Energy Partition to the Workpiece for Grinding with Aluminum Oxide and CBN Abrasive Wheels

1995 ◽  
Vol 117 (2) ◽  
pp. 160-168 ◽  
Author(s):  
S. Kohli ◽  
C. Guo ◽  
S. Malkin
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Aluminum Oxide ◽  
Lower Energy ◽  
Energy Input ◽  
Thermal Damage ◽  
Cubic Boron Nitride ◽  
Energy Partition ◽  
Abrasive Wheel ◽  
Very High

An experimental investigation is reported of the energy partition to the workpiece for grinding of steels with aluminum oxide and cubic boron nitride (CBN) abrasive wheels. The energy input to the workpiece was obtained by measuring the temperature distribution in the workpiece using an embedded thermocouple technique and matching the results with analytically computed values. It was found that 60-75 percent of the grinding energy is transported to the workpiece as heat with an aluminum oxide abrasive wheel, as compared to only about 20 percent with CBN wheels. An analysis of the results indicates that the much lower energy partition to the workpiece with CBN can be attributed to its very high thermal conductivity whereby a significant portion of the grinding heat is transported to the abrasive instead of to the workpiece. The much lower energy partition to the workpiece with CBN wheels results in much lower grinding temperatures and a greatly reduced tendency for thermal damage to the workpiece.

Effective Thermal Conductivity and Viscosity of Nanofluids

2005 ◽  
Author(s):  
S. M. S. Murshed ◽  
K. C. Leong ◽  
C. Yang
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Aluminum Oxide ◽  
Effective Thermal Conductivity ◽  
Titanium Oxide ◽  
Present Model ◽  
Geometrical Structure ◽  
Dispersion Of Nanoparticles

This paper presents a model to determine the effective thermal conductivity (ETC) of nanofluids. The model was developed by considering the geometrical structure of dispersed nanoparticles in base fluids. For the experimental investigation, nanofluids were prepared by suspending aluminum oxide (Φ80 nm) and titanium oxide (Φ15 nm and Φ10×40 nm) nanoparticles in deionized (DI) water and taken through longtime (8–10 hours) sonication for proper mixture of nanoparticles. Cetyltrimethylammoniumbromide (CTAB) surfactant was used to ensure better stability and dispersion of nanoparticles in the base fluids. The thermal conductivity and viscosity of the nanofluids were measured and compared with the predictions by various models. The present model gives better prediction of the effective thermal conductivity of nanofluids compared to existing models.

WIELAND-K88

Alloy Digest ◽  
2005 ◽  
Vol 54 (12) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Stress Relaxation ◽  
Copper Alloy ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Relaxation Resistance ◽  
Temperature Performance ◽  
Very High

Abstract Wieland K-88 is a copper alloy with very high electrical and thermal conductivity, good strength, and excellent stress relaxation resistance at elevated temperatures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: CU-738. Producer or source: Wieland Metals Inc.

Experimental Investigation of very High Frequency Slot Antenna on M-60A-1 Tank

1977 ◽  
Author(s):  
D. V. Campbell ◽  
William Kennebeck ◽  
A. Zanella ◽  
Paul Sexton
Keyword(s):  
Experimental Investigation ◽  
High Frequency ◽  
Slot Antenna ◽  
Very High Frequency ◽  
Very High

Experimental investigation of extinction properties and thermal conductivity of metal-coated dielectric fibers in vacuum

1987 ◽  
Vol 8 (2) ◽  
pp. 263-280 ◽  
Author(s):  
H. Reiss ◽  
F. Schmaderer ◽  
G. Wahl ◽  
B. Ziegenbein ◽  
R. Caps
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation

Numerical Simulation & Experimental Investigation of SMT Laser Microsoldering Thermal Process

1991 ◽  
Vol 226 ◽  
Author(s):  
Wang Chunqing ◽  
Qian Yiyu ◽  
Jiang Yihong
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Experimental Investigation ◽  
Thermal Process ◽  
Light Wave ◽  
Light Reflection ◽  
Lead Wire ◽  
Wire Surface ◽  
Conductivity Variation ◽  
Thermal Conductivity Variation

AbstractIn this paper,a numerical simulation of thermal process in the SMT laser microsoldering joint has been developed, in which, the influence on thermal process of the factors such as the thermal conductivity variation of solder with temperature, light reflection coefficient of the lead wire surface, and heat exchange on the surface of SMT materials all have been considered. In order to carry this numerical calculation practice and prove it's results,the reflexive characteristic of light wave to the SMT materials has been gauged,and the dynamic temperature process of laser microjoint has been measured by a new experimental method which was invented by the authors.The results of numerical simulation have been borne out by the tests, and the influences of heating parameters on thermal process has been analysed in this paper.The conclusions will be advantageous to the further study of the microjoint quality control in the SMT laser microsoldering.

