A mullite/mullite nanocomposite powder has been synthesized, composed of nanometer-size 3Al2O3 · 2SiO2 (‘3 : 2’) mullite precipitates within a matrix of the high alumina 2Al2O3 · SiO2 (‘2 : 1’) mullite. Historically, the transition from the metastable high-alumina phase to the thermodynamically stable ‘3 : 2’ phase of mullite has been thought to be a continuous process, involving a continuous s...

carbon nanotubes were synthesized over a series of zn-containing fe/alumina catalysts by chemical vapor deposition method at two reaction temperatures of 850 and 950 °c using methane as a carbon source. catalysts were synthesized by keeping fe concentration constant and varying zn concentration to study the effects of zn. the catalysts were characterized using x – ray powder diffraction and n2 ...

in this research, the high-energy planetary mill was employed to produce nanocrystalline ti-50al(γ)(at%) powders. initial powders were mechanically alloyed in 99.9999% and 90% purities of argon and also air atmosphere with alloying times up to 50h. the effect of impurity of argon atmosphere on the microstructure and the rate of phase transformation of ti-50al were investigated during mechanical...

The synthesis of NiO nanoparticles was done by sol-gel method. Nickel Acetate Tetrahydrate ((CH3COO)2 –Ni·4H2O) was dissolved in ethanol with constant stirring to obtain a clear and light greenish sol. Oxalic acid solution was used to obtain a thick green gel, then dried in an oven to get dried gel and was then grinded into fine powders and calcined for different time periods to obtain nanocrys...

Plastic deformation of nanocrystalline Fe was investigated by nanoindentation. Samples, synthesized by mechanical attrition, consisted of powder particles with diameters greater than 30 mm. The average grain diameters within the particles of different samples ranged from 10 nm to 10 mm. To avoid potential artifacts, samples were prepared without use of heat treatment, and measurements were cond...

It has recently been reported that in the Y203-stabilized tetragonal zirconia phase (TZP) system the addition of a small amount of transition-metal oxides (e.g. CuO, MnO and ZnO) which form a liquid or amorphous grain boundary phase significantly enhances superplasticity [1, 2]. In CuO-added 2Y-TZP abrupt changes have been found in the stress exponent and activation energy across the melting te...

Low-dimensional cuprous nitride (Cu3N) was synthesized by nitridation (ammonolysis) of cuprous oxide (Cu2O) nanocrystals using either ammonia (NH3) or urea (H2NCONH2) as the nitrogen source. The resulting nanocrystalline Cu3N spontaneously decomposes to nanocrystalline CuO in the presence of both water and oxygen from air at room temperature. Ammonia was produced in 60% chemical yield during Cu...

New porous biomaterials based on hydroxyapatite (HAp) were designed as obturation materials for dental cavities. Synthetic HAp powder with a particle diameter of 150 m was agglutinated using three different polyurethane monocomponents (rigid, semi-rigid, and flexible), enabling the matching of their properties to those of real teeth. Alumina particles were also added in some cases. Our new hybr...

On the basis of the affinity of alumina towards hydroxyl functional groups, a solid phase microextraction (SPME) fiber was constructed using alumina powder and poly(vinyl chloride) (PVC). Different compositions were tested and alumina:PVC (97:3) was selected as an optimun composition. A piece of silver wire was used as fiber support. The fiber producing was simple and could be completed in a fe...

OBJECTIVES The aim of the present study was to test cutting efficiency of different materials against conventional alumina in an air abrasion system. MATERIALS AND METHODS The powder samples were divided into three groups: Group 1 - alumina (control), Group 2 - 45S5 bioactive glass, and Group 3 - hydroxyapatite. 30 microscope glass slides of 0.5 mm thickness were used as an alternative of hum...