Damping Properties of Hard Coatings for Engine Applications

2010 ◽  
Vol 66 ◽  
pp. 126-135 ◽  
Author(s):  
Peter J. Torvik
Keyword(s):  
Hard Coatings ◽  
Thermal Barrier ◽  
Proper Selection ◽  
Coating Materials ◽  
Transition Range ◽  
Material Parameters ◽  
Specific Temperature ◽  
Plasma Sprayed ◽  
Selection Of

Although blade coating materials dissipate vibratory energy while acting as thermal barrier coatings or protecting the substrate against corrosion or erosion, the inherent nonlinearity of these materials complicates the determination of the necessary material parameters. While plasma-sprayed ceramics alone do not appear to provide the desired levels of dissipation, notable increases in damping have been found to result from the inclusion of small amounts of viscoelastic materials. With proper selection of the added component, the resulting coating may be tailored for high damping in a specific temperature range. Vacuum infiltration of polymeric components into plasma-sprayed ceramics raise the dissipation to desired levels for temperatures of 93-135 oC; co-spraying mixtures of ceramics and glass frits leads to extremely high damping in the transition range of the glass, typically 550-800 oC.

Development of Performance Grading Map of Nepal Based on Superpave System

2020 ◽  
Vol 8 ◽  
pp. 61-64
Author(s):  
Sunita Kharbuja ◽  
Thusitha Chandani Shahi ◽  
Rajan Duwal
Keyword(s):  
Prediction Models ◽  
Daily Maximum ◽  
Climatic Zones ◽  
Performance Grade ◽  
Specific Temperature ◽  
Analysis System ◽  
Performance Grading ◽  
Selection Of

The Performance of the bituminous binder plays important role in the overall performance of the pavement system. One of the major cause of pavement failure is the bitumen grade, i.e selection of suitable grade of bitumen. Therefore, performance grading of bituminous binder is inevitable for the specific temperature and climatic zones. This study is focused on the determination of performance grading of bituminous binder for various temperature zones in Nepal. In this study, twenty one years’ daily maximum and minimum secondary temperature data of 70 meteorological stations were collected and were analyzed for temperature zoning. Performance grading of bituminous binder was conducted with the help of Strategic Highway Research Program (SHRP) and Long-Term Pavement Performance Program (LTPP) prediction models. The concept of Superpave has been adopted for the analysis, which stands for superior performing asphalt pavement. The Superpave mix design includes a new analysis system based on performance characteristics of the pavement layer. The bituminous binder grades for Nepal have been determined on the basis of air temperature thereafter predicting the pavement temperatures. The study has determined seven different performance grade zones based on SHRP and four different performance grade zones based on LTPP model. The study synthesized the Performance Grade (PG) map of the country.

scholarly journals Determination of mercury thermospecies in South African coals in the enhancement of mercury removal by pre-combustion technologies

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mpho Wendy Mathebula ◽  
Nikolai Panichev ◽  
Khakhathi Mandiwana
Keyword(s):  
South African ◽  
Bituminous Coal ◽  
Total Mercury ◽  
Mean Value ◽  
Thermal Release ◽  
Power Stations ◽  
Coal Classification ◽  
Specific Temperature ◽  
Selection Of

Abstract Samples of South African bituminous coals were analysed for total mercury (Hg) and Hg thermospecies concentrations using an RA-915 + Zeeman Mercury Analyser. Total mercury concentrations in samples of coals (n = 57) ranged between 10 ng g−1 and 493 ng g−1 with a mean value of 150 ± 53 ng g−1. Thermospecies of Hg were determined by monitoring Hg response as a function of sample temperature, increasing at 0.8 °C/s from ambient to 720 °C. This approach provides important information on thermal release of Hg species, as indicated by their appearance over specific temperature intervals. This permits identification of the presence of Hg thermospecies in coal and their quantification in each time (temperature) interval. It was found that 76% of tested bituminous coal samples release Hg species within low temperature intervals (20–180 °C and180–360 °C). The information generated in this study will aid in the selection of suitable coals for pre-combustion treatment that can lead to significant reduction of atmospheric Hg emission during coal combustion at power stations. This analytical approach can also be used for the creation of a system of coal classification based on the temperature of release of various Hg thermospecies.

Citrus Artifact Interference in Aflatoxin M1 Determination in Milk

1981 ◽  
Vol 64 (6) ◽  
pp. 1383-1385
Author(s):  
Ralph L Price ◽  
Karen V Jorgensen ◽  
Michael Billotte
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Dairy Cows ◽  
Aflatoxin M1 ◽  
Proper Selection ◽  
False Positive Test ◽  
Citrus Waste ◽  
Layer Chromatography ◽  
Selection Of

Abstract Dried citrus waste was fed to dairy cows, their milk was extracted, and aflatoxin M1 was quantitated by using both high pressure liquid chromatography (HPLC) and thin layer chromatography (TLC). Results indicate that a compound from the citrus waste, which is excreted into the milk, interferes with the HPLC determination of aflatoxin M1 in milk and causes a false positive test. This interference can be overcome by using TLC with proper selection of developing solvents.

Quality factor of circular microdiaphragm with surface effects in contact with liquids

2020 ◽  
pp. 108128652095489
Author(s):  
RM Zhang ◽  
SS Zhou ◽  
AQ Li
Keyword(s):  
Residual Stress ◽  
Approximate Solution ◽  
Quality Factor ◽  
Acoustic Radiation ◽  
Surface Effects ◽  
Resonant Sensors ◽  
Material Parameters ◽  
Tension Parameter ◽  
Selection Of

This paper reports an investigation of the influences of surface effects and residual stress on the quality factor of a circular microdiaphragm in contact with liquids on one side. Acoustic radiation, as the main source of energy dissipation, can decrease the quality factor of a circular microdiaphragm. An approximate solution for the natural frequency can be obtained based on the Rayleigh–Ritz energy method. The results show that the influence of surface effects on the quality factor is obvious, in particular for thinner microdiaphragms. A stiffened surface decreases the quality factor, while a softened surface increases it. Furthermore, the quality factor increases with increases in the normalized tension parameter k for both stiffened and softened surfaces. If k is greater than 30, the influence of the surface effects on the quality factor must be considered. The results can provide effective guidance for the determination of dimensions and selection of material parameters in designing microdiaphragm resonant sensors.

HOT CORROSION OF CERIA-YTTRIA STABILIZED ZIRCONIA PLASMA SPRAYED THERMAL BARRIER COATING BY EUTECTIC VANDIUM PENTAOXIDE-SODIUM SULFATE

2018 ◽  
Vol 18 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Mohammed J Kadhim ◽  
Mohammed H Hafiz ◽  
Maryam A Ali Bash
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Monoclinic Phase ◽  
Volume Fraction ◽  
High Volume ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Plan View ◽  
Barrier Coating ◽  
Plasma Sprayed

The high temperature corrosion behavior of thermal barrier coating (TBC) systemconsisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coatwere characterized. The upper surfaces of CYSZ covered with 30 mg/cm2 , mixed 45 wt%Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC andinteraction times from 1 up to 8 h. The upper surface plan view of the coatings wereidentified for topography, roughness, chemical composition, phases and reaction productsusing scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-raydiffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed thephase transformation of nontransformable tetragonal (t') into monoclinic phase, presence ofYVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed theformation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.The formation of these compounds were combined with formation of monoclinic phase (m)from transformation of nontransformable tetragonal phase (t').

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