MARQUES, A. M.; http://lattes.cnpq.br/1967336098510989; MARQUES, Alex Messias.
Resumo:
The amorphous alloys of tungsten with iron group metals, obtained by
electrodeposition have attracted increasing interest in recent years in view of its
excellent properties for technological applications such as magnetic properties,
mechanical properties, wear resistance and corrosion, among other. These
properties are mainly related to composition and chemical homogeneity and the
absence of defects associated with the crystalline state. Several authors have
highlighted that these materials are potentially one of the most promising to replace
the conventional hard chromium coatings, which for decades has distinguished itself
worldwide as one of the most used because of its high hardness (greater than 800
Hv) and corrosion protection. The attainment of these alloys can be made by different
techniques. However, electrodeposition has been one of the most used because it
allows obtaining high-purity chemical deposits with different compositions and
thicknesses and allows also take different types of substrates, having various
geometric shapes. In general, these systems retain some unusual properties of
tungsten, such as high corrosion resistance, hardness, low coefficient of expansion
and high thermal conductivity, and resist any attack by mineral acid at room
temperature. Most of the quotes on this subject are related to adjustments of
electrolytes and operational parameters for obtaining good quality alloy in optimized
conditions, leaving gaps in relation to obtaining those under industrial conditions. In
general, the experiments are restricted to areas with small electrodes to be coated
and electroplated made under very refined compared to the control of acquisition
parameters. This is a practical limitation for use of these materials. In this study, we
sought to obtain Ni-W-P alloys in a Hull cell on 1010 steel substrate from an
electrolyte composition already established in the literature. Were made to the
physical and chemical characterizations of the alloys investigated the effects of wide
variation in current density on the chemical composition, surface morphology,
corrosion resistance and hardness of the same.