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Matrix Phase (matrix + phase)
Kinds of Matrix Phase Selected AbstractsMicrostructural Investigation of Walking Parts of Military Tanks Coated with Arc SprayingADVANCED ENGINEERING MATERIALS, Issue 7 2008U. Ozsarac The walking parts are the most important mechanical components in military tanks and other vehicles having palettes. The matrix phase of carrying wheels is Cu-based aluminum alloy. In this study, the microstructure of walking parts of military tanks was investigated deeply by optically and scanning electron microscopy. [source] Texture Development in Barium Titanate and PMN,PT Using Hexabarium 17-Titanate HeterotemplatesINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2005Toshio Kimura Bulk BaTiO3 ceramics with ,111,-texture have been prepared by the modified templated grain growth method, using platelike Ba6Ti17O40 particles as templates, and the mechanism of texture development is examined. The Ba6Ti17O40 particles induce the abnormal growth of BaTiO3 grains, and a structure similarity between {001} of Ba6Ti17O40 and {111} of BaTiO3 gives ,111,-texture to abnormally grown BaTiO3 grains. Thus, the ,111,-texture develops in the BaTiO3 matrix. The use of platelike Ba6Ti17O40 particles has been extended to a 0.65Pb(Mg1/3Nb2/3)O3,0.35PbTiO3 matrix, but the matrix phase is decomposed by extensive chemical reactions between the matrix and template phases. [source] Rheological, morphological, mechanical, and barrier properties of PP/EVOH blendsADVANCES IN POLYMER TECHNOLOGY, Issue 3 2001Jong Ho Yeo Using the biaxially oriented film process, polypropylene (PP)/ethylene-vinyl alcohol copolymer (EVOH) blends with an improved barrier property could be obtained by generating a laminar structure of the dispersed phase in the matrix phase. This laminar morphology, induced by biaxial orientation, was found to result in a significant increase in the oxygen barrier property of PP/EVOH (85/15) blends by about 10 times relative to the pure PP. In this study, compatibility in the PP/EVOH blend system was evaluated by investigating the influence of compatibilizer on the rheological, morphological, and mechanical properties of the blends. In addition, the effects of compatibilizer content, draw ratio, and draw temperature on the oxygen permeability and morphology of biaxially drawn blend films were also studied. It was revealed that an optimum amount of compatibilizer, maleic anhydride grafted PP, should be used to improve the barrier property of the PP/EVOH blends with a well-developed laminar structure. The draw ratio and draw temperature had a significant influence on the permeability of the blends. The blend films exhibited a more pronounced laminar structure when the blends were stretched biaxially under processing conditions of higher draw ratio and draw temperature, resulting in higher barrier properties. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 191,201, 2001 [source] Reaction-induced nucleation and growth v. grain coarsening in contact metamorphic, impure carbonatesJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2010A. BERGER Abstract The understanding of the evolution of microstructures in a metamorphic rock requires insights into the nucleation and growth history of individual grains, as well as the coarsening processes of the entire aggregate. These two processes are compared in impure carbonates from the contact metamorphic aureole of the Adamello pluton (N-Italy). As a function of increasing distance from the pluton contact, the investigated samples have peak metamorphic temperatures ranging from the stability field of diopside/tremolite down to diagenetic conditions. All samples consist of calcite as the dominant matrix phase, but additionally contain variable amounts of other minerals, the so-called second phases. These second phases are mostly silicate minerals and can be described in a KCMASHC system (K2O, CaO, MgO, Al2O3, SiO2, H2O, CO2), but with variable K/Mg ratios. The modelled and observed metamorphic evolution of these samples are combined with the quantification of the microstructures, i.e. mean grain sizes and crystal size distributions. Growth of the matrix phase and second phases strongly depends on each other owing to coupled grain coarsening. The matrix phase is controlled by the interparticle distances between the second phases, while the second phases need the matrix grain boundary network for mass transfer processes during both grain coarsening and mineral reactions. Interestingly, similar final mean grain sizes of primary second phase