Corrosion study of a water filter

Abstract

A water filter was inspected in order to determine the origin and chemical nature of several corrosion products on its surface. The metallic material base was analyzed to be a lead brass with a nickel coating of 4–5 µm thickness.

The plastic base, as well as the rod and nut, was impregnated by similar deposits whose chemical nature was mainly oxides, carbonates and chlorides, according to the EDX analysis. Some white deposits were observed in the nut and rod, probably corresponding to zinc oxide. These deposits may be formed upstream by the pipe materials or the sediments that the fluid may carried inside the pipe.

The absence of a nickel coating leaded to corrosion pits in some areas of the rod and nut. This corrosion has initiated on the surface, and has progressed through the beta phase that was zinc impoverished, to the inner zone of the filter.