Zincand silver-doped mullite ceramic discs were prepared and tested as potentially resistant materials against bacterial adhesion and biofilm formation. Elemental analysis and X-ray diffraction studies showed that zinc ions were incorporated in the structural framework of the mullite, while silver ions remained outside the mullite crystal lattice, which allowed their slow (0.02 ppm/24 hours) le...

The high temperature treatment of kaolinite-muscovite alternate layers doped by bismuth oxide was studied by TGA and DTA, X ray diffraction, and electron microscopy (SEM). Thermal analyses shows that the two main transformation stages are the dehydroxylation of phyllosilicates and the structural reorganization of the whole assembly. During dehydroxylation, a progressive decrease of the structur...

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...

Whiteware compositions prepared using Pugu kaolin and industrial grade quartz and feldspar were studied with respect to varying sintering temperatures. The strength developed was correlated to mullite (3Al2O3.2SiO2) content and the microstructure. It was observed that within the vitrification temperature range, the strength mainly depended on the mullite content and the bulk density. Above the ...

Mullite fibers with diameters from 400 nm to 10 lm were fabricated from the sol–gel precursors using the electrospinning method. During the precursor synthesis, the hydrolysis was controlled to obtain highly viscous mullite sols. The viscous mullite sols were then diluted and mixed with a small amount of polyethylene oxide. Controlling the precursor rheology and spinning conditions, we obtained...

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...

Cracks free mullite-alumina Functionally Gradient Ceramics (FGC) have been obtained by sequential slip casting of Mullite-alumina slurries with diserent mullite/alumina ratios. These slurries were prepared with 65 % solids content and viscosities rangingpom 10 to 40 mPa.s. 7he presence of cracks perpendicular to the FGC layers have been attributed to residual stresses developed because of the m...

Kaolin particles are usually ̄aky in shape. In the present study, kaolin powder compacts were prepared by applying the diepressing technique. The kaolin ̄akes tend to lie down on the plane which is perpendicular to the die-pressing direction. The powder compact thus shows anisotropic shrinkage after ®ring. A series of phase transformations take place as the kaolin is ®red at elevated temperatur...

n air plasma spray process has been used to deposit tri-layer environmental barrier coatings consisting of a silicon bond coat, a mullite interiffusion barrier, and a Yb2SiO5 top coat on SiC substrates. Solidified droplets in as-deposited Yb2SiO5 and mullite layers were discovered to be epleted in silicon. This led to the formation of an Yb2SiO5 + Yb2O3 two-phase top coat and 2:1 mullite (2Al2O...

In this communication, high-strength mullite ceramics was prepared from bauxite and high-aluminum fly ash that is a by-product of coal combustion in thermal power plants. The effects of the doping V(2)O(5) on the bulk density, apparent porosity, bending strength and microstructure of mullite ceramics were studied in detail. It was indicated that 5-10 mol% V(2)O(5) reduced the sintering temperat...