and second phases newly formed by nucleation are observed, although the latter formed later but at higher temperatures. Moreover, different kinetic processes, attributed to different driving forces for growth of the newly nucleated grains in comparison with coarsening processes of the pre-existing phases, must have been involved. Chemically induced driving forces of grain growth during reactions are orders of magnitudes larger compared to surface energy, allowing new reaction products subjected to fast growth rates to attain similar grain sizes as phases which underwent long-term grain coarsening. In contrast, observed variations in grain size of the same mineral in samples with a similar T,t history indicate that transport properties depend not only on the growth and coarsening kinetics of the second phases but also on the microstructure of the dominant matrix phase during coupled grain coarsening. Resulting microstructural phenomena such as overgrowth and therefore preservation of former stable minerals by the matrix phase may provide new constraints on the temporal variation of microstructures and provide a unique source for the interpretation of the evolution of metamorphic microstructures. [source] Petrogenesis of lawsonite and epidote eclogite and blueschist, Sivrihisar Massif, TurkeyJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2006P. B. DAVIS Abstract The Sivrihisar Massif, Turkey, is comprised of blueschist and eclogite facies metasedimentary and metabasaltic rocks. Abundant metre- to centimetre-scale eclogite pods occur in blueschist facies metabasalt, marble and quartz-rich rocks. Sivrihisar eclogite contains omphacite + garnet + phengite + rutile ± glaucophane ± quartz + lawsonite and/or epidote. Blueschists contain sodic amphibole + garnet + phengite + lawsonite and/or epidote ± omphacite ± quartz. Sivrihisar eclogite and blueschist have similar bulk composition, equivalent to NMORB, but record different P,T conditions: ,26 kbar, 500 °C (lawsonite eclogite); 18 kbar, 600 °C (epidote eclogite); 12 kbar, 380 °C (lawsonite blueschist); and 15,16 kbar, 480,500 °C (lawsonite-epidote blueschist). Pressures for the Sivrihisar lawsonite eclogite are among the highest reported for this rock type, which is rarely exposed at the Earth's surface. The distribution and textures of lawsonite ± epidote define P,T conditions and paths. For example, in some lawsonite-bearing rocks, epidote inclusions in garnet and partial replacement of matrix epidote by lawsonite suggest an anticlockwise P,T path. Other rocks contain no epidote as inclusions or as a matrix phase, and were metamorphosed entirely within the lawsonite stability field. Results of the P,T study and mapping of the distribution of blueschists and eclogites in the massif suggest that rocks recording different maximum P,T conditions were tectonically juxtaposed as kilometre-scale slices and associated high- P pods, although all shared the same exhumation path from ,9,11 kbar, 300,400 °C. Within the tectonic slices, alternating millimetre,centimetre-scale layers of eclogite and blueschist formed together at the same P,T conditions but represent different extents of prograde reaction controlled by strain partitioning or local variations in fO2 or other chemical factors. [source] Effects of Ca/Ti Cosubstitution upon Microwave Dielectric Characteristics of CaSmAlO4 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2009Xie Cheng Fan (Ca1+xSm1,x)(Al1,xTix)O4 (0,x,0.4) ceramics were synthesized by solid-state reaction method and their microstructures and microwave dielectric properties were investigated. X-ray diffraction analysis and energy-dispersive X-ray analysis indicated that the matrix phase was a solid solution with a composition represented by the chemical formula (Ca1+xSm1,x) (Al1,xTix)O4 and minor amount of (Ca,Sm)(Al,Ti)O3 secondary phase was detected. Ca/Ti cosubstitution could significantly improve the microwave dielectric characteristics of CaSmAlO4 ceramics, and the excellent microwave dielectric characteristics were obtained in the modified ceramics as ,r=19,23, Q×f=49 100,118 700 GHz, and ,f=,15,15 ppm/°C. [source] High-Temperature Instability of Li- and Ta-Modified (K,Na)NbO3 PiezoceramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Yongli Wang This paper addresses the high-temperature instability of Li- and Ta-modified (K,Na)NbO3 piezoceramics. The grains with abnormal size evolve out of the fine matrix grains during high-temperature annealing. They are found to be precipitates with a tetragonal tungsten bronze structure, which result from the volatilization