Synthesis of nano-crystalline alumina powder by a chemical pyrophoric reaction using citric acid and ammonia was investigated by varying the pH of the precursor solution, which played an important role in controlling the morphology of the synthesised powder. The flaky morphology obtained at pH = 2 could be modified to fine desegregated particulate form by varying the pH of the solution to 10. T...

In this paper, a wax-based binder was developed for low-pressure injection molding of very fine (0,4 μm) average particle size alumina ceramic bodies. The major component used in the binder mixture was paraffin wax. The process of binder removal from the green ceramics presented several difficulties especially when the ceramic powder was very fine, and the pieces had large cross-section. The pr...

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...

Rheology of powder suspensions is a key factor in many processing routes, and better understanding of the parameters that control the rheology improves technical progress by reducing the empirical factors in the formulation of powder slurries. The strict requirements for the production of transparent polycrystalline alumina demand a fundamental understanding of powder handling and processing st...

Due to their limited length of structural coherence nanocrystalline materials show very diffuse powder X-ray diffraction patterns that are difficult to interpret unambiguously. We demonstrate that a combination of high-energy X-ray powder diffraction and atomic pair distribution function analysis can be used to both assess the geometry (i.e., size and shape) and determine the internal atomic or...

Spray drying is widely used for producing granulated feed materials for compaction process, which is the current industrial method for manufacturing alumina-zirconia femoral heads. The optimization of the granules compaction behavior requires the control of the slurry rheology. Moreover, for a dual-phase ceramic suspension, the even phase distribution has to be kept through the atomization step...

It is known that work pieces with nanocrystalline structure condition have much higher performance than those with an ordinary structure. There are known number of techniques for manufacturing of nanocrystalline materials in powder condition however a question of manufacturing bulk pieces in the same nanocrystalline state mentioned is that compaction and synthesizing of nanocrystalline powders ...

The high temperature corrosion behavior of sputtered nanocrystalline K38 coating with and without yttrium addition under mixed molten salt film in air was investigated. Accelerated corrosion occurred on the coating without yttrium (Y) addition locally after 60 h exposure at 900 °C, which resulted in negative weight gain in kinetics. A uniform and protective alumina scale formed on surface of th...

Amorphous powder of composition corresponding to Ni60Ti20Zr20 (in at%) was obtained by ball milling in a high-energy mills starting from pure elements. Formation of the amorphous structure was observed already after 20 h of milling, although complete amorphization occurred after 40 h. The microhardness of powders increased from about 30 HV for pure elements to above 400 HV (1290 MPa) after 40 h...