Mechanochemical synthesis of hydroxyapatite using cuttlefish bone and chicken eggshell as calcium precursors.

This work explores the possibility of synthesising hydroxyapatite via mechanochemical route using biogenic calcium carbonate sources, namely calcite in chicken eggshell and aragonite in cuttlebone. The calcium source and orthophosphoric acid in ratio complying with Ca/P = 1.67 were submitted to high-energy ball milling with transferred energy values in the 1.

Microstructural changes in copper-graphite-alumina nanocomposites produced by mechanical alloying.

Microstructural features of nanostructured copper-matrix composites produced via high-energy milling were studied. Copper-graphite-alumina batches were planetary ball milled up to 16 h; copper-graphite batches were also prepared under the same conditions to evaluate the effect of contamination from the milling media. The microstructure of the produced materials was characterized by field emission gun scanning electron microscopy/energy-dispersive spectroscopy and related to Raman, X-ray diffraction, and particle size analysis results.

Microstructural characterization of concrete prepared with recycled aggregates.

Several authors have reported the workability, mechanical properties, and durability of concrete produced with construction waste replacing the natural aggregate. However, a systematic microstructural characterization of recycled aggregate concrete has not been reported. This work studies the use of fine recycled aggregate to replace fine natural aggregate in the production of concrete and reports the resulting microstructures.

A study on the aqueous dispersion mechanism of CuO powders using Tiron.

Tiron is an anionic surface active agent, known to render extremely efficient results in the dispersion of metallic oxides such as Al(2)O(3), ZrO(2) and TiO(2). Its dispersion mechanism upon these oxides outcomes from efficient complexation of the corresponding metallic cation, leading to chemisorption of the dispersant molecule upon the oxide surface. In the present work, the effect of Tiron on the stabilization of CuO particles in aqueous suspension is studied to clarify the dispersant's role in the change of colloidal properties and its underlying stabilization mechanism, and also to quantify processing conditions for the oxide.