2007

In aeronautic field there is always a continuous research, implementation and application of more and more advanced technologies. This leads to the adoption of lasers in the aluminium sheets cutting to create plane external structures as an alternative at the more consolidate mechanical cutting techniques such as the use of punching machines.

This paper presents corrosion resistance results in salt fog spray test of duplex stainless steels obtained through powder metallurgy starting from austenitic X2CrNiMo 17-12-2, martensitic X6Cr13 powders by controlled addition of alloying elements in the right quantity to obtain the chemical composition of the structure similar to biphasic one. In the preparations of mixtures the Schaffler's diagram was taken into consideration. The prepared mixtures of powders have been sintered in a vacuum furnace with argon backfilling.

In the present work, a new humidity sensor based on nanostructured hematite deposited by a wet chemical route on a low-cost natural inorganic phylosilicate (sepiolite) powder was obtained. The nanometric character of these particles has been evaluated by X-ray diffraction, thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) and transmission electron microscopy.

A screen-printed thick film was developed to be overlapped to a gas sensing device for preserving it from contamination and degradation occurring in hostile environments, and also for improving its selectivity to a single pollutant gas when exposed to a complex atmosphere. This protective layer incorporated Al2O3 doped with Cs or Ba oxides as a catalyst material for eliminating gaseous interfering species, precisely CO2, to improve sensor response to CO.

The preparation of pure Y3Al5O12 (YAG) and 50 vol% Al2O3–YAG composite powders by a wet chemical route is presented. The role of the synthesis temperature during reverse-strike precipitation has been investigated, showing its relevant effect on the purity and homogeneity of YAG powder. The composite material was prepared by comparing two different synthesis routes. A composite powder was synthesized via reverse-strike temperature-controlled co-precipitation. In the latter case, a pure-alumina precursor was firstly reverse-strike precipitated and then doped with an yttrium salt solution.