Microsilica, or silica fume, is an amorphous type of silica mostly collected as byproduct of the silicon and ferrosilicon alloy production. In this work, low shrinkage alumina-mullite ceramic composites were prepared from mixtures of calcined alumina, silica fume and aluminum metal powder and sintered at 1550 o C for 2 hrs. The influence of silica fume and aluminum powder on the densification p...

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...

In-situ alumina-zirconia composite bodies were fabricated by heat treatment of gibbsite-zircon-kaolinite mixture at 1450℃. The current research investigated crystallization behavior and mechanical properties of the mentioned mixture in the presence of 5 wt.% MgO as an additive. X-ray diffraction (XRD) results showed that alumina, zirconia, and magnesium aluminosilicate were crystallized during ...

Homogeneous distribution of mullite in the matrix of alumina can be obtained through sol-gel method. In this work, nanopowder of alumina-mullite composite was synthesized with high homogeneity and high purity. So aluminum chloride hexahydrate and tetraethyl orthosilicate were used instead of alumina or mullite nanopowder. Studying the simultaneouse thermal analysis (STA) of mullite precursor re...

Recent studies have shown that the mullitization of diphasic aluminosilicate matrices comprising transitional alumina and amorphous silica occurs via a nucleation and growth process. Nucleation is preceded by a temperature-dependent incubation period. Following this incubation period, rapid nucleation of mullite occurs, producing about 1.8 X 10" nuclei/cm3, which remains constant throughout the...

Mono-phase bio-ceramics (alumina and zirconia) are widely used as femoral heads in total hip replacements (THR) as an alternative to metal devices. Unfortunately, the orthopaedic community reports significant in-vivo failures. Material scientists are already familiar with composites like alumina zirconia. Since both are biocompatible, this could prove to be a new approach to implants. This pape...

BACKGROUND Zirconia was introduced as an alternative to alumina for use in the femoral head. The yttria stabilized zirconia material was improved by adding alumina. We evaluated highly cross-linked polyethylene wear performance of zirconia in total hip arthroplasty. The hypothesis was that alumina stabilized zirconia could decrease highly cross-linked polyethylene wear. METHODS Highly cross-l...

A continuum theory for non-Newtonian flow of a two-phase composite containing rigid inclusions is presented. I t predicts flow suppression by a factor of (1 V)p, where V is the volume fraction of the rigid inclusion and q depends on the stress exponent and the inclusion shape. Stress concentrations in the rigid inclusion have also been evaluated. As the stress exponent increases, flow suppressi...