Materials Literature
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The flexural behavior of 2-D continuous fiber-reinforced ceramic composites (CFCC) is modeled using a finite element analysis. This model extends the analysis of Steif and Trojnacki [1] to account for the effect of the weak interlaminar properties of most 2-D CFCCs on their flexural behavior. The model predictions con…
The axial and radial coefficients of thermal expansion (CTE) of HS (T300), HM (M40), and UHM (P100) carbon fibers have been computed, within the 20°–430°C temperature range, from thermal expansion measurements performed on unidirectional composites with the fibers embedded in an isotropic glassy SiO2-15 mol% B2O3 matr…
Whiskers are of interest for toughening polycrystalline ceramics. Nonoxide whiskers are available commercially but can oxidize and lose their effectiveness at high temperatures in oxidizing atmospheres. The availability of oxide whiskers would offer the potential of high toughness and oxidation resistant ceramic compo…
A thin and dense SiC layer has been formed on fine diamond particles in micron meter sizes. The diamond particles were placed over the SiO powder bed in a crucible and heated at 1350°C in vacuum. The Sic layer was uniformly formed with a thickness of about 10 nm for 3 hrs heating. TEM observation showed that the SiC l…
An experiment relating to the application of a dry process for the preparation of a ceramic mix for fast-single-fired vitrified tile, usually prepared via wet process, is described. The experiment made possible a comparison between the dry and wet systems on the same mix. The results obtained on the L, a, b scale rela…
This paper describes Sic, Si-Ti-C-O, Si-N-O and Si-N fibers. The tensile strength of SiC fibers obtained by the heat treatment aboue 1300°C of thermal oxidation-cured polycarbosilane fibers decreases rapidly with the increase of temperature. The improvement of high-temperature tensile strength has been studied using t…
The gas pressure sintering (GPS) behavior of reaction-bonded silicon nitride (RBSN) with Yfi3 and La/)3 additives has been studied It has been found that: Under the pressure range of the present work, the aspect ratio of grains increased with raising the nitrogen pressure during sintering. The bend strength of the sin…
Tailored precursors in the systems Si-C-N(Ti) were synthesized for various appli- cations by different reaction types by using the same two chlorosilanes. For the liquid phase infiltration (LP1)-process coammonolysis of CH3Cl2SiH and CH3Cl2SiCH=CH2 leads to a liquid cross-linkable precursor with a high ceramic yield (…
The potential for zirconia-based ceramics is wide ranging. Current interest has focused on tough, high strength ceramics for advanced heat engines. Many other applications seek to utilize the remarkable properties ofzirconia ceramics–thermal, mechanical electrical and optical. Many technical problems have to be overco…
Thermogravimetric analysis was used to study the reaction kinetics associated with high-temperature air oxidation of graphite- or BN-coated Nicalon fiber-reinforced SiC composites. For those with graphite interlayers, the shapes of the thermogravimetric curves, and the dependencies of weight changes on interfacial lay…
Improved mechanical behavior in Nicalon/SiC composites has been produced by controlling the interfacial bond through coating of the fibers with thin films before densification. Varying degrees of bonding have been achieved with different coating materials and film thicknesses. The effects of bonding on fiber pullout,…
Abstract Based on the data of X‐ray phase and microstructure analysis, the sample composition was optimized in order to provide maximum size of the textured macrograins of YBa2Cu3O7‐δ and of the crystallites in the Y2BaCuO5‐BaCuO2‐CuO, Y2Cu2O5‐BaCuO2 systems. The growth rate has been studied and the YBa2Cu3O7‐δ growth…
Radiation field produced by cosmic radiations in the earth's atmosphere is very complex and is significantly different from that found in the nuclear industry and other environments at ground level. Aircraft crew and frequent flyers are exposed to high levels of cosmic radiations of galactic and solar origin and to se…
This paper explains how diffusion banier coatings on fiber could be exploited to serve as mechanical fuses to isolate impinging reaction zone cracks by interface delaminating. Requirements of the interface toughness for the specific tailoring of the fiber/coating interface are given. It is explained how the scaling be…
By studying a cluster model containing Ni region (phase), Ni3Al region (phase) and Ni/Ni3Al region (interface) with a first-principles method, the occupation behavior and the ductility effect of zirconium in a Ni-Ni3Al system were investigated. It is found that zirconium has a stronger segregation tendency to Ni regio…
As a part of the Joint Center for Structural Genomics (JCSG) biological targets, the structures of soluble domains of membrane proteins from Thermotoga maritima were pursued. Here, we report the crystal structure of the soluble domain of TM1634, a putative membrane protein of 128 residues (15.1 kDa) and unknown functi…
A micromechanics analytical model based on the consistent shear lag theory is developed for predicting the failure modes in a fiber-reinforced unidirectional ceramic matrix composite. The model accounts for the relatively large matrix stiffness. The fiber and matrix stresses are established as functions of the applied…
The glass formation was investigated in the melt-spun AI-rich Al-Co-Y alloys by the microstructure evolution. The best glass former Al88Co5Y7 with the thickness of 230 mu m was found, and its glass forming ability (GFA) was higher than that of previously reported Al88Co4Y8 alloy. This result indicates that GFA is stro…
(119)Sn chemical shift tensors of crystalline trialkyltin functionalized octameric spherosilicates, Si(8)O(20)(SnMe(3))(8), have been determined by fitting sideband intensities in solid-state magic angle spinning (MAS) NMR spectra. Tin chemical shift parameters are exquisitely sensitive to the presence of water of cry…
Abstract The impact fatigue behavior of laminated wood bonded with water based polymer‐isocyanate resin (WPI) and resorcinol–formaldehyde resin (RF) was investigated. The number of cyclic blows to failure (Nb) for laminated wood was lower than that for solid wood. For laminated wood, Nb showed a significant decrease w…