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Alloying elements have an important effect on phase formation in solid-state chemical reactions. From the viewpoint of thermodynamics, applying the Miedema model and Kohler equation, a thermodynamic model for a solid-state multicomponent system was presented. Using this model, the activity of Ti in SiC f /Ti composites was evaluated, and the influence of different alloying elements on the interfacial chemical reactions in SiC f /Ti composites at high temperature was investigated from a thermodynamic viewpoint. The calculation results showed that most alloying elements, such as Al, Sn, Ni, Fe, Cu, Mn, Cr, Mo, and V, can reduce the activity of Ti and hinder the interfacial chemical reactions in SiC f /Ti composites, but an alloying element such as Nb can decrease the stability of the interfacial chemical reactions in SiC f /Ti composites, in most cases. [ABSTRACT FROM AUTHOR]

In the present work, a new model is developed to predict ternary diffusion coefficients in liquid state based on hard sphere theory and the Miedema model, and the diffusion coefficients are theoretically determined starting from the quantities of the pure component. Using this model, the diffusion coefficient of Ti in the TiB2/Al composite is evaluated and the influence of alloying element additions on the diffusion coefficient of Ti is discussed. The results indicate that additions of Si can promote the diffusion of Ti. Meanwhile, other elements including Ca, Fe, Mg, V, Ni, La, and Zr can hinder the diffusion of Ti. It is furthermore concluded that not only the phase diagram but also considerations concerning the kinetics are required to produce the desirable phases. [ABSTRACT FROM AUTHOR]

From the viewpoint of thermodynamics, using the Wilson equation and an extended Miedema model, the effect of the alloying element on the stability of the precipitated phases during the fabrication of in-situ reinforced TiB2/Al composites was evaluated. The result shows that additions of alloying elements, such as Mg, Cu, Zr, Ni, Fe, V, and La, can promote the formation of Al3Ti and TiB2 phases. Particularly, Zr has the most pronounced effect among these alloying elements. In addition, alloying elements can hinder the formation of AlB2 to a small extent. The calculation results also show that it is easier for magnesium to react with the salts to form TiB2 than aluminum during the fabrication of in-situ reinforced TiB2Al using the flux-assisted synthesis (FAS) technology. [ABSTRACT FROM AUTHOR]

Non- and nickel-loaded carbon matrix composites were made from rice husk to measure their electromagnetic shielding (EMS) capacities in the range of 30–1500 MHz. The results showed that the EMS capacity was dependent on carbonization temperature, content of nickel loading, molding pressure and pore size diameter. The combination of carbonization at 1200°C, molding at 20 MPa and loading of 6 wt% nickel can provide 80–60 dB EMS capacity over the measuring frequency range. [ABSTRACT FROM AUTHOR]

In the present work, the polytypism of SiC and the interfacial structure between SiC and Al were investigated using X-ray diffraction (XRD) and high resolution transmission electron microscopy (HREM). It was approved that 15R could be juxtaposed with 6H stacking sequences in the same SiC reinforcement and a structural transformation zone was also observed. The Al4C3 compound can nucleate on SiC at the SiC/Al interface with the growth orientation parallel to the C axis of SiC. Mechanisms for the observed phenomena were also discussed in detail. [ABSTRACT FROM AUTHOR]

The composite interfaces play an important role in determining the resultant composite properties, especially the development of interfacial reaction during remelting is critical to the commercialization and sustainable-development of metal matrix composites. In this paper, the interfacial reaction characteristics of SiCp/Al-Si system composites during multiple-remelting were investigated by Differential Scanning Calorimeter (DSC). It was found that the interfacial reactions were not sensitive to remelting number, remelting temperature and reinforcement volume fraction after a degree of reaction, and the results also suggested that the preventation effects of Si upon the interfacial reaction SiCp/Al were mainly attributed to the Si released from the interfacial reaction, while the original Si content in the master alloy also has the same effect only after a given Si content. [ABSTRACT FROM AUTHOR]

The properties and the structures of liquid melt above the liquidus play an important role in determining the resultant properties of the alloy and the composite. In this paper, the melt structures of SiCp/Al composites with two different reinforcement volume fractions were investigated using liquid metal X-ray diffraction and differential scanning calorimetry. The experimental results showed that the melt structures of SiCp/Al composite are different from that of liquid matrix alloy, a Si–Si hump in the pair radial distribution function in SiCp/Al composite melt and the DSC trace indicated that Si is not well distributed above the liquidus, the size change of short-range-order (SRO) in SiCp/Al composite melt indicated the diffusion of Si from chemical reaction between SiC and molten Al is possible only after a given temperature or after some extent concentration fluctuation of Si. The mechanisms for the observed phenomenon are also discussed in this paper. [ABSTRACT FROM AUTHOR]

Biomorphic SiO2 fibers were synthesized with cotton tissue as the template and with cetyltrimethylammonium bromide (CTAB) as surfactant through a surface sol-gel process. The as-prepared samples retain well the original morphology of cotton and show a uniform and large amount of nanopores. Sliver nanoparticles were successfully incorporated into the nanopores through impregnation and chemical reduction to form SiO2/Ag composite fibers. Ag nanoparticles with mean diameter approximately 3 nm have a size distribution in accordance with the nanoporosity of SiO2 matrix. Such composite fibers show prominent surface plasma resonance (SPR) effect, and during heat treatment under increasing temperatures, the SPR intensity is enhanced because of the size effect, and the SPR position undergoes a redshift first and then a blueshift. [ABSTRACT FROM AUTHOR]