Effective Moduli of Two-Layered Spherical Inclusions Reinforced Composites

A model is proposed to evaluate the,effective modufi of a composite reinforced by two-layered spherical inclusions.This model is based on the localisation problem of a two- layered spherical inclusion embedded in an infinite matrix.The interations of the reinforced phases are taken into account by using the average matrix stress concept.When the external layer vanishes,the proposed model reduces to the classical Mori-Tanaka's model for spherical inclusions.Theoretical results for the composite of polyester matrix filled by hollow glass spheres and voids show excellent agreement with experimental results.

Influence of spherical inclusions on effective thermoelectric properties of thermoelectric composite materials

A homogenization theory is developed to predict the influence of spherical inclusions on the effective thermoelectric properties of thermoelectric composite materials based on the general principles of thermodynamics and Mori-Tanaka method.The closed-form solutions of effective Seebeck coefficient,electric conductivity,heat conductivity,and figure of merit for such thermoelectric materials are obtained by solving the nonlinear coupled transport equations of electricity and heat.It is found that the effective figure of merit of thermoelectric material containing spherical inclusions can be higher than that of each constituent in the absence of size effect and interface effect.Some interesting examples of actual thermoelectric composites with spherical inclusions,such as insulated cavities,inclusions subjected to conductive electric and heat exchange and thermoelectric inclusions,are considered,and the numerical results lead to the conclusion that considerable enhancement of the effective figure of merit is achievable by introducing inclusions.In this paper,we provide a theoretical foundation for analytically and computationally treating the thermoelectric composites with more complicated inclusion structures,and thus pointing out a new route to their design and optimization.

Bounds on the overall properties of composites with ellipsoidal inclusions

A new model is put forward to bound the effective elastic moduli of composites with ellipsoidal inclusions. In the present paper, transition layer for each ellipsoidal inclusion is introduced to make the trial displacement field for the upper bound and the trial stress field for the lower bound satisfy the continuous interface conditions which are absolutely necessary for the application of variational principles. According to the principles of minimum potential energy and minimum complementary energy, the upper and lower bounds on the effective elastic moduli of composites with ellipsoidal inclusions are rigorously derived. The effects of the distribution and geometric parameters of ellipsoidal in- clusions on the bounds of the effective elastic moduli are an- alyzed in details. The present upper and lower bounds are still finite when the bulk and shear moduli of ellipsoidal inclusions tend to infinity and zero, respectively. It should be mentioned that the present method is simple and needs not calculate the complex integrals of multi-point correlation functions. Meanwhile, the present paper provides an entirely different way to bound the effective elastic moduli of composites with ellipsoidal inclusions, which can be developed to obtain a series of bounds by taking different trial displacement and stress fields.

THE EFFECTIVE PROPERTIES OF PIEZOELECTRIC COMPOSITE MATERIALS WITH TRANSVERSELY ISOTROPIC SPHERICAL INCLUSIONS

The effective properties of piezoelectric composite materials are very important in engineering. In this paper, the closed_form solutions of the constraint_strain and the constraint_electric_field of a transversely isotropic spherical inclusion in an infinite non_piezoelectric matrix are obtained. The dilute solutions of piezoelectric composite materials with transversely isotropic spherical inclusions are also given. The solutions in the paper can be readily utilized in analysis and design of piezoelectric composite materials or smart materials and smart structures.

AN EXPLICIT EXPRESSION OF THE EFFECTIVE MODULI FOR COMPOSITE MATERIALS FILLED WITH COATED INCLUSIONS

The obvious shortcoming of the generalized self-consistent method (GSCM) is that the effective shear modulus of composite materials estimated by the method can not be expressed in an explicit form. This is inconvenient in engineering applications. In order to overcome that shortcoming of GSCM, a reformation of GSCM is made and a new micromechanical scheme is suggested in this paper. By means of this new scheme, both the effective bulk and shear moduli of an inclusion-matrix composite material can be obtained and be expressed in simple explicit forms. A comparison with the existing models and the rigorous Hashin-Shtrikman bounds demonstrates that the present scheme is accurate. By a two-step homogenization technique from the present new scheme, the effective moduli of the composite materials with coated spherical inclusions are obtained and can also be expressed in an explicit form. The comparison with the existing theoretical and experimental results shows that the present solutions are satisfactory. Moreover, a quantitative comparison of GSCM and the Mori-Tanaka method (MTM) is made based on a unified scheme.

