http://idea.library.drexel.edu/handle/1860/1127 Search the Channel search http://idea.library.drexel.edu/simple-search http://idea.library.drexel.edu/handle/1860/2751 Title: Sliding wear properties of HVOF thermally sprayed nylon-11 and nylon-11/ceramic composites on steel <br/> <br/>Authors: Jackson, L.; Ivosevic, M.; Knight, Richard; Cairncross, R. A. <br/> <br/>Abstract: Polymer and polymer/ceramic composite coatings were produced by ball-milling 60 μm Nylon- 11 together with nominal 10 vol.% of nano and multi-scale ceramic reinforcements and HVOF spraying these composite feedstocks onto steel substrates to produce semi-crystalline micron and nano-scale reinforced coatings polymer matrix composites. Room temperature dry sliding wear performance of pure Nylon-11, Nylon-11 reinforced with 7 nm silica, and multi-scale Nylon- 11/silica composite coatings incorporating 7-40 nm and 10 μm ceramic particles was characterized using a pin-on-disk tribometer. Coefficient of friction and wear rate were determined as a function of applied load and coating composition. Surface profilometry and scanning electron microscopy were used to characterize and analyze the coatings and wear scars. The pure Nylon-11 coating experienced less wear than the composites due to the occurrence of two additional wear mechanisms: abrasive and fatigue wear. Sun, 29 Oct 2006 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2732 Title: Effect of heating rate on recrystallization of twin roll cast aluminum <br/> <br/>Authors: Sun, Naiyu; Patterson, Burton R.; Suni, Jaakko P.; Doherty, Roger D.; Weiland, Hasso; Kadolkar, Puja; Blue, Craig A.; Thompson, Gregory B. <br/> <br/>Abstract: The effect of heating rate on precipitation and recrystallization behavior in twin roll cast (TRC) AA3105 has been investigated by three different means: conventional air furnace, controlled infrared, and lead bath heating. Experimental results showed that as-recrystallized grain size decreased and became more equiaxed as the annealing heating rate increased. These results were explained via time-temperature-transformation (TTT) curves for both dispersoid precipitation and recrystallization. With the faster heating rate, recrystallization could occur before precipitation of Mn present in the unhomogenized TRC samples. At a heating rate of 50 degree C/s the material underwent grain growth after recrystallization at 500 degree C. No sign of grain growth was observed in materials annealed with lower heating rates, 3 degrees C/s, 0.5 degree C/s, and 0.01 degree C/s due to greater dispersoid precipitation. Sat, 29 Dec 2007 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2722 Title: Kinking nonlinear elastic solids, nanoindentations, and geology <br/> <br/>Authors: Barsoum, Michel W.; Murugaiah, A.; Kalidindi, Surya R.; Zhen, T. <br/> <br/>Abstract: The physical mechanism responsible for nonlinear elastic, hysteretic, and discrete memory response of nonlinear mesoscopic elastic solids has to date not been identified.We show, by nanoindenting mica single crystals, that this response is most likely due to the formation of dissipative and fully reversible, dislocation-based kink bands. We further claim that solids with high c=a ratios, which per force are plastically anisotropic, should deform by kinking, provided they do not twin. These kinking nonlinear elastic solids include layered ternary carbides, nitrides, oxides, and semiconductors, graphite, and the layered phases, such as mica, present in nonlinear mesoscopic elastic solids. Thu, 24 Jun 2004 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2721 Title: Sapphire: a kinking nonlinear elastic solid <br/> <br/>Authors: Basu, S.; Barsoum, Michel W.; Kalidindi, Surya R. <br/> <br/>Abstract: Kinking nonlinear elastic (KNE) solids are a recently identified large class of solids that deform fully reversibly by the formation of dislocation-based kink bands [Barsoum et al. Phys. Rev. Lett. 92, 255508 2004 .] We further conjectured that a high c/a ratio—that ensures that only basal slip is operative—is a sufficient condition for a solid to be KNE. The c/a ratio of sapphire is 2.73 and thus, if our conjecture is correct, it should be a KNE solid. Herein by repeatedly loading—up to 30 times—the same location of sapphire single crystals of two orientations—A and C—with a 1 m radius spherical nanoindenter, followed by atomic force microscopy, we showed that sapphire is indeed a KNE solid. After pop-ins of the order of 100 nm, the repeated loadings give rise to fully reversible, reproducible hysteresis loops wherein the energy dissipated per unit volume per cycle Wd is of the order of 0.5 GJ/m3. Wd is due to the back and fro motion of the dislocations making up the incipient kink bands that are fully reversible. The results presented here strongly suggest that—like in graphite and mica—kink bands play a more critical role in the room temperature constrained deformation of sapphire than had hitherto been appreciated. Our interpretation is also in agreement with, and