Materials Literature
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Alumina ceramics constitute an important class of structural ceramics. Their use in the structural applications has increased in the recent past and is likely to go up further as progress is made in their processing and understanding their mechanical behaviour. Low reliability, as reflected in the Weibull modulus m, a…
Supported nickel catalysts are used for steam reforming of natural gas and methanation of carbon oxides in hydrogen-rich streams in the production of ammonia, methanol and hydrogen. These catalysts are loaded into reactors in the oxide form and are then activated into metallic nickel state by in-citu reduction. The ac…
Austenitic stainless steels with low carbon content have good corrosion resistance in nitric acid solutions. However, these steels are susceptible to corrosion in nitric acid solutions which contain highly oxidizing ions such as Cr2O72-, Run+ etc. One of these is called "End Grain Corrosion" or "Tunnelling Corrosion".…
Drain-gate breakdown of GaAs metal-semiconductor-field-effect transistors (MESFETs) was analyzed using high frequency waveform probing. Peak dmin-gate voltage was theoretically and experhentally found to be a determining breakdown factor. The impact ionization induced conduction component of the gate and drain current…
The lattice distortion and size of crystallites along a particular lattice direction in solid pharmaceuticals were determined by profile analysis using a peak profile of X-ray powder diffraction. The analysis was carried out according to either the paracrystal or micro strain model. After correction for instrumental b…
The reaction between tetraphenylphthalonitrile and 4-phthalonitrile or 6-tert-butylnaphthalonitrile in the presence of copper(I) chloride gives a non-statistical mixture of non-symmetrical phthalocyanines from which 2:2 complexes are separated; in the reaction between substituted phthalo- and naphthalonitriles the 2:2…
HRTEM observations require ultra-thinned specimens and, due to the very small thick- ness (1 to 30 nm), an elastic stress relaxation may occur near the free surfaces of strained heterostruc- tures. These relaxation phenomena can modify the structural features of the thinned specimens with respect to the bulk materials…
A simple titrimetric method for the rapid determination of free nitric acid concentration and total acidity in process samples of zirconium nitrate is described. This paper also details a theoretical method of deducing the zirconium oxide content of these samples based on the free and total acidity values. Sodium fluo…
To evaluate the potential benefits of strontium treatment of steel compared to calcium, steel-clad wires of calcium-silicon, calcium and strontium were fabricated. Lengths of these wires were injected to 35 kg heats of AISI 1045 steel. Samples for total calcium or strontium, oxygen, sulphur, and aluminum were taken as…
Kinetics of enthalpy relaxation upon physical aging was examined for both amorphous, isotropic poly (ethylene terephthalate)(PET) and semi-crystalline, anisotropic PET samples below their glass transition temperature (Tg). After isothermal aging a DSC endothermic peak was observed near Tg and its shape, size and posit…
Effects of water, anions, and dissolved oxygen content in methanol solutions on the corrosion of iron have been examined by immersion corrosion and electrochemical polarization tests. The corrosion of iron in methanol solutions was controlled by passivation behavior of iron. The passivity of iron was stabilized by wat…
, ew issues are getting -e atten- nology include fluids and greases, Some silicones are supplied as neat F tion from textile x-facturers and emulsions, rubber products and resins. fluids, while others are in the form of suppliers today than the m-kxun- Silicones find application in many emulsions or room temperature c…
A novel technique is presented which allows the experimental determination of the emission cross-section spectrum of the pump transition of praseodymium in ZBLAN glass. The technique is based on measuring the population density of the upper level as a function of pump power as well as wavelength. The emission and abso…
The design, analysis and testing of composite-to-metal joints for the ARPA Man-Rated Demonstration Article are discussed. The first is a composite-to-titanium sphere joint designed to react sphere membrane stress with block compression loading. A series of uniaxial compression tests to simulate this joint assembly was…
ZrO2-MgO-Al2O3 powder composites were prepared by calcining gelled mixtures of Mg(OH)2, Zr-n-butoxide and Al-sec-butoxide (or Al2O3) at 1000°C for 2h. The calcined powder was cold isostatic pressed at 200MPa and sintered at 1500 to 1650°C for 1h. Fine and homogeneous tetragonal-ZrO2 grains were dispersed in the sinter…
Beta-Si3N4 powder made by the imide-decomposition method was gas-pressure sintered at 1800°C for 4h in 1MPa N2 gas. This material had a microstructure of “in-situ composite” and excellent mechanical properties (strength: 780MPa, fracture toughness: 7.5MPa·m1/2), whereas β-Si3N4 powder made by the silicon nitridation m…
Mullite/zirconia composite materials were characterized in terms of electrical conductivities, structure and microstructure. It was found that the conductivity assumes a minimum at about 10mass% ZrO2. The highest conductivity was observed in the range of 60-100mass% ZrO2. XRD studies have revealed that the tetragonal…
Scanning electron microscopy (SEM) was used to investigated the effects of volatile solvents (such as water, propanone, ethanol, methanol or ethyl ether), treatment and drying processes, microwave ovens, drying ovens, and vacuum desiccators or freeze driers, on silica morphology. Silica gel was obtained from diluted s…
Experimental results on the platelet adhesion, and CHO cell adhesion and growth onto nonionic surfactant which is composed of a long alkyl chain (n = 12-18) as the hydrophobic part, and a polyethyleneoxide (PEO) segment (n = 10-23) as the hydrophilic part coated and air-plasma treated PSf surfaces are presented in ter…
Microstructures and magnetic properties of the Nd-Fe-B magnets sintered by adding Dy compound powder are examined. The Nd15Fe77B8 powders are mixed with Dy40Al30Cu30 compound powders and then sintered, followed by an appropriate heat treatment. It is found by EPMA analysis that the R2Fe14B main phase is composed of a…