Shielding Effectiveness of Composites Containing Flaky Inclusions

To investigate the quantitative relationship between the electromagnetic-shielding property of composites and the distribution of inclusions, a scheme for predicting the shielding effectiveness of composites containing variously-distributed flaky inclusions is proposed. The scheme is based on equivalent parameters of homogeneous comparison materials and the plane-wave shielding theory. It leads to expli- cit formulas for the shielding effectiveness of multi-layered composites in terms of microstructural parameters that characterize the shape, distribution and orientation of the inclusions. For single layer composite that contains random and aligned flaky silver-coated carbonyl-iron particles with fractions of different volume, the predicted shielding effectiveness agrees well with the experimental data. As for composites containing aligned flaky particles,the shielding effectiveness obtained by the proposed scheme and experiment data is higher than that the random case, e.g. about 20 dB higher at 750 MHz. The proposed scheme is a straightforward method for optimizing future composite de- signs.

Decrepitation Thermometry and Compositions of Fluid Inclusions of the Damoqujia Gold Deposit,Jiaodong Gold Province,China:Implications for Metallogeny and Exploration

The recently discovered Damoqujia （大磨曲家） gold deposit is a large shear zone-hosted gold deposit of disseminated sulphides located in the north of the Zhaoping （招平） fault zone, Jiaodong （胶东） gold province, China. In order to distinguish the temperature range of cluster inclusions from different mineralization stages and measure their compositions, 16 fluid inclusions and 5 isotopic geochemistry samples were collected for this study. Corresponding to different mineralization stages, the multirange peaks of quartz decrepitation temperature （250-270, 310-360 and 380-430℃） indicate that the activity of ore-forming fluids is characterized by multistage. The ore-forming fluids were predominantly of high-temperature fluid system （HTFS） by CO2-rich, and SO4^2--K^＋ type magmatic fluid during the early stage of mineralization and were subsequently affected by low-temperature fluid system （LTFS） of CH4-rich, and Cl^--Na^＋/Ca^2＋ type meteoric fluid during the late stage of mineralization. Gold is transferred by Au-HS^- complex in the HTFS, and Au-Cl^- complex can be more important in the LTFS. The transition of fluids from deeper to shallow environments results in mixing between the HTFS and LTFS, which might be one of the most key reasons for gold precipitation and large-scale mineralization. The ore-forming fluids are characterized by high-temperature, strong-activity, and superimposed mineralization, so that there is a great probability of forming large and rich ore deposit in the Damoqujia gold deposit. The main bodies are preserved and extend toward deeper parts, thereby suggesting a great potential in future.

Effect of Cu addition on microstructural evolution and hardening of mechanically alloyed Al-Ti-O in-situ composite

The microstructure formation and strengthening of an Al-5 wt.%TiO2 composites with additions of 5 wt.%Cu and 2 wt.% stearic acid(as a process control agent, PCA) during mechanical alloying and subsequent thermal exposure were studied. The powder composites were prepared by high-energy ball milling for up to 10 h. Single line tracks of the powders were laser melted. Optical and scanning electron microscopy, XRD analysis and differential scanning calorimetry were used to study microstructural evolution. The results showed that the Cu addition promotes an effective mechanical alloying of aluminum with Ti O2 from the start of milling, resulting in higher microhardness(up to HV 290), while the PCA, on the contrary, postpones this process. In both cases, the composite granules with uniform distribution of Ti O2 particles were formed. Subsequent heating of mechanically alloyed materials causes the activation of an exothermic reaction of Ti O2 reduction with aluminum, the start temperature of which, in the case of Cu addition,shifts to lower values, that is, the transformation begins in the solid state. Besides, the Cu-added material after laser melting demonstrates a more dispersed and uniform structure which positively affects its microhardness.

