Effect of Inert Gas Flow Nature on SiC Microtube Synthesis

2005 ◽  
pp. 220-225 ◽  
Author(s):  
Jae Won Kim ◽  
Seoung Soo Lee ◽  
Dong Ho Park ◽  
Yeon Gil Jung ◽  
Je Hyun Lee ◽  
...  
Keyword(s):  
Gas Flow ◽  
Inert Gas

Semi-Solid Slurry Casting Using Gas Induced Semi-Solid Technique to Enhance the Microstructural Characteristics of Al-4.3Cu Alloy

2019 ◽  
Vol 285 ◽  
pp. 253-258
Author(s):  
M. Abdi ◽  
S.G. Shabestari
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Temperature Drop ◽  
Inert Gas ◽  
Globular Structure ◽  
Cast Sample ◽  
A206 Alloy ◽  
Gas Purging ◽  
Semi Solid ◽  
Conventionally Cast

Semi-solid processing of Al-4.3%Cu (A206) alloy was performed by Gas Induced Semi-Solid (GISS) process in different condition. The flow rate of argon gas, starting temperature for gas purging (the temperature of superheated-melt) and the duration of gas purging were three key process variables which were changed during this investigation. It was found that inert gas purging near liquidus, significantly, led to the microstructural modification from fully dendritic to globular structure. Thermal analysis was successfully implemented through CA-CCTA technique to understand the cause of the microstructure change during GISS process. The results showed that gas purging into the melt leads to temperature drop of the melt to its liquidus just after a few seconds from start of gas purging. In fact, copious nucleation was induced by cooling effect of inert gas bubbles. Microstructural features were characterized in semi-solid as well as on conventionally cast samples. The optimum gas purging temperature, injection time, and inert gas flow rate was determined in semi-solid processing to obtain the best globularity in the microstructure of a long freezing range alloy. However, the microstructure of the conventionally cast sample was fully dendritic with shrinkage which affects the soundness of casting products.

Respiratory and inert gas exchange during high-frequency ventilation

1982 ◽  
Vol 52 (3) ◽  
pp. 683-689 ◽  
Author(s):  
H. T. Robertson ◽  
R. L. Coffey ◽  
T. A. Standaert ◽  
W. E. Truog
Keyword(s):  
Gas Exchange ◽  
High Frequency ◽  
Gas Flow ◽  
Inert Gases ◽  
Inert Gas ◽  
High Frequency Ventilation ◽  
Physiological Dead Space ◽  
Volume Ventilation ◽  
Frequency Ventilation ◽  
Carrier Gases

Pulmonary gas exchange during high-frequency low-tidal volume ventilation (HFV) (10 Hz, 4.8 ml/kg) was compared with conventional ventilation (CV) and an identical inspired fresh gas flow in pentobarbital-anesthetized dogs. Comparing respiratory and infused inert gas exchange (Wagner et al., J. Appl. Physiol. 36: 585--599, 1974) during HFV and CV, the efficiency of oxygenation was not different, but the Bohr physiological dead space ratio was greater on HFV (61.5 +/- 2.2% vs. 50.6 +/- 1.4%). However, the elimination of the most soluble inert gas (acetone) was markedly enhanced by HFV. The increased elimination of the soluble infused inert gases during HFV compared with CV may be related to the extensive intraregional gas mixing that allows the conducting airways to serve as a capacitance for the soluble inert gases. Comparing as exchange during HFV with three different density carrier gases (He, N2, and Ar), the efficiency of elimination of Co2 or the intravenously infused inert gases was greatest with He-O2. However, the alveolar-arterial partial pressure difference for O2 on He-O2 exceeded that on N2-O2 by 5.4 Torr during HFV. The finding agrees with similar observations during CV, suggesting that this aspect of gas exchange is not substantially altered by HFV.

