Corrosion of Spheroidal Graphite Cast Iron with Different Boundary Length Between Graphite Nodule and Matrix in Sulfuric Acid Aqueous Solution

Abstract

In order to evaluate the influence of boundar y length(BL)between graphite nodule and matrix on the corrosion rate of spheroidal graphite cast iron, the corrosion test was performed in a sulfuric acid solution at pH 2. The presence of graphite nodule was considered to influence the corrosion at the boundary between matrix and graphite nodule. The contiguous length between graphite nodule and matrix per unit area was defined as BL. The corrosion potential and rate were measured. The surface morphology of the specimens was observed. Anodic dissolution of the matrix in the vicinity of the graphite nodules took place preferentially. As a result, the graphite nodules were detached from the matrix. The graphite nodules worked as cathode. However, no influence of BL on corrosion rate was seen.

Tribological Behavior of Cast Iron in Ethanol with and without Oleic Acid

“…In the ethanol solution, oleic acid acts as an electrolyte as well as an oiliness agent. A local cell, where iron metal acts as an anode and graphite acts as a cathode, is formed on the surface of the cast iron disk [5,11,21]. Galvanic corrosion between iron and graphite then occurs on the cast iron disk.…”

“…The carbon content of cast iron is higher than that of steel, and graphite is crystallized in the iron base in a cast iron structure. The cast iron tends to form local cells where iron metal acts as an anode and graphite acts as a cathode [11]. Therefore, cast iron may be more sensitive to the electrolyte action of a long-chain carboxylic acid than steel.…”