2008

The correlation between the evaluation of the mechanical and of the fatigue behaviour of the rheocast, T5 and T6 heat treated SSM A356 aluminium alloy with respect to the microstructures of the component has been investigated. The study has been carried out on a suspension arm injected in a rheocasting 800 tons plant in Stampal S.p.A. The new rheocasting is a process that allows obtaining the alloys in a semisolid state directly from the liquid state, by controlled cooling of the molten alloys.

The investigation of the performance of small single PEMFC was carried out by employing a purposely designed test bench with complete control of the operational parameters. A MEA preparation method was also developed constituting the base for testing new electrocatalytic materials or improved electrode assembling techniques. Beyond determining the polarization curves, other tests have been carried out like electrical resistance measurement by the current interruption method and voltammetric characterization.

Ordered mesoporous carbon (OMC)was used as catalyst (Pt) support in polymer electrolyte membrane fuel cells (PEMFC) with the aim of increasing its effectiveness towards the oxygen reduction reaction (ORR). The mesoporous carbon (CMK3 type) was synthesized as inverse replica of a silica template (SBA-15). Platinization was achieved by impregnation with chloroplatinic acid hexahydrate, H 2PtCl 6, followed by a reduction in H 2 flow at 573K. Samples containing 20wt% in Pt were prepared and characterized by ICP, XRD and HRTEM analysis.

Platinum catalysts supported on ordered mesoporous carbons (OMC) are described. The mesoporous carbon support, CMK3 type, was synthesised as an inverse replica of a SBA-15 silica template. The platinum catalysts (i.e. Pt 20 wt% and Pt 10 wt%, respectively), obtained through a conventional wet impregnation method, have been investigated to determine their structural characteristics and electrochemical behaviour.

The effect of forming method (cold isostatic pressing and slip casting) on particle packing and the consequent effects on densification, phase transformation and microstructural evolution were evaluated during sintering of a transition alumina powder (Nanotek®, particle size of 47nm,delta and gamma phases). It is well known that the transformation of transition alumina towards the stable alpha phase has a critical influence on the sintering behaviour.

A basic and a modified AISI H11 steels were selected for the research. Impact toughness and microstructure in the quenched and tempered state were analysed. Cyclic immersions in molten aluminium with the aim of simulating the washout, typical of aluminium die casting tools, were applied. Optical and electronic microscopy analysis were used to evaluate damages provided by washout on the specimen surface. XRD measurements were applied to identify the corrosion and soldering products deposited on the steel surface.