Estudo da influencia do pH na liga NiFe e de sua propriedade por DMA.

Abstract

The alloys of the iron group (Fe) obtained by electrodeposition , have properties as: hardness, strength, high thermal stability and more corrosion resistance. Although the Ni is a metal widely used in many areas of industry, especially with its characteristics of corrosion resistance is not always possible to use it in pure state, because its high cost. Therefore, it's necessary an alloy with a less noble metal, like as iron (Fe) used in this work, so to make a NiFe alloy. The solutions used to obtain these deposits were prepared from NiSO4e FeSO4 Watts-bath. The pH of the solution was adjusted to, 4 and 5 and for this adjustment was added sodium hydroxide (NaOH). The process variables such as pH, current density and the bath composition, may affect the alloy deposition kinetics, the morphology and structure of the deposits obtained. The electrodeposited match a higher Fe content characterized as anomalous The corrosion test amid NaCl 3,0M it presents a potential more positive in the electrodeposition pH 4, as well as polarization resistance. The analyzes for MEV/EDX show that electrodeposited with pH 5 presented morphologies with cracks and grain much smaller obtained in 3 and 4, as described in the literature. By the Analysis Dynamic-Mechanical (DMA), the electrodeposition NiFe 200C presented compelling inflection.