CeraMat

An improved gel-casting procedure was successfully exploited to produce porous ceramic bodies having controlled porosity features in terms of mean pore size, total pore volume as well as pore geometry. The gel-casting process in which a natural gelatine for food industry is used as gelling agent was firstly set-up to prepare dense alumina and zirconia components. Then, commercial PE spheres, sieved to select proper dimensional ranges, were added to the starting slurries as pore-forming agent.

Deagglomeration of a nanocrystalline transition alumina performed using different techniques was first demonstrated to be active in the achievement of a better powder compaction ability under uniaxial pressing and consequently in the development of a highly dense and homogeneous microstructure during pressureless sintering. A major effect, however, was associated to the heating rate chosen during the densification cycle.

This article reports the study of a transition nanometric alumina both as such and after prolonged magnetic stirring in bi-distilled water. Stirring was effective in inducing a significant reduction of starting particles agglomeration and modification of the surface properties of the material. The formation of an Al(OH)3 (gibbsite) phase after magnetic stirring in water was detected by means of XRD on powdered samples. Correspondingly, Infra Red spectrum of magnetically stirred alumina outgassed at 150 °C showed a band at ca.

Here we report how thermal treatments of a surface modified α-alumina powder on which a zirconium oxide precursor was grafted can be tailored so as to obtain an alumina-zirconia composite powder with well-controlled phase distribution and size.

Fluorine-substituted hydroxyapatites are considered promising materials for bone scaffolding. In this study a systematic investigation on F-half substituted hydroxyapatite (F-HAp, Ca10(PO4)6OHF) obtained by precipitation is reported. Results on composition analysis, thermal behaviour, and sinterability are presented for a comparison with the respective pure hydroxyapatite. Samples were characterised by electron microscopy, induced coupled plasma-atomic emission spectroscopy, thermal analysis, infrared spectroscopy, N2 adsorption measurements, X-ray diffraction and dilatometry.

An ultra-fine alumina powder was doped with yttrium or zirconium chloride to produce Al2O3–5 vol.%ZrO2 (AZ-5) and Al2O3–5 vol.%YAG (AY-5) composite powders. Composite samples and pure alumina, used as a reference, were submitted to dilatometric analyses up to 1500–1550 °C at 2, 5 and 10 °C/min for supplying the data required for the modeling of their sintering behaviour. The best fit for the three samples was obtained by applying an Avrami–Erofeev nucleation and growth model (An) and a subsequent power law reaction (AnFn).

This paper deals with the development of macro-porous components made of a carbonated hydroxyapatite (HAp) nanopowder which was extracted from pig bones. Prior to sintering, the powder was treated at 700 °C for 1 h. During calcination, a partial carbonate decomposition occurred yielding CaO. In order to eliminate this by-product, the calcined HAp was washed in distilled water several times, checking the effect of washings by FT-IR spectroscopy.