Inhibition Effects of Pyrazine and Piperazine on the Corrosion of Mg-10Gd-3Y-0.5Zr Alloy in an Ethylene Glycol Solution

Daobing Huang,Yuanqiang Tu,Xingpeng Guo,Guangling Song

doi:10.4236/ajac.2013.46a005

Daobing Huang, Yuanqiang Tu + Show 2 more

Open Access

https://doi.org/10.4236/ajac.2013.46a005

Copy DOI

Abstract

The corrosion and inhibition effect of magnesium-based rare-earth containing alloy Mg-10Gd-3Y-0.5Zr (GW103) was studied in an ethylene glycol (EG) solution mixed with organic inhibitors. The inhibition efficiencies of piperazine and pyrazine inhibitors on the corrosion of GW103 were compared by means of potentiodynamic polarization curve, electrochemical impedance spectroscopy (EIS) and weight loss measurements. It was found that the corrosion process of GW103 alloy in EG solution was hindered by these two inhibitors and the inhibition of pyrazine was more effective than that of piperazine. It was implied that pyrazine could be an effective inhibitor for GW103 in an ethylene glycol coolant solution.

Highlights

Magnesium alloys as structural materials is being seriously considered in the auto industry due to their high strength/weight ratios which are critical to aircrafts and vehicles [1]
The higher frequency capacitive loop could be assigned to the capacitance and resistance of the film on the alloy surface, while low frequency capacitive loop should be related to the corrosion process of the substrate Mg alloy exposed to the solution in the film pores
It is shown that the addition of piperazine and pyrazine to the ethylene glycol solution improves the corrosion resistance of the magnesium alloy, which is in accordance with the results of the polarization curves

Summary

Introduction

Magnesium alloys as structural materials is being seriously considered in the auto industry due to their high strength/weight ratios which are critical to aircrafts and vehicles [1]. There is very limited information published on the corrosivity of ethylene glycol, the major constituent of a coolant, and the magnesium. Recently we find [5] that many organic chemicals can have an inhibition effect on Mg-10Gd-3Y-0.5Zr (GW103), a promising engine block Mg alloy. Encouraged by these promising findings, in this study we continue the search for more suitable organic inhibitors for the Mg alloy in the ethylene glycol solution

Sample and Solution Preparation

Electrochemical Measurements

Immersion Test

Inhibition Effect of Organic Piperazine and Pyrazine

Weight Loss Measurements

Conclusions