Analysis of Plasma Properties and Deposition of Amorphous Silicon Alloy Solar Cells Using Very High Frequency Glow Discharge

1999 ◽  
Vol 557 ◽  
Author(s):  
B. Yan ◽  
J. Yang ◽  
S. Guha ◽  
A. Gallagher
Keyword(s):  
Solar Cells ◽  
High Frequency ◽  
Lower Energy ◽  
Ionic Current ◽  
Ion Bombardment ◽  
Half Width ◽  
Rf Plasma ◽  
Very High Frequency ◽  
Very High ◽  
Ionic Energy

AbstractPositive ionic energy distributions in modified very-high-frequency (MVHF) and radio frequency (RF) glow discharges were measured using a retarding field analyzer. The ionic energy distribution for H2 plasma with 75 MHz excitation at a pressure of 0.1 torr has a peak at 22 eV with a half-width of about 6 eV. However, with 13.56 MHz excitation, the peak appears at 37 eV with a much broader half-width of 18 eV. The introduction of SiH4 to the plasma shifts the distribution to lower energy. Increasing the pressure not only shifts the distribution to lower energy but also broadens the distribution. In addition, the ionic current intensity to the substrate is about five times higher for MVHF plasma than for RF plasma. In order to study the effect of ion bombardment, the deposition of a-Si alloy solar cells using MVHF was investigated in detail at different pressures and external biases. Lowering the pressure and negatively biasing the substrate increases ion bombardment energy and results in a deterioration of cell performance. It indicates that ion bombardment is not beneficial for making solar cells using MVHF. By optimizing the deposition conditions, a 10.8% initial efficiency of a-Si/a-SiGe/SiGe triple-junction solar cell was achieved at a deposition rate of 0.6 nm/sec.

Development of Operating Temperature Prediction Method Using Thermophysical Properties Change of Thermal Barrier Coatings

2004 ◽  
Vol 126 (1) ◽  
pp. 102-106 ◽  
Author(s):  
T. Fujii ◽  
T. Takahashi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Barrier Coatings ◽  
Operating Temperature ◽  
Thermal Barrier ◽  
Conductivity Measurements ◽  
Barrier Coatings ◽  
Barrier Performance ◽  
Very High ◽  
General Method ◽  
Exposure Conditions

Thermal barrier coatings (TBCs) have become an indispensable technology as the temperature of turbine inlet gas has increased. TBCs reduce the temperature of the base metal, but a reduction of internal pores by sintering occurs when using TBCs, and so the thermal barrier performance of TBCs is deteriorated. This in turn increases the temperature of the base metal and could shorten its lifespan. The authors have already clarified by laboratory acceleration tests that the deterioration of the thermal barrier performance of TBCs is caused by a decrease in the noncontact area that exists inside TBCs. This noncontact area is a slit space that exists between thin layers and is formed when TBCs are coated. This paper examines the relations between the decrease of the noncontact area and the exposure conditions, by measuring the thermal conductivity and the porosity of TBCs exposed to the temperatures that exist in an actual gas turbine, and derives the correlation with exposure conditions. As a result, very high correlations were found between the thermal conductivity and exposure conditions of TBCs, and between the porosity and exposure conditions. A very high correlation was also found between the thermal conductivity and porosity of TBCs. In addition, techniques for predicting TBC operating temperature were examined by using these three correlations. The correlation of diameter and exposure conditions of the gamma prime phase, which exists in nickel base super alloys, is used as a general method for predicting the temperature of parts in hot gas paths. This paper proposes two kinds of operating temperature prediction methods, which are similar to this general method. The first predicts the operating temperature from thermal conductivity measurements of TBCs before and after use, and the second predicts the operating temperature from thermal conductivity measurements of TBCs after use and porosity measurements before use. The TBC operating temperatures of a combustor that had been used for 12,000 hours with an actual E-class gas turbine were predicted by these two methods. The advantage of these methods is that the temperature of all parts with TBC can be predicted.

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