High-temperature annealing of macroporous silicon in an inert-gas flow

2017 ◽  
Vol 51 (9) ◽  
pp. 1153-1163 ◽  
Author(s):  
E. V. Astrova ◽  
N. E. Preobrazhenskiy ◽  
S. I. Pavlov ◽  
V. B. Voronkov
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Inert Gas ◽  
Macroporous Silicon ◽  
High Temperature Annealing

Effect of Inert Gas Flow Rate on Homogenization and Inclusion Removal in a Gas Stirred Ladle

2010 ◽  
Vol 81 (12) ◽  
pp. 1056-1063 ◽  
Author(s):  
M. Ek ◽  
L. Wu ◽  
P. Valentin ◽  
D. Sichen
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Inert Gas ◽  
Gas Flow Rate ◽  
Inclusion Removal

Enhancing fatigue resistance of activated tungsten inert gas welded UNS S32750 super duplex stainless steel by optimizing its technological properties

2020 ◽  
pp. 1-11
Author(s):  
A. Arunmani ◽  
T. Senthilkumar
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Duplex Stainless Steel ◽  
Fatigue Resistance ◽  
Process Parameters ◽  
Gas Flow ◽  
Welding Process ◽  
Travel Speed ◽  
Inert Gas ◽  
Super Duplex Stainless Steel

In engineering industries and heavy manufacturing plants, fatigue life of joints plays a pivotal role in determining the overall life span of the welded joint. In this paper, an advanced fusion joining technique, namely activated tungsten inert gas welding, was used for joining UNS S32750 super duplex stainless steel, with ZnO as activation flux. For the enhancement of fatigue resistance of joints, important welding process parameters were fluctuated according to a developed central composite design model. Empirical relationships were developed between the process parameters and the fatigue strength of the joints, which was correlated with the number of cycles to failure (NCF). Using analysis of variance, the significance of the developed fatigue model was ascertained. Using response surface methodology, optimization of process parameters for enhancement of fatigue resistance was done. It was observed that at the optimized activated tungsten inert gas weld process parameters of travel speed of welding torch at 69.85 mm/min, weld current at 125.20 A, and shielding gas flow rate at 14.77 L/min, a high fatigue life of 7.66396 × 108 NCF was obtained and the model was validated to very high predictability. Microstructural variations in the fatigue-tested specimens were evaluated for identifying the grain modifications.

Einfluß der Strömungsform des Gases auf die chemischen Transportprozesse in Halogenglühlampen

1974 ◽  
Vol 29 (10) ◽  
pp. 1471-1477
Author(s):  
Gerhard M. Neumann
Keyword(s):  
High Pressure ◽  
Laminar Flow ◽  
Gas Phase ◽  
Flow Separation ◽  
Gas Flow ◽  
Chemical Transport ◽  
Transport Processes ◽  
Inert Gas ◽  
Good Accord ◽  
Incandescent Lamps

Abstract By raising the inert gas pressure and thus changing the type of gas flow chemical transport processes in tubular halogen incandescent lamps may be influenced. At medium pressures in the region of laminar flow separation of halogen and inert gas due to thermodiffusion occurs, the halogen cycle breaks down, and bulb blackening of the lamp is observed. At low and high pressure, where the streaming behaviour of the gas phase is dominated by diffusion or turbulence, separation of halogen and inert gas is overcome and the lamps stay clean. Observed pressures for changing from laminar to turbulent flow are 3.5 atm in xenon, 5.5 atm in krypton, and > 8 atm in argon in good accord with the well-known Reynolds' criterion.

Fabrication of Apatite/Titanium Functionally Graded Coating Using Supersonic Free-Jet PVD

2009 ◽  
Vol 631-632 ◽  
pp. 187-192
Author(s):  
Atsushi Yumoto ◽  
Takahisa Yamamoto ◽  
Ichiro Shiota ◽  
Naotake Niwa
Keyword(s):  
Composite Coating ◽  
Gas Flow ◽  
Supersonic Nozzle ◽  
In Vitro Study ◽  
Functionally Graded ◽  
Inert Gas ◽  
Coating Film ◽  
Evaporation Chamber ◽  
Free Jet

Hydroxyapatite (HAp) is very attractive in medical field. The objective of this study is to produce HAp/Ti composite coating with Supersonic Free-Jet PVD (SFJ-PVD). The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas flow and to form a thick coating film. In a gas evaporation chamber, a source material is evaporated to form nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a deposition chamber with an inert gas flow through a transfer pipe. The gas flow is generated by the pressure difference between the chambers and accelerated to the supersonic flow of 4.2 Mach through a specially designed supersonic nozzle. With SFJ-PVD, we obtain a uniform high-density HAp/Ti composite coating. XRD analysis reveals that the composite coating is composed of Ti and HAp. An in-vitro study was carried out to investigate the bioactivity of the HAp/Ti composite coating under simulated body fluid.

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