ABSTRACT
Corrosion resistance of zinc coated sintered steel parts was studied by using electrochemical methods. A wide range of industrially produced coatings, including electroplated and hot dip zinc as well as Dacromet® and cold or hot zinc dust deposition treatments, were investigated.
Conventional corrosion tests were employed to compare corrosion resistance, whereas electrochemical test methods were used, to obtain a better understanding of the mechanisms which control corrosion processes and the corrosion rate.
The experimental results of this study showed protection of sintered steel by coatings is possible when the process is very well controlled; however, defects in the coating can always be present due to the substrate porosity, and these will be of different types and extents depending on the kind of deposition treatment employed. The proposed treatments are also discussed on the basis of some economical and technological parameters such as costs, tolerance requirements, chemical composition and density of the sintered parts.
With these facts in mind the use of sacrificial coatings can be recommended because of the possibility of cathodic protection operating at coating defects.
