PetroMat

Varallo Sacred Mountain was realized at the end of the fifteenth century on initiative of the Franciscan Father Bernardino Caimi as a place of prayer, meditation and evocation of the Christian faith and has been included in the UNESCO World Heritage List since 2003. Some of its buildings show at the moment manifold maintenance, conservation and restoration problems. Therefore, in the frame of a detailed program of interventions, a research cooperation has been launched, aiming at singling out the existent materials and, as much as possible, their working techniques.

Composite and nanocomposite ceramics have achieved special interest in recent years when used for biomedical applications. They have demonstrated, in some cases, increased performance, reliability, and stability in vivo, with respect to pure monolithic ceramics. Current research aims at developing new compositions and architectures to further increase their properties. However, the ability to tailor the microstructure requires the careful control of all steps of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering.

In order to develop ceria-stabilized zirconia (Ce-TZP) ceramics suitable for biomedical applications, composite materials should be developed. In this work, three different Ce-TZP-based composites were prepared by adding rounded α-Al2O3 grains and two kinds of elongated particles, SrAl12O19 and CeMgAl11O19. Composite powders were prepared through a surface coating route, which allowed a precise tailoring of chemical and phase composition as revealed by HRTEM. A limited cerium diffusion inside zirconia grains was revealed when CeMgAl11O19 was added to zirconia matrix.

In order to fulfill the clinical requirements for strong, tough and stable ceramics used in dental applications, we designed and developed innovative zirconia-based composites, in which equiaxial α-Al2O3 and elongated SrAl12O19 phases are dispersed in a ceria-stabilized zirconia matrix. The composite powders were prepared by an innovative surface coating route, in which commercial zirconia powders were coated by inorganic precursors of the second phases, which crystallize on the zirconia particles surface under proper thermal treatment.

Hydroxyapatite (HA) nanopowders were synthesised following two different precipitation routes: (a) from calcium nitrate and diammonium hydrogen phosphate solutions and (b) from calcium hydroxide suspension and phosphoric acid solution.

Synthetic hydroxyapatites incorporating small amounts of Si have shown improved biological performances in terms of enhanced bone apposition, bone in-growth and cell-mediated degradation. This paper reports a systematic investigation on Si-substituted hydroxyapatite (Si 1.40 wt%) nanopowders produced following two different conventional wet methodologies: (a) precipitation of Ca(NO3)2.4H2O and (b) titration of Ca(OH)2. The influence of the synthesis process on composition, thermal behaviour and sinterability of the resulting nanopowders is studied.

This paper reports a systematic investigation on Mg-substituted hydroxyapatite (Ca10−xMgx(PO4)6(OH)2) nanopowders produced by precipitation of Ca(NO3)2·4H2O and Mg(NO3)2. The Mg content ranged between 0.6 and 2.4 wt%. Semicrystalline Mg-substituted hydroxyapatite powders made up of needle-like nanoparticles were obtained, the specific surface area ranged between 87 and 142 m2/g. Pure hydroxyapatite nanopowder decomposed around 1000 °C.

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.

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.