Ordovician Seawater Composition:Evidence from Fluid Inclusions in Halite

Fluid inclusions in halite can directly record the major composition of seawater,however Ordovician halite is very rare.Ordovician is a key time during the evolution history.However there are no Ordovician seawater data reported except from the data from the halite from the

Determination of elastic moduli of composite medium containing bimaterial matrix and non-uniform inclusion concentrations

Reservoir porous rocks usually consist of more than two types of matrix materials, forming a randomly heterogeneous material. The determination of the bulk modulus of such a medium is critical to the elastic wave dispersion and attenuation. The elastic moduli for a simple matrix-inclusion model are theoretically analyzed. Most of the efforts assume a uniform inclusion concentration throughout the whole single-material matrix. However, the assumption is too strict in real-world rocks. A model is developed to estimate the moduli of a heterogeneous bimaterial skeleton, i.e., the host matrix and the patchy matrix. The elastic moduli, density, and permeability of the patchy matrix differ from those of the surrounding host matrix material. Both the matrices contain dispersed particle inclusions with different concentrations. By setting the elastic constant and density of the particles to be zero, a double-porosity medium is obtained. The bulk moduli for the whole system are derived with a multi-level effective modulus method based on Hashin＇s work. The proposed model improves the elastic modulus calculation of reservoir rocks, and is used to predict the kerogen content based on the wave velocity measured in laboratory. The results show pretty good consistency between the inversed total organic carbon and the measured total organic carbon for two sets of rock samples.

Chemical Composition of the Primitive Mantle Source of Peridotite Inclusions at Mount Lianshan, Liuhe County,Jiangsu Province

: This paper presents a study of the major and trace element compositions of fresh mantle-derived spinel lherzolite and harzburgite inclusions from Cenozoic alkaline basalt in Mount Lianshan and Mount Panshi, Liuhe County, Jiangsu Province. An estimation is made of the contents of the major elements and some of the trace elements in the primitive mantle source region of the area, from which the authors have obtained MgO/Al2O3= 7.86. The contents of MgO and Al2O3 are also obtained as 37.58% and 4.78% respectively based on the correlation of MgO-Al2O3. Then, the contents of various elements in the primitive mantle are calculated using their regression equations with MgO, and the compositon of the primitive mantle, a basic issue in geochemistry study, is discussed on that basis.

A GENERALIZED SELF-CONSISTENT MORI-TANAKA MODEL FOR PREDICTING THE EFFECTIVE MODULI OF THE COATED INCLUSION BASED COMPOSITE MATERIALS

The weak point of the generalized self-consistent method (GSCM) isthat its solution for the effective shear moduli involves determiningthe complicated displacement and strain fields in con- stituents.Furthermore, the effective moduli estimated by GSCM cannot beexpressed in an explicit form. Instead of following the procedure ofGSCM, in this paper a generalized self-consistent Mori- Tanaka method(GSCMTM) is developed by means of Hill's interface condition and theassumption that the strain in the inclusion is uniform. A comparisonwith the existing theoretical and experimental results shows that thepresent GSCMTM is sufficiently accurate to predict the effectivemoduli of the coated inclusion-based composite materials.

Fluid-melt Inclusions in Fluorite of the Huanggangliang Skarn Iron-Tin Deposit and Their Significance to Mineralization

For the first time, fluid-melt inclusions are found in fluorite of the Huanggangliang skarn iron-tin deposit (HSID). The fluorite was formed in the main stage of mineralization, named the hydro-skarnization stage. The inclusions contain various components such as Fe, Mg and Cr from deep sources. The melts of primary inclusions are mainly Ca- and F-rich and those of secondary inclusions tend to become Si-rich. During this evolution process, the melts and iron daughter minerals decreased and even vanished. These facts reveal that the evolution of the primary mineralizing fluids and the differentiation of the fluids and melts are the main factors leading to the deposition of Fe, Sn and other elements. This discovery confirms the magmatic genesis of the HSID and has filled in the gaps in the research of magmatogenic skarn deposits and furnished new methods for such research. Furthermore, it has enlarged the scope of the research on fluid inclusions.

