dc.description.abstract | Lead hardened through oxide scattering is investigated as raw materials for the
fabrication of the support gratings of lead accumulators in order to increase their
life service. For the preparation of lead powder hardened through oxide scattering
we used air jet pulverisation, a technique specific to powder metallurgy. Two
research approaches are presented in the paper: one in which the oxide was
introduced through oxidised lead powder, and the other in which additional lead
oxide was introduced. Oxide dispersion into metallic matrix was achieved by
pronounced deformation through extrusion of the powder. During extrusion, the
particles are compelled to pass through the mould calibration zone and
consequently they are considerably deformed. As an effect of this deformation, the
particles of fragile oxide which cover the lead powder particles are crashed and
carried away to the material flowing through the matrix longitudinally on the
extruded semi-product. The content of oxide introduced in matrix by the oxidised
lead powder depends on the powder particle size. This paper presents the effect of
the powder particle size and oxide phase dispersion in the metallic matrix on the
mechanical, chemical and electrical properties of the extruded semi-products. The
semi-products made from lead powder belonging to the grain size class of < 40 μm
and oxide particles allowance have the highest mechanical resistance and the best
corrosion behaviour. Using controlled oxidised lead powder better extruded semiproducts
are obtained in terms of mechanical resistance, corrosion behaviour and
electrical conductivity as compared with lead and Pb-Sb alloy. A higher electrical
conductivity represents an important advantage especially for the starting
accumulators where the voltage fall should be as low as possible. | ro_RO |