NOVEL TYPE OF GRADIENT-DISTRIBUTED WIRE BEAM ELECTRODE MEASURED IN 3.5 wt.% NaCl AND ITS APPLICATION IN FAST DETECTION TECHNIQUE

In this paper, the electrochemical performance of a novel gradient-distributed wire beam electrode (WBE) is measured in different corrosion medium. This electrode contains three kinds of carbon steel with different carbon content. WBE was consisted of 100 carbon steel wires and regularly prepared into a 10×10 matrix. The carbon steel wires for each row is the same, but the adjacent rows are different. The electrochemical corrosion behavior of regions with different carbon steel wires can be tested clearly. The results revealed that the heterogeneity of local corrosion of metal, which can be well studied by WBE, meanwhile, the phenomenon of polarity reversal can also be detected. Corrosion potential–current distribution map of the novel WBE showed obvious striped features when immersed in 3.5wt.% NaCl solution with different pH (pH=2, 6 and 12). Corrosion firstly occurred in the high carbon steel region in the acidic conditions, and then quickly spreads to other areas, eventually causing the entire surface of the WBE to be corroded. While in the neutral salt solution, only the regions of high carbon steel and some part of medium carbon steel area appeared obvious anode currents during a long time testing. When the pH of corrosive solution reached to 12, the corrosion rate is greatly reduced and then corrosion process is suppressed. This new method can evaluate the corrosion resistance of materials more accurately.