Degree of Brine Evaporation and Origin of the Mengyejing Potash Deposit：Evidence from Fluid Inclusions in Halite

The Mengyejing potash deposit is located in the southern port of the Simao Basin, Yunnan Province, and is hosted in mid-Cretaceous strata. The chemical compositions of fluid inclusions in halite crystals, collected from the level-610 adit in the deposit, were analysed by laser ablation inductively coupled plasma mass spectrometry（LA-ICP-MS）. The results show that the brine is of the Na-K-Mg-Ca-Cl type and has K concentrations that are distinctly higher than those of Mg and Ca, unlike normal brines associated with Cretaceous halite. The high K concentrations indicate that the degree of evaporation of the ancient Mengyejing saline lake was very high, reaching the sylvite deposition stage but rarely reaching the carnallite deposition stage. The trajectory of the H and O isotopic compositions of the brines in the halite-hosted fluid inclusions corresponds to intense evaporation, indicating that the net evaporation exceeded the net inflow of brines. These brine compositions in halite-hosted fluid inclusions were likely formed by the dissolution of previously deposited K-bearing minerals by fresh continental and/or seawater, forming a type of modified seawater, with deep hydrothermal fluids potentially supplying additional potassium. The basin likely experienced multiple seawater incursion, dissolution and redeposition events in a high-temperature environment with high evaporation rates.

Theory and Practice of Oxide Inclusion Composition and Morphology Control in Spring Steel Production

In order to control the composition,morphology and size distribution of oxide inclusions in spring steel,the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxide inclusion precipitated at different temperatures was determined based on thermodynamic equilibrium for spring steel 60Si2 MnA,and has been verified by practice.The size distribution of non-metallic inclusions electrolytically extracted from specimens of hot rolled spring steel was determined by image analyzer.The results show that there are a great deal of large inclusions in spring steel produced by the conventional process,and the quantity and the size of large inclusions in spring steel produced by new process are largely reduced.As a result,the fatigue properties of the spring steel produced by new process are highly improved,and the ratio ofσ-1/σbis raised from 0.451 to 0.468.

Geochemical characteristics of the fluid inclusions in the Gangxi Fault Belt, Huanghua Depression, Bohai Bay Basin, China

We studied the geochemical characteristics of the fluid inclusions in the Ordovician carbonates and the Oligocene Shahejie Formation sandstones from 15 wells in the Gangxi Fault Belt, Huanghua Depression. The fluid inclusions are all sec- ondary with gas/liquid ratio of 5%~10%. Base on Raman they are mainly composed of H2O, CO2 and CH4. The homogenization temperatures, combined with burial and geothermal history of the host rock, indicate that the fluid flows in the Shahejie Formation and the Ordovician carbonates were trapped in Neocene. Using a VG5400 mass spectrometer, the helium isotopic compositions were analyzed. Interpretation of results suggested a significant amount of mantle-derived helium mainly accumulating in the intersections of the NWW trending Xuzhuangzi and NE trending Gangxi faults. The maturity of hydrocarbon decreases from the intersection to the outside pointing out that the fluid related to the NWW trending Xuzhuangzi and NE trending Gangxi faults. These factors implied the fluid inclusions have a close relationship to the local tectonic setting. Gangxi Fault Belt experienced intensive Neo-tectonic activities in Cenozoic. Widespread faulted-depressions and strong volcanic eruptions manifested its tec- tonic status of extensional stress field. Mantle uplift caused the movement of magma that carried mantle-derived gases and deep heat flows, the deep-rooted tension faults provided the passages for the gases and heat flows to shallow crust levels.

