Transient Thermal Response of a Rotating Cylindrical Silicon Nitride Workpiece Subjected to a Translating Laser Heat Source, Part II: Parametric Effects and Assessment of a Simplified Model

1998 ◽  
Vol 120 (4) ◽  
pp. 907-915 ◽  
Author(s):  
J. C. Rozzi ◽  
F. P. Incropera ◽  
Y. C. Shin
Keyword(s):  
Temperature Distribution ◽  
Convection Heat Transfer ◽  
Surface Region ◽  
Ambient Air ◽  
Laser Source ◽  
Maximum Temperature ◽  
Depth Of Cut ◽  
Beam Diameter ◽  
Radial Temperature ◽  
Near Surface

In a companion paper (Rozzi et al., 1998), experimental validation was provided for a transient three-dimensional numerical model of the process by which a rotating workpiece is heated with a translating laser beam. In this paper, the model is used to elucidate the effect of operating parameters on thermal conditions within the workpiece and to assess the applicability of an approximate analysis which is better suited for on-line process control. From detailed numerical simulations, it was determined that the thickness of a surface thermal layer decreases with increasing workpiece rotational speed and that the influence of axial conduction on the workpiece temperature distribution increases with decreasing laser translational velocity. Temperatures increase throughout the workpiece with increasing laser power, while the influence of increasing beam diameter is confined to decreasing near-surface temperatures. Temperature-dependent thermophysical properties and forced convection heat transfer to the laser gas assist jet were found to significantly influence the maximum temperature beneath the laser spot, while radiation exchange with the surroundings and mixed convection to the ambient air were negligible. The approximate model yielded relations for calculating the radial temperature distribution within an r-φ plane corresponding to the center of the laser source, and predictions were in reasonable agreement with results of the numerical simulation, particularly in a near-surface region corresponding to the depth of cut expected for laser-assisted machining.

scholarly journals Numerical Simulation and Experimental Study on Temperature Distribution of Self-Lubricating Packing Rings in Reciprocating Compressors

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Jia Xiaohan ◽  
Zhang Qingqing ◽  
Feng Jianmei ◽  
Peng Xueyuan
Keyword(s):  
Temperature Distribution ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Radial Temperature ◽  
Operational Conditions ◽  
External Cooling ◽  
Packing Rings ◽  
Compressor Reliability

The nonuniform abrasion failure and high-temperature thermal failure of packing rings have a significant influence on compressor reliability, particularly that of oil-free compressors. In this study, a test rig was constructed to measure the dynamic temperature of packing rings under different operational conditions in an oil-free reciprocating compressor. The dynamic axial and radial temperature distributions of the packing rings were obtained using an innovative internal temperature testing device that kept the thermocouples and packing box relatively static during compressor operation. A three-dimensional heat transfer model was also developed to analyze the temperature distribution of the packing boxes, piston rod, and cylinder during such operation. Good agreement was observed between the simulation results and experimental data, which showed an average relative error of less than 2.35%. The results indicate that the pressure ratio exerts a significant effect on the axial temperature distribution and determines which packing ring reaches the maximum temperature. They also show the average temperature to rise with an increase in the rotational speed and to fall with an improvement in the external cooling conditions. Finally, the material of the packing rings was found to affect the temperature gradient from their inner to outer surface.

Numerical Simulation of Turbulent Heat Transfer on a Rotating Disk With an Impinging Jet

2010 ◽  
Author(s):  
M. H. Saidi ◽  
H. Karrabi ◽  
H. B. Avval ◽  
A. Asgarshamsi
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Rotating Disk ◽  
Turbulent Heat Transfer ◽  
Maximum Temperature ◽  
Turbulent Heat ◽  
Cooling Process ◽  
Maximum Temperature Difference

A numerical study has been earned out to investigate the fluid flow structure and convective heat transfer due to a circular jet impinging on a rotating disk. The temperature distribution and convection heat transfer coefficient on the disk are calculated. Flow is considered to be steady, incompressible and turbulent. k-ε RNG model is used to model the turbulent flow. Two new criteria are introduced and used to evaluate the performance of cooling process which are maximum temperature difference on the disk and the average temperature of the disk. The first parameter shows the uniformity of temperature distribution in the disk and the second shows the effect of both thermo physical properties of the disk material and cooling process. In order to verify the numerical approach, results have been compared with the experimental data which shows a good agreement.