and segregation of the alkali metal elements. With the growth of the abnormal grains the composition of the perovskite matrix phase also changes remarkably, as has been suggested by EDX analysis (for Na) and electric measurements (for Li). These variations lead to a large increase in the tetragonal/orthorhombic phase transition temperature and appreciable variations in the dielectric, ferroelectric, and piezoelectric properties of the ceramic samples. Control of the volatilization of the alkali metal elements can efficiently depress the abnormal grain growth and the compositional segregation. [source] Microstructure,magnetic properties relationships in nanocrystalline Nd,Fe,Co,Ge,B annealed ribbonsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2006R. Gholamipour Abstract In this work, the effects of Ge addition on the microstructure and magnetic properties of some rapidly quenched Nd13.5Fe(74.9,z )Co5.5Gez B6 alloys with z = 0.0, 0.18, 0.36, 0.54, 0.72 and 0.9 prepared by a rapid solidification method were studied. For the first time, detailed microstructural study of nanometer size grain boundaries enriched with very small amount of Ge as well as Nd was carried out using 3 Dimensional Atom Probe (3DAP) technique. The magnitudes of Br and (BH )max were seen to increase for the samples substituted with up to 0.36 at% Ge in spite of the fact that Ge is a non-magnetic atom. This was related to the observed change of Co concenteration in matrix phase. However, the magnetic properties deteriorated for the samples with Ge addition beyond 0.36 at%. The observed magnetic properties are discussed in relation with the observed microstructural changes monitored by 3DAP and TEM techniques. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Extrusion of polyethylene/polypropylene blends with microfibrillar-phase morphologyPOLYMER COMPOSITES, Issue 8 2010Martina Polaskova Extrusion of immiscible polymers under special conditions can lead to creation of microfibrillar-phase morphology, ensuring significant increase of mechanical properties of polymer profiles. Polyethylene/polypropylene blend extrudates with microfibrillar-phase morphology (polypropylene microfibrils reinforcing polyethylene matrix phase) were prepared through continuous extrusion with semihyperbolic-converging die enabling elongation and orientation of microfibrils in flow direction. Structure of extruded profiles was examined using electron microscopy and wide-angle X-ray scattering. Tensile tests proved that extrudates with microfibrillar-phase morphology show significantly higher mechanical properties than the conventional extrudates. The presented concept offers possibility of replacing the existing expensive multi-component medical devices with fully polymeric tools. POLYM. COMPOS., 31:1427,1433, 2010. © 2009 Society of Plastics Engineers [source] An experimental study of morphology and rheology of ternary Pglass-PS-LDPE hybridsPOLYMER ENGINEERING & SCIENCE, Issue 6 2003Peter C. Guschl Ternary blends of low-density polyethylene (LDPE), polystyrene (PS), and a low Tg tin-based phosphate glass (Pglass) were prepared at compositions ranging from 0,50 vol% Pglass in which either LDPE or PS was the continuous matrix phase. Differential scanning calorimetry was used to investigate the phase behavior of the pure components, PS-LDPE blends and binary Pglass-polymer hybrids. Interesting steady-shear and transient rheology was observed for the hybrids. In particular, the steady shear viscosity curves for the hybrids of ,Pglass , 30% exhibited unusual, four-region flow behavior, similar to that of liquid crystalline polymers. Two Newtonian plateaus at low ( , 0.1 s,1) and moderate (0.4 , , s,1) shear rates connected by two distinct shear-thinning regimes were apparent. This observed rheology is ascribed to a unique composite morphology of these multi-component systems. Rheological data on the binary Pglass-polymer systems suggest that the presence of the Pglass within both PS and LDSE contributes significantly to this unusual behavior, perhaps because of the interfacial behavior between the phases. Micrographs obtained via scanning electron microscopy reveal preferential placement of the Pglass phase dispersed within the PS-phase and surrounding the LDPE phase. Optical shearing data confirmed the evolution of this microstructure under specific shear conditions. [source] Mixed matrix membrane materials with glassy polymers.POLYMER ENGINEERING & SCIENCE, Issue 7 2002Part Mixed matrix materials comprising molecular sieve entities embedded in a polymer matrix can economically