Replacing high-strength frictional materials with lightweight composite alternatives is currently a global challenge for researchers. In this work, aluminum alloy (AA2900)-based metal-matrix composites reinforced 6 wt.% α-alumina were fabricated then subjected to T6 heat treatment followed by case hardening. The resulting samples exhibited improved hardness, strength behavior, and stress–strain...

The heating of porous dielectrics, beef–air (b/a) and beef–oil (b/o), attached with ceramic, metallic or ceramic–metallic composite supports, has been studied analytically using microwaves. Three test porosities were considered, 0.3, 0.45 and 0.6. A preliminary understanding of enhanced heating and power absorption within the material was obtained from the average power vs slab depth plots. The...

We compared results for the liquid-chromatographic determination of free norepinephrine and epinephrine in urine after purifying the catechols by the following methods: (a) acid-washed alumina, (b) weak cation-exchange resin (WCX), (c) a combination of weak cation-exchange resin followed by alumina (WCX-alumina), and (d) commercially available phenylboronic acid adsorbent. We evaluated analytic...

The stability and electronic properties of carbon in α-Al2O3 are investigated using density functional theory. In the host lattice, the substitutional C prefers the Al site under the O-rich conditions, whereas the O site is preferred by carbon under the Al-rich conditions. The calculated results predict a direct relationship between the thermodynamic and optical transition levels with the degre...

A major obstacle to using superconducting quantum interference devices (SQUIDs) as qubits is flux noise. We propose that the heretofore mysterious spins producing flux noise could be O_{2} molecules adsorbed on the surface. Using density functional theory calculations, we find that an O_{2} molecule adsorbed on an α-alumina surface has a magnetic moment of ~1.8 μ_{B}. The spin is oriented perpe...

In the present work, Al2O3-CeO2 composite nanopowders were synthesized via co-precipitation method. The sinterability of the synthesized powders was investigated. The results showed that the transformation of transition phases of alumina to α-Al2O3 takes place at 1200 °C. TEM images showed that the powders was composed of nanoparticles in the range of 30−70 nm. The densification of composites s...

Cell adhesion, migration, and proliferation are significantly affected by the surface topography of the substrates on which the cells are cultured. Alumina is one of the most popular implant materials used in orthopedics, but few data are available concerning the cellular responses of mesenchymal stem cells (MSCs) grown on nanoporous structures. MSCs were cultured on smooth alumina substrates a...

Catalysts based on zirconia and alumina-supported tungsten oxides (3–18 wt% W) with a small loading of platinum (0.3 Pt) were selected to study the influence W loading, support type, preparation methods hydroisomerization n-dodecane. The alumina- zirconia-supported catalysts show different catalytic properties that play an important role in n-dodecane conversion. Specific surface area acidity a...