<ji>In Situ</i>Synthesis of Titanium Matrix Composite (Ti-TiB-TiC) through Sintering of TiH₂-B₄C

Fully densified in-situ reinforced (TiB + TiC)-Ti matrix composites have been produced from TiH2-B4C mixtures using pressure less sintering or hot pressing technique. With increasing content of reinforcing components the sintering is retarded. The materials with more than 20 - 30 vol. % were only completely densified by hot pressing technique. Hardness values of the Ti matrix composites produced are up to 5 times higher than that of the sintered pure Ti produced from TiH2. This is caused beside the higher hardness of the inclusions also by hardening the matrix due to solubility of B and C in the titanium.

Tourmalinization at the Darasun goldfield,Eastern Transbaikalia:Compositional,fluid inclusion and isotopic constraints

Zoned tourmaline （schorl-dravite） in the matrix of hydrothermal explosive breccia and ore veins in gold deposits, Chita region, Eastern Transbaikalia, Russia, are associated with Na- and K-rich porphyry-type subvolcanic intrusives. 61So values of tourmaline from three gold deposits （Darasun, Talatui, Teremkinskoye） are ＋8.3%, ＋7.6%, and --6.0% and calculated 6180 values of fluids respon- sible for the tourmalinization are ＋7.3%, ＋7.7%, and ＋4.2%, respectively. These data imply an igneous fluid source, except at the Teremkin deposit where mixing with meteoric water is indicated. Wide ranges of Fe3＋/Fetot and the presence of vacancies characterize the Darasun deposit tourmaline indicating wide ranges off（O2） and pH of mineralizing fluids. Initial stage tourmalines from the gold deposits of the Darasun ore district are dravite or high mg schorl. Second stage tourmaline is characterized by oscillatory zoning but with Fe generally increasing towards crystal rims indicating decreasing temperature. Third stage tourmaline formed unzoned crystals with XMg （mole fraction of Mg） close to that of the first stage tourmaline, due to a close association with pyrite and arsenopyrite. From Fe^3＋/Fetot values, chemical composition and crystallization temperatures, logf（O2） of mineralizing fluids ranged from ca. -25 to 20, much higher than for the gold-bearing beresite-listvenite association, indicating that tourmalinization was not related to gold mineralization.

Structure and Mechanical Properties of Waterborne Polyurethane-based Composites Filled with Self-assembled Supramolecular Nanoplatelets

New composites of waterborne polyurethane （WPU） as a matrix were prepared by incorporating rigid supramolecular nanoplatelets （SNs） as filler, which were self-assembled by the selective inclusion of β-cyclodextrin （β-CD） onto poly（propylene oxide） （PPO） segment in the poly（ethylene oxide）- block-PPO-block-poly（ethylene oxide） （PEO-b-PPO-b-PEO）. It is worth noting that, when the loading level of SN is lower than 3wt%, the SNs with moderate PEO length result in the simultaneous increase in strength, elongation and Young＇s modulus in contrast with neat WPU. If there is no stretching free PEO chain, both strength and elongation decrease in spite of an increase in Young＇s modulus. However, too long PEO chains result in the decrease of mechanical performances while the relatively higher loading-level of SNs also inhibits the enhancement of strength and elongation.

Prediction of Effective Elastic Modulus of Biphasic Composite Materials

Two semi-empirical approaches for prediction of elastic modulus of biphasic composites have been proposed. Developed relations are for pore free matrix and pore free filler and found to depend on nonlinear contribution of volume fraction of constituents as well as ratio of elastic properties of individual phases. These relations are applied for the calculation of effective elastic modulus mainly for Al2O3-NiAl, SiC-Al, Alumina-Zirconia, Al-Al2O3, W-glass and Flax-Resin composite materials. Theoretical predictions using developed relations are compared with experimental data. It is found that the predicted values of effective elastic modulus using modified relations are quite close to the experimental results.