increase membrane permselectivity, thereby addressing a key challenge hindering the widespread use of membrane-based gas separations. Prior work has clarified the importance of proper selection of the dispersed sieve phase and the continuous matrix phase based on their intrinsic transport properties. Proper material selection for the two components, while necessary, is not sufficient since the interfacial contact zone appears to be equally important to achieve optimum transport properties. Specifically, it was found that chemical coupling of the sieve to the polymer can lead to better macroscopic adhesion but to even poorer transport properties than in the absence of the adhesion promoter. This counterintuitive behavior may be attributed to a nanometric region of disturbed packing at the polymer sieve interphase. The poor properties are believed to result from "leakage" of gas molecules along this nanometric interface. The Maxwell model was modified to take into account these complexities and to provide a first order quantification of the nanometric interphase. The analysis indicates that optimization of the transport properties of the interfacial region is key to the formation of ideal mixed matrix materials. This approach is used in the second part of this paper to form successful mixed matrix membrane materials. [source] Hydroxyapatite as a filler for biosynthetic PHB homopolymer and P(HB,HV) copolymersPOLYMER INTERNATIONAL, Issue 7 2003Antje Bergmann Abstract This paper deals with some of the fundamental problems encountered when using a semicrystalline polymer as the matrix phase for a particulate-filled composite. As our model system we adopted poly-(R)-3-hydroxybutyrate, PHB, and two copolymers of (R)-3-hydroxybutyrate and (R)-3-hydroxyvalerate, P(HB,HV), for the matrix phase, and the mineral calcium hydroxyapatite as a particulate filler. The structure and properties of compression-moulded films of various compositions were investigated by polarized light microscopy, wide-angle X-ray scattering and mechanical testing. It was found that the degree of crystallinity of the matrix was lower in filled samples, and that the spherulitic crystallization of the matrix appeared to cause the filler particles to form agglomerates, which would not be as effective a reinforcement as finely dispersed primary filler particles. The tensile strength, strain-to-break and tensile modulus of samples of different compositions were analysed using well-known theories for composite behaviour. Copyright © 2003 Society of Chemical Industry [source] Purification,chemical structure,electrical property relationship in gold nanoparticle liquids,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2010Robert I. MacCuspie Abstract Macroscopic assemblies of nanoparticles with fluid like characteristics, i.e. nanoparticle liquids (NPLs), are a new class of materials that exhibit unique properties compared with dispersions of nanoparticles in a molecularly distinct matrix phase. By focusing on reaction ratios, techniques to maximize concentration of reactants and quantification of chemical content during washing steps, a high degree of control over the purity of NPLs was maintained while allowing for easy scalability in batch sizes and synthesis throughput. A range of tertiary amines and quaternary ammoniums were used to successfully synthesize Au NPLs from a range of Au nanoparticles with nominal diameters from 6 to 20 nm and initially stabilized with either citrate or dodecanethiol. Stable Au NPLs after purification exhibited a sub-equivalence ratio of canopy to ligand molecules within the corona. This small canopy density most likely arose from the incommensurate areal density of anionic charge within the ligand shell relative to the larger size of the cationic canopy molecule, resulting in a population of cation,anion pairs too weakly bound to be retained in the initial assembly of the canopy post-purification. Finally, increasing either the volume fraction or molecular weight of the canopy was found to increase exponentially the electrical resistance of the bulk NPLs. Removal of excess canopy molecules created a conductive Au NPL that improved hot-current switching durability by at least two orders of magnitude beyond prior reports. Published in 2010 by John Wiley & Sons, Ltd. [source] Precursor-derived Si,(B,)C,N ceramics: thermolysis, amorphous state and crystallization,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2001Joachim Bill Abstract The preparation of silicon nitride- and carbide-based ceramics by solid-state thermolysis of polysilazanes and