can explain most, recent nanoindentation results on sapphire. Wed, 15 Mar 2006 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2719 Title: Determination of unknown stress states in silicon wafers using microlaser Raman spectroscopy <br/> <br/>Authors: Narayanan, S.; Kalidindi, Surya R.; Schadler, Linda S. <br/> <br/>Abstract: A new technique was developed to predict the unknown in-plane stress state and the magnitude of the stress components in (111) silicon wafers using micro-Raman spectroscopy. The approach is based on analyzing the combined signal from the initially degenerate peaks of the F2g mode in silicon as a function of the angle between the incident laser polarization and the polarization selected from the scattered beam using an analyzer. The peak position of the combined signal when plotted as a function of the angle was found to contain the information required to estimate the magnitude of the individual stress components in the plane-stress condition. The development of this technique is described in this paper for (111) silicon wafers. Sun, 31 Aug 1997 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2684 Title: Probing elastic modulus and depth of bottom-supported inclusions in model tissues using piezoelectric cantilevers <br/> <br/>Authors: Yegingil, Hakki; Shih, Wan Y.; Shih, Wei-Heng <br/> <br/>Abstract: We have experimentally investigated the depth sensitivity limit of a piezoelectric cantilever tissue elastic modulus sensor and simultaneously determined the elastic modulus and the depth of a tumor directly. Using model tissues consisting of bottom-supported modeling clay inclusions of various depths in a gelatin matrix, we empirically determined that the depth sensitivity limit of a piezoelectric cantilever sensor was twice the linear dimension of the indentation area or the cantilever width . Knowing the depth sensitivity limit of the individual cantilever sensor as input and treating a model tissue that has the gelatin matrix on top and the modeling clay inclusion at the bottom as two springs in series, we showed that the elastic moduli and depths of the hard inclusions could be simultaneously determined with the elastic modulus profiles measured by two cantilevers with different widths as input. Thu, 01 Nov 2007 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2680 Title: Mechanical properties and tuning of three-dimensional polymeric photonic crystals <br/> <br/>Authors: Juodkazis, Saulius; Mizeikis, Vygantas; Seet, Kock Khuen; Misawa, Hiroaki; Wegst, Ulrike G. K. <br/> <br/>Abstract: Mechanical properties of photopolymerized photonic crystal PhC structures having woodpile and spiral three-dimensional architectures were examined using flat-punch indentation. The structures were found to exhibit a foamlike response with a bend-dominated elastic deformation regime observed at strain levels up to 10%. Numerical simulations of optical properties of these PhC structures demonstrate the possibility of achieving a substantial and reversible spectral tuning of the photonic stop gap wavelength by applying a mechanical load to the PhC. Mon, 10 Dec 2007 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2645 Title: Large deformation simple compression of a copper single-crystal <br/> <br/>Authors: Kalidindi, Surya R.; Anand, L. Mon, 29 Mar 1993 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2619 Title: Water structure and its influence on the flotation of carbonate and bicarbonate salts <br/> <br/>Authors: Ozdemir, O.; Çelik, M. S.; Nickolov, Z. S.; Miller, J. D. <br/> <br/>Abstract: Interfacial water structure is a most important parameter that influences the collector adsorption of salt minerals such as borax, potash and trona. According to previous studies, salts can be classified as water structure makers and water structure breakers. Water structure making and breaking properties of salt minerals in their saturated brine solutions are essential to explain their flotation behavior. In this work, water structure making-breaking studies in solutions of carbonate and bicarbonate salts (Na2CO3, K2CO3, NaHCO3 and NH4HCO3) in 4 wt% D2O in H2O mixtures have been performed by FTIR analysis of the OD stretching band. This method reveals a microscopic picture of the water structure making/breaking character of the salts in terms of the hydrogen bonding between the water molecules in solution. The results from the vibrational spectroscopic studies demonstrate that carbonate salts (Na2CO3 and K2CO3) act as strong structure makers, whereas bicarbonate salts (NaHCO3 and NH4HCO3) act as weak structure makers. In addition, the changes in the OD band parameters of carbonate and bicarbonate salt solutions are in agreement with the viscosity characteristics of their solutions. Sun, 29 Oct 2006 22:58:59 GMT http://idea.library.drexel.edu/handle/1860/2589 Title: The median age technique for assessing currency of consumer health information monographic collections in public libraries <br/> <br/>Authors: Li, Guisu Fri, 29 Dec 2006 22:58:59 GMT