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Different Volume Fraction (different + volume_fraction)
Selected AbstractsMicrostructure Tailored Functionally Graded Alumina/Lanthanum Hexaaluminate Ceramics for Application as Thermal Barrier Coatings,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Zahra Negahdari The thermal and mechanical properties of a functionally graded lanthanum hexaaluminate-alumina ceramic are described. The gradation of functionality is based on different volume fraction of lanthanum hexaaluminate, varying from 0 to 80 vol% and corresponding porosity from 2 to 32 vol%. The highest volume fraction of lanthanum hexaaluminate enables a five time reduced thermal diffusivity as compared to alumina. The fracture toughness and elastic modulus is highest for a 20 vol% lanthanum hexaaluminate-alumina composite. [source] Effect of Filler Content on the Dielectric Properties of PTFE/ZnAl2O4,TiO2 CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Sherin Thomas ZnAl2O4,TiO2 (ZAT)/polytetrafluoroethylene (PTFE) composites were prepared by powder processing method. The structure and microstructure of the composites were analyzed using X-ray diffraction and scanning electron microscopic techniques. The effect of different volume fraction of ZAT (0,0.6) on the dielectric properties of the composites was investigated at 1 MHz and at the microwave frequency of 7 GHz. The dielectric properties (relative permittivity and dielectric loss) were found to increase with the ZAT content. The samples with 60 vol.% of ZAT filler showed a relative permittivity of 3.9 and dielectric loss of 0.009, respectively, at 7 GHz. The variation of relative permittivity and dielectric loss showed only a very small variation with temperature in the range 25°,70°C for various ZAT/PTFE composites. The relative permittivity obtained experimentally were compared with that of the theoretical values predicted using modified Lichtenecker, Jayasundere,Smith, and Series mixing formulae. They were found to agree well with the predicted values for low filler content. [source] Preparation and thermal properties of zirconium tungstate/copper compositesMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 9 2008X. Yan Metall-Matrix-Verbundwerkstoffe; thermische Eigenschaften; Pulver Prozess Abstract ZrW2O8/Cu composites were prepared by the powder metallurgy method. Electroless plating was used to deposit copper on ZrW2O8 powder before sintering. The thermal expansion and thermal conductivity of composites were measured in the temperature range from 25 oC to 200 oC and compared with those predicted from various theoretical models. The results show that the coefficient of thermal expansion of ZrW2O8/ Cu composites with a different volume fraction of ZrW2O8 is greater than the theoretically calculated value. The thermal conductivities of ZrW2O8/ Cu composites increase with a higher copper content and decrease upon elevated temperature. The thermal conductivity of composites with a different volume fraction of ZrW2O8 is lower than the theoretically calculated value. Fertigungsverfahren und thermische Eigenschaften von Zirkonium Wolfram/Kupfer Verbundwerkstoffen No Abstract [source] Nanoindentation of a Pseudoelastic NiTiFe Shape Memory Alloy,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Janine Pfetzing-Micklich Nanoindentation is a suitable tool for characterizing the local mechanical properties of shape memory alloys (SMA) and to study their pseudoelastic behavior. There is a special interest in indenting with different indenter tips (as not all tips are associated with strain states that predominantly induce the martensitic transformation) and in indenting at different temperatures, where different phases are present. In this study, we perform nanoindentation on a ternary NiTiFe SMA with different indenter tips and at various testing temperatures. For nanoindentation with spherical tips, load,displacement hystereses clearly indicate pseudoelastic behavior, whereas indentation with Berkovich tips results in more pronounced plastic deformation. Testing at different temperatures is associated with different volume fractions of austenite, martensite, and R-phase. The corresponding nanoindentation responses differ considerably in terms of pseudoelastic behavior. Best pseudoelastic recovery is found at testing temperatures close to the R-phase start temperature, even though this temperature is below the austenite finish temperature, which is a well-known lower temperature bound for full recovery in macroscopic tests. Our results are discussed considering micromechanical aspects and the interaction between stress-induced phase transformation and dislocation plasticity. [source] Concentration dependent Raman and IR study on salicylaldehyde in binary mixturesJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2007A. Anis Fathima Abstract A vibrational spectroscopic study of binary mixtures of salicylaldehyde (SA) in three different solvents (polar and nonpolar) is presented. The vibrational modes ,(CO), hydroxyl stretching mode (COH) and aldehydic (CH) stretching vibration were analyzed. Changes in wavenumber position and full width half maximum have been explained for neat as well as binary mixtures with different volume fractions of the reference system, SA, in terms of inter- and intramolecular hydrogen bonding. The IR spectra of these mixtures have also been taken and compared with the Raman data. The spectral changes have been well explained using the concentration fluctuation model and solute,solvent interaction. Copyright © 2007 John Wiley & Sons, Ltd. [source] Measurement and prediction of thermal conductivity for hemp fiber reinforced compositesPOLYMER ENGINEERING & SCIENCE, Issue 7 2007T. Behzad The thermal conductivity of hemp fiber reinforced polymer composites were studied from the steady state temperature drop across samples exposed to a known heat flux. The transverse and in-plane thermal conductivities for oriented and randomly oriented composites for different volume fractions of fiber were investigated. Experimental results showed that the orientation of fibers has a significant effect on the thermal conductivity of composites. To validate the experimental results, the heating tests for the thermal conductivity measurements were simulated by a finite element model using the thermal conductivity values obtained from the experiments. Predicted temperatures show close agreement with measured temperatures. Moreover, the experimental results of thermal conductivities of composites at different directions were compared with two theoretical models and illustrated good agreement between the obtained results and models. POLYM. ENG. SCI. 47:977,983, 2007. © 2007 Society of Plastics Engineers [source] | ||||||||||