polysilylcarbodiimides is described. Results on the ceramization of the preceramic compounds and the architecture of the corresponding amorphous states obtained by spectroscopic means and by X-ray and neutron scattering are reviewed. Fundamental correlations between the composition and structure of the preceramic compounds and the architecture of the amorphous state are revealed. Furthermore, the crystallization behavior of the amorphous precursor-derived Si,C,N ceramics is treated. Moreover, the influence of boron on the thermal stability of the amorphous state is described. The high-temperature behavior of these Si,B,C,N solids can be correlated with their phase composition. Ceramic materials with compositions located close to the three-phase equilibrium SiC,+,BN,+,C exhibit a high temperature stability up to 2000,°C. This effect is accompanied by the formation of a metastable solid consisting of Si3N4 and SiC nanocrystals that are embedded in a turbostratic B,C,N matrix phase. Based on thermodynamic considerations, a model for the high-temperature stability effect is proposed. Copyright © 2001 John Wiley & Sons, Ltd. [source] New Routes for Fabricating Ultrafine-Grained Microstructures in Bulky Steels without Very-High Strains,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Nobuhiro Tsuji Abstract Several routes to produce ultrafine-grained structures in steels without severe plastic deformation are introduced. The key point of the ideas is to combine plastic deformation with the phase transformation of matrix phases. When as-quenched martensite in steels is used as a starting microstructure, sub-micrometer grain-sized structures can be obtained easily. Another example using a dual-phase steel composed of soft and hard phases is also discussed. Repeating plastic deformation and phase transformation is also effective in obtaining nanostructures in an austenitic stainless steel. Examples of strips of UFG stainless steels in industry and their applications are presented. [source] A comparison of boundary element and finite element methods for modeling axisymmetric polymeric drop deformationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 7 2001Russell Hooper Abstract A modified boundary element method (BEM) and the DEVSS-G finite element method (FEM) are applied to model the deformation of a polymeric drop suspended in another fluid subjected to start-up uniaxial extensional flow. The effects of viscoelasticity, via the Oldroyd-B differential model, are considered for the drop phase using both FEM and BEM and for both the drop and matrix phases using FEM. Where possible, results are compared with the linear deformation theory. Consistent predictions are obtained among the BEM, FEM, and linear theory for purely Newtonian systems and between FEM and linear theory for fully viscoelastic systems. FEM and BEM predictions for viscoelastic drops in a Newtonian matrix agree very well at short times but differ at longer times, with worst agreement occurring as critical flow strength is approached. This suggests that the dominant computational advantages held by the BEM over the FEM for this and similar problems may diminish or even disappear when the issue of accuracy is appropriately considered. Fully viscoelastic problems, which are only feasible using the FEM formulation, shed new insight on the role of viscoelasticity of the matrix fluid in drop deformation. Copyright © 2001 John Wiley & Sons, Ltd. [source] Effect of Thermal Initiator Concentration on the Electrical Behavior of Polymer-Derived Amorphous Silicon CarbonitridesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2008Yansong Wang The electric conductivity of polymer-derived silicon carbonitrides made from a polysilazane modified with different amounts of thermal initiator is measured at room temperature. It is found that the thermal initiator has a significant effect on the electric conductivity, which first increases and then decreases with increasing thermal initiator concentration. The highly conductive sample exhibits a very high piezoresistive coefficient and weak temperature dependence as compared with the low conductive samples. The microstructures of the materials are characterized using a Raman spectroscope. Based on these results, two conducting mechanisms are identified: the highly conductive sample is dominated by the tunneling,percolation mechanism, while the low conductive samples are dominated by matrix phases. The effect of the thermal initiator on the development of the microstructures of the materials is discussed. [source] | |||||||||||||||||||||||||