the molten metal fills in turbulent way, and the defects of sputter and air entrainment will appear. The correlation between the wall thickness of casting and the critical filling velocity presented in this paper can be used for the optimization of filling velocity.

scholarly journals Rectified Diffusion of Gas Bubbles in Molten Metal during Ultrasonic Degassing

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 536
Author(s):  
Yuning Zhang ◽  
Yuning Zhang
Keyword(s):  
Analytical Solution ◽  
Molten Metal ◽  
Molten Aluminum ◽  
Present Model ◽  
Gas Bubbles ◽  
Ultrasonic Field ◽  
Hydrogen Bubbles ◽  
Diffusion Of Hydrogen ◽  
Diffusion Behaviors

In the present paper, an analytical solution of rectified diffusion of processes of gas bubbles in molten metal is derived for the purpose of predicting the diffusion behaviors of gas bubbles during ultrasonic degassing. In the present model, a theoretical threshold (in terms of the amplitude of the applied ultrasonic field) is determined for the evaluation of the ultrasonic degassing effects. The diffusion of hydrogen bubbles in molten aluminum is predicted, so as to provide examples to illustrate the important findings of the present work.

scholarly journals Persistent dark states in anisotropic central spin models

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tamiro Villazon ◽  
Pieter W. Claeys ◽  
Mohit Pandey ◽  
Anatoli Polkovnikov ◽  
Anushya Chandran
Keyword(s):  
Relaxation Time ◽  
Solid State ◽  
Quantum Dot ◽  
Large Deviations ◽  
Thermal Equilibrium ◽  
Relaxation Times ◽  
System Size ◽  
Small Perturbations ◽  
Spin Models ◽  
Spin Bath

Abstract Long-lived dark states, in which an experimentally accessible qubit is not in thermal equilibrium with a surrounding spin bath, are pervasive in solid-state systems. We explain the ubiquity of dark states in a large class of inhomogeneous central spin models using the proximity to integrable lines with exact dark eigenstates. At numerically accessible sizes, dark states persist as eigenstates at large deviations from integrability, and the qubit retains memory of its initial polarization at long times. Although the eigenstates of the system are chaotic, exhibiting exponential sensitivity to small perturbations, they do not satisfy the eigenstate thermalization hypothesis. Rather, we predict long relaxation times that increase exponentially with system size. We propose that this intermediate chaotic but non-ergodic regime characterizes mesoscopic quantum dot and diamond defect systems, as we see no numerical tendency towards conventional thermalization with a finite relaxation time.

Sign in / Sign up

Export Citation Format

Share Document