Monitoring of Dopant Activation in Sub-Surface P-Type Si Using the Surface Charge Profiling (SCP) Method

1996 ◽  
Vol 448 ◽  
Author(s):  
P. Roman ◽  
J. Staffa ◽  
S. Fakhouri ◽  
J. Ruzyllo ◽  
E. Kamieniecki
Keyword(s):  
Surface Charge ◽  
Boron Concentration ◽  
Surface Region ◽  
Ambient Air ◽  
Epitaxial Layers ◽  
Near Surface ◽  
Si Substrates ◽  
Boron Doped ◽  
Order Of Magnitude ◽  
P Type

AbstractIn this study the SCP (Surface Charge Profiling) method, based on non-contact, small-signal ac-SPV measurement is used to study thermal activation of boron in the near surface region of p-type Si wafers. Boron tends to form pairs with impurities such as hydrogen, iron and copper in the near surface region of Si substrates which render it inactive. During device processing, activation of boron may take place resulting in uncontrolled variations in active boron concentration in the near surface region.In this work, both boron doped, polished CZ wafers and wafers with boron doped epitaxial layers are studied. In the former case, the concentration of active boron in the near surface region was initially up to an order of magnitude less than the bulk concentration determined from four-probe measurements, but increased with the temperature of an anneal in ambient air and approached the bulk value. In contrast, the wafers with epitaxial layers showed no consistent variations of surface dopant concentration with temperature. These results confirmed previous findings that the near surface region of the polished wafers is contaminated with metals introduced during polishing operations. The SCP method was found to be very effective in monitoring variations in active boron concentration in the near-surface region.

Three-Dimensional Finite Element Analysis in Cutting Temperature for High Speed Milling of Titanium Alloys

2011 ◽  
Vol 189-193 ◽  
pp. 2259-2263
Author(s):  
You Xi Lin ◽  
Cong Ming Yan
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Titanium Alloys ◽  
High Speed ◽  
Three Dimensional ◽  
Cutting Temperature ◽  
Maximum Temperature ◽  
Depth Of Cut ◽  
High Speed Milling ◽  
Radial Depth

A three dimensional fully thermal-mechanical coupled finite element model had been presented to simulate and analyze the cutting temperature for high speed milling of TiAl6V4 titanium alloy. The temperature distribution induced in the tool and the workpiece was predicted. The effects of the milling speed and radial depth of cut on the maximum cutting temperature in the tool was investigated. The results show that only a rising of temperature in the lamella of the machined surface is influenced by the milling heat. The maximum temperature in the tool increases with increasing radial depth of cut and milling speed which value is 310°C at a speed of 60 m/min and increases to 740°C at 400m/min. The maximum temperature is only effective on a concentrated area at the cutting edge and the location of the maximum temperature moves away from the tool tip for higher radial depths of milling. The predicted temperature distribution during the cutting process is consistent with the experimental results given in the literature. The results obtained from this study provide a fundamental understanding the process mechanics of HSM of titanium alloys.

FEM Analysis of Temperature in High Speed Cutting of TiAl6V4 Alloys

2012 ◽  
Vol 522 ◽  
pp. 201-205
Author(s):  
You Xi Lin ◽  
Cong Ming Yan ◽  
Zheng Ying Lin
Keyword(s):  
Temperature Distribution ◽  
High Speed ◽  
Metal Cutting ◽  
Cutting Temperature ◽  
Fem Analysis ◽  
Element Model ◽  
Maximum Temperature ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Radial Depth

mprovements in modeling and simulation of metal cutting processes are required in advanced manufacturing technologies. A three dimensional fully thermal mechanical coupled finite element model had been applied to simulate and analyze the cutting temperature for high speed milling of TiAl6V4 titanium alloy. The temperature distribution induced in the tool and the workpiece was predicted. The effects of the milling speed and radial depth of cut on the maximum cutting temperature in the tool was investigated. The results show that only a rising of temperature in the lamella of the machined surface is influenced by the milling heat. The maximum temperature in the tool increases with increasing radial depth of cut and milling speed which value is 310°C at a speed of 60 m/min and increases to 740°C at 400m/min. The maximum temperature is only effective on a concentrated area at the cutting edge and the location of the maximum temperature moves away from the tool tip for higher radial depths of milling. The predicted temperature distribution during the cutting process is consistent with the experimental results given in the literature. The results obtained from this study provide a fundamental understanding the process mechanics of HSM of TiAl6V4 titanium alloys.

XPS Analysis of Silicon Oxycarbide Formed on the Surface of Rf-Sputter Deposited SiC Thin Films

2007 ◽  
Vol 353-358 ◽  
pp. 1871-1874 ◽  
Author(s):  
Kun Xue ◽  
Li Sha Niu ◽  
Hui Ji Shi ◽  
Ji Wen Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Region ◽  
Ambient Air ◽  
Annealed Sample ◽  
Silicon Oxycarbide ◽  
Near Surface ◽  
X Ray ◽  
Sputter Deposited ◽  
Extended Exposure ◽  
Sic Films

Sputter deposited SiC films with and without annealing were characterized using X-ray photoelectron spectroscopy (XPS). A complex transition layer, containing silicon oxycarbide (SiCxOy), between the SiO2 layer grown during extended exposure to ambient air or annealing and SiC substrate was investigated. Furthermore, the presence of excessive amorphous carbon was detected in the near-surface region for annealed sample. We justified the differences of composition and chemical bonding in these two oxide layers in terms of different oxidation kinetics involved.

Sliding Wear of Titanium

1997 ◽  
Vol 119 (1) ◽  
pp. 31-35 ◽  
Author(s):  
S. V. Kailas ◽  
S. K. Biswas
Keyword(s):  
Temperature Distribution ◽  
Strain Rate ◽  
Sliding Wear ◽  
Normal Load ◽  
Surface Region ◽  
Sliding Velocity ◽  
Compression Tests ◽  
Near Surface ◽  
Flat Surfaces ◽  
Temperature Strain

Titanium pins were slid against flat surfaces of alumina disks under dry condition and a normal load of 50N at sliding speeds varying from 0.1 to 4 ms−1. Estimated strain rate and temperature distribution in the subsurface when superposed on a microstructure evolution map in temperature-strain rate space give the microstructural response of the material to different sliding velocities at different subsurface depths. The map was obtained by conducting uniaxial compression tests. The experimentally observed variation in wear rate with sliding velocity was found to have a qualitative correspondence with the predicted variation of microstructure in the near surface region.

Flow Fields Investigation and Temperature Distribution on a Rotating Disk Imposed by a Turbulent Impinging Jet

2010 ◽  
Author(s):  
H. Karrabi ◽  
S. Rasoulipour
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Convection Heat Transfer ◽  
Rotating Disk ◽  
Maximum Temperature ◽  
Cooling Process ◽  
Maximum Temperature Difference ◽  
Average Temperature ◽  
Disk Material ◽  
Good Agreement

Numerical investigation of fluid flow structure and convective heat transfer due to a circular jet impinging on a rotating disk is performed. Temperature and convection heat transfer coefficient are calculated. Flow is considered to be steady, incompressible and turbulent. k-ε RNG model is used to model the turbulent flow. Results are compared with experimental data showing good agreement. Two new criteria are introduced and used to evaluate the performance of cooling process, the first is maximum temperature difference on the disk, and the second is the average temperature of the disk. The first parameter shows the uniformity of temperature distribution in the disk and the second shows the effect of both thermo physical properties of the disk material and cooling process.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

The Effects of Ion Implantation on the Surface Features of Inconel 600

1985 ◽  
Vol 43 ◽  
pp. 288-289
Author(s):  
John D. Rubio
Keyword(s):  
Grain Boundary ◽  
Ion Implantation ◽  
Nuclear Power ◽  
Power Plants ◽  
Surface Region ◽  
Selective Dissolution ◽  
Boundary Region ◽  
Near Surface ◽  
Inconel 600 ◽  
Steam Generator Tubing

The degradation of steam generator tubing at nuclear power plants has become an important problem for the electric utilities generating nuclear power. The material used for the tubing, Inconel 600, has been found to be succeptible to intergranular attack (IGA). IGA is the selective dissolution of material along its grain boundaries. The author believes that the sensitivity of Inconel 600 to IGA can be minimized by homogenizing the near-surface region using ion implantation. The collisions between the implanted ions and the atoms in the grain boundary region would displace the atoms and thus effectively smear the grain boundary.To determine the validity of this hypothesis, an Inconel 600 sample was implanted with 100kV N2+ ions to a dose of 1x1016 ions/cm2 and electrolytically etched in a 5% Nital solution at 5V for 20 seconds. The etched sample was then examined using a JEOL JSM25S